Search

Statement of problem Various strategies have been proposed to reduce the cement space of foundation restorations for endodontically treated teeth. However, they may add more operative steps, or the dentist must keep different sizes of drills and posts in stock. A 2-piece universal adjustable post system has been developed to overcome this problem, but whether the system has acceptable fatigue survival performance is unclear. Purpose The purpose of this in vitro study was to evaluate the fatigue survival and stress distribution of endodontically treated teeth without a ferrule and restored with different glass fiber post strategies versus a recently introduced universal 2-piece fiber post system. Material and methods Bovine incisor roots were randomly assigned to 3 groups as per the post used (n=13): adapted glass fiber post with post space preparation of the same size, composite resin-custom glass fiber post (CTM), and universal 2-piece glass fiber-reinforced composite resin post (UNI). The posts were adhesively luted, the composite resin core was added, and a composite resin crown was produced with computer-aided design and computer-aided manufacturing (CAD-CAM), and then adhesively luted to each core. A fatigue test was performed with the stepwise stress method (10 000 cycles/step; 20 Hz; load=100 N to 750 N; step=50 N) until fracture, and the failure mode analyzed. The stress distribution was evaluated by finite element analysis with the maximum principal stress criteria by following the parameters of the in vitro test. The solids were considered homogeneous, linear, and isotropic, except for the glass fiber post (orthotropic), and a load of 450 N at 30 degrees was applied. The fatigue failure load and the number of cycles for failure were analyzed with Kaplan-Meier and Mantel-Cox (log rank test) (α=.05). The finite element analysis results were analyzed with colorimetric graphs. Results The highest fatigue failure load and the number of cycles for failure were found in the UNI system, whereas the lowest results were found in the CTM group. All groups exhibited repairable failures. The finite element analysis showed the lowest stress in root dentin in the UNI system. The CTM system had the largest stress regions at the dentin and dentin-core interface. Conclusions The use of a 2-piece universal glass fiber post system resulted in more fatigue behavior compared with composite resin-custom glass fiber posts.

To compare 2 different resin composites and 2 adhesive systems used in a new restorative protocol (partial restoration) to treat non-carious cervical lesions associated with gingival recession type 1 (RT1).Eighty combined defects (CDs) were treated with a partial restoration and periodontal plastic surgery for root coverage. The CDs were randomly assigned to one of the following groups: NP + TE (n = 20), nanofilled composite and 2-step total-etch adhesive system; NP + UA (n = 20), nanofilled composite and universal adhesive system; MH + TE (n = 20), microhybrid composite and 2-step total-etch adhesive; MH + UA (n = 20), microhybrid composite and universal adhesive. Restorations were assessed using the United States Public Health Service (USPHS) criteria at 1 week (baseline) and 6, 12, and 24 months. Survival rate, periodontal parameters, dentin hypersensitivity (DH), and aesthetics were also evaluated.After 24 months, only the MH + TE group did not lose any restoration, with no significant differences between groups. For surface roughness parameter, MH presented 83.3% of the restorations scoring Bravo, whereas NP presented 48.5% of the restorations scoring Bravo. All groups presented restorations with marginal discoloration. All periodontal parameters behaved similarly, regardless of the restorative material. All groups presented significant reductions of dentin hypersensitivity and improved aesthetic perceptions (p 0.05).Both resin composites and adhesives tested can be combined for partial restorations to treat CDs.This new restorative-surgical protocol to treat CDs presents satisfactory outcomes. The partial restorations can be successfully executed with both combinations of adhesives and resin composites evaluated in this investigation. TRN : ClinicalTrial.gov: NCT03215615; registration date July 12, 2017.

Made available in DSpace on 2022-05-01T09:31:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Objectives: This study evaluated the effect of deep margin elevation (DME) and restorative materials (leucite-reinforced glass–ceramics [C] vs. indirect resin composite [R]) on the fatigue behavior and stress distribution of maxillary molars with 2-mm deep proximal margins restored with MOD inlay. Methods: Fifty-two extracted human third molars were randomly assigned into four groups (n = 13): C; DME + C; R; and DME + R. Inlays were fabricated in CAD-CAM and bonded to all teeth. The fatigue behavior was assessed with the stepwise stress test (10,000 cycles/step; step = 50 N; 20 Hz; initial load = 200 N). Fatigue failure loads and the number of cycles were analyzed with 2-way ANOVA and Tukey’s test (p < 0.05) and Kaplan–Meier survival plots. The stress distribution was assessed with finite element analysis. The models were considered isotropic, linear, and homogeneous, and presented bonded contacts. A tripod axial load (400 N) was applied to the occlusal surface. The stress distribution was analyzed with the maximum principal stress criterion. Results: For fatigue, there was no difference for DME factor (p > 0.05). For the material factor, the load and number of cycles for failure were statistically higher in the R groups (p < 0.05). The finite element analysis showed that resin composite inlays concentrated more stress in the tooth structure, while ceramic inlays concentrated more stress in the restoration. Non-reparable failures were more frequent in the resin composite inlays groups. Conclusions: DME was not negative for fatigue and biomechanical behaviors. Resin composite inlays were more resistant to the fatigue test, although the failure mode was more aggressive. Clinical significance: DME does not impair mechanical behavior. Resin composite inlays failed at higher loads but with a more aggressive failure mode. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp), 777th Eng. Francisco José Longo Av., SP Post-Graduate Program in Dentistry University of Taubaté (UNITAU), 09th Rua Dos Operários St., SP Graduate Program of Oral Science Prosthodontics Unit School of Dentistry Federal University of Santa Maria (UFSM) Roraima Av, RS School of Dentistry São Francisco University (USF), 218th São Francisco de Assis Av., SP Department of Restorative Dentistry Institute of Science and Technology São Paulo State University (Unesp), 777th Eng. Francisco José Longo Av., SP Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp), 777th Eng. Francisco José Longo Av., SP Department of Restorative Dentistry Institute of Science and Technology São Paulo State University (Unesp), 777th Eng. Francisco José Longo Av., SP

Objectives This article evaluated the effect of substrates rigidities on the post-fatigue fracture resistance of adhesively cemented simplified restorations in lithium disilicate glass ceramic. Methods Precrystalized computer-aided design/computer-aided manufacturing ceramic blocks were processed into disc-shaped specimens (n = 10, Ø = 10 mm), mimicking a simplified restoration at two thicknesses (0.5 and 1.0 mm). Thereafter, the discs were cemented onto different base substrates (dentin analogue [control], dentin analogue with a central core build-up of resin composite [RC], or glass ionomer cement [GIC]). The specimens were subjected to mechanical cycling in a chewing simulator (100 N, 1 × 106 cycles, 4 Hz) and then subjected to thermocycling aging (10,000 cycles, 5/37/55°C, 30 seconds). After the fatigue protocol, the specimens were loaded until failure (N) in a universal testing machine. Finite element analysis calculated the first principal stress at the center of the adhesive interface. Results The results showed that “restoration thickness,” “type of substrate,” and their interaction were statistically significant (one-way analysis of variance; p Conclusion More flexible base material reduces the fracture load and increases the stress magnitude of adhesively cemented lithium disilicate restorations regardless the ceramic thickness. Therefore, more rigid substrates are suggested to be used to prevent restoration mechanical failures.

This study evaluated the effect of resin cement coating with high and low viscosities on the flexural fatigue strength of machined lithium disilicate glass-ceramic. Discs (IPS e.max CAD; Ivoclar Vivadent) were prepared and divided according to the surface condition (machining [M]-CEREC inLab; and polishing [P]-laboratory procedures), resin cement coating (with or without), and cement viscosity (high [H] and low [L]). The ceramic bonding surface was etched/primed by a one-step primer application followed by resin cement application (Variolink N base + high or low viscosity catalyst; Ivoclar Vivadent). Biaxial flexural fatigue strength was evaluated on a piston-on-three-ball set by the step-test method (n = 15) (initial stress: 60 MPa; incremental steps: 20 MPa; 10,000 cycles/step, at 20 Hz). Weibull statistics were used for fatigue data. Contact angle, topographic, and fractographic analysis were also performed. Machining produced statistically lower contact angle than polishing and a significant detrimental effect on the fatigue behavior (σ

Objectives: The aim of this study was to compare the effect of three different access cavities on the tissue removal, deflection, fracture resistance, and stress distribution of extracted maxillary central incisors. Materials and methods: Forty human maxillary central incisors were randomly assigned in four experimental group (n = 10) including conservative access cavity “CAC,” traditional access cavity “TAC,” invasive access cavity “IAC,” and without access cavity (control group). Cone-beam computed tomography “CBCT” scans were used to evaluate the tissue removal during the different access cavities. All specimens were restored with composite resin (Admira Fusion, Voco, Cuxhaven, Germany) and embedded in acrylic resin blocks after simulating the periodontal ligament using red wax, then the specimens were submitted to the deflection test applying a load of 250 N and to the load-to-fracture test after artificial aging in a mechanical cycling machine (150 N, 5 × 106 cycles, 10 Hz). Lastly, stress distribution was assessed by three-dimensional finite element analysis (3D-FEA), simulating the specimens restoration by two types of composite resins of low and high elastic modulus (8 and 18 GPa respectively) after the access cavities. The data were submitted to Shapiro–Wilk and KS normality tests. Then, they were analyzed by one-way ANOVA and Tukey tests with a significance level (α ≤ 0.05). Results: CBCT scans showed a significant difference of worn tissues in CAC and TAC when compared to the IAC (P < 0.0001). In deflection test, CAC showed lower deformation values than the TAC and IAC. Load-to-fracture test presented no significant difference among the three experimental groups (P = 0.6901). 3D-FEA showed that the more conservative the access cavity, the higher the stress magnitude. Conclusions: CAC promote less worn tissue; however, this does not improve the stress distribution or fracture resistance of endodontically treated maxillary incisors. Clinical relevance: Clinicians should reconsider the pros and cons of the conservative access cavity.

Made available in DSpace on 2021-06-25T11:10:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 This study evaluated the polymerization shrinkage stress of three tooth preparation designs for indirect ceramic overlay by finite element analysis: isthmus preparation (IST); without isthmus preparation (wIST); and non-retentive preparation (nRET). The models were created based in prepared dental typodonts and were digitally impressed with an intraoral scanner. The interfaces in all models were considered perfectly bonded and all materials were considered homogeneous, linear, and isotropic. The polymerization shrinkage of the cement layer (100 µm) was simulated and evaluated by maximum principal stress criteria. The stress peaks followed this sequence: restoration = IST (13.4 MPa) > wIST (9.3 MPa) > nRET (9 MPa); cement layer = IST (16.9 MPa) > wIST (12.6 MPa) > nRET (10-7.5 MPa); and teeth = IST (10.7 MPa) > wIST (10.5 MPa) > (9 MPa). For the cement layer, the non-retentive preparation (nRET) had the lowest shrinkage stress from all the groups, obtaining a more homogeneous stress distribution on the cement surface. Regarding the abutment teeth, the IST generated a higher shrinkage stress area on the dental structure, concentrating higher stress magnitude at the axiopulpar and axiogingival angles. Non-retentive preparation seems to reduce polymerization shrinkage stress. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNESP) Departament of Dentistry Postgraduate Program in Dentistry University of Taubaté (UNITAU) Private Practice Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNESP)

Statement of problem: The trueness and precision of intraoral scanners (IOSs) and the effect of intracoronal restorations have been reported. However, studies addressing the accuracy of IOSs in reproducing different complete coverage onlay preparation designs are lacking. Purpose: The purpose of this in vitro study was to evaluate the influence of complete coverage onlay preparation design and intraoral scanning devices on the accuracy of digital scans in terms of trueness and precision. Material and methods: Three preparation designs on the mandibular first molar were considered: a traditional preparation design with isthmus reduction (IST), a traditional preparation design without isthmus reduction (wIST), and simplified nonretentive preparation (nRET). Digital scans of epoxy resin mandibular arch reference models of the preparations (containing second premolar, first molar, and second molar) were obtained by using 3 IOSs (iTero Element 2 [ELE], Trios 3 [TRI], and Primescan [PRI]) (n=10). Trueness (μm) and precision (μm) were analyzed by superimposing the digital scan on the digital reference models obtained with a high-accuracy industrial scanner (ATOS Core 80) in a tridimensional metrology software program. Accuracy was quantified by the absolute deviation (μm). Local and overall mean positive and negative deviations for trueness were also obtained. Data were analyzed by using the Kruskal-Wallis and Dunn tests with a statistical software program (α=.05). Results: The nonretentive preparation groups obtained higher trueness (3.8 μm) and precision (2.7 μm) than the IST and wIST groups (trueness=7.5 to 6.3 μm, precision=5.5 to 4.6 μm). Trueness values were lower with ELE×IST (16 μm), followed by ELE×wIST (13 μm), and PRI×IST (7.8 μm). In general, no difference was found between PRI and TRI scanners (6.3 to 5.9 μm), with lower performance for ELE (13 μm). Positive deviations were higher on the proximal box of the IST and wIST preparation and on the occlusal box of the IST group. Negative deviation was higher on the ELE×IST occlusal box. Conclusions: Different intraoral scanners and preparation designs influenced the accuracy of digital scans. A more complex preparation such as IST and wIST showed higher deviation. The iTero Element 2 scanner exhibited higher deviation for both trueness and precision.

Changes in the organic matrix of composite resins have been proposed to improve their surface properties. However, polishing systems may perform differently in different materials. This study compared the effect of polishing systems on the surface roughness of four composite resins containing different resin monomers: Admira Fusion (nanohybrid containing pure ormocer), Aura Bulkfill (nanohybrid containing Bis-GMA, UDMA), Charisma Diamond (nanohybrid containing TCD-DI-HEA) and Vittra APS (nanofilled containing UDMA). Cylinders (N = 120, n = 10) were prepared from each material and the top surface of each specimen was grounded using a diamond finishing bur. Baseline measurements of surface roughness (Ra) were recorded using a contact profilometer and the specimens of each composite were divided into three subgroups according to the polishing system: one-step, two-step, three-step. Ra measurements were recorded also after polishing. Data were analyzed using three-way ANOVA and Tukey’s test (p < 0.05). The baseline roughness of all composites was significantly reduced after polishing (p < 0.001). The two-step polishing system provided the smoothest surface for Admira Fusion (0.0770 ± 0.0171) and Charisma (0.1091 ± 0.0090), whereas for Aura and Vittra no significantly differences were found for the three polishing systems tested. The surface smoothness seems to be more material dependent than step dependent, but all tested systems provided clinically acceptable results.

Made available in DSpace on 2022-05-01T08:44:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-02-01 Objectives: To make an in vitro assessment of fracture resistance of weakened and non-weakened teeth receiving intraradicular reinforcement using Rebilda bundled glass fiber–reinforced composite posts (GT), Rebilda conventional glass fiber posts (RP), or both systems combined (GT + RP). Materials and methods: Eighty sound bovine incisors were prepared and divided randomly into eight groups as follows: (a) nWnR: without simulating weakness, and without intraradicular reinforcement; (b) WnR: simulating weakness, but without intraradicular reinforcement; (c) nWGT: without simulating weakness, but with GT; (d) WGT: simulating weakness, and with GT; (e) nWRP: without simulating weakness, but with RP; (f) WRP: simulating weakness, and with RP; (g) nWGTRP: without simulating weakness, but with GT + RP; (h) WGTRP: simulating weakness, and with GT + RP. The specimens were subjected to the load-to-fracture test using the DL-2000MF universal testing machine. The finite element method assessed the mechanical behavior and stress distribution in endodontically treated teeth. Results: The groups nWGTRP and WGTRP presented the best results in the load-to-fracture test, with the former being better than the latter, but with no statistically significant difference (P > 0.05). However, there was a significant difference between these and the other groups (P < 0.05), except for nWRP. Stress distribution inside the canal wall was different among the groups, with promising mechanical behavior for nWGTRP and nWRP. Conclusions: The Rebilda conventional fiber post (RP), combined with the Rebilda bundled glass fiber–reinforced composite post (GT) improves the resistance and stress distribution of immature teeth. Clinical relevance: Longitudinal fracture is less frequent in teeth restored with GT and RP posts. Department of Restorative Dentistry Endodontics Division Institute of Science and Technology São Paulo State University (UNESP), Av. Francisco José Longo 777, São Dimas, SP Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNESP) Department of Restorative Dentistry Operative Dentistry Division Institute of Science and Technology São Paulo State University (UNESP) Department of Restorative Dentistry Endodontics Division Institute of Science and Technology São Paulo State University (UNESP), Av. Francisco José Longo 777, São Dimas, SP Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNESP) Department of Restorative Dentistry Operative Dentistry Division Institute of Science and Technology São Paulo State University (UNESP)

Made available in DSpace on 2022-05-01T10:51:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Evidence regarding the effect of the onlay preparation design for different CAD/CAM restorative materials considering the preservation of cusps is lacking. Molars were 3D-modeled in four preparation designs for onlay restoration: Traditional design with functional cusp coverage (TFC), non-retentive design with functional cusp coverage (NFC), traditional design with non-functional cusp coverage (TNFC) and non-retentive design with non-functional cusp coverage (NNFC). The restorations were simulated with two CAD/CAM restorative materials: LD—lithium disilicate (IPS e.max CAD) and RC—resin composite (GrandioBloc). A 100 N axial load was applied to the occlusal surface, simulating the centric contact point. Von Mises (VM) and maximum principal (Pmax) stress were evaluated for restorations, cement layer and dental substrate. The non-retentive preparation design reduced the stress concentration in the tooth structure in comparison to the conventional retentive design. For LD onlays, the stress distribution on the restoration intaglio surface showed that the preparation design, as well as the prepared cusp, influenced the stress magnitude. The non-retentive preparation design provided better load distribution in both restorative materials and more advantageous for molar structure. The resin composite restoration on thenon-functional cusp is recommended when the functional cusp is preserved in order to associate conservative dentistry and low-stress magnitude. School of Dentistry Universidad Espíritu Santo Institute of Science and Technology São Paulo State University (Unesp) São José dos Campos Department of Dental Materials Academic Centre for Dentistry Amsterdam (ACTA) University of Amsterdam and Vrije Universiteit Amsterdam Department of Dentistry Center for Biological and Health Sciences Western Paraná State University (Unioeste) Fraunhofer JL IDEAS Department of Industrial Engineering University of Naples Federico II School of Dentistry University of Naples Federico II Institute of Science and Technology São Paulo State University (Unesp) São José dos Campos

Prefabricated glass fiber-reinforced composite posts have been widely used because of their esthetic properties and favorable biomechanical behavior; however, because they are prefabricated, they may not adapt to the anatomy of all root canals. This case report describes a procedure for restoring teeth with a custom, 1-piece, fiber-reinforced composite post and core fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM). The excellent adaptation of this custom endodontic post enables the use of a thinner, homogenous cement layer; in addition, it eliminates the need to construct a composite resin core build-up. Although more clinical and in vitro studies are needed to better define the appropriate clinical protocols and assess various materials, CAD/CAM technology allows post and core restorations to be manufactured in a predictable and simplified way.

Evidence regarding the effect of the onlay preparation design for different CAD/CAM restorative materials considering the preservation of cusps is lacking. Molars were 3D modeled in four preparation designs for onlay restoration: traditional design with functional cusp coverage (TFC), non-retentive design with functional cusp coverage (NFC), traditional design with non-functional cusp coverage (TNFC), non-retentive design with non-functional cusp coverage (NNFC). Restorations were simulated with two CAD/CAM restorative materials: LD – lithium disilicate (IPS e.max CAD) and RC - resin composite (GrandioBloc). A 100 N axial load was applied to the occlusal surface simulating the centric contact point. Von Mises (VM) and maximum principal (Pmax) stresses were evaluated for restorations, cement layer and dental substrate. The non-retentive preparation design reduced the stress concentration in the tooth structure in comparison to the conventional retentive design. For LD onlays, the stress distribution on the restoration intaglio surface showed that the preparation design as well as the prepared cusp, influenced the stress magnitude. The non-retentive preparation design provided better load distribution in both restorative materials and more advantageous for tooth structure. The resin composite restoration on non-functional cusp is recommended when functional cusp is preserved, in order to associate conservative dentistry and low stress magnitude.

Made available in DSpace on 2022-05-01T09:47:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-02 The aim of this study was to evaluate the effect of biologically oriented preparation technique on the stress concentration of endodontically treated upper central incisors restored with zirconia crown (yttria-stabilized zirconia polycrystalline ceramic) through finite element analysis (FEA). Four models of maxillary central incisors containing enamel, dentin, periodontal ligament, cortical and medullary bone were created in CAD. Each model received a polymeric core-build up with nanofilled dental resin composite. The evaluated models were SM—preparation in shoulder 90◦; CM—chamfer preparation; BOPT—biologically oriented preparation technique and BOPTB—BOPT preparation 1 mm below the cement-enamel junction. All models received zirconia crowns (5Y-TZP), fiberglass post and 1 mm ferrule. The models were imported into the analysis software with parameters for mechanical structural testing using the maximum principal stress and the tensile strength as the analysis criteria. Then, load of 150 N was applied at the cingulum with 45◦ slope to the long axis of the tooth, with the fixed base for each model. The type of marginal preparation affected the stresses concentration in endodontically treated teeth and in the zirconia crown margin. Considering the stress magnitude only, BOPT is a viable option for anterior monolithic zirconia crowns; however, with the highest stress magnitude at the restoration margin. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp) Faculty of Dentistry Universidade Estadual do Oeste do Paraná (UNIOESTE) Department of Dentistry University of Taubaté (UNITAU) 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)

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 2020-12-12T01:41:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Objective: The masticatory function is one of the most complex neuropsychological mechanisms in human motor performance and it depends on several factors, such as bite force, muscle coordination, morphology, and number of teeth in occlusion. To evaluate the influence of different rehabilitation treatments such as complete and partial dentures, masticatory forces, and the dynamics of mandibular elevator muscles. Material and Methods: the maximum bite force (force transducer) and electrical activity (superficial electromyography) associated with the masseter and temporal muscles were quantified. These factors were evaluated at rest position and isometric contraction. The data were subjected to descriptive statistics and compared based on the experimental groups, through ANOVA and Tukey’s tests. Results: for bite force, the ANOVA test showed statistical difference between groups and Tukey’s test showed that the force measured in the removable partial dentures group was 44.75% lower than that of the control group, while for complete denture wearers, there was a reduction of 74.4% in bite force in relation to the control group. For electromyographic activity, there was no statistical difference between groups. Pearson’s correlation test (α = 5%) showed positive correlation between the variables of bite force and electromyographic activity only for the control group. Conclusion: it was concluded that the loss of dental elements and their replacement with either partial or complete dentures has a great influence on bite force and electromyographic activity of the masseter and temporal muscles. 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 Department of Social Dentistry and Children’s São Paulo State University (Unesp) Institute of Science and Technology São José dos Campos Department of Biosciences and Oral Diagnosis 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 Department of Social Dentistry and Children’s São Paulo State University (Unesp) Institute of Science and Technology São José dos Campos Department of Biosciences and Oral Diagnosis

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 2021-06-25T11:08:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Statement of problem: Chairside computer-aided design and computer-aided manufacturing (CAD-CAM) materials that do not require any firing steps are a promising option to expedite restoration production; however, little information is available to determine the most suitable material for each clinical situation. Purpose: The purpose of this in vitro study was to evaluate the effect of simulated toothbrushing on surface gloss, roughness, and wear of chairside CAD-CAM materials. Material and methods: Disk-shaped specimens (n=15) were prepared of the following materials: ENA—VITA Enamic; LAV—Lava Ultimate; EMP—IPS Empress CAD; CER—Cerasmart; GRA—Grandio blocs. Gloss (Gloss Unit—GU) and surface roughness (Ra—μm) were evaluated before and after simulated toothbrushing (100 000 strokes). Wear (μm) was assessed by contact profilometry. Additional analyses of microhardness by scanning electron microscopy were also performed. Data were analyzed with 2-way repeated measures ANOVA test for roughness and gloss, and 1-way ANOVA for wear (α=.05). To estimate the correlation between Ra and GU, the Pearson correlation was calculated. Results: Before brushing, CER showed the lowest Ra (PGRA), with the exception of LAVA, which was similar to ENA, and EMP showing improved wear resistance. A strong negative correlation (-0.925) between GU and Ra values was detected (P

A odontologia sofre constantemente mudanças nos seus padrões de qualidade, porém, sempre devemos lançar mão, independente do procedimento restaurador, da famosa tríade: saúde, função e estética. Objetivo: Este relato de caso tem por finalidade demonstrar a técnica de facetas diretas em resina composta. Materiais e Métodos: Utilizou-se guia de silicone em resina composta de forma direta para reabilitar uma paciente com múltiplos diastemas anterossuperiores. Resultado: A utilização da guia em silicone facilitou a confecção da concha palatina por já ter formato, comprimento e largura preestabelecidos no enceramento diagnóstico. Paciente, jovem, demonstrou bastante entusiasmo após o término do procedimento. Conclusão: ainda na atualidade é possível não utilizar formas invasivas para reabilitações, principalmente nos casos de pacientes jovens.

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)

Made available in DSpace on 2020-12-12T01:21:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-08-01 Microscopy has been widely used to complement the data of studies related to dentin bonding; however, different specimen preparation methods may influence the analysis. Aiming to contribute to the reported scenario, this study evaluated the effect of two specimen-sectioning methods (cleavage and diamond disk cut) on the quality of the scanning electron microscopy (SEM) images. Four crowns of human molars were selected and had an area of approximately 6 mm2 of dentin exposed. They were then divided into two groups according to the universal adhesive application: total and self-etching modes. Then, composite blocks were built up and the specimens were stored in deionized water to allow the postcuring. The specimens were further divided according to the sectioning method: cleavage or diamond disk cut. Four specimens were obtained from each tooth. They were desiccated, placed on aluminum stubs, sputter-coated with gold, and observed in a scanning electron microscope, with ×2000 of magnification. The quality of the SEM images were evaluated by two calibrated examiners and classified into four scores (1–4). Mann–Whitney test (p

Made available in DSpace on 2022-04-28T19:47:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The aim of this study was to assess the resin microshear bond strength (μSBS) and the surface topography of lithium disilicate ceramic milled by CAD/CAM and to compare it with in-lab methods that simulate the topography of milled surfaces; thus, assessing the feasibility of those in-lab methods for in vitro microshear studies. The study was composed of 2 control groups (CAD/CAM group – discs were milled by a CAD/CAM system; POL – polished ceramics surface) and 4 testing groups (SiC – manual grinding simulation with #60 silicon carbide paper; WS – manual grinding with #60 wood-sandpaper; DB – grinding with a fine cylindrical diamond bur; MANDREL – grinding with a CAD/CAM bur coupled to a mandrel). After production, the ceramic samples were crystallized. Surface treatment with hydrofluoric acid (HF) and silane was performed on the bonding surface, then the starch matrices were filled by the resin cement and light-activated. The specimens (n= 45) were submitted to μSBS after 24 h of storage in water (37° C) and the failure pattern was analyzed. Topographic analysis, surface roughness, contact angle, and fractal dimension were performed. One-way ANOVA and Tukey's post-hoc tests were run for roughness, while Bonferroni’ post hoc was used for μSBS data. Fractal dimension data was qualitatively assessed. No difference was found in the μSBS between in-lab simulation methods and the milled group, while the polished group presented the lowest μSBS values. The CAD/CAM milled specimens presented the highest roughness values, while the POL the lowest ones. In regards to surface complexity, no difference was found among all simulated groups and the CAD/CAM group, with an exception for the POL group. All conditions presented an increase in surface complexity after HF etching. Therefore, the resin bond strength to lithium disilicate glass-ceramic is not influenced by the in-lab simulation method, meaning they are predictable approaches when evaluating the resin bonding to the tested ceramic; the surface polishing underestimates the bond results in ∼40%. MSciD and PhD Graduate Programs in Oral Science – Prosthodontic Units Faculty of Odontology Federal University of Santa Maria Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) – Institute of Science and Technology MSciD and PhD Graduate Programs in Physics Department of Physics Federal University of Santa Maria (UFSM) Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) – Institute of Science and Technology

Resumo Introdução Com a dificuldade de obtenção de dentes humanos para estudos in vitro, autores relatam e preconizam o uso de dentes extraídos de arcadas bovinas para testar técnicas de diferentes segmentos da Odontologia. Entretanto, para que as pesquisas tenham eficácia científica, estes dentes necessitam tratamento adequado para manter suas características e simular condições in vivo. Objetivo Analisar a resistência de união (RU) adesiva à dentina em dentes bovinos restaurados com adesivo convencional Adper® Single Bond 2 (3M ESPE, St. Paul, MN, EUA) e compósito Opallis Flow (Dentscare LTDA., Joinville, SC, BRA), tendo como fatores de estudo solução e tempo de armazenamento. Metodologia As amostras foram congeladas sob armazenamento em 2 soluções: timol 0,1% e cloramina 0,5%, em 4 diferentes períodos: 1 semana, 1 mês, 3 meses e 6 meses. Foram obtidos 8 grupos experimentais (n=64) e 1 grupo controle (n=8), totalizando 9 grupos. Após o período de restauração, os dentes foram armazenados em estufa a 37 ºC, imersos em água destilada e, em seguida, testados em máquina de ensaios universal (EMIC DL 500, São José dos Pinhais, PR, Brasil), com análise estatística dos resultados. Resultado A comparação entre os grupos experimentais e controle mostrou diferença estatisticamente significante (p

Made available in DSpace on 2021-06-25T11:02:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-09-01 The aim of this study was to evaluate the effect of in-lab simulation procedures performed on a lithium disilicate ceramic luted to a dentin-analogue material regarding the fatigue performance and topographic changes. Lithium disilicate ceramic (IPS e.max CAD) discs (Ø = 13.5 mm and 1.5 mm of thickness) were produced in different ways: milled in a CAD/CAM system (CAD/CAM – control group); mirror-polished (POL group); produced in-lab and ground with #60 silicon carbide paper (SiC group); with #60 wood sandpaper (WS group); with a fine diamond bur (DB group); or with a CAD/CAM bur adapted in a handpiece with a custom mandrel (MANDREL group). The ceramic discs were adhesively luted (Multilink N) onto dentin analogue discs (Ø = 12 mm and 2 mm of thickness) and fatigue testing (n = 19 discs) was performed by step-stress methodology (initial load of 200 N; step-size of 50 N; 10,000 cycles per step; 20 Hz). Surface roughness and contact angle analysis were also performed. According to Kaplan-Meier and post-hoc Mantel-Cox (log-rank), distinct fabrication methods affected the fatigue performance of bonded glass-ceramic discs (p< 0.001). The CAD/CAM group presented the lowest fatigue failure loads (1250 N) and number of cycles for failure (185,000), while the POL groups obtained the highest results (1752 N; 284,444 cycles). The in-lab groups had intermediate values (1355 – 1526 N; 206,052 – 238,684 cycles). Polished specimens presented the lowest roughness values (Ra = 0.041 μm), while the SiC (1.604 μm), WS (1.701 μm), and MANDREL (1.867 μm) groups showed statistically similar roughness values to the CAD/CAM group (1.738 μm). Despite differences before etching, the contact angle was similar among the milled and simulated groups after etching, except for the polished group. Even with some topographic similarities, the tested in-lab simulation methods were not able to mimic the milled specimens in terms of fatigue findings, leading to distinct magnitude of overestimations of the results. MSciD and PhD Graduate Programs in Oral Science – Prosthodontic Units 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 and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos

Smile, besides being an important factor in the self-esteem of human, has been considered the “ateway” to many opportunities today. However, there are some changes can be found and which can provide the aesthetic, functional and psychological impairment of the individual, like the diastema, defined by a spacing between adjacent teeth. Objectives: thus, we intend to show through a case an aesthetic rehabilitation of a young patient with the presence of diastema anterosuperiores teeth using composite resin of direct insertion and minimal wear of dental structure. Results: the result was extremely satisfying for both, the patient and the professional, proving the efficiency of composite resins in cases of rehabilitation when well indicated. Conclusion: thus, with the increase in the quality of technical and aesthetic materials, the use of this, subsequent to orthodontic treatment in patients who still show gaps between the teeth, provides ease and security to the professional in performing the procedure, obtaining better results. Smile, besides being an important factor in the self-esteem of human, has been considered the “ateway” to many opportunities today. However, there are some changes can be found and which can provide the aesthetic, functional and psychological impairment of the individual, like the diastema, defined by a spacing between adjacent teeth. Objectives: thus, we intend to show through a case an aesthetic rehabilitation of a young patient with the presence of diastema anterosuperiores teeth using composite resin of direct insertion and minimal wear of dental structure. Results: the result was extremely satisfying for both, the patient and the professional, proving the efficiency of composite resins in cases of rehabilitation when well indicated. Conclusion: thus, with the increase in the quality of technical and aesthetic materials, the use of this, subsequent to orthodontic treatment in patients who still show gaps between the teeth, provides ease and security to the professional in performing the procedure, obtaining better results.

Made available in DSpace on 2019-08-28T18:55:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2019 This study evaluated the effect of the CAD/CAM burs experience (newer vs older as consequence of the milling sequence) on fatigue failure load (FFL), number of cycles for failure (CFF), and survival rates of lithium disilicate glass-ceramic simplified restorations adhesively cemented to a dentin analogue substrate. Three sets of CAD/CAM burs were used to mill disc-shaped ceramic specimens (1 bur set - 18 milled discs with 10 mm diameter and 1.5 mm thickness), considering the bur experience as a result of the milling sequence to compose the study groups: G1-6 - discs obtained from the 1st to 6th milling of each bur set; G7-12 - specimens from the 7th to 12th milling; G13-18 - discs from the 13th to 18th. Discs of dentin analogue (G10, 10 mm diameter and 2.0 mm thickness) were made to serve as substrate (base material) and randomly assigned into pairs with the respective ceramic discs. Then, the ceramic discs were adhesively cemented onto the dentin analogue substrate, composing a three-layer specimen that mimics a monolithic restoration of a posterior tooth. Specimens were tested under stepwise fatigue approach: frequency = 20 Hz, 5000 cycles at maximum load of 400 N to accommodate the testing assembly, followed by incremental steps of 200 N with initial load ranging from 10 to 1000 N, to a maximum of 20,000 cycles/each step, until the occurrence of failure (radial crack). FFL and CFF were recorded at the end of the testing and subjected to statistical analysis. Supplementary roughness analysis of the milled surface was performed (n = 18) using a contact profilometer. Residual stress after milling and acid etching were accessed via X-ray Diffractometry analysis. FFL and CFF were not affected by increase on bur experience (no statistical differences among groups), despite that, it affected both Ra and Rz parameters (G1-6 had the smoothest surface). The residual stress concentration was negligible (milling did not induce residual stress concentration). It is concluded that the fatigue behavior of adhesively cemented lithium-disilicate glass-ceramic restorations was not influenced by CAD/CAM bur experience (newer vs older as consequence of the milling sequence), and so the residual stress concentration induced by milling was negligible. [de Andrade, Guilherme Schmitt; Diniz, Vandeberg; Datte, Carlos Eduardo; Bottino, Marco Antonio; de Melo, Renata Marques] Sao Paulo State Univ Unesp, Inst Sci & Technol, Dept Dent Mat & Prosthodont, Sao Jose Dos Campos, Brazil [Venturini, Andressa Bonin; Valandro, Luiz Felipe] Fed Univ Santa Maria UFSM, Fac Odontol, Prosthodont Unit, Oral Sci, Floriano Peixoto 1184, BR-97015372 Santa Maria, RS, Brazil [Rocha Pereira, Gabriel Kalil] Merid Fac IMED, Sch Dent, Passo Fundo, RS, Brazil [Amaral, Marina] Universidade de Taubaté (Unitau) , Dept Dent Prosthet Dent [Bastos Campos, Tiago Moreira] Aeronaut Technol Inst ITA, Dept Phys, Sao Jose Dos Campos, Brazil

Introdução: Atualmente é alto o índice de pacientes com sinais e sintomas de disfunções temporomandibulares, de etiologia multifatorial. Sendo o desgaste e apertamento dentário, as principais queixas caracterizadas pelo bruxismo. Além de afetar a estética, essa alteração é responsável pela modificação da oclusão do paciente, prejudicando a relação e distribuição de forças entre os dentes antagonistas. Sabe-se que, dentro do conceito de oclusão mutuamente protegida, os dentes anteriores estão aptos a receber forças oblíquas, enquanto os dentes posteriores recebem as verticais. Entretanto, com a ausência de guia canina, durante o movimento mandibular de lateralidade, os dentes posteriores apresentam contatos mal distribuídos, gerando forças oblíquas mastigatórias, resultando em desgastes e interferências comprometendo o sistema estomatognático. Objetivo: Descrever procedimentos executados em um paciente com histórico de bruxismo, devolvendo guia canina através da utilização de fragmentos cerâmicos E-max. Relato do caso clínico: Observou-se a ausência de guia canina, cujo tratamento de escolha foi o reestabelecimento das características anatômicas dos caninos com fragmentos confeccionados em cerâmica, ajuste oclusal e indicação posterior de uso contínuo de placa miorrelaxante em resina acrílica. Resultado Tratamento funcional com estética satisfatória e reestabelecimento da guia canina do paciente e sua oclusão mutuamente protegida. Conclusão: O tratamento relatado com fragmentos cerâmicos favoreceu os movimentos mandibulares excursivos e devolveu aspectos fisiológicos da oclusão, contribuindo na melhora dos sinais e sintomas do bruxismo e na qualidade de vida do paciente.

Resin roughness and staining is a common problem in dentistry. Objective: the aim of this study was to verify the influence of single and multiple-steps polishing techniques on color stability and surface roughness of differents composite resins. Groups were (n=10): FS+CS. Filtek Supreme XT + clear strip; FS+PG. Filtek Supreme XT+PoGo; FS+SF. Filtek Supreme XT+Sof-Lex; AM+CS. Amelogen+clear strip; AM+PG. Amelogen+PoGo; AM+SF. Amelogen+Sof-Lex; TEC+CL .TetricEvoCeram + clear strip; TEC+PG .Tetric EvoCeram+ PoGo; TEC+SF .Tetric EvoCeram+Sof-Lex; CED+CS .Ceram X Duo+clear strip; CED+PG. Ceram X Duo+PoGo; CED+SF. Ceram X Duo+Sof-Lex. The initial color and roughness were determined before and after the polishing procedures. All specimens were stored for 7 days in coffee solution and the color assessment was performed. Two specimens from each group were evaluated by scanning electron microscopy. Roughness and color data were submitted to ANOVA and Tukey tests(pG7(5.8f)=G10(5.7ef)>G1(3.7c), followed by the G6(5.9f)>G9(3.1bc)=G12(2.1ab)>G3(1.7a). G3, after 7 days, presented the lowest values for ΔE(1.704). The lowest roughness values were observed when the clear strips were used regardless material type. The Sof-Lex system provided the lowest surface roughness values for all tested composite resins. Among composite resins the highest roughness values were found for Amelogen (G5-0.49 and G6-0.35), regardless polishing technique. All tested materials presented changes in color after immersion in coffee solution. The roughness surface and the staining of composite resins are material and polishing technique dependents.

Made available in DSpace on 2020-12-12T02:41:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Statement of problem: Manufacturers of the recently introduced nanofilled bis-acryl composite resins no longer recommend polishing to produce interim restorations; however, whether this advice is appropriate is unclear. Purpose: The purpose of this in vitro study was to evaluate the effect of the type of interim resin material, polishing procedure, and artificial staining on surface roughness, gloss, and color. Material and methods: Disk-shaped specimens were prepared from 1 unfilled acrylic resin (Duralay) and 3 bis-acryl composite resins (Structur 3—nanofilled, Systemp C&B—microhybrid, Proviplast—microhybrid). The specimens of each material were assigned to 2 subgroups (n=15): polished and unpolished. Surface roughness (Ra—μm), gloss (UB), and color (ΔE) were analyzed at baseline and after 14 days of artificial staining. Roughness and gloss data were separately analyzed by 3-way ANOVA and color by 2-way ANOVA, followed by the post hoc Tukey test (α=.05). Results: The baseline roughness of all materials was significantly reduced by the polishing procedure, whereas the baseline gloss was increased (P

Made available in DSpace on 2019-10-06T16:52:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-10-01 Background: Carious lesions and dental fractures cause weakening in the dental structure. In these situations, endodontic treatment and prosthetic rehabilitation using an intraradicular post are indicated. However, the postspace preparation of the root canal further weakens the dental remnant, especially if there is no ferrule present. This study aimed to evaluate the stress distribution in endodontically treated upper premolars treated with different rehabilitation approaches. Materials and Methods: An endodontically treated first upper premolar was modeled for finite element analysis. Three different approaches were carried out on this model: rehabilitation with fiberglass post (FCP), endocrown (ECW), or buildup. The models were exported in STEP format to the analysis software (ANSYS 17.2, ANSYS Inc., Houston, TX, USA). The solids were considered isotropic, homogeneous, and linearly elastic. A mechanical, structural static analysis was used as the criterion of maximum principal stress to show regions under tensile stress to evaluate the stress distribution in the restoration, cementation line, and root. A load of 400 N (90°) was applied to the lingual triangular ridge. The values of maximum principal stress in MPa were evaluated through colorimetric graphs. Results: Similar stress concentration was observed for all groups. However, the ECW group presented higher values in the restoration/cement interface and root dentin. Conclusions: All the treatment modalities had favorable mechanical behavior to support the masticatory loads; nevertheless, the ECW group presented a higher risk of detachment failure. Dental Materials and Proshodontics São Paulo State University (Unesp) Institute of Science and Technology, Av Engenheiro Francisco José Longo, 777 Dental Materials and Proshodontics São Paulo State University (Unesp) Institute of Science and Technology, Av Engenheiro Francisco José Longo, 777

Quanto menor a superfície da área, maior a resistência de união, pois, espécimes com pequena área de superfície apresentam melhor distribuição de estresse, bem como reduzido número de defeitos internos. O objetivo deste estudo foi verificar a resistência de união ao microcisalhamento de espécimes com dois diferentes diâmetros, 0.55 mm e 0.76 mm. 40 fatias de cerâmica Suprinity, com 1,3 mm de espessura, polidas em lixa #600, foram divididas aleatoriamente em dois grupos (n=20). Em cada fatia, quatro áreas adesivas foram delimitadas por fita adesiva, sendo então fixadas as matrizes circulares. Os espécimes foram condicionados com ácido fluorídrico a 5% (FGM) por 20 s, lavados e secos; então silanizados (RelyX Ceramic Primer - 3M ESPE) e secos com jato de ar. As matrizes foram preenchidas com cimento resinoso RelyX U200 3M ESPE e fotopolimerizadas por 100 s. Após 24 h em água deionizada a 37o C, os espécimes foram submetidos ao teste de microcisalhamento sob velocidade de 0,5 mm/min. Os dados normais e homogêneos foram submetidos à ANOVA para o experimento inteiramente casualizado, não exibindo diferença significativa (p =0,62) entre as duas áreas avaliadas – 23,74±4,49 e 24,85±4,41, respectivamente para as áreas 0,55 e 0,76 mm. Concluímos que, não há diferença na resistência de união ao microcisalhamento quando se utilizam as diferentes áreas adesivas estudadas.