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Made available in DSpace on 2022-04-29T08:45:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Dental composites are aesthetic materials widely used in Dentistry for replacing hard dental tissues lost due to caries or traumas. The aim of this study was to fabricate low-shrinkage dental composite charged with nanoclay fillers (montmorillonite Cloisite®—MMT) and evaluate their cytotoxicity and physicomechanical properties. Four dental composites were produced from the same organic matrix: Bis-GMA/TEGDMA (30 wt.%). The filler system was constituted of BaSi, SiO2, and MMT in the following concentrations (wt.%): 93.8/6.2/0, 89.1/5.9/5, 86.7/5.8/7.5, and 84.4/5.6/10 (E0: 0; E5: 5%; E7.5: 7.5%; E10: 10% of MMT nanoclays). The following properties were tested: in vitro cytotoxicity, flexural strength, elastic modulus, volumetric shrinkage, water sorption, water solubility, and hygroscopic expansion. Scanning electron microscopy was used to characterize composites’ topography. Data were analyzed by one-way ANOVA and Tukey’s HSD post hoc test (p < 0.05). MMT nanoclays did not affect the cytotoxicity. E5 and E7.5 groups showed a significant decrease in polymerization shrinkage while maintained the overall physicomechanical properties. The inclusion of 5 and 7.5 wt.% of MMT nanoclays allowed the fabrication of dental composites with low cytotoxicity and low polymerization shrinkage, without jeopardizing the overall behaviour of their physicomechanical properties (flexural strength, elastic modulus, water sorption, water solubility, and hygroscopic expansion). These aspects suggest that the usage of MMT nanoclays could be an effective strategy to formulate new dental composites with clinical applicability. Department of Operative Dentistry College of Dentistry Oklahoma University Analytical Laboratory of Restorative Biomaterials-LABiom-R Faculdade de Odontologia Universidade Federal Fluminense, Niterói Department of Dental Materials and Prosthodontics School of Dentistry São Paulo State University-UNESP, SP Department of Operative Dentistry IOPUC, Rua Marquês de São Vicente, 389-Gávea, RJ Department of Restorative Dentistry School of Dentistry Rio de Janeiro State University Department of Dental Materials and Prosthodontics School of Dentistry São Paulo State University-UNESP, SP

Made available in DSpace on 2021-06-25T11:13:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 The aim of the present study was to investigate the effect of shrinking and no shrinking dental filling materials combination in posterior restorations under the combined effects of polymerization shrinkage and occlusal load by means of 3D Finite Elements Analysis. Six computer-generated and restored class I or class II cavities models of a lower molar were designed in the CAD software and evaluated according to the cavity and restorative procedure. Different shrinking and no shrinking adhesive materials combination with diverse Young’s modulus were considered. A food bolus was modeled on the occlusal surface replicating the chewing load using static linear analyses Polymerization shrinkage was simulated for the shrinking different restorative materials. The maximum principal stress was selected as analysis criteria. All models exhibited higher stresses along the dentine restoration interfaces with different magnitude and a similar stress trend along enamel restoration interface. Stress values up to 22 MPa and 19 MPa were recorded in the enamel and restoration, respectively. The use of elastic not shrinking material layer in combination with bulk fill composite reduced the stress magnitude in dentine and enamel to replace dental tissues. Class I and class II posterior cavities adhesively restored with shrinking filling material’s combination showed the most unfavorable stress concentrations and the multilayer technique is a promising restorative alternative in posterior adhesive restorations when deep dentin and enamel volumes are missing. School of Dentistry University of Naples Federico II, via S. Pansini 5 Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University-UNESP Fraunhofer JL IDEAS Department of Industrial Engineering University of Naples Federico II Endodontic Clinical Section School of Dentistry Department of Biomedical and Neuromotor Sciences University of Bologna-Alma Mater Studiorum School of Dentistry University of Taubaté–UNITAU, Taubaté Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University-UNESP

Made available in DSpace on 2020-12-12T02:41:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-01 PURPOSE. This study evaluated the influence of prosthesis weight and number of implants on the bone tissue microstrain. MATERIALS AND METHODS. Fifteen (15) fixed full-arch implant-supported prosthesis designs were created using a modeling software with different numbers of implants (4, 6, or 8) and prosthesis weights (10, 15, 20, 40, or 60 g). Each solid was imported to the computer aided engineering software and tetrahedral elements formed the mesh. The material properties were assigned to each solid with isotropic and homogeneous behavior. The friction coefficient was set as 0.3 between all the metallic interfaces, 0.65 for the cortical bone-implant interface, and 0.77 for the cancellous bone-implant interface. The standard earth gravity was defined along the Z-axis and the bone was fixed. The resulting equivalent strain was assumed as failure criteria. RESULTS. The prosthesis weight was related to the bone strain. The more implants installed, the less the amount of strain generated in the bone. The most critical situation was the use of a 60 g prosthesis supported by 4 implants with the largest calculated magnitude of 39.9 mm/mm, thereby suggesting that there was no group able to induce bone remodeling simply due to the prosthesis weight. CONCLUSION. Heavier prostheses under the effect of gravity force are related to more strain being generated around the implants. Installing more implants to support the prosthesis enables attenuating the effects observed in the bone. The simulated prostheses were not able to generate harmful values of peri-implant bone strain. Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) Institute of Science and Technology Department of Dentistry Faculty of Pindamonhangaba (FUNVIC) Department of Dental Materials Science Academic Centre for Dentistry Amsterdam (ACTA) The University of Amsterdam and Free University Amsterdam Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) Institute of Science and Technology

Made available in DSpace on 2022-04-29T08:31:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-01 The loss of dental structure caused by endodontic treatment is responsible for a decrease in tooth resistance, which increases susceptibility to fracture. Therefore, it is important that minimally invasive treatments be performed to preserve the dental structure and increase the resistance to fracture of endodontically treated posterior teeth. To evaluate under axial loads, using the finite element method, the stress distribution in endodontically treated molars restored with both transfixed or vertical glass fiber posts (GFP) and resin composite. An endodontically treated molar 3D-model was analyzed using finite element analyses under four different conditions, class II resin composite (G1, control model), vertical glass fiber post (G2), transfixed glass fiber posts (G3) and vertical and transfixed glass fiber posts (G4). Ideal contacts were considered between restoration/resin composite and resin composite/tooth. An axial load (300 N) was applied to the occlusal surface. The resulting tensile stresses were calculated for the enamel and dentin tissue from five different viewports (occlusal, buccal, palatal, mesial and distal views). According to the stress maps, similar stress trends were observed, regardless of the glass fiber post treatment. In addition, for the G1 model (without GFP), a high-stress magnitude can be noticed in the proximal faces of enamel (7.7 to 14 MPa) and dentin (2.1 to 3.3 MPa) tissue. The use of transfixed glass fiber post is not indicated to reduce the stresses, under axial loads, in both enamel and dentin tissue in endodontically treated molar with a class II cavity. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp), São José dos Campos Graduate Program in Dentistry Department of Dentistry University of Taubaté (UNITAU) Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp), São José dos Campos

Made available in DSpace on 2019-10-06T16:28:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-01 Increasingly more young patients have been submitted to reconstruction of the Temporomandibular Joint (TMJ), so, the prostheses must to present more functional longevity. Objective: To evaluate the effect of diamond-like carbon film (DLC)over titanium alloy (Ti6Al4V)and polyethylene (UHWPE)samples, their mechanical and chemical properties and cellular cytotoxicity. Methods: Titanium and UHWPE specimens, with 2.5 cm in diameter and 2 mm thickness were coated through plasma enhanced chemical vapor deposition (PECVD)with DLC or DLC doped with silver (DLC-Ag). Scanning electron microscopy (SEM)morphological analysis, Energy-dispersive spectroscopy (EDS)chemical analysis, scratching test, mechanical fatigue test, surface roughness analysis, and cellular cytotoxicity were performed. Data were statistically analyzed using one-way ANOVA (p < 0.05)or two-way ANOVA and multiple comparison Tukey test. Results: In the SEM analysis, morphological differences were observed on substrates after DLC deposition. The film chemically modified the substrate surfaces, according to the EDS analysis. The initial critical load failure occurred at 6.1 N for DLC and 9.7 N for the DLC-Ag film. The DLC film deposition over the polyethylene promoted a decrease in the polymer's damaged area after mechanical fatigue cycling. The cytotoxicity analysis demonstrated less biocompatibility in experimental groups, when compared to control, however, increased biocompatibility was observed, at 10 days, in all groups. Conclusion: The diamond-like carbon coating enhanced the chemical and mechanical properties from substrates, however modified biological interaction course of the titanium alloy (Ti6Al4V)and polyethylene (UHWPE)samples. Parameters for film deposition remain to be improved in order to obtain best biocompatibility. Department of Dental Materials and Prosthodontics Institute of Science and Technology of São José dos Campos São Paulo State University (UNESP) Department of Bioscience and Oral Diagnosis Institute of Science and Technology São Paulo State University - UNESP Department of Physic Technical Institute Aerospace (ITA) Department of Dental Materials and Prosthodontics Institute of Science and Technology of São José dos Campos São Paulo State University (UNESP) Department of Bioscience and Oral Diagnosis Institute of Science and Technology São Paulo State University - UNESP

Made available in DSpace on 2019-10-06T15:24:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Objective: To evaluate the fatigue failure load via staircase approach and stress distribution via FEA of different ceramic configurations arranged in multilayers composed of ceramic materials with different elastic moduli and compare them to monolayer models. Methods: CAD–CAM ceramic blocks were used to shape 0.3 mm and 1.5 mm thick discs, corresponding to: feldspathic (F), 64 GPa; lithium disilicate (L), 95 GPa; and Yttrium-partially stabilized tetragonal zirconia (Y-TZP) (Y), 209.3 GPa. The 0.3 mm discs were arranged in 4 layers cemented with resin cement (Multilink N), and the 1.5 mm discs were not treated, in such a way that the final thickness of all specimens was 1.5 mm (±0.15 mm). The following 6 groups were tested: F (F: monolithic); L (L: monolithic); LLFF (L + L + F + F); FFLL (F + F + L + L); YLFF (Y + L + F + F); YLLF (Y + L + L + F). The loads-to-fracture were obtained using the biaxial flexural strength test until failure and the data were run using one-way ANOVA and Tukey's multiple comparisons (α = 0.05) tests. The biaxial bending test was also simulated through finite element analysis (FEA) to identify the tensile stress generated at each layer of the groups. Mean fatigue failure load (100,000 cycles; 20 Hz) was determined using the staircase approach. The fracture analysis was performed by stereomicroscope and scanning electron microscopy. Results: The load to fracture (N) were obtained as follows: L (592.9 ± 73.8) D > FFLL (319.78 ± 43.59) C > YLLF (246.75 ± 24.89) B > F (167.13 ± 9.84) A > YLFF (166.51 ± 15.24) A > LLFF (165.46 ± 22.75) A ; and the fatigue failure load (N): L (310.92 ± 26.73) F > FFLL (190.17 ± 8.32) E > F (106.21 ± 2.81) D > YLLF (96.48 ± 5.73) C > YLFF (89.56 ± 2.38) B > LLFF (77.23 ± 6.33) A . The origin of all of the tested specimens was located at the tensile region of the discs, as encountered in FEA. Significance: The material under tensile stress is determinant for the restoration's strength and the adhesive interface negatively influenced the mechanical behavior of the multilayer structures. Institute of Science and Technology of São Jose dos Campos São Paulo State University (UNESP) Post-Graduation Program in Oral Science Santa Maria Federal University (UFSM) Faculty of Odontology Santa Maria Federal University (UFSM) Institute of Science and Technology of São Jose dos Campos São Paulo State University (UNESP)

Made available in DSpace on 2022-04-28T17:22:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 Different all-ceramic crown designs are available to perform indirect restoration; however, the mechanical response of each model should still be elucidated. The study aims to evaluate the stress distribution in three different zirconia crown designs using finite element analysis. Different three-dimensional molar crowns were simulated: conventional bilayer zirconia covered with porcelain, a monolithic full-contour zirconia crown, and the cutback modified zirconia crown with porcelain veneered buccal face. The models were imported to the computer-aided engineering (CAE) software. Tetrahedral elements were used to form the mesh and the mechanical properties were assumed as isotropic, linear and homogeneous materials. The contacts were considered ideal. For the static structural mechanical analysis, 100 N occlusal load was applied and the bone tissue was fixed. Maximum principal stress showed that the stress pattern was different for the three crown designs, and the traditional bilayer model showed higher stress magnitude comparing to the other models. However, grayscale stress maps showed homogeneous stress distribution for all models. The all-ceramic crown designs affect the stress distribution, and the cutback porcelain-veneered zirconia crown can be a viable alternative to adequate function and esthetic when the monolithic zirconia crown cannot be indicated. Sao Paulo State Univ, Inst Sci & Technol, Dept Dent Mat & Prosthodont, BR-12220000 Sao Jose Dos Campos, Brazil Univ Taubate UNITAU, Dept Dent, BR-12020270 Tautabe, Brazil Sao Paulo State Univ, Inst Sci & Technol, Dept Dent Mat & Prosthodont, BR-12220000 Sao Jose Dos Campos, Brazil

Made available in DSpace on 2021-06-25T11:15:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Purpose: To evaluate the effect of fibromucosa height on the stress distribution and displacement of mandibular total prostheses during posterior unilateral load, posterior bilateral load and anterior guidance using the finite element analysis (FEA). Material and methods: 3D virtual models were made to simulate the stress generated during different mandibular movements in a total prosthesis. The contacts were simulated according to the physiology, being considered perfectly bonded between cortical and medullar bones; and between cortical bone and mucosa. Non-linear frictional contact was used for the total prosthesis base and fibromucosa, allowing the prosthesis to slide over the tissue. The cortical bone base was fixed and the 100 N load was applied as unilateral load, posterior bilateral load and anterior guidance simulation. The required results were for maximum principal stress (MPa), microstrain (mm/mm) and total displacement (mm). The numerical results were converted into colorimetric maps and arranged according to corresponding scales. Results: The stress generated in all situations was directly proportional to the fibromucosa height. The maximum principal stress results demonstrated greater magnitude for anterior guidance, posterior unilateral and posterior bilateral, respectively. Only posterior unilateral load demonstrated an increase in bone microstrain, regardless of the fibromucosa height. Prosthesis displacement was lower under posterior bilateral loading. Conclusion: Posterior bilateral loading is indicated for total prosthesis because it allows lower prosthesis displacement, lower stress concentration at the base of the prosthesis and less bone microstrain. Department of Dental Materials and Prosthetics São Paulo State University (UNESP) Institute of Science and Technology São José dos Campos Dental School Department of Prosthesis and Oral-Facial Surgery Pernambuco Federal University (UFPE). Recife Department of Dental Materials and Prosthetics São Paulo State University (UNESP) Institute of Science and Technology São José dos Campos Dental School

This research describes the gene expression of molecules related to inflammation and bone metabolism in all patients submitted to dental implant surgery attended at a Brazilian institution. A convenience sample was collected over 2 years. The bone samples were processed for extraction of total RNA and reverse transcription of cDNA. Relative quantification by real-time polymerase chain reaction of target genes was performed. The sample was characterized demographically and according heath conditions. The patients were grouped. The control group was composed of 17 healthy patients, 6 patients were included in the antihypertensive therapy group, 3 were smokers, another 3 were smokers and were under antihypertensive treatment, and 3 were ex-smokers (smoked for 10 years but had quit for at least 5 years). The ex-smoker group presented the highest values, and the Hypertensive group presented the lowest values of Macrophage colony-stimulating factor, Osteonectin, Bone Morphogenetic Protein II, and Integrin. All smokers demonstrated expression values comparable to the Control group. The highest expression values of Osteopontin, RUNX, and Alkaline Phosphatase were observed in the Hypertensive and the Smoker group, while the lowest values were found in the Hypertensive group. Smokers, Ex-smokers, and the Control group demonstrated similar values. As conclusion, gene downregulation was observed in patients under anti-hypertensive therapy. Smoke seems to reduce expression of genes involve in bone formation and increase genes responsible for resorptive activity. This pattern of genic expression may be involved in higher implant loss, observed in smokers. Stop smoke seems to return expression of some of these genes. Esta investigación describe la expresión génica de moléculas de la inflamación y el metabolismo óseo en pacientes sometidos a cirugía de implantes dentales tratados en una institución brasileña. Se recogió una muestra de conveniencia durante 2 años. Las muestras de hueso se procesaron para la extracción del ARN total y la transcripción inversa del ADNc. Se realizó la cuantificación relativa por reacción en cadena de la polimerasa, en tiempo real, de los genes diana. Los pacientes fueron agrupados em: sanos, grupo en terapia antihipertensiva, grupo fumadores, grupo fumadores y estaban en tratamiento antihipertensivo y grupo exfumadores (fumaban durante 10 años, pero dejar de fumar durante al menos 5 años). El grupo de exfumadores tuvo las expresiones más altas y el grupo de hipertensos tuvo los valores más bajos de Factor estimulante de colonias de macrófagos, osteonectina, proteína morfogenética ósea e integrina. Todos los fumadores demostraron valores de expresión comparables a los del grupo de control. Los valores más altos de expresión de Osteopontina, RUNX y fosfatasa alcalina se observaron en los grupos Hipertenso y Fumador, mientras que los valores más bajos se encontraron en el grupo Hipertenso. Fumadores, exfumadores y el grupo Control mostraron valores similares. Como conclusión, el humo parece reducir la expresión de genes implicados en la formación ósea y aumentar los genes responsables de la actividad de resorción. Este patrón de expresión génica puede estar involucrado en una mayor pérdida de implantes, observada en fumadores. Detener el humo parece devolver la expresión de algunos de estos genes. Esta pesquisa descreve a expressão gênica de moléculas relacionadas à inflamação e ao metabolismo ósseo em todos os pacientes submetidos à cirurgia de implante dentário atendidos em uma instituição brasileira. Uma amostra de conveniência foi coletada ao longo de 2 anos. As amostras ósseas foram processadas para extração do RNA total e transcrição reversa do cDNA. A quantificação relativa por reação em cadeia da polimerase, em tempo real, dos genes alvo, foi realizada. Os pacientes foram agrupados. O grupo controle foi composto por 17 pacientes saudáveis, 6 foram incluídos no grupo em terapia anti-hipertensiva, 3 eram fumantes, outros 3 eram fumantes e estavam em tratamento anti-hipertensivo e 3 eram ex-fumantes (fumaram por 10 anos, mas pararam de fumar por pelo menos 5 anos). O grupo ex-fumante apresentou as maiores expressões e o grupo Hipertenso apresentou os menores valores de Fator estimulador de colônias de macrófagos, Osteonectina, Proteína Morfogenética Óssea II e Integrina. Os maiores valores de expressão de Osteopontina, RUNX e fosfatase alcalina foram observados no grupo Hipertenso e Fumante, enquanto os menores valores foram encontrados no grupo Hipertenso. Fumantes, Ex-fumantes e o grupo Controle demonstraram valores semelhantes. Como conclusão o fumo parece reduzir a expressão de genes envolvidos na formação óssea e aumentar genes responsáveis pela atividade reabsortiva. Esse padrão de expressão gênica pode estar envolvido na maior perda de implantes observada em fumantes. Parar de fumar parece retornar a expressão de alguns desses genes.

Made available in DSpace on 2021-06-25T11:13:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-02 The aim of the present investigation was to calculate the stress distribution generated in the root dentine canal during mechanical rotation of five different NiTi endodontic instruments by means of a finite element analysis (FEA). Two conventional alloy NiTi instruments F360 25/04 and F6 Skytaper 25/06, in comparison to three heat treated alloys NiTI Hyflex CM 25/04, Protaper Next 25/06 and One Curve 25/06 were considered and analyzed. The instruments’ flexibility (reaction force) and geometrical features (cross section, conicity) were previously investigated. For each instrument, dentine root canals with two different elastic moduli(18 and 42 GPa) were simulated with defined apical ratios. Ten different CAD instrument models were created and their mechanical behaviors were analyzed by a 3D-FEA. Static structural analyses were performed with a non-failure condition, since a linear elastic behavior was assumed for all components. All the instruments generated a stress area concentration in correspondence to the root canal curvature at approx. 7 mm from the apex. The maximum values were found when instruments were analyzed in the highest elastic modulus dentine canal. Strain and von Mises stress patterns showed a higher concentration in the first part of curved radius of all the instruments. Conventional Ni-Ti endodontic instruments demonstrated higher stress magnitudes, regardless of the conicity of 4% and 6%, and they showed the highest von Mises stress values in sound, as well as in mineralized dentine canals. Heat-treated endodontic instruments with higher flexibility values showed a reduced stress concentration map. Hyflex CM 25/04 displayed the lowest von Mises stress values of, respectively, 35.73 and 44.30 GPa for sound and mineralized dentine. The mechanical behavior of all rotary endodontic instruments was influenced by the different elastic moduli and by the dentine canal rigidity. Endodontic Clinical Section Department of Biomedical and Neuromotor Sciences School of Dentistry University of Bologna-Alma Mater Studiorum University of Taubaté (UNITAU), Taubaté Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University—UNESP Department of Chemical Materials and Industrial Production Engineering University of Naples Federico II and the Center for Advanced Biomaterials for HealthCare@CRIB Istituto Italiano di Tecnologia School of Dentistry University of Naples Federico II Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University—UNESP

Made available in DSpace on 2021-06-25T11:13:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 Background: This study evaluated the effect of interim restorative materials (acrylic resin (AR), resin composite (RC) or polyetheretherketone (PEEK) for dental computer-aided design/computeraided manufacturing (CAD/CAM)) on the stress distribution of a posterior three-unit fixed partial denture. Methods: The abutment teeth (first molar and first premolar) were modeled using the BioCAD protocol containing 1.5 mm of axial reduction and converging axial walls. A static structural analysis was performed in the computer-aided engineering software, and the Maximum Principal Stress criterion was used to analyze the prosthesis and the cement layers of both abutment teeth. The materials were considered isotropic, linearly elastic, homogeneous and with bonded contacts. An axial load (600 N) was applied to the occlusal surface of the second premolar. Results: Regardless of the restorative material, the region of the prosthetic connectors showed the highest tensile stress magnitude. The highest stress peak was observed with the use of RC (129 MPa) compared to PEEK and AR. For the cement layers, RC showed the lowest values in the occlusal region (7 MPa) and the highest values for the cervical margin (14 MPa) compared to PEEK (21 and 12 MPa) and AR (21 and 13 MPa). Conclusions: Different interim restorative materials for posterior fixed partial dentures present different biomechanical behavior. The use of resin composite can attenuate the stress magnitude on the cement layer, and the use of acrylic resin can attenuate the stress magnitude on the connector region. Institute of Science and Technology São Paulo State University (Unesp) Department of Clinical and Experimental Medicine Messina University AOU Policlinico “G.Martino”, Via Consolare Valeria School of Dentistry University of Naples Federico II Institute of Science and Technology São Paulo State University (Unesp)

Made available in DSpace on 2021-06-25T11:13:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 The purpose of this study is to evaluate the effect of pulp chamber extension angles and filling material mechanical properties on the biomechanical response of a ceramic endocrown. A 3D model of maxillary molar that underwent endodontically treatment was exported to computer aided design software to conduct finite element analysis (FEA). The endocrown model was modified considering different pulp chamber extension angles (right angle; 6°, 12° and 18° of axial divergence). The solids were imported into the computer aided engineering software in Standard for the Exchange of Product Data (STEP) format. Nine different filling materials were simulated to seal the orifice of the root canal system under each endocrown restoration (resin composite, bulk-fill resin composite, alkasite, flowable resin composite, glass ionomer cement, autocured resin-reinforced glass ionomer cement, resin cement, bulk-fill flowable resin composite, zinc oxide cement), totaling 36 models. An axial load (300 N) was applied at the occlusal surface. Results were determined by colorimetric graphs of von-Misses stress (VMS) and Maximum Principal Stress (MPS) on tooth, cement layer, and endocrown restorations. VMS distribution showed a similar pattern between the models, with more stress at the load region for the right-angled endocrowns. The MPS showed that the endocrown intaglio surface and cement layer showed different mechanical responses with different filing materials and pulp chamber angles. The stress peaks plotted in the dispersion plot showed that the filling material stiffness is proportional to the stress magnitude in the endocrown, cement layer and tooth adhesive surface. In addition, the higher the pulp chamber preparation angle, the higher the stress peak in the restoration and tooth, and the lower the stress in the cement layer. Therefore, 6° and 12° pulp chamber angles showed more promising balance between the stresses of the adhesive interface structures. Under the conditions of this study, rigid filling materials were avoided to seal the orifice of root canal system when an endocrown restoration was planned as rehabilitation. In addition, the pulp chamber axial walls were prepared between 6° and 12° of divergence to balance the stress magnitude in the adhesive interface for this treatment modality. School of Dentistry University of Taubaté Department of Human Pathology in Adulthood and Childhood “G. Barresi” University Hospital “G. Martino” of Messina, Via Consolare Valeria 1 Institute of Science and Technology São Paulo State University (Unesp) São José dos Campos Department of Biomedical and Dental Sciences and Morphofunctional Imaging University of Messina Institute of Science and Technology São Paulo State University (Unesp) São José dos Campos

The goal of this study was to evaluate the stress distribution in an endocrown restoration according to different provisional restorative materials. An endodontically treated maxillary molar model was selected for conducting the finite element analysis (FEA), with a determined amount of dental remnant of 1.5 mm. The model was imported to the analysis software (ANSYS 19.2, ANSYS Inc., Houston, TX, USA) in STEP format. All contacts were considered perfectly bonded. The mechanical properties of each structure were considered isotropic, linear, elastic, and homogeneous. Three different provisional restorative materials were simulated (acrylic resin, bis-acrylic resin, and resin composite). An axial load (300 N) was applied at the occlusal surface in the center of the restoration. Results were determined by colorimetric stress maps of maximum principal stress, maximum shear stress, and total deformation. The different materials influenced the stress distribution for all structures, the higher the material’s elastic modulus, the lower the stress magnitude on the cement layer. In the present study, all provisional restorative materials showed similar stress patterns in the endocrown and on the cement layer however, with different magnitude. Based on this study limitation, the use of resin composite to manufacture provisional endocrowns is suggested as a promising material to reduce the stresses in the cement layer and in the dental tissue surfaces.

This study evaluated the effect of the combination of three different onlay preparation designs and two restorative materials on the stress distribution, using 3D-finite element analysis. Six models of first lower molars were created according to three preparation designs: non-retentive (nRET), traditional with occlusal isthmus reduction (IST), and traditional without occlusal isthmus reduction (wIST), and according to two restorative materials: lithium-disilicate (LD) and nanoceramic resin (NR). A 600 N axial load was applied at the central fossa. All solids were considered isotropic, homogeneous, and linearly elastic. A static linear analysis was performed, and the Maximum Principal Stress (MPS) criteria were used to evaluate the results and compare the stress in MPa on the restoration, cement layer, and tooth structure (enamel and dentin). A novel statistical approach was used for quantitative analysis of the finite element analysis results. On restoration and cement layer, nRET showed a more homogeneous stress distribution, while the highest stress peaks were calculated for LD onlays (restoration: 69–110, cement layer: 10.2–13.3). On the tooth structure, the material had more influence, with better results for LD (27–38). It can be concluded that nRET design showed the best mechanical behavior compared to IST and wIST, with LD being more advantageous for tooth structure and NR for the restoration and cement layer.

Made available in DSpace on 2021-06-25T11:15:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 This study evaluated the stress distribution in five different class II cavities of premolar models restored with conventional or bulk-fill flowable composite by means of finite element analysis (FEA) under shrinkage and occlusal loading. An upper validated premolar model was imported in the software, and five class II cavities with different occlusal extensions and dimensions were prepared: horizontal cavity on the mesial surface (horizontal slot), mesio-occlusal cavity, mesial cavity (vertical slot), tunnel type cavity and direct access cavity. The models were restored with conventional or bulk-fill flowable resin composite. The tested materials were considered as homogeneous, linear, and isotropic. The Maximum Principal Stress criteria was chosen to evaluate the tensile stress results. The lowest shrinkage stress value was observed in the direct access cavity restored with bulk-fill flowable resin composite (36.12 MPa). The same cavity, restored with conventional composite showed a score of 36.14 MPa. The horizontal slot cavity with bulk-fill flowable showed a score of 46.71 MPa. The mesio-occlusal cavity with bulk-fill flowable had a score of 53.10 MPa, while with conventional composite this was 55.35 MPa. Higher shrinkage stress was found in the vertical slot cavity with conventional resin 56.14 MPa, followed by the same cavity with bulk-fill flowable 56.08 MPa. Results indicated that the use of bulk-fill flowable composite resin more significantly decreased the polymerization shrinkage stress magnitude. The larger the cavity and the volume of material necessary to restore the tooth, the greater the residual stress on enamel and dentin tissue. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNESP) Department of Dentistry University of Taubaté (UNITAU) Department of Oral and Maxillo Facial Sciences “Sapienza” University of Rome Department of Neurosciences Reproductive and Odontostomatological Sciences School of Dentistry University of Naples Federico II Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNESP)

(1) Background: Trauma is a very common experience in contact sports, however, there is an absence of data regarding the effect of athletes wearing mouthguards (MG) associated with ankylosed maxillary central incisor during a traumatic impact. (2) Methods: To evaluate the stress distribution in the bone and teeth in this situation, models of maxillary central incisor were created containing cortical bone, trabecular bone, soft tissue, root dentin, enamel, periodontal ligament, and antagonist teeth were modeled. One model received a MG with 4-mm thickness. Both models were subdivided into finite elements. The frictionless contacts were used and a nonlinear dynamic impact analysis was performed in which a rigid object hit the model at 1 m&middot, s&minus, 1. For each model, an ankylosed periodontal ligament was simulated totaling 4 different situations. The results were presented in von-Mises stress maps. (3) Results: A higher stress concentration in teeth and bone was observed for the model without a MG and with ankylosed tooth (19.5 and 37.3 MPa, respectively), the most promising mechanical response was calculated for patients with healthy periodontal ligament and MG in position (1.8 and 7.8 MPa, respectively). (4) Conclusions: The MG&rsquo, s use is beneficial for healthy and ankylosed teeth, since it acts by dampening the generated stresses in bone, dentin, enamel and periodontal ligament. However, patients with ankylosed tooth are more prone to root fracture even when the MG is in position compared to a healthy tooth.

Made available in DSpace on 2021-06-25T10:53:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul This study evaluated the influence of distinct substrates on the mechanical fatigue behavior of adhesively cemented simplified restorations made of glass, polycrystalline or polymer infiltrated-ceramics. CAD/CAM ceramic blocks (feldspathic – FEL; lithium disilicate – LD; yttria-stabilized zirconia – YZ; and polymer-infiltrated ceramic network – PICN) were shaped into discs (n = 15, Ø = 10 mm; thickness = 1.0 mm), mimicking a simplified monolithic restoration. After, they were adhesively cemented onto different foundation substrates (epoxy resin – ER; or Ni–Cr metal alloy – MA) of the same shape (Ø = 10 mm; thickness = 2.0 mm). The assemblies were subjected to fatigue testing using a step-stress approach (200N-2800 N; step-size of 200 N; 10,000 cycles per step; 20 Hz) upon the occurrence of a radial crack or fracture. The data was submitted to two-way ANOVA (α = 0.05) to analyze differences considering ‘ceramic material’ and ‘type of substrate’ as factors. In addition, a survival analysis (Kaplan Meier with Mantel-Cox log-rank post-hoc tests; α = 0.05) was conducted to obtain the survival probability during the steps in the fatigue test. Fractographic and finite element (FEA) analyzes were also conducted. The factors ‘ceramic material’, ‘type of substrate’ and the interaction between both were verified to be statistically significant (p < .001). All evaluated ceramics presented higher fatigue failure load (FFL), cycles for failure (CFF) and survival probabilities when cemented to the metallic alloy substrate. Among the restorative materials, YZ and LD restorations presented the best fatigue behavior when adhesively cemented onto the metallic alloy substrate, while FEL obtained the lowest FFL and CFF for both substrates. The LD, PICN and YZ restorations showed similar fatigue performance considering the epoxy resin substrate. A more rigid foundation substrate improves the fatigue performance of adhesively cemented glass, polycrystalline and polymer infiltrated-ceramic simplified restorations. PhD Post-Graduate Program in Oral Science (Prosthodontic Unit) Faculty of Odontology Federal University of Santa Maria Department of Dental Materials and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos Department of Dental Materials Science Academic Centre for Dentistry Amsterdam (ACTA) Universiteit van Amsterdam and Vrije Universiteit Department of Dental Materials and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos CAPES: 001 Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul: 18/2551-0000520-7

Made available in DSpace on 2020-12-12T02:13:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 Objective: This study aimed to evaluate the biomechanical behaviour of endodontically treated teeth with direct veneer that received or not intra-radicular glass fiber post by finite elements analysis. Material and methods: Six models were designed, varying the presence or absence of glass fiber post and the thickness of direct veneer (0.5, 0.7 and 1 mm). Tridimensional models of maxillary central incisors were obtained with CAD software, Rhinoceros 4.0, and transferred to CAE software, ANSYS 17.2, which a 100N load was applied in a 45° on the lingual surface to simulate functional movements. Geometry contacts were bonded, and the structures were isotropic, linear, elastics, and homogeneous. After coherence and convergence analysis of mashes, the chosen fail criterion was the maximum principal stresses. Results: For cement, glass fiber post, the stress distribution was similar independently of glass fiber post presence or veneer thickness. Models with glass fiber post had better stress distribution and lower values of maximum stress for inner dentin and veneers. Veneers with 0.5 and 1 mm had higher stress concentration areas. Conclusions: It can be concluded that glass fiber post is favorable for restored teeth with direct veneers, and very thin or very thick preparations can damage the biomechanical behavior of restorations. São Paulo State University (UNESP) Institute Science and Technology São José dos Campos Departament of Restorative Dentistry São Paulo State University (UNESP) Institute Science and Technology São José dos Campos Departament of Dental Materials and Prosthodontics São Paulo State University (UNESP) Institute Science and Technology São José dos Campos Departament of Restorative Dentistry São Paulo State University (UNESP) Institute Science and Technology São José dos Campos Departament of Dental Materials and Prosthodontics

Made available in DSpace on 2020-12-12T02:33:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-17 This study evaluated the influence of the surface treatment and aging on the biaxial flexural strength of ceramic materials cemented to a dentin analogue. One hundred twenty disc-shaped specimens were allocated into 12 groups considering three study factors: ceramic material (lithium disilicate, leucite-based ceramic and hybrid ceramic), surface treatment (10% hydrofluoric acid etching + silane or self-etching glass-ceramic primer) and Aging (with 10,000 thermocycles of 5–37–55 °C or without). A tri-layer assembly was designed to mimic a cemented restoration (Variolink N) into a dentin analogue. All samples were submitted to the biaxial flexural strength assay. The flexural strength in MPa was calculated using the finite element method for each sample considering thickness, material properties, and the load to fracture during the in vitro test. Fractographic analysis was also performed. The data was evaluated using three-way ANOVA and Tukey test (α = 5%). ANOVA showed influence for the Material*Treatment*Aging interaction on the flexural strength (p = 0.011). The highest strength was calculated for lithium disilicate ceramic + self-etching ceramic primer without aging (499 ± 17 MPa)A and the lowest value for hybrid ceramic material + acid etching with aging (424 ± 48 MPa)E. According to the Weibull modulus, the most predictable strength was calculated for lithium disilicate + acid etching after aging. Acid etching or self-etching ceramic primer promotes similar immediate biaxial flexural strength for each evaluated ceramic. In the long-term, superior strength was observed using acid etching for lithium disilicate and the self-etching ceramic primer for the hybrid ceramic while no difference was observed for leucite-based ceramic. Clinical implications: Some protocols combining the CAD/CAM ceramic material and the surface treatment could present suitable and stable flexural strength. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp) Dental Materials Unit Center for Dental and Oral Medicine Clinic for Fixed and Removable Prosthodontics and Dental Materials Science University of Zürich Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp)

Different techniques are available to manufacture polymer-infiltrated ceramic restorations cemented on a chairside titanium base. To compare the influence of these techniques in the mechanical response, 75 implant-supported crowns were divided in three groups: CME (crown cemented on a mesostructure), a two-piece prosthetic solution consisting of a crown and hybrid abutment, MC (monolithic crown), a one-piece prosthetic solution consisting of a crown, and MP (monolithic crown with perforation), a one-piece prosthetic solution consisting of a crown with a screw access hole. All specimens were stepwise fatigued (50 N in each 20,000 cycles until 1200 N and 350,000 cycles). The failed crowns were inspected under scanning electron microscopy. The finite element method was applied to analyze mechanical behavior under 300 N axial load. Log-Rank (p = 0.17) and Wilcoxon (p = 0.11) tests revealed similar survival probability at 300 and 900 N. Higher stress concentration was observed in the crowns&rsquo, emergence profiles. The MP and CME techniques showed similar survival and can be applied to manufacture an implant-supported crown. In all groups, the stress concentration associated with fractographic analysis suggests that the region of the emergence profile should always be evaluated due to the high prevalence of failures in this area.

Made available in DSpace on 2020-12-12T02:31:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-01 Objectives: This study aimed to evaluate the effect of different materials and undercut on the removal force and stress distribution in the supporting tooth and in the circumferential clasp used in removable partial prosthesis. Methods: Upper molars prepared for Akers circumferential clasp with retention and opposing arm were modeled, scanned, elaborated with CAD software and the geometries imported in FEA and analyzed. Six different materials were selected for the clasp (Polyamide, Polyoxymethylene, Polyetheretherketone - PEEK, Gold alloy, Titanium and CoCr) and 3 different undercuts (0.25, 0.50 and 0.75 mm), totaling 18 groups. Results: The clasps presented greater stress in their structure and potentially greater damage to the dental enamel when made with rigid materials and with more undercut; however, they presented greater ability to remain in position. Significance: Polyamide with a higher undercut is an esthetic alternative to rigid metallic clasps. It showed promising behavior because it strongly reduces the damage to the enamel, and even with an undercut of 0.75, the retention is lower than for CoCr with a 0.25 undercut, and this retention might still be sufficient. Polyoxymethylene and Polyetheretherketone (PEEK) are not suitable materials for the clasps, because the maximum stress occurring during removal with higher undercuts is higher than the material strength. PhD Graduate Program in Restorative Dentistry São Paulo State University (Unesp) Institute of Science and Technology, Av. Eng. Francisco José Longo, nº 777. Jardim São Dimas Department of Dental Materials Science Academic Center for Dentistry Amsterdam (ACTA) Universiteit van Amsterdam and Vrije Universiteit, Gustav Mahlerlaan #3004 PhD Graduate Program in Restorative Dentistry São Paulo State University (Unesp) Institute of Science and Technology, Av. Eng. Francisco José Longo, nº 777. Jardim São Dimas

Made available in DSpace on 2020-12-12T02:37:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Purpose: Different titanium bases for implant-supported prostheses can present different mechanical behavior. The goal of this study was to evaluate the torque before and after fatigue, the load to failure, and stress concentration of zirconia restorations cemented or notched to a titanium base. Materials and Methods: Forty implants were included in polyurethane cylinders and divided into two groups: zirconia restoration cemented on a titanium base and zirconia restoration notched on a titanium base. The specimens had their torque loosening and vertical misfit evaluated before and after cyclic fatigue (200 N/2 Hz/2 x 106 cycles/3 6 7°C). Load to failure was evaluated in a universal testing machine (1 mm/min, 1,000 kgf). Failures were evaluated by scanning electron microscopy. Three-dimensional models were created, and the stress concentration was calculated using the finite element method. Data from the in vitro tests were submitted to two-way analysis of variance and Tukey test (α =.5). Results: The cemented restorations presented less torque loosening (19.79 to 15.95 Ncm), lower vertical misfit (3.7 to 10.5 μm), lower stress concentration in the restoration (88.2 to 99.8 MPa), and higher fracture load (451.3 to 390.8 N) than notched restorations. Conclusion: The presence of a cement layer between the restoration and titanium base reduced the susceptibility to abutment screw loosening, improved the resistance to compressive load, and reduced the stress concentration in the restoration. Department of Dental Materials and Prosthodontics São Paulo State University (Unesp) Institute of Science and Technology Department of Dental Materials and Prosthodontics São Paulo State University (Unesp) Institute of Science and Technology

Made available in DSpace on 2020-12-12T01:29:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Background: This in vitro study evaluated the effect of framework type on the survival probability of temporary implant-supported crowns and on the implant platform structure after dynamic fatigue. Material and Methods: Thirty (30) external hexagon implants (3.75 x 10 mm) were embedded in acrylic resin following the ISO-14801. Standardized temporary crowns (n=10, N=30) were manufactured in acrylic resin and divided according to the framework type: Total plastic, Plastic with CoCr base and Titanium. The crowns were installed onto the implants (20N. cm) and fatigued (100N, 2 Hz) to determine the crowns' survival probability for missions of 300.000 and 600.000 cycles. Fatigue data were submitted to the Kaplan-Meier test followed by Wilcoxon and Log Rank, all with α = 5%. The implant platforms were parametrically inspected based on the scanning before and after the fatigue to evaluate the damage. The strain values were analyzed using One-way ANOVA and Tukey test, all with α = 5%. Results: ANOVA revealed that the Total plastic showed less implant damage (-0.07 ±-0.03 mm) than the Plastic with CoCr base (-0.08 ±-0.04 mm) and the Titanium (-0.10 ±-0.01 mm) frameworks. Therefore, the framework type to manufacture implant-supported temporary crowns influences the fatigue survival of the restoration and the implant platform damage. The Plastic with CoCr base and Titanium frameworks showed superior reliability than the Total plastic framework which could not survive 600,000 cycles. Conclusions: The Plastic with CoCr base and the Titanium framework are suitable for restorations over 3 months in use, without a difference in the implant platform damage. Department of Dental Materials and Proshodontics Faculty of Pindamonhangaba (FUNVIC) Department of Dental Materials and Proshodontics São Paulo State University (Unesp) Institute of Science and Technology Department of Prosthodontics School of Dentistry University of Sao Paulo Department of Dental Materials and Proshodontics São Paulo State University (Unesp) Institute of Science and Technology

Made available in DSpace on 2020-12-12T01:22:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Background: This study evaluated the mechanical response of a removable partial denture (RPD) in Kennedy Class II according to being associated or not with implants. Material and Methods: Four RPDs were manufactured for a Kennedy Class II: CRPD-Conventional RPD, RPD+ 1M, RPD+2M and RPD+12M, respectively, signifying implant assisted RPDs with the implant installed in the first molar, second molar, and in the first and second molars. The finite element method was used to determine the most damaged support tooth under compressive load (300N, 10s) and strain gauge analysis was used to evaluate the microstrain. All groups were submitted to a retentive force analysis (0.5 mm/mm, 100kgf). Microstrain and retentive force data were submitted to One-way ANOVA and the Tukey test, all with α=5%. Results: High microstrain was observed in the second premolar adjacent to the edentulous space under compression load (p < 0.01). RPD+12M presented lower microstrain, however being similar to RPD+2M. RPD+1M presented a higher mean value of retentive force, but similar to RPD+12M. FEM showed RPD assisted by implants concentrates less stress in the periodontal ligament. The association of two implants was sufficient to decrease the stress generated in the implants. The most stressed region for the o-ring abutment was the threads, and the group with two implants showed the lowest stress concentration. Conclusions: In cases of Kennedy Class II, the association of RPD with implants in the molar region is a favorable option for patient rehabilitation, reducing the movement of the direct retainer adjacent to the edentulous space, increasing the removal force and decreasing the stress magnitude in the periodontal ligament. Department of Dental Materials and Proshodontics São Paulo State University (Unesp) Institute of Science and Technology São Paulo State University (Unesp) Institute of Science and Technology Department of Dental Materials and Proshodontics São Paulo State University (Unesp) Institute of Science and Technology São Paulo State University (Unesp) Institute of Science and Technology

Made available in DSpace on 2018-12-11T17:37:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-09-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Objectives: To investigate the influence of different materials for monolithic full posterior crowns using 3D-Finite Element Analysis (FEA). Methods: Twelve (12) 3D models of adhesively-restored teeth with different crowns according to the material and its elastic modulus were analysed: Acrylic resin, Polyetheretherketone, Composite resin, Hybrid ceramic, pressable and machinable Zirconia reinforced lithium silicate, Feldspathic, Lithium disilicate, Gold alloy, Cobalt–Chromium alloy (Co–Cr), Zirconia tetragonal partially stabilized with yttria, and Alumina. All materials were assumed to behave elastically throughout the entire deformation. Results in restoration and cementing line were obtained using maximum principal stress. In addition, maximum shear stress criteria was used for the cementing line. Results: Restorative materials with higher elastic modulus present higher stress concentration inside the crown, mainly tensile stress on an intaglio surface. On the other hand, materials with lower elastic modulus allow stress passage for cement, increasing shear stress on this layer. Stiffer materials promote higher stress peak values. Significance: Materials with higher elastic modulus such as Co–Cr, zirconia and alumina enable higher tensile stress concentration on the crown intaglio surface and higher shear stress on the cement layer, facilitating crown debonding. Department of Dental Materials and Prosthodontics São Paulo State University (Unesp) Institute of Science and Technology, Av. Eng. Francisco José Longo, no. 777, Jardim São Dimas Federal University of Rio Grande do Norte (UFRN) Department of Dentistry Division of Prosthodontics Department of Dental Materials and Prosthodontics São Paulo State University (Unesp) Institute of Science and Technology, Av. Eng. Francisco José Longo, no. 777, Jardim São Dimas FAPESP: #2017/11535-3

Made available in DSpace on 2018-11-12T17:28:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-08-01. Added 1 bitstream(s) on 2018-11-12T17:36:48Z : No. of bitstreams: 1 S1807-25772018000400237.pdf: 559449 bytes, checksum: 7a90aa5fe0733cc2eba27e6583ca3fca (MD5) ResumoIntroduçãoA inclinação dos implantes pode ser corrigida através de mini-pilares de diferentes angulações.ObjetivoAnalisar a influência de implantes com hexágono externo em diferentes inclinações (3 níveis) na distribuição de microdeformações geradas em torno de três implantes.MétodoUm modelo geométrico de osso foi criado através do software CAD Rhinoceros (versão 5.0 SR8, Mcneel North America, Seattle, WA, EUA). Três implantes (4,1 × 13 mm) foram modelados e inseridos no interior do substrato em três diferentes inclinações: 0º, 17º e 30º. Em seguida, todos os grupos receberam mini-pilares cônicos, parafusos de fixação e prótese simplificada. A geometria final foi exportada em formato STEP para software de análise e todos os materiais foram considerados homogêneos, isotrópicos e linearmente elásticos. Uma carga axial (300N) foi aplicada no centro da prótese. Um estudo in vitro foi conduzido com as mesmas condições e grupos para validar o modelo tridimensional.ResultadoA concentração de tensão ocorreu na área externa dos implantes, em contato com o osso cortical e o hexágono externo. Para o simulador ósseo, a deformação aumentou na região peri-implantar de acordo com o aumento da inclinação do implante. A diferença entre os grupos foi significativa (p = 0.000). O grupo de 30º apresentou maior concentração de tensão e deformação.ConclusãoO aumento da microdeformação e das tensões ao redor dos implantes aumenta diretamente proporcional ao aumento do ângulo de instalação. AbstractIntroductionImplant inclinations can be corrected using mini abutments at different angulations.ObjectiveTo analyze the influence of external hexagon implants in different inclinations (3 levels) on the microstrain distribution generated around three implants.MethodA geometric bone model was created through Rhinoceros CAD software (version 5.0 SR8, Mcneel North America, Seattle, WA, USA). Three implants (4.1 × 13 mm) were modeled and inserted inside the substrate at three different inclinations: 0º, 17º and 30º. Next, all groups received mini conical abutments, fixation screws and a simplified prosthesis. The final geometry was exported in STEP format to analysis software and all materials were considered homogeneous, isotropic and linearly elastic. An axial load (300N) was applied on the center of the prosthesis. An in vitro study was conducted with same conditions and groups for validating the tridimentional model.ResultStress was concentrated on the external area of the implants, in contact with the cortical bone and external hexagon. For the bone simulator, the strain increased in the peri-implant region according to the increase in the implant’s inclination. The difference between groups was significant (p = 0.000). The 30º group presented higher stress and strain concentration.ConclusionThe microstrain and stress increase around implants directly proportional to the increase of the installation angle. Faculdade de Pindamonhangaba Universidade Estadual Paulista Instituto de Ciência e Tecnologia Departamento de Materiais Odontológicos e Prótese Universidade Estadual Paulista Instituto de Ciência e Tecnologia Departamento de Materiais Odontológicos e Prótese

Made available in DSpace on 2018-12-11T17:38:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Purpose: Due to recurring doubts by athletes regarding the effectiveness of mouthguards (MG), this study evaluated the stress distribution in the skull and teeth as a consequence of different impacts. Methods: Two human skulls were created using modeling software: one in maximum intercuspidal position and the other with a MG. Next, a boxing glove was allocated into each of the coordinate axes (x, y and z) to represent a boxing punch (1000N): Jab (x), Cross (y) or Uppercut (z). The six models were imported to the analysis software and the geometries were subdivided into a specific number of elements. The bonded contacts simulated a situation in which the athlete would not lose their MG during impact. The system constriction was in the foramen magnum region. The results were presented in stress maps and graphs. Results: A higher stress concentration in teeth was shown for the model without a MG under direct impact on the upper central incisors. According to von Mises stress, each punch resulted in stress being produced in distinct areas of the skull. The displacement was proportional to the Maximum Principal Stress result. MG use decreased the jaw movement relative to the maxilla and reduced the stress magnitude during impact in all situations. Conclusions: MG use is beneficial for all simulated impacts and assists in dampening the generated stresses. Direct impacts on tooth regions showed the higher stress values and the most efficacy in protection was evidenced when using a MG. Department of Dental Materials and Prosthodontics São Paulo State University (Unesp) Institute of Science and Technology, Av. Eng. Francisco José Longo, No. 777. Jardim São Dimas Department of Dental Materials and Prosthodontics São Paulo State University (Unesp) Institute of Science and Technology, Av. Eng. Francisco José Longo, No. 777. Jardim São Dimas

Background To assist clinicians in deciding the most suitable restorative materials to be used in the crowns and abutment in implant rehabilitation. Material and methods For finite element analysis (FEA), a regular morse taper implant was created using a computer aided design software. The implant was inserted at the bone model with 3 mm of exposed threads. An anatomic prosthesis representing a first maxillary molar was modeled and cemented on the solid abutment. Considering the crown material (zirconia, chromium-cobalt, lithium disilicate and hybrid ceramic) and abutment (Titanium and zirconia), the geometries were multiplied, totaling eight groups. In order to perform the static analysis, the contacts were considered bonded and each material was assigned as isotropic. An axial load (200 N) was applied on the crown and fixation occurred on the base of the bone. Results using Von-Mises criteria and micro strain values were obtained. A sample identical to the CAD model was made for the Strain Gauge (SG) analysis; four SGs were bonded around the implant to obtain micro strain results in bone tissue. Results FEA results were 3.83% lower than SG. According to the crown material, it is possible to note that the increase of elastic modulus reduces the stress concentration in all system without difference for bone. Conclusions Crown materials with high elastic modulus are able to decrease the stress values in the abutments while concentrates the stress in its structure. Zirconia abutments tend to concentrate more stress throughout the prosthetic system and may be more susceptible to mechanical problems than titanium. Key words:Finite element analysis, dental implants, ceramic.

Objective: This study evaluated the effects of the incorporation of silver nanoparticles (AgNPs) obtained from Fusarium oxysporum on heat-activated acrylic resin (HAAR) and their influence on resin’s surface roughness, hardness, color alteration and antimicrobial capacity against Candida albicans . Material and Methods: For this, 50 discs of HAAR (2x5 mm) were produced and divided into three groups, Control: HAAR; Ag1: HAAR plus 0.539 mg of AgNPs; and Ag2: HAAR plus 1.1 mg of AgNPs. Knopp hardness (HK), surface roughness (Ra and Rz) and color alteration according to the CIE Lab were measured. Specimens were then evaluated in vitro with regard to C. albicans biofilm formation through formed colony count (CFU/mL). Scanning Electron Microscopy (SEM) and Atomic force microscopy (AFM) analyses were performed. Results: The addition of AgNPs of both concentrations changed Ra, Rz and HK significantly. There was statistically significant difference for L (p=0.00); a*(p=0.00) and b*(p=0.00) parameters. There were no differences between Ag1 and Ag2 biofilm formation, but the comparison of both with the control group presented a significant reduction (p=0.0091) on biofilm formation. SEM and AFM images showed no signs of NPs clustering. Conclusion: It can be concluded tha AgNPs incorporation in HAAR was effective in reducing C. albicans activity, with a slight change in color and hardness of the material, being effective therefore, in regions such as the dental prostheses palate, which have lesser aesthetic appeal. Keywords Acrylic resins; Silver; Antimicrobial agents.

Purpose: To evaluate the stress and strain generated in a fixed four-element prosthesis under the application of axial and nonaxial loads using a simplified implant-supported fixed prosthesis model. Materials and Methods: A 3-dimensional model was constructed containing 3 implants with a conventional anatomical prosthesis (G1). The second model with the same implant system received the simplified prosthesis (G2). A load of 300 N was applied at an axial point and a nonaxial point through finite element analysis software. Results: The G2 group showed different values of stress concentration in the prosthesis, fixation screw, retention screw, and abutments when compared with G1. Within a limit of 10% degrees of acceptability, the stress on the implants and the bone strain were enclosed for both models of prostheses. Conclusion: The simplified fixed prosthesis evaluated presents biomechanical behavior similar to an anatomical prosthesis in the implants and in the surrounding bone structure.

Objective: The aim of this study was to observe the influence of different occlusal contacts in a superior pre-molar structure using Finite Element Analysis. Material and Methods: A three-dimensional model of a superior pre-molar was designed to simulate three occlusion situations, namely central occlusion and two types of lateral occlusion contacts. The model presents enamel, dentin, a periodontal ligament and a fixation cylinder separately. All materials were considered isotropic, linear and homogeneous, and the contacts of each structure were perfectly bonded. On analysis software, a load was applied to an occlusal surface at 40° to the long axis on lateral contacts, and directed to the long axis on central occlusion contact. Results: The results were obtained in stress maps and the maximum values were then plotted in table for quantitative comparison, with the enamel concentrating more stress than dentin and the occlusal contact presenting the worst biomechanical behavior. Conclusion: Within the limitations of this study, it is possible conclude that: eccentric contacts have higher potential to develop abfraction lesions on the cervical region of teeth, thus increasing the magnitude of tensile and shear stresses.KeywordsFinite Elements Analysis, Abfraction; Stress distribution; Occlusion, Premolar.

Objective: An ideal biomechanics minimizes the stress between implant and bone that can provide success for osseointegrated implants. This study evaluated the strain concentration in surrounding tissue and stress in the components of two implants with different prosthetic connections through an in vitro and in silico methods. Methods: Twenty polyurethane blocks were divided into two groups (n=10) followed by the installation of internal hexagon (IH) (AS Technology – Titanium Fix, Sao Jose dos Campos, Brazil) or locking taper implants (LT) (Bicon Dental Implants). For strain gauge (SG) method, four sensors were placed around the implants. For finite element analysis (FEA), the same block was modeled and analyzed. An axial load (30 kgf) was applied for both methodologies. The values of stress and strain were analyzed for correlation to SG. Results: For SG, LT presented a mean of strain most aggressive (-932) than IH (-632). For FEA, LT showed less stress (-547) then IH (-1169). Conclusion: For two implant’s system, microstrain values capable to induce unwanted bone remodeling were not measured. However, for IH implant, the presence of a retention screw has the disadvantage to concentrate stress while a solid abutment dissipates the axial load through the implant that suggests a better performance for LT group. Keywords: Finite elements analyses; Dental implant; Strain gauge.

Made available in DSpace on 2018-12-11T17:23:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-07. Added 1 bitstream(s) on 2019-10-09T18:32:05Z : No. of bitstreams: 1 S1806-83242017000100281.pdf: 685232 bytes, checksum: a6f1f55b607649a8d98919417e64b7bc (MD5) This study evaluated the effect of implantoplasty on different bone insertion levels of exposed implants. A model of the Bone Level Tapered implant (Straumann Institute, Waldenburg, Switzerland) was created through the Rhinoceros software (version 5.0 SR8, McNeel North America, Seattle, WA, USA). The abutment was fixed to the implant through a retention screw and a monolithic crown was modeled over a cementation line. Six models were created with increasing portions of the implant threads exposed: C1 (1 mm), C2 (2 mm), C3 (3 mm), C4 (4 mm), C5 (5 mm) and C6 (6 mm). The models were made in duplicates and one of each pair was used to simulate implantoplasty, by removing the threads (I1, I2, I3, I4, I5 and I6). The final geometry was exported in STEP format to ANSYS (ANSYS 15.0, ANSYS Inc., Houston, USA) and all materials were considered homogeneous, isotropic and linearly elastic. To assess distribution of stress forces, an axial load (300 N) was applied on the cusp. For the periodontal insert, the strains increased in the peri-implant region according to the size of the exposed portion and independent of the threads' presence. The difference between groups with and without implantoplasty was less than 10%. Critical values were found when the inserted portion was smaller than the exposed portion. In the exposed implants, the stress generated on the implant and retention screw was higher in the models that received implantoplasty. For the bone tissue, exposure of the implant's thread was a damaging factor, independent of implantoplasty. Implantoplasty treatment can be safely used to control peri-implantitis if at least half of the implant is still inserted in bone. Universidade Estadual Paulista - UNESP, Institute of Science and Technology, Department of Dental Materials and Prosthodontics, São José dos Campos, SP, Brazil Universidade de Guarulhos - UnG, Dental Research Division, Department of Periodontology and Oral Implantology, Guarulhos, SP, Brazil

Made available in DSpace on 2020-12-10T19:49:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 The aim of this study was to evaluate the effects of different frameworks on the biomechanical behavior of implant-supported provisional single crowns to indicate or not the use of plastic framework as infrastructure. For finite element analysis, a hemi-jaw stone model was scanned and modeled with an external hexagon implant. A framework was screwed onto the implant and a crown was constructed over it. The set was made in triplicate according to framework type: plastic, cobalt-chromium (CoCr), and titanium. Models were exported in volumetric format to analysis software where structures were considered isotropic, linear, elastic, and homogeneous. Axial loads (100, 200, and 300 N) were applied to the fossa bottom, and the system's fixation occurred on the bone base. For strain-gauge analysis, the same hemi-jaw model was built in polyurethane and an implant was placed on it. Three crowns were made, each one with a different framework. Four strain gauges were glued around the implant to obtain microstrain values. The data were analyzed by three-way analysis of variance (ANOVA) and Tukey tests (P < .05). Finite element analysis exhibited microstrain results for bone, von Mises stress values for the implant and screw, and maximum principal stress values for the crown. For computational method, as the applied load increased, so did the stress generated. Titanium frameworks concentrated more stress in the crown and bone, while plastic ones concentrated more in the implant and screw. ANOVA showed that the higher the load value and the framework elastic modulus, the higher the generated microstrain in bone. It can be concluded that all evaluated framework types can be used in the manufacturing of provisional crowns. Sao Paulo State Univ Unesp, Dept Dent Mat & Prosthodont, Inst Sci & Technol, Av Eng Francisco Jose Longo,777 Jardim Sao Dimas, BR-12245000 Sao Jose Dos Campos, SP, Brazil Pindamonhangaba Coll, Dept Dent Mat & Prosthodont, Fac Pindamonhangaba FUNVIC, Pindamonhangaba, SP, Brazil Sao Paulo State Univ Unesp, Dept Dent Mat & Prosthodont, Inst Sci & Technol, Av Eng Francisco Jose Longo,777 Jardim Sao Dimas, BR-12245000 Sao Jose Dos Campos, SP, Brazil

Made available in DSpace on 2020-12-12T01:10:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Purpose: This randomized clinical trial evaluated the influence of the occlusogingival distance (OGD) of noncarious cervical lesions (NCCLs) on the clinical performance of a regular bulk-fill resin composite and a regular nanofilled resin composite. Methods and Materials: A total of 140 restorations were randomly placed in 77 participants by one operator. NCCLs were divided into four groups (n=35) according to OGD (1.5 mm610% or 3 mm610%) and resin composites (Filtek Bulk Fill Posterior [B] or Filtek Z350 XT [C]) used: 1.5 mm-B, 1.5 mm-C, 3 mm-B, and 3 mm-C. A two-step self-etch adhesive (Clearfil SE Bond) was applied following manufacturer instructions in all restorative procedures. Restorations were polished 1 week after placement. Clinical evaluation was performed at baseline (7 days), 6 months, and 1 year by two calibrated examiners, according to the modified US Public Health Service criteria evaluating fractures/retention, marginal staining, marginal adaptation, recurrence of caries, anatomic form, postoperative sensitivity, and surface texture. The Kruskal-Wallis test was used for intergroup comparison in each followup; the Friedman analysis of variance, followed by the least significant difference test (multiple comparisons) was used for intragroup comparison between baseline and follow-up times (a=0.05). Results: Two restorations were lost at 12 months (1 for 1.5 mm-B and 1 for 3 mm-B). The retention rates at 12 months were 100% for 1.5 mm-C, 97% for 1.5 mm-B, 100% for 3 mm-C; and 97% for 3 mm-B, with no statistical difference among the groups (p=0.570). At 12 months, a statistically significant difference was found among the follow-up times for the same group (1.5 mm-B, 1.5 mm-C, and 3 mm-B) regarding the marginal staining criterion; moreover, the 3 mm-C group showed a significant difference from 6 months. No significant difference was found for the other parameters. Conclusion: Both resin composites showed acceptable clinical performance, and the OGD of NCCLs did not influence the clinical performance of resin composite restorations after 12 months. Academic Group of Clinical Research (GAPEC Department of Restorative Dentistry Institute of Science and Technology Sao Paulo State University-UNESP, Av Francisco José longo, 777 Department of Restorative Dentistry Institute of Science and Technology Sao Paulo State University-UNESP Department of Dental Material and Prosthodontics Institute of Science and Technology Sao Paulo State University-UNESP Academic Group of Clinical Research (GAPEC Department of Restorative Dentistry Institute of Science and Technology Sao Paulo State University-UNESP, Av Francisco José longo, 777 Department of Restorative Dentistry Institute of Science and Technology Sao Paulo State University-UNESP Department of Dental Material and Prosthodontics Institute of Science and Technology Sao Paulo State University-UNESP

Made available in DSpace on 2020-12-12T01:42:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-12-01 The present study elucidates the mechanical performance of different designs of resin-bonded fixed dental prostheses made of lithium disilicate simulating masticatory loads of anterior or canine guidance. A three-dimensional model of maxilla was constructed containing central incisor and canine teeth, with edentulous space of the lateral incisor. Three designs of prosthesis were created: retained in central incisor (1-I), retained in canine (1-C) and fixed in both teeth (2-IC). The computational analysis was performed for load in canine and central incisor separately (100N, 45°). The tensile and shear stresses were calculated for the resin-bonded fixed dental prosthesis, bonding surface of each retainer and cement layer using 3D finite element analysis. The 20 highest stress values were analyzed using two-way ANOVA and post-hoc Tukey test, all with α = 5%. The computational analysis showed that 2-retainer resin-bonded fixed dental prosthesis presented the worst prognosis regardless of the mandibular movement. ANOVA showed that Mandibular movement*Retainer interaction influenced on the tensile and shear stresses values (p < 0.01). Higher stresses were observed in the connector region for all groups (13–82.2 MPa; 11–70.2 MPa). In order to reduce the stress concentration in the resin-bonded fixed dental prosthesis and the retainer made of lithium disilicate, the occlusion may serve as the selection criteria of the unitary abutment for better sustainability. Post-Graduate Program in Restorative Dentistry (Prosthodontic) Department of Dental Materials and Prosthodontics São Paulo State University (Unesp/SJC) Department of Dental Materials Science Academic Centre for Dentistry Amsterdam (ACTA) Universiteit van Amsterdam and Vrije Universiteit, Gustav Mahlerlaan #3004 Post-Graduate Program in Restorative Dentistry (Prosthodontic) Department of Dental Materials and Prosthodontics São Paulo State University (Unesp/SJC), Engenheiro Francisco José Longo Avenue, 777, São José dos Campos/SP Department of Restorative Dentistry Division of Prosthodontics Federal University of Rio Grande do Norte (UFRN) University of Zürich Dental Materials Unit Center for Dental and Oral Medicine Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Rämistrasse 71 Post-Graduate Program in Restorative Dentistry (Prosthodontic) Department of Dental Materials and Prosthodontics São Paulo State University (Unesp/SJC) Post-Graduate Program in Restorative Dentistry (Prosthodontic) Department of Dental Materials and Prosthodontics São Paulo State University (Unesp/SJC), Engenheiro Francisco José Longo Avenue, 777, São José dos Campos/SP

The aim of this study was to investigate the three-dimensional wear, volumetric loss and surface roughness after chewing simulation of two glass ceramics. Lithium disilicate (LD, Emax CAD, Ivoclar) and Zirconia reinforced lithium silicate (ZLS, Vita Suprinity, Vita Zhanfabrick) discs (n=20/g) were scanned to obtain stereolithography (STL) files for each sample. All discs were submitted to chewing simulation with sliding configuration (30 N, 300,000 cycles, 6 mm and 1.7 Hz) with steatite as antagonist. The samples were then scanned again and the volume loss and the deepest defect depth was measured using the superimposed file from the baseline using three-dimensional digital parametric inspection software (GOM Inspect, Braunschweig, Germany). Surface roughness (Ra and Rz) was analyzed with a contact profilometer. Data were analyzed by one-way ANOVA and Tukey test (α=0.5%). ANOVA showed significant differences among the groups. Considering the ceramic volume loss, wear depth defect length and Rz roughness, LD (-22.09±5.57%; 0.80±0.06 µm; 3.08±1.02 µm) showed higher mean values than ZLS (-15.67±4.51%; 0.56±0.09 µm; 1.51±0.90 µm). Ra mean values were similar for both materials (p=0.064). All discs exhibited slight surface scratches along with the sliding direction with pitted wear patterns, while large cracks were observed on wear traces. These same areas can be identified in blue, overlapping the STL files before and after chewing simulation in inspection software. The linear reduction generated by sliding contact shows a graph with a similar wear pattern shape. ZLS was more resistant to wear than LD, with less volume loss and shallower surface defects. Resumo O objetivo deste estudo foi investigar o desgaste tridimensional, perda volumétrica e rugosidade após a simulação de mastigação de dois materiais vitro-cerâmicos. Discos de dissilicato de lítio (LD, Emax CAD, Ivoclar) e silicato de lítio reforçado com zircônia (ZLS, Vita Suprinity, Vita Zhanfabrick) (n=20/g) foram confeccionados e digitalizados para obtenção de arquivos de estereolitografia (STL) de cada amostra. Todos os discos foram submetidos à simulação de mastigação com configuração deslizante (30 N, 300.000 ciclos, 6 mm e 1,7 Hz) com esteatita como antagonista. As amostras foram escaneadas novamente e a perda de volume e o defeito mais profundo foram medidos usando o arquivo sobreposto da linha de base através de um software de inspeção paramétrica digital e tridimensional (GOM Inspect, Braunschweig, Alemanha). A rugosidade superficial (Ra e Rz) foi avaliada através de rugosímetro de contato. Os resultados foram analisados por ANOVA 1-fator e teste Tukey (α=0,5%). ANOVA mostrou diferenças significantes entre os grupos. Considerando a perda de volume cerâmico, comprimento do defeito e rugosidade Rz, LD (-22,09±5,57%; 0,80±0,06 µm; 3,08±1.02 µm) apresentou valores médios superiores a ZLS (-15,67±4,51%; 0,56±0,09 µm; 1.51±0.90 µm). Todos os discos exibiram pequenos arranhões na superfície conforme a direção de deslizamento com padrões de desgaste, enquanto grandes ranhuras foram observadas nos traços de desgaste. Essas mesmas áreas podem ser identificadas em azul, sobrepondo os arquivos STL antes e depois da simulação de mastigação no software de inspeção. A redução linear gerada pelo contato deslizante mostra um gráfico com uma forma de padrão de desgaste semelhante. ZLS foi mais resistente ao desgaste do que LD, com menor perda de volume e menores defeitos superficiais.

Objectives To evaluate the influence of the restorative technique on the mechanical response of endodontically-treated upper premolars with mesio-occluso-distal (MOD) cavity. Materials and methods Forty-eight premolars received MOD preparation (4 groups, n = 12) with different restorative techniques: glass ionomer cement + composite resin (the GIC group), a metallic post + composite resin (the MP group), a fiberglass post + composite resin (the FGP group), or no endodontic treatment + restoration with composite resin (the CR group). Cusp strain and load-bearing capacity were evaluated. One-way analysis of variance and the Tukey test were used with α = 5%. Finite element analysis (FEA) was used to calculate displacement and tensile stress for the teeth and restorations. Results MP showed the highest cusp (p = 0.027) deflection (24.28 ± 5.09 µm/µm), followed by FGP (20.61 ± 5.05 µm/µm), CR (17.72 ± 6.32 µm/µm), and GIC (17.62 ± 7.00 µm/µm). For load-bearing, CR (38.89 ± 3.24 N) showed the highest, followed by GIC (37.51 ± 6.69 N), FGP (29.80 ± 10.03 N), and MP (18.41 ± 4.15 N) (p = 0.001) value. FEA showed similar behavior in the restorations in all groups, while MP showed the highest stress concentration in the tooth and post. Conclusions There is no mechanical advantage in using intraradicular posts for endodontically-treated premolars requiring MOD restoration. Filling the pulp chamber with GIC and restoring the tooth with only CR showed the most promising results for cusp deflection, failure load, and stress distribution.

BACKGROUND: The rehabilitation of canine guidance can be performed with adhesive indirect materials, but can the restoration thickness be reduced without mechanical disadvantages? Thus the goal of this study was to analyze the stress of upper canines which received different thicknesses of ceramic fragments for the rehabilitation of the canine guidance using finite element analysis. METHODS: A superior canine was modeled using a computer aided design software. The dental tissues were individually shaped containing enamel, dentin and periodontal ligament. The following three different ceramic fragment thicknesses were then implemented: 0.3, 0.7 and 1.5 mm. Lithium disilicate was chosen as the ceramic material. The solid geometries were exported to the analysis software. The materials were considered isotropic, homogeneous and linear. The set was submitted to efforts in the incisal third in the palatine face to analyze maximal principal stress, mimicking mandibular lateral movement. The applied load was 100N, and the fixation region was on the medullary bone. RESULTS: For restoration, the thinner the ceramic, the higher the stress concentration was; while for the adhesive surface of teeth, the thicker the ceramic, the higher the stress concentration. CONCLUSIONS: The smaller the ceramic thickness was, the lower stress concentration showed at the adhesive interface, while the stress concentration was higher on the restoration intaglio surface.

Made available in DSpace on 2019-10-06T16:28:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-08-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The goal of this study was to compare the mechanical response of resin-bonded fixed dental prosthesis (RBFDP)made in zirconia, metal, lithium disilicate and composite resin cemented using resin cements with different elastic modulus. For the finite element analysis, a three-dimensional model of partial right maxilla was used to create a model with edentulous space in the second premolar and the cavity's preparation on the first pre-molar and first molar to receive a RBFDP. The model was imported to the analysis software in which they were divided into mesh composed by nodes (371,101)and tetrahedral elements (213,673). Each material was considered isotropic, elastic and homogeneous. No-separation contacts were considered between restoration/resin cement and resin cement/tooth. For all other structures the contacts were considered ideal. The model fixation occurred at the base of the bone and an axial load of 300 N was applied on the pontic occlusal surface. To simulate polymerization shrinkage effects on the cement, the thermal expansion approach was used. The displacement and maximum principal stress (in MPa)were selected as failure criteria. The prosthesis made in composite resin showed higher displacement, while in zirconia showed higher stress concentration. Tensile stress between restoration/cement, cement and cement/cavity was directly proportional to the restorative material's elastic modulus. The more rigid cement increases the tensile zones in the cement layer but decreases the stress between prosthesis and cement. The molar cavity showed higher stress concentration between restoration/cement than the preparation in the pre-molar tooth. The use of composite resin for the manufacturing of RBFDP increases the displacement of the set during the loading. However, it reduces the amount of stress concentration at the adhesive interface in comparison with the other materials. Post-Graduate Program in Restorative Dentistry (Prosthodontic) Department of Dental Materials and Prosthodontics São Paulo State University (Unesp/SJC) Department of Dental Materials Science Academic Centre for Dentistry Amsterdam (ACTA) Universiteit van Amsterdam and Vrije Universiteit, Gustav Mahlerlaan #3004, 1081, LA Amsterdam Post-Graduate Program in Restorative Dentistry (Prosthodontic) Department of Dental Materials and Prosthodontics São Paulo State University (Unesp/SJC), Engenheiro Francisco José Longo Avenue, 777 University of Zürich Dental Materials Unit Center for Dental and Oral Medicine Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Rämistrasse 71 Post-Graduate Program in Restorative Dentistry (Prosthodontic) Department of Dental Materials and Prosthodontics São Paulo State University (Unesp/SJC) Post-Graduate Program in Restorative Dentistry (Prosthodontic) Department of Dental Materials and Prosthodontics São Paulo State University (Unesp/SJC), Engenheiro Francisco José Longo Avenue, 777 FAPESP: 18/09207-0

Made available in DSpace on 2019-10-06T16:31:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-09-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The study aimed to evaluate the influence of cavosurface angle on stress concentration and gap formation in class V restorations. Cylindrical cavities 3 mm in diameter were prepared in forty-five bovine incisors, changing only the angle of the bur in relation to the flat surface of the tooth. The cavities maintained the same volume (17.67 mm³). The samples were divided according to the cavosurface angle, into three groups (n = 15): 90°, 120°, 135°. After adhesive application (Futurabond U, VOCO), the cavity was filled with bulk placement of a resin composite (GrandioSO, VOCO). The teeth were analyzed with stereomicroscopy. Data of marginal gap formation were statistically analyzed with a one-way analysis of variance (ANOVA) followed by Tukey tests (significance level: α = 0.05). Finite element analysis (FEA) was used to study residual stress in these geometries and to correlate those stresses with experimentally measured gap formation. The elastic modulus and polymerization shrinkage were determined for FEA. Residual shrinkage stresses were expressed in maximum principal stress (MPS). There was a significant difference in the gap formation among the groups (p = 0.001). A significantly lower marginal gap formation was found for 120° and 135° angles, with no significant difference between them. The cavosurface angle at 90° caused substantially higher stresses, in the restoration interface, with greater marginal gap. For the 120° and 135° angles, the stress concentrations were smaller and were located in the dental structure. The cavosurface angle influenced the marginal gap formation and stress concentration. Department of Restorative Dentistry São Paulo State University - UNESP Institute of Science and Technology, São José dos Campos Department of Biomedical and Applied Sciences Division of Dental Biomaterials Indiana University School of Dentistry (IUSD) Department of Dental Materials and Prosthodontics São Paulo State University - UNESP Institute of Science and Technology, São José dos Campos Department of Restorative Dentistry São Paulo State University - UNESP Institute of Science and Technology, São José dos Campos Department of Dental Materials and Prosthodontics São Paulo State University - UNESP Institute of Science and Technology, São José dos Campos CNPq: 30764

Because the main complication of implant-supported prostheses is torque loosening and/or fixation screw fracture, the goal of this study was to evaluate the torque before and after fatigue (screw placement and removal, respectively), single load-to-failure (compression test), and stress concentration of straight and angled abutments. Eighty implants were included in polyurethane cylinders. Half of the implants received straight abutments (group S, n = 40) and the other half received angled abutments (group A, n = 40). The abutments for cemented prostheses were installed with a torque of 20 Ncm. Eighty titanium structures were machined and cemented on the abutments with zinc-phosphate cement. After storage for 24 hours, half of the specimens had their torque loosening evaluated and were then immediately submitted to a compressive test in a universal testing machine (1 mm/minute, 1,000 kgf), while the other half were subjected to cyclic fatigue (200 N at 2 Hz for 2 × 106 cycles at 37°C) as an aging protocol (n = 20 from each group). The aged samples then had their torque loosening measured and were also submitted to the compression test. Representative samples were evaluated by scanning electron microscopy. Two bidimensional models similar to the in vitro specimens were created and analyzed using the finite element method to evaluate the stress concentration. Data from the in vitro tests were submitted to two-way analysis of variance and Tukey test, both with significance at P = .5. The results show that angled abutments are less capable of maintaining the installation torque and are less resistant during the single load-to-failure test. The von Mises stress concentration was higher for group A in the cervical region. The straight abutments have better prognosis than angled abutments and less susceptibility to mechanical failures.

Made available in DSpace on 2019-10-06T16:05:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-02-01 Objectives: The purpose of the study was to characterize the microstructure, constituents, and mechanical properties of mono and bilayered zirconia specimens infiltrated with silica by the sol gel method. Methods: 180 zirconia discs (14-mm diameter) were divided in 3 groups (n = 60) according to thickness (1.2, 0.5 mm) and further divided in two groups (n = 30) according to treatment (infiltrated or not). Disk thickness was 1.2 mm for the control samples. Veneering feldspathic porcelain had two thicknesses (0.5 mm and 1 mm) at the tops of the zirconia discs. All groups were subjected to the biaxial flexural test in an aqueous medium. Weibull analysis was performed for determination of the Weibull modulus (m) and characteristic strength (σ0). The specimens were characterized by SEM and EDS and XRD. Hardness and elastic modulus were measured by nano-indentation and pulse-echo methods, respectively. Fracture toughness was determined by the nano-indentation technique. A scratch test was used for evaluation of the adhesion between the zirconia and porcelain. Results: There was less variability (higher Weibull modulus) in the infiltrated monolithic specimens; biaxial flexural strength was not statistically higher in the veneered infiltrated specimens and was decreased for the 1-mm veneered infiltrated group. The diffractograms showed formation of ZrSiO4 crystal phase. Hardness also increased in the infiltrated monolithic zirconia, whereas fracture toughness decreased. Adhesion between zirconia and porcelain was superior in the non-infiltrated monolithic specimens. Conclusions: Infiltration increased the structural homogeneity and hardness of the monolithic zirconia, but it reduced fracture toughness, and the adhesion to porcelain. Clinical significance: Within the limitations of the present study, it is possible to recommend the infiltration of silica gel in zirconia only for monolithic restorations. Univ. Estadual Paulista (UNESP) Institute of Science and Technology at São José dos Campos Department of Dental Materials and Prosthodontics, Eng. Francisco José Longo Avenue 777 Aeronautics Technological Institute (ITA), 50 Praça Marechal Eduardo Gomes Institute of Advanced Studies (IEAV) Aerospace Technical Center, Rodovia dos Tamoios Km 5,5, Torrão de Ouro Univ. Estadual Paulista (UNESP) Institute of Science and Technology at São José dos Campos Department of Dental Materials and Prosthodontics, Eng. Francisco José Longo Avenue 777

Background: The goal of this study was to evaluate the influence of dental substrate simulator material, and the presence of root and periodontal ligament on the stress distribution in an adhesively-cemented monolithic crown.Material and methods: Five (5) 3D models according to the substrate simulator material and shape were modeled with CAD software for conducting non-linear finite element analysis (FEA): Tooth with and without periodontal ligament - subgroup "pl" (groups Tooth+pl and Tooth-pl), machined tooth in epoxy-resin with and without pulp chamber - subgroup "pc" (ER+pc and ER-pc) and simplified epoxy-resin substrate without pulp chamber and roots (SiER). Next, adhesively-cemented monolithic crowns in zirconia reinforced lithium silicate were modeled over each substrate. The solids were then imported in STEP format to the analysis software and the contact between teeth and cylinder was considered perfectly bonded; whereas, the contacts involving the resin cement were considered as non-separated. The materials were considered isotropic, linearly elastic, and homogeneous. An axial load (600 N) was applied to the occlusal surface and results of maximum principal stress (MPa) on the restoration were required.Results: FEA revealed that all evaluated subtracts showed the crown intaglio surface as the most stressed region. The average stress and stress peaks were similar for restorations cemented onto Tooth+pl, Tooth-pl and ER+pc substrates, but, 13% higher in comparison to ER-pc and SiER substrates.Conclusions: Simplified substrates can be used to evaluate posterior full crown behavior without periodontal ligaments and roots, since the rigidity of the specimen is taken into account. Key words:Finite element analysis, axial loading, computed assisted numerical analisys, monolithic crowns,methodological study.

Background To evaluate the stress distribution in a maxillary central incisor with different post and cores made of six CAD/CAM materials with different elastic modulus in the absence of ferrule using the finite element analysis. Material and methods A three-dimensional endodontically treated maxillary central incisor restored with an all-ceramic crown was modelled in Rhinoceros (5.0 SR8, McNeel). The geometries were analyzed in ANSYS 17.2 (ANSYS Inc.) considering isotropic, homogeneous, linearly elastic materials with perfectly bonded contacts. The elastic moduli (E) of the post-and-cores defined the groups to be compared: nanoceramic resin (E=12.8GPa); composite resin (E=16GPa); hybrid ceramic (E=34.7GPa); lithium disilicate (E=95GPa); titanium (Ti-Al6-V4) (E=112GPa); and Y-TZP material (E=209.3GPa). The set was constrained in the cortical bone and loaded (45°/100 N) on the incisor palatine face. Stress distribution was analyzed by Maximum Principal Stress criteria for the crown-core cement line, Post-and-core's cement line, Post-and-core system and Dentin. Results The stress distribution at the crown-core cement line (11.4 - 13.2 MPa) was inversely proportional to the increase of the elastic modulus of the post-core approaches, while it was direct proportional on the post-and-core (4.7 - 40 MPa) and cement line (4.1 - 6.2 MPa). Stress distribution on the dentin was similar for all groups (24.7 - 25.3). Conclusions Post-and-core made by CAD/CAM seems to be an efficient treatment alternative, since it is a conservative approach, promotes better aesthetic quality and it allows the control of the cement line thickness. Key words:Endodontically treated teeth, Post-and-core technique, Ceramic crown, Finite element analysis, Biomimetics.

Made available in DSpace on 2020-12-12T01:20:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Background: This study evaluated the presence of a silica-nylon mesh and two cantilever lengths on the biomechanical behavior of complete-arch implant-supported prostheses. Material and Methods: Twenty-four (24) complete mandibular arch implant-supported prostheses were divided into 4 groups according to the presence of reinforcing mesh (with or without) and the cantilever length (molar-15 mm or premolar-5 mm). The specimens were submitted to strain gauge analysis (30-kgf, 10 s) at different points (molar and premolar). Three-dimensional models were created based on the in vitro specimens, and the results in the bone (microstrain), prostheses (tensile stress), implants and prosthetic screws (von-Mises stress) were evaluated using the finite element method (FEM). All materials were considered homogeneous, isotropic and linear. Strain gauge data were submitted to 3-way analysis of variance and the Tukey test (α=.05). FEM results were qualitatively analyzed using colorimetric graphs. Results: The microstrain magnitude for the prostheses with reinforcement was 519.91±359 and 583.33±661 without reinforcement (p=.001). The microstrain values for loading on the molar was 867.49±784 and on the premolar was 235.75±145. FEM corroborated with the in vitro findings for the bone behavior. The load application in the premolar showed reduced stress concentration, and a significant difference was observed between the presence or absence of the reinforcement for the prostheses. Conclusions: Silica-nylon mesh reduced the peri-implant microstrain and the prosthesis stress regardless of the cantilever extension. For temporary complete-arch implant-supported prostheses, the limitation of the cantilever to the premolar region improves the biomechanical response during load application. Department of Dental Materials and Proshodontics São Paulo State University (Unesp) Institute of Science and Technology Department of Dentistry (Prosthethic Dentistry) University of Taubaté (Unitau) Department of Prosthodontics Brazcubas Education Department of Dental Materials and Proshodontics São Paulo State University (Unesp) Institute of Science and Technology

Made available in DSpace on 2021-06-25T11:15:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Objetives: this study aimed to fabricate electrospun-based polyetherimide (PEI) fibers, under controlled parameters, and to perform a diameter analysis for potential mechanical improvement of dental materials. Material and Methods: PEI pallets (0.75 g) were dissolved in 2 mL of chloroform and then processed by electrospinning, under a flow rate of 1mLh- 1, three different electrical voltages (10kV, 15kV and 20kV) and three distances (10 cm, 15 cm and 18 cm) between the needle tip and collector. These parameter combinations resulted in nine experimental groups that were analyzed using scanning electron microscopy (SEM) and image processing program for diameter measurement. Statistical analysis was performed using two-way ANOVA with post-hoc Tukey (5% significance). Results: from SEM images it was possible to observe formation of solid, misaligned and flawless defect-free fibers. And from the statistical analysis, distance (p = 0,0026) and the electric tension (p = 0,0012) showed a significant difference, but not for interaction between then (p = 0,4486). Conclusion: thus, it can be concluded that there is a possibility of the morphology control of PEI electrospun fibers, such as diameter, that can be used for a variety of applications such as incorporation in dental materials in order to improve its properties. Institute of Science and Technology of Sao Jose dos Campos São Paulo State University (UNESP) Institute of Science and Technology of Sao Jose dos Campos São Paulo State University (UNESP)

Purpose To evaluate the effect of replacement of inadequate complete dentures on salivary flow and taste perception in geriatric patients. Materials and Methods Thirty-three patients, 13 males and 20 females, with a mean age of 64.4 years were submitted to stimulated and unstimulated salivary flow rate and salivary pH measurements, and sense of taste evaluation. Tests were performed 3 months before complete denture substitution and 3 weeks after denture insertion. Results The mean for unstimulated saliva (USS) was 2.1 ml before and 2.7 ml after replacement (p = 0.003). The mean volume of stimulated saliva was 6.3 ml before and 8.2 ml after replacement (p = 0.004). The pH mean of USS was 7.8 ± 0.44 before and 8.02 ± 0.41 after replacement (p = 0.005). No statistically significant difference was determined in the sense of taste before and 3 weeks after complete denture replacement. Conclusions The replacement of inadequate complete dentures increases saliva flow; however, it does not improve taste perception.

Made available in DSpace on 2020-12-12T01:37:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) This study aimed to synthesize and characterize non-woven acrylonitrile butadiene styrene (ABS), polyamide-6 (P6), and polystyrene (PS) nanofibers, and evaluate their effects on the flexural strength and fracture resistance of fiber-modified polymethyl methacrylate (PMMA) resin. ABS, P6, and PS polymer solutions were prepared and electrospun into fiber mats, which were characterized by means of morphological, chemical, physical, and mechanical analyses. The fiber mats were then used to modify a thermally-activated PMMA resin, resulting in four testing groups: one unmodified group (control) and three fiber-modified groups incorporated with ABS, P6, or PS fiber mats. Flexural strength, work of fracture, and fractographic analysis were performed for all groups. Data were analyzed using Kruskal-Wallis or ANOVA tests (α = 0.05). The fiber diameter decreased, respectively, as follows: ABS > P6 > PS. Only the P6 fiber mats demonstrated a crystalline structure. Wettability was similar among the distinct fiber mats, although tensile strength was significantly greater for P6, followed by ABS, and then PS mats. Flexural strength of the fiber-modified PMMA resins was similar to the control, except for the weaker P6-based material. The work of fracture seemed to be greater and lower when the P6 and PS fibers were used, respectively. The fiber-modified groups exhibited a rougher pattern in the fractured surfaces when compared to the control, which may suggest that the presence of fibers deviates the direction of crack propagation, making the fracture mechanism of the PMMA resin more dynamic. While the neat PMMA showed a typical brittle response, the fiber-modified PMMA resins demonstrated a ductile response, combined with voids, suggesting large shear deformation during fracture. Altogether, despite the lack of direct reinforcement in the mechanical strength of the PMMA resin, the use of electrospun fibers showed promising application for the improvement of fracture behavior of PMMA resins, turning them into more compliant materials, although this effect may depend on the fiber composition. Graduate Program in Dentistry São Paulo State University (UNESP) Department of Conservative Dentistry School of Dentistry Federal University of Rio Grande do Sul Department of Dental Materials and Prosthodontics Institute of Science and Technology UNESP Department of Cariology Restorative Sciences and Endodontics University of Michigan School of Dentistry Graduate Program in Dentistry São Paulo State University (UNESP) Department of Dental Materials and Prosthodontics Institute of Science and Technology UNESP CNPq: 310659/2014-0 CNPq: 310973/2014-7 CAPES: CAPES; code 001

The current study aimed to evaluate the mechanical behavior of two different maxillary prosthetic rehabilitations according to the framework design using the Finite Element Analysis. An implant-supported full-arch fixed dental prosthesis was developed using a modeling software. Two conditions were modeled: a conventional casted framework and an experimental prosthesis with customized milled framework. The geometries of bone, prostheses, implants and abutments were modeled. The mechanical properties and friction coefficient for each isotropic and homogeneous material were simulated. A load of 100 N load was applied on the external surface of the prosthesis at 30&deg, and the results were analyzed in terms of von Mises stress, microstrains and displacements. In the experimental design, a decrease of prosthesis displacement, bone strain and stresses in the metallic structures was observed, except for the abutment screw that showed a stress increase of 19.01%. The conventional design exhibited the highest stress values located on the prosthesis framework (29.65 MPa) between the anterior implants, in comparison with the experimental design (13.27 MPa in the same region). An alternative design of a stronger framework with lower stress concentration was reported. The current study represents an important step in the design and analysis of implant-supported full-arch fixed dental prosthesis with limited occlusal vertical dimension.