Search

The objective of this work was to study the effect of different heating-up procedures and isothermal treatment times on crystallization, densification and properties of a sintered non-stoichiometric lithium silicate glass-ceramic. Glass samples containing SiO2, Li2O and K2O as main constituents, besides minor amounts of other oxides such as Al2O3, P2O5 and ZrO2, were melted at 1500 °C - 60 min and subsequently fragmented (

Objetivo: Testar a hipótese nula de que a orientação das ranhuras superficiais não influencia na vida em fadiga de fios de níquel-titânio (NiTi). Material e Métodos: Segmentos de fio de NiTi (Moreli, Sorocaba/SP, Brasil) medindo 30mm e com diâmetro de 0,40mm fo- ram utilizados. As ranhuras foram criadas em relação à direção longitudinal, em 45 e 90 graus. O fio foi analisado sob microscopia eletrônica de varredura e a rugosidade, quantificada por interferometria. O número de ciclos para a fratura (NCF) foi determinado pelo teste de flexão rotativa. Resultados: A rugosidade entre os grupos de 45 e 90 graus apresentou diferenças estatisticamente significativas (p

Dental implant treatment requires an available bone volume in the implantation site to ensure the implant’s mechanical stability. When the bone volume is insufficient, one must resort to surgical means such as guided bone regeneration (GBR). In GBR surgery, bone grafts and membranes are used. The objective of this work is to manufacture and characterize the in vitro and in vivo properties of resorbable collagen type I membranes (Green Membrane®) for GBR. Membrane surface morphology was characterized by SEM and roughness was measured using an interferometric noncontact 3D system. In vivo skin sensitization and toxicity tests have been performed on Wistar rats. Bone defects were prepared in 24 adult male rats, filled with biomaterials (Blue Bone® and Bio Oss®) and covered with collagen membranes to maintain the mechanical stability of the site for bone regeneration. The incisions were closed with simple stitches; and 60 days after the surgery, the animals were euthanized. Results showed that the analyzed membrane was homogeneous, with collagen fiber webs and open pores. It had no sign of cytotoxicity and the cells at the insertion site showed no bone morphological changes. There was no tissue reaction and no statistical difference between Blue Bone® and Bio Oss® groups. The proposed membrane has no cytotoxicity and displays a biocompatibility profile that makes it suitable for GBR.

Purpose: The aim of this work was to evaluate osseointegration of endosteal implants with two different surface treatments at early stages (~3 weeks) in the tibia of healthy and ovariectomized rabbits. Materials and Methods: The study comprised 10 adult New Zealand female rabbits (Oryctolagus cuniculus; 6 months and 3.0 ± 0.5 kg). Five animals were subjected to bilateral ovariectomy to mimic osteoporotic-like conditions, and the remaining rabbits (n = 5) served as the healthy control group. After 3 months, specimens from the ovariectomized and control groups were subject to implant placement in both tibiae, using two different types of surface treatment. A total of 36 implants were placed, n = 18 acid-etched and n = 18 anodized. After 3 weeks, euthanasia of the animals was performed, and samples were obtained for processing. Bone-to-implant contact and bone area fraction occupancy were quantified to evaluate the osseointegration parameters around the implant surface and within the thread area, respectively, and nanoindentation tests were performed to determine elastic modulus and hardness of the new bone. Both analyses were performed on the entire implant (total), as well as individually within the cortical and bone marrow cavity area. Results: All animals were evaluated with no signs of infection or postoperative complications. The total bone-to-implant contact and bone area fraction occupancy results, independent of surface treatment, yielded significant differences between the ovariectomized and control groups (P = .002 and P < .001, respectively). In the marrow cavity, analyzing the surface treatments independently as a function of bone condition, the only differences detected were in the anodized treatment (P = .04). Regarding the elastic modulus, differences were detected only with the anodized implants between the ovariectomized and control groups (P = .015). Conclusion: At 3 weeks after implant placement, there were better osseointegration values of the implants in the healthy control group compared with the ovariectomized group independent of surface treatment. Also, specifically in the medullary region of the rabbit tibia, the acid-etched implants had more uniform osseointegration values in conditions of low-quality bone in comparison to the anodized implants, histomorphometrically and biomechanically.

Titanium alloys have been widely used as biomaterials. However, contact of titanium with body fluids can release toxic ions due to degradation. The present work aimed to compare the wettability and corrosion resistance of two Ti alloys without toxic ions, Ti–30Nb–7Zr (TNZ) and Ti–47Nb (TN), with those of the commercial biomedical alloy Ti–6Al–4V-ELI (ASTM F136). Corrosion studies were carried out in a three-electrode cell conventional system, which Ti alloys as working electrodes were exposed to 0.9% sodium chloride electrolyte at 37 °C to determine if they have surface properties adequate for biomedical applications. α and β phases present on the microstructure were distinguished using scanning electron microscopy (SEM). Chemical surface composition was performed using X-ray photoelectron spectroscopy (XPS) analysis. Surface energy was determined by wettability testing. For TN and TNZ alloys the microstructure consisted of a β matrix, although only TNZ exhibited α precipitates. In contrast, F136 alloy microstructure presents α matrix, which was strengthened by the β phase. All alloys tested exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive oxide film. The results showed that ASTM F136 is more hydrophilic but less corrosion resistant than the TN and TNZ alloys. It remains to be seen in practical applications whether the lower hydrophobicity of TN and TNZ alloys is compensated by lower toxicity and higher corrosion resistance.

In this work, in vitro testing was used to study the properties of non-crosslinked type 1 bovine derived collagen membranes used in bone regeneration surgery. Collagen membranes were prepared, their surface roughness was quantified by interferometry, their morphology was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), their wettability was measured by the contact angle technique, their mechanical properties were investigated by tensile testing, their phase transformation temperatures were measured by Differential Scanning Calorimetry (DSC), and their biocompatibility was evaluated by immunological testing. The calorimetry tests showed that the membrane is formed only by type 1 collagen. The SEM observations showed that the morphology consists of layers of highly organized collagen fibers and patterns of striated fibrils typical of type 1 collagen. The small contact angle showed that the membrane is hydrophilic, with the possibility of rapid absorption of body fluids. The tensile tests showed that the membrane has enough elasticity, ductility, and mechanical strength for use in tissue regeneration. With the immunostaining technique, it was possible to confirm the membrane biocompatibility.

The aim of this work was to study the degradation of yttria-stabilized tetragonal zirconia (Y-TZP) directly exposed to the oral environment. Four groups of Y-TZP were tested G1: TZ-PX-242A, Zpex®; G2: TZ-PX-357, Zpex Yellow®; G3: ProtMat®, and G4: LAVA Frame®. The samples were attached to the base of temporary full dentures of patients and aged for 100 days. In this way, one surface of the samples was exposed to the oral environment. The samples (25 × 2 × 1.5 mm) were cut from noncommercial (G1 and G2) and commercially available (G3 and G4) presintered zirconia blocks. Quantitative and qualitative analyses were performed by X-ray fluorescence (XRF). Microstructural characterization was performed by scanning electron microscopy (SEM), X-ray diffraction (XRD), 3D surface roughness measurements and grain size measurements. The mechanical properties were determined by a four-point bending test. The data were analyzed by one-way ANOVA (p ≤ 0.05), Tukey's test and Weibull analysis. The results showed a tetragonal-monolithic transformation in the zirconia after oral aging. The surface roughness increased in all groups, and groups G3 and G4 showed increases in their flexural strengths.

The aim of this in vitro study was to evaluate the effect of air polishing on the implant abutment surface using different abrasive powders: sodium bicarbonate and amino acid glycine. Fifteen grade III machined surface titanium disks with 8-mm diameter and 2-mm thickness were divided in 3 groups of 5 samples each and subjected to air polishing for 20 seconds with an Ultrajet Flex air-abrasive device and a distinct prophylaxis protocol: air and water (G1); air, water, and sodium bicarbonate (G2); and air, water; and amino acid glycine (G3). After the air polishing, the average roughness (Ra) of the samples was measured using an optical profilometer, and the obtained data were statistically analyzed. We found that G1 and G3 had similar Ra, while Ra values for G2 were significantly higher. This study demonstrated that air-polishing powders containing glycine had less of an effect on the roughness of the surface of titanium disks compared with sodium bicarbonate powders. Future in vivo studies will be conducted to investigate the clinical relevance of the present results.

Made available in DSpace on 2019-10-06T15:35:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) In this work, the influence of milling strategy and cutter wear on the flexural strength of sintered Y-TZP ceramics machined in a CAD-CAM system, was investigated. Pre-sintered Y-TZP blocks were machined with tungsten carbide (WC) milling cutters and divided into three groups: a) samples machined with New Cutting Tools (NCT); b) samples machined with End-of-life cutting tools (ELCT); and c) samples machined and subsequently polished. The samples were machined parallel and perpendicularly to the diameter of pre-sintered Y-TZP blocks aiming to evaluate the effect of the machining orientation on roughness. After cutting, the specimens were sintered at 1530 °C for 2 h and characterized. After sintering, dense Y-TZP samples presenting grain size average of 0.81 ± 0.23 μm, hardness of 1205 ± 12 HV, K C of 7.7 ± 0.4 MPam 1/2 and flexural strength of 1207 ± 199 MPa were obtained. Furthermore, the control roughness (polished surfaces) presented R a = 0.058 ± 0.011 μm. The surface roughness of the samples was influenced by the machining methodology using NCT mills, with R a = 0.386 ± 0.149 μm and R a = 0.292 ± 0.105 μm for samples machined parallel and perpendicularly to the pre-sintered Y-TZP blocks, respectively. The use of ELCT led to a roughness increasing (R a = 0.582 ± 0.183 μm for samples milled perpendicularly, and R a = 0.919 ± 0.164 μm for samples cut parallel to the pre-sintered blocks. The flexural strength of the sintered Y-TZP decreases with use of ELCT as consequence of surface roughness increasing, resulting from wear of WC mills, which presented chippings with sizes ranging from 30 to 340 μm in the cutting edge. Universidade do Estado do Rio de Janeiro - Faculdade de Tecnologia de Resende UERJ-FAT, Rodovia Presidente Dutra, km 298 Universidade Estadual Paulista - Faculdade de Engenharia de Guaratinguetá UNESP/FEG, Av. Ariberto Pereira da Cunha, 333, Portal das Colinas Centro Universitário de Volta Redonda - UniFOA, Av. Paulo Erlei Alves Abrantes, 1325 - Três Poços Instituto Militar de Engenharia Materials Science Department, Pça Gen. Tibúrcio, 80, Praia Vermelha Universidade Estadual Paulista - Faculdade de Engenharia de Guaratinguetá UNESP/FEG, Av. Ariberto Pereira da Cunha, 333, Portal das Colinas CNPq: n° 311119/2017-4 FAPERJ: n° E26-201.476/2014

The major role of integrins is to mediate cell adhesion but some of them are involved in the osteoblasts-titanium (Ti) interactions. In this study, we investigated the participation of integrins in osteoblast differentiation induced by Ti with nanotopography (Ti-Nano) and with microtopography (Ti-Micro). By using a PCR array, we observed that, compared with Ti-Micro, Ti-Nano upregulated the expression of five integrins in mesenchymal stem cells, including integrin β3, which increases osteoblast differentiation. Silencing integrin β3, using CRISPR-Cas9, in MC3T3-E1 cells significantly reduced the osteoblast differentiation induced by Ti-Nano in contrast to the effect on T-Micro. Concomitantly, integrin β3 silencing downregulated the expression of integrin αv, the parent chain that combines with other integrins and several components of the Wnt/β-catenin and BMP/Smad signaling pathways, all involved in osteoblast differentiation, only in cells cultured on Ti-Nano. Taken together, our results showed the key role of integrin β3 in the osteogenic potential of Ti-Nano but not of Ti-Micro. Additionally, we propose a novel mechanism to explain the higher osteoblast differentiation induced by Ti-Nano that involves an intricate regulatory network triggered by integrin β3 upregulation, which activates the Wnt and BMP signal transductions. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1303-1313, 2019.

The aim of this work was to analyze the properties and shear bond strength (SBS) of lithium disilicate to resin cement before and after etching the glass-ceramic surfaces. Lithium-metasilicate samples were heat treated and characterized by Scanning Electron Microscopy, X-ray diffraction and roughness measurement. For the analysis of the shear bonding strength (SBS) of lithium disilicate to dental resin cement, three groups (n = 12) of Li2Si2O5 were prepared: 1°)without treatment (NT); 2°)surface etching with hydrofluoric acid(HF), followed by silane agent and adhesive treatment; 3°) surface treatment with a self-etching ceramic primer (SECP). After the heat-treatment, the samples had Li2Si2O5 crystalline phase dispersed in a residual amorphous phase. Roughness of the NT and SECP samples was smaller that of the HF samples. Samples without surface treatment (NT) had the lowest SBS (5.5MPa). HF(24.2MPa) and SECP(24.8MPa) samples has similar SBS. Weibull statistics showed that HF-samples are more reliable than NT and SECP. The SBS was significantly increased by either HF etching and SECP surface treatment. While the chemical characteristics of the surface submitted to SECP treatment are considered to be responsible for the SBS increase, the main adhesion mechanism after HF etching is the increase in surface roughness.

Introduction: Excess of adhesive around brackets negatively impact oral health of orthodontic patients. Objective: Evaluate the influence of orthodontic bonding system in removal of adhesive flash around orthodontic brackets. Methods: Based on their characteristics, four orthodontic bonding systems were selected: lightcuring adhesive (G1 - TransbondTM XT); pink pigmented light-curing adhesive (G2- TransbondTM Plus Color Change); resin-modified glass ionomer cement (G3 - FujiOrthoTM LC); and auto-curing adhesive (G4 - ConciseTM). For each group (n=10), a single operator placed metal brackets on bovine teeth (n=40) and used an explorer tip to visually remove flash excess. After curing / setting, the sampleswere taken to a stereomicroscope and the Axio Vision 4.4 software was used to measure the area of remnant adhesive flash around each bracket. The quantitative data obtained was analyzed by the Kruskal-Wallis and Dunn’s post hoc test at = 0.05. Results: The results show that the resin-modified glass ionomer cement (G3) had a larger area of remnant material than the other groups. There was no statistical difference between the other groups (G1, G2, and G4), independently of pigmentation or curing technique. Conclusion: It was concluded that the use of a resin-modified glass ionomer cement results in a larger area of remnant flash excess, which can negatively impact oral health. Pigmentation and curing technique did not influence on remnant flash excess. Introdução: O excesso de material de colagem que permanece ao redor dos bráquetes impacta negativamente a saúde bucal dos pacientes ortodônticos. Objetivo: Avaliar a influência dos sistemas de colagem ortodônticos na remoção de excesso de adesivo ao redor de bráquetes. Métodos: Baseado em suas características, quatro sistemas de colagem ortodônticos foram selecionados: adesivo fotopolimerizável (G1 – TransbondTM XT); adesivo fotopolimerizável com pigmentação rosa (G2 - TransbondTM Plus Color Change); cimento de ionômero de vidro reforçado com resina (G3 - FujiOrthoTM LC); e adesivo autopolimerizável (G4 - ConciseTM). Para cada grupo (n=10), um único operador posicionou os bráquetes em dentes bovinos (n=40) e utilizou uma sonda exploradora para remoção visual do excesso de material de colagem. Após a polimerização / tempo de cura, as amostras foram levadas ao estereomicroscópio e o software Axio Vision 4,4 foi utilizado para mensurar a área de excesso de adesivo remanescente ao redor de cada bráquete. Os dados quantitativos obtidos foram analisados pelos testes de Kruskal-Wallis e post-hoc de Dunn em significância de = 0,05. Resultados: O cimento de ionômero de vidro reforçado por resina (G3) apresentou a maior área de remanescente de excesso. Não houve diferença estatisticamente significativa entre os demais grupos (G1, G2 e G4), independente da pigmentação ou do método de polimerização. Conclusão: O uso de cimento de ionômero de vidro reforçado por resina resulta em maior área de excesso remanescente, o que pode impactar negativamente a saúde bucal. A pigmentação e o método de polimerização não influenciaram no excesso de material remanescente.

Igor da Silva Brum,1 Lucio Frigo,2 Paulo Goncalo Pinto dos Santos,1 Carlos Nelson Elias,3 Guilherme Aparecido Monteiro Duque da Fonseca,2 Jorge Jose de Carvalho4 1Implantology Department, School of Dentistry, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil; 2Periodontology Department, School of Dentistry, Universidade Guarulhos, São Paulo, Brazil; 3Instituto Militar de Engenharia, Rio de Janeiro, Brazil; 4Biology Department, School of Medicine, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, BrazilCorrespondence: Lucio FrigoPeriodontology Department, School of Dentistry, Universidade Guarulhos, Praça Teresa Cristina, 01, Guarulhos, São Paulo, 07023-070, BrazilTel/Fax +55-11- 2464-1684Email luciofrigo@uol.com.brBackground: Synthetic biomaterials have played an increasingly prominent role in the substitution of naturally derived biomaterials in current surgery practice. In vitro and in vivo characterization studies of new synthetic biomaterials are essential to analyze their physicochemical properties and the underlying mechanisms associated with the modulation of the inflammatory process and bone healing.Purpose: This study compares the in vivo tissue behavior of a synthetic biomaterial nano-hydroxyapatite/beta-tricalcium phosphate (nano-HA/ß-TCP mixture) and deproteinized bovine bone mineral (DBBM) in a rat calvarial defect model. The innovation of this work is in the comparative analysis of the effect of new synthetic and commercially xenogenic biomaterials on the inflammatory response, bone matrix gain, and stimulation of osteoclastogenesis and osteoblastogenesis.Methods: Both biomaterials were inserted in rat defects. The animals were divided into three groups, in which calvarial defects were filled with xenogenic biomaterials (group 1) and synthetic biomaterials (group 2), or left unfilled (group 3, controls). Sixty days after calvarial bone defects filled with biomaterials, periodic acid Schiff (PAS) and Masson’s trichrome staining, immunohistochemistry tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase-9 (MMP-9), and electron microscopy analyses were conducted.Results: Histomorphometric analysis revealed powerful effects such as a higher amount of proteinaceous matrix and higher levels of TNF-α and MMP-9 in bone defects treated with alloplastic nano-HA/ß-TCP mixture than xenogenicxenogic biomaterial, as well as collagen-proteinaceous material in association with hydroxyapatite crystalloids.Conclusion: These data indicate that the synthetic nano-HA/ß-TCP mixture enhanced bone formation/remodeling in rat calvarial bone defects. The nano-HA/ß-TCP did not present risks of cross-infection/disease transmission. The synthetic nano-hydroxyapatite/beta-tricalcium phosphate mixture presented adequate properties for guided bone regeneration and guided tissue regeneration for dental surgical procedures.Keywords: biomaterial, hydroxyapatite, beta-tricalcium phosphate, bone healing, histomorphometry

Summary Objectives To analyse, in vitro, surface properties and the shear bond strength after debonding and polishing procedures of ceramic brackets directly bonded to 0.3-0.5-mm thick feldspathic veneers. Materials and methods Fifty six feldspathic ceramic veneers samples (0.3 to 0.5-mm thick) were allocated into groups according to veneers surface treatment procedures: (S) glaze layer was retained; (SHF) hydrofluoric (HF) acid etch; (SOXA) Al2O3 sandblasting; and (SB) diamond burs roughening. Specimens were treated with silane Monobond N® and ceramic brackets bonded with Transbond XT®. Shear bonding strength (SBS) was assessed with a universal testing machine and ARI evaluated under a stereomicroscopic coupled to a digital camera. Remaining bonding composite was removed using a porcelain polishing kit and surface roughness assessed with a stylus profilometer. Results No statistically significant differences were identified for SBS among the study groups (S, SHF, SOXA and SB) (P > 0.05). The majority of the specimens presented ARI scores 3 and 2 (P > 0.05). All of the study groups presented increased surface roughness after debonding and polishing procedures (P Conclusions Surface treatment with hydrofluoric acid etch, Al2O3 sandblasting and diamond bur did not enhance SBS of orthodontic brackets bonded to ceramic veneers. Ceramic surfaces treated with diamond burs presented significantly increased roughness after adhesive removal.

Orthodontic implants have become a reliable method in orthodontic practice for providing temporary additional anchorage. These devices are useful to control skeletal anchorage in less compliant patients or in cases where absolute anchorage is necessary. There are a great number of advantages in this new approach which include: easy insertion, decreased patient discomfort, low price, immediate loading, reduced diameter, versatility in the forces to be used, ease of cleaning, and ease of removal. However, proper management of the screws by the practitioner is necessary to increase the success rate of the technique. The purposes of orthodontic implants and dental implants are different. The purpose of this paper is to update practitioners on the current concepts of orthodontic implants and orthodontic mechanics.

Commercially pure titanium (Ti G2 and Ti G4) and the Ti–6Al–4V (Ti G5) alloy have limitations for biomedical applications, due to either low mechanical strength (Ti G2, Ti G4) or the possible release of toxic ions (Ti G5). Since Ti alloys have a low hardening coefficient, it is very difficult to improve their mechanical properties by work hardening. The purpose of this work was to compare the mechanical and clinical properties of Ti G4 nanostructured after severe plastic deformation by ECAP (Ti G4 Hard) with those of Ti G2, Ti G4 and Ti G5. Bars, disks and dental implants made with Ti G2, Ti G4, Ti G5 and Ti G4 Hard were tested. Mechanical tests (tension, compression, hardness, elastic modulus, fatigue and torque) and roughness measurements were performed. The results of the mechanical tests showed that Ti G4 Hard has a higher mechanical strength and a lower elastic modulus than Ti G2, Ti G4 and Ti G5. Scanning electron microscopy and roughness measurements results showed that acid etched Ti G4 Hard nanostructured has better surface morphological features than Ti G2, Ti G4 and Ti G5. The clinical performances of Ti G4 and Ti G4 Hard were similar. The high mechanical strength of Ti G4 Hard means that it can be used to replace Ti G5 in several clinical applications, with the advantage of not releasing toxic ions. The Ti G4 Hard dental implants have adequate mechanical properties and can be inserted in areas with low bone volume. Keywords: Titanium, High strength cp Ti, Strain hardening, Ti nanostructured, Dental implant, ECAP

The Cr-Co-Mo alloys are commonly used in dentistry for prosthetic components and dental implant supported prosthesis. These alloys present high corrosion resistance owing to a passive oxide film on the surface. However, the oral environment is an aggressive system, due to pH variation, chloride and fluoride ions presence, that can decrease the metal alloy corrosion resistance. Although Cr-Co-Mo alloys have been used for a long time, their electrochemical properties on different pH have not been studied yet. This study aimed to evaluate the electrochemical properties of Cr-Co-Mo alloy in NaCl 0.9% solution in different pH and mouthwash solution. To imitate the oral environment, electrolytes with a pH equal to 2, 3, and 6 were used. Corrosion studies were performed by open circuit potential observation, potentiodynamic polarization curve, chronoamperometry and electrochemical impedance. The results showed that the analyzed alloy has good corrosion resistance under experimental conditions, although the acidified NaCl 0.9% solution increased the corrosion current, particularly in cathodic potentials.

The aim of the present study was to evaluate the influence of blue thermal treatment on the torsional resistance behavior of M-Wire Reciproc files (VDW, Munich, Germany).Ten M-Wire Reciproc R25 (25/0.08v) and 10 Reciproc Blue R25 (25/0.08v, VDW) instruments were used. The torque and angle of rotation at failure of new instruments (n = 10) were measured according to ISO 3630-1. Three millimeters of each instrument tip was clamped to a small load cell by a lever arm linked to the torsion axis. The fracture surface of all fragments was examined with a scanning electron microscope. Results were statistically analyzed using the Student t test at a significance level of P .05.The maximum torsional strength of M-Wire Reciproc was higher than Reciproc Blue instruments (P .05). Reciproc Blue instruments showed significantly higher angular rotation to fracture than M-Wire Reciproc instruments (P .05). Scanning electron microscopy of the fracture surface showed similar and typical features of torsional failure for the 2 types of instruments, including concentric abrasion marks and the fibrous dimple marks at the center of rotation.Reciproc Blue instruments showed a higher angle of rotation to fracture but a lower torque to failure than M-Wire Reciproc instruments.

Objective: This study compared the fatigue behavior of endodontic instruments manufactured with conventional NiTi alloy electropolishing, RaCe (FKG Dentaire, LaChauxdeFonds, Switzerland), with instruments manufactured with NiTi CM Wire subjected to thermomechanical treatment, in the manufacturing process, HyFlex CM (Coltène Whaledent, Cuyahoga Falls, Ohio, USA), both with similar geometry and dimensions in order to determine the influence of the manufacturing process in the fatigue resistance. Methods: The methodoly consisted of twenty HyFlex CM and RaCe instruments with D0 0.25 mm, taper 0.06 mm / mm, 25 mm length, both with triangular cross section. The fracture resistance was evaluated by static fatigue test, using a stainless artificial canal with 5mm of radius (86°), recording the time and calculating the number of cycles until fracture occurs (NCF). For statistical analysis the Student t test was used The fractured instruments surface was analyzed by SEM. Results: The NCF was significantly higher for HyFlex CM instruments in comparison with RaCe files (P˂0.05) being 1336% more resistant to fatigue. The analysis of the fractured surface by SEM showed ductile-kind morphological characteristics for both instruments and the absence of plastic deformation. Conclusion: HyFlex CM instruments present higher values of NCF. Thus, it can be concluded that the thermal treatment to which these instruments with CM Wire alloy are submitted makes them more resistant to fracture than Race instruments manufactured with conventional NiTi alloy electropolishing. RESUMO Objetivo: Este estudo comparou a vida em fadiga de instrumentos endodônticos fabricados com a liga de NiTi convencional com eletropolimento de superfície, RaCe (FKG Dentaire, LaChauxdeFonds, Suiça), com instrumentos fabricados com a liga de NiTi CM Wire, submetidos a tratamento termomecânico, no processo de fabricação, HyFlex CM (Coltene Whaledent, Cuyahoga Falls, Ohio, EUA), ambos com geometria e dimensões semelhantes, visando determinar a influência do processo de fabricação das ligas e do acabamento superficial na resistência à fadiga. Métodos: Foram utilizados vinte instrumentos HyFlex CM e RaCe com D0 0,25mm, conicidade 0,06mm/mm, 25mm de comprimento, ambos com seção transversal triangular. A resistência à fratura foi avaliada através de teste estático de fadiga ciclica, utilizando um canal artificial em aço-inoxidável com 5mm de raio (86°), sendo registrado o tempo e calculado o número de ciclos para ocorrer a fratura (NCF). Para análise estatística empregou-se o teste t de Student. As superfícies de fratura dos instrumentos foram analisadas em MEV. Resultados: O NCF foi significativamente maior para os instrumentos HyFlex CM em comparação com as limas RaCe (p˂0,05), sendo 1336% mais resistentes à fadiga. A análise das superfícies fraturadas em MEV revelou características morfológicas do tipo dúctil para ambos os instrumentos e ausência de deformação plástica. Conclusão: Os instrumentos HyFlex CM apresentaram valores mais elevados de NCF. Deste modo, pode-se concluir que o tratamento térmico a qual estes instrumentos com a liga CM Wire foram submetidos os torna mais resistentes à fratura do que os instrumentos Race, fabricados com a liga de NiTi convencional com eletropolimento.

Two distinct AISI type 316 stainless steels, of Brazilian and Swedish origins, were compared regarding their creep fracture mechanisms at 600, 700 and 800°C. The possible mechanisms associated with the creep fracture strength were identified by means of fracture maps proposed either by Ashby and collaborators or by Miller and Langdon. Experimental creep results were consistent with the general Ashby and collaborators map for face centered cubic alloys. By contrast, the two different 316 steel displayed significant differences in the model-based map of Miller and Langdon. In the present work, changes in the maps frontier are proposed as well as the introduction of a new field in the map related to grain boundary precipitation. These propositions allowed the Miller and Langdon map to be coherent with the experimental creep fracture results of both 316 stainless steels.

The aim of this study was to evaluate, in vitro, the microbiological sealing at the implant and different angles frictional prosthetic abutment interface, submitted or not to mechanical cycling, as well as the deactivation force and evaluation of the implant-abutment interface by scanning electron microscopy. For this study, the sealing capacity of eighty sets of abutments/implants of each angle, with and without mechanical cycling, with internal conical connection (locking tapper) (4.3 mm × 9.0 mm) constituted in Titanium alloy (Ti6Al4V), and stainless steel angled prosthetic abutment was evaluated (18Cr14Ni2.5Mo) according to ASTM F138-13a (Arcsys, FGM, Joinville, Brazil), 6 mm high and 4.2 mm in diameter at the coronary portion, and 3.5 mm high transmucosal, in 4 different angles (0, 5, 10 and 20°). After in vitro tests, 100% biological sealing was observed at the implant / prosthetic abutment interface within cycled and non-cycled conditions, for the straight, 5, 10 and 20° inclination groups. There was no statistically significant difference in the removal force of the prosthetic abutments at different angles, under non-cycled conditions; however, under mechanical loading, the deactivation force was significantly higher for straight prosthetic abutments than with 10 and 20° of angulation. Surface analysis revealed good adaptation between implants and abutments, and the presence of wear areas, independently of mechanical loading. It is concluded that the analysis of implant and prosthetic abutment interface revealed good adaptation between the parts, for all analyzed samples.

AIM To report the main differences seen by direct visual inspection between original and counterfeit Reciproc instruments, together with an evaluation of instrument bending resistance, cyclic fatigue, surface finish, Vickers microhardness and chemical composition. METHODOLOGY The visual aspects of original Reciproc R25 (VDW, Munich, Germany) and counterfeit Reciproc R25 instruments (claimed to be original, supposedly with dimensions similar to those of Reciproc R25 files, bought at www.mercadolivre.com.br) were evaluated under direct observation, stereomicroscopy and scanning electron microscope. The flexibility of original and counterfeit Reciproc R25 was determined via 45° bending tests according to the ISO 3630-1 specification. Instruments were also subjected to cyclic fatigue resistance, measuring the time to fracture in an artificial stainless steel canal with a 60° angle and 5-mm radius of curvature. The fracture surfaces of all fragments were examined under a scanning electron microscope. Roughness of the instruments was quantified using a profilometer, and the microhardness test was carried out using a Vickers hardness tester. Energy-dispersive X-ray microanalysis (EDX) was also carried out. Results were analysed statistically using the Student's t-test at a significance level of P

The aim of the present study was to evaluate the influence of Blue thermal treatment on the bending resistance and cyclic fatigue of conventional M-Wire Reciproc files (VDW, Munich, Germany). The roughness pattern and the microhardness of the files were also assessed.Flexibility of standard Reciproc R25 files and the corresponding Blue prototypes was determined by 45° bending tests according to the ISO 3630-1 specification. Instruments were also subjected to cyclic fatigue resistance, measuring the time to fracture in an artificial stainless steel canal with a 60° angle and a 5-mm radius of curvature. The fracture surface of all fragments was examined with a scanning electron microscope. The roughness of the working parts was quantified by using a profilometer, and the microhardness test was performed using the Vickers hardness tester. Results were statistically analyzed using the Student t test with a level of significance set at P .05.Reciproc Blue instruments presented a significantly longer cyclic fatigue life and significantly lower bending resistance than the original Reciproc instrument (P .05). Regarding the roughness pattern, there was no significant difference between Reciproc Blue and the original Reciproc instruments (P .05), whereas Reciproc Blue revealed significantly lower microhardness than the original Reciproc instrument (P .05).Reciproc Blue nickel-titanium showed improved all-around performance when compared with conventional M-Wire superelastic nickel-titanium, demonstrating improved flexibility and fatigue resistance, and reduced microhardness while maintaining similar characteristics of the surface.

O titânio comercialmente puro (Ti cp) e o principal material usado na fabricacao dos implantes dentarios osseointegraveis. Para melhorar os indices de sucesso do tratamento odontologico e reduzir o tempo de osseointegracao dos implantes, foram desenvolvidas varias metodologias de tratamento da superficie dos implantes. Para caracterizar as morfologias das superficies dos implantes sao usadas as analises no microscopio eletronico de varredura (MEV), rugosidade, molhabilidade, identificacao de possiveis contaminantes, ensaios in-vitro de culturas de celulas e in-vivo com animais. Entre as tecnicas citadas, as mais usadas sao as analises no MEV, as medidas dos parâmetros da rugosidade e da molhabilidade. Alguns trabalhos disponiveis na literatura sugerem a caracterizacao somente do valor de Ra sem apresentar uma explicacao para a escolha deste parâmetro. No presente trabalho e feita a proposta de um modelo matematico para quantificar a relacao entre os varios parâmetros da rugosidade 3D (Ra, Rq, Rz, Rms, Pico, Vale, PV, R3z e Smax) com a molhabilidade e a energia de superficie do Ti cp com dois tamanhos de grao (micrometricos e sub-micrometricos) e submetidos ao tratamento com acido. Os resultados mostraram que para o nivel de confianca de 95%, as propriedades das superficies do Ti cp tratados com acido sao mais influenciadas pelos parâmetros de rugosidade Ra e Rms. Palavras-chave: titânio, rugosidade, molhabilidade, metodologia de LASSO

Objective The aim of this study was to evaluate and compare the effect of heat treatment at different temperatures on the color and flexibility of nickel-titanium endodontic instruments. Methods Thirty-six nickel-titanium K-file endodontic instruments were divided into six groups and submitted to heat treatment at several temperatures between 450ºC and 750ºC. The color was visually observed. Cantilever-bending tests were performed to measure the flexibility of the instruments. The data were statistically evaluated by one-way analysis of variance and Tukey post hoc comparisons. Results It was observed that the color becomes darker as the heating temperature increases. The flexibility is significantly higher after the heat treatment (P < 0.05). Instruments treated at 650ºC and 750ºC had higher flexibility than those treated at lower temperatures (450ºC, 500ºC and 550ºC) (P < 0.05). Conclusion Heat treatment has a significant effect on the surface color and flexibility of nickel-titanium endodontic instruments. The highest flexibility was observed in instruments heated at 650ºC and 750ºC.

The objective of this work was to characterize the properties of a synthetic biomaterial composite with nanoparticles size (Blue Bone). This biomaterial is a composite recommended for dental and orthopedic grafting surgery, for guided bone regeneration, including maxillary sinus lift, fresh alveolus filling, and treatment of furcation lesions. The nano biomaterials surface area is from 30% to 50% higher than those with micro dimensions. Another advantage is that the alloplastic biomaterial has homogeneous properties due to the complete manufacturing control. The analyzed biomaterial composite was characterized by XRD, cytochemistry, scanning electron microscopy, porosimetry and in vivo experiments (animals). The results showed that the analyzed biomaterial composite has 78.76% hydroxyapatite [Ca5(PO4)3(OH)] with monoclinic structure, 21.03% β-tricalcium phosphate [β -Ca3(PO4)2] with trigonal structure and 0.19% of CaO with cubic structure, nanoparticles with homogeneous shapes, and nanoporosity. The in vivo experiments showed that the composite has null cytotoxicity, and the site of insertion biomaterials has a high level of vascularization and bone formation. The conclusion is that the synthetic biomaterial with Blue Bone designation presents characteristics suitable for use in grafting surgery applications.

Background From the consolidation of surface treatments of dental implants and knowledge on the cellular mechanisms of osseointegration, studies have highlighted the importance of a connective tissue seal against the implant to prevent contamination from the oral environment and consequent biofilm formation. Objective This in vitro study aimed to evaluate whether different titanium surface treatments using acid solutions promoted an increase in collagen secretion, proliferation, and viability of fibroblasts. Material and methods Commercially pure grade-4 titanium disks (6 × 2 mm) were treated with different acid solutions (hydrochloric, nitric, and sulfuric) for 20 and 60 min, respectively, obtaining mean surface roughness of 0.1 to 0.15 μm and 0.5 to 0.7 μm. Human fibroblasts were seeded onto different surfaces and assessed after 24 h, 48 h, and 72 h for cell proliferation and viability using Trypan blue staining and MTT, respectively, as well as the secretion of type I collagen on to such surfaces using ELISA. Machined titanium surfaces were used as controls. Data were statistically analyzed using one-way ANOVA and Fisher's LSD test for multiple comparisons, adopting a significance level of 5%. Results No significant difference was observed in cell proliferation for the different surfaces analyzed. Cell viability was significantly lower on the machined surface, after 48 h, when compared to the groups treated with acid for 20 or 60 min, which did not differ from each other. The expression of type I collagen was lowest on the acid-treated surfaces. Conclusion The results showed that the acid treatment proposed did not promote fibroblast proliferation and viability nor favor type I collagen synthesis.

TMAOH-dispersed nanoparticles of magnetite were first prepared through the reduction–precipitation of ferric chloride with Na2SO3 and NH4OH. The TMAOH-dispersed (Fe3O4) magnetic nanoparticles were then surface-coated with poly(L-co-D,L lactic acid-co-trimethylene carbonate) (PLDLA-co-TMC) to obtain the corresponding hybrid system (Fe3O4/TMAOH/PLDLA-co-TMC). Samples of so prepared material were analyzed by Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), magnetization measurements up to 2.5 T, and Mossbauer spectroscopy. Results indicate that this magnetic iron oxide soon after the synthesis is structurally close enough to a typically pure stoichiometric magnetite. FTIR data support clears evidences confirming the efficiency of the solvent displacement method to assure coating the TMAOH-dispersed (Fe3O4) magnetic nanoparticles with the terpolymer while preserves the main chemical structural characteristic of the nanosized magnetite.

Statement of problem Modifications have been made in the microstructure and sintering parameters of monolithic zirconia to improve esthetics qualities and avoid chipping of 2-layer restorations. However, how these modifications affect the physical and mechanical properties of zirconia is unclear. Purpose The purpose of this in vitro study was to compare the influence of different sintering parameters on the microstructure, 4-point flexural strength, density, and grain size of 2 commercially available zirconia advocated for the fabrication of monolithic dental prostheses and 1 commercially available zirconia for use as a core material. Material and methods Three presintered blocks (Ceramill Zolid, Prettau, and IPS e.max ZirCAD) were used. Specimens were cut and sintered as per the manufacturer's recommendation or as per a modified heating protocol. Ceramill Zolid (Z1450) was sintered at 1450 °C, Prettau (P1600) was sintered at 1600 °C, and IPS e.max ZirCAD (I1530) was sintered at 1530 °C by following the manufacturer's heating protocol. Groups Ceramill Zolid Z1530 and Z1600 were sintered at temperatures higher than the manufacturer's recommendation. Specimens from each group (n=13) were analyzed with X-ray diffraction (XRD), density calculus, average grain size measurement, and 4-point flexural tests. Data were compared by using ANOVA (α=.05). Results XRD analysis showed the presence of a tetragonal metastable phase in all groups before and after sintering. No significant differences were found in relative density values for the 3 Ceramill groups (5.98 g/cm3). Groups I1530 (6.03 g/cm3) and P1600 (6.03 g/cm3) had similar density results greater than 6.00 g/cm3. The average grain size of all groups remained lower than 1 μm. P1600 had the highest grain size (0.817 μm), and Z1450 presented the lowest grain size (0.465 μm). P1600 showed the most homogeneous flexural strength and the highest Weibull modulus (m=8.22). Z1530 presented the lowest Weibull modulus (m=4.58). IPS e.max ZirCAD (I1530) had the highest flexural strength (1057.41 ±150.54 MPa), and Ceramill Zolid Z1450 had the lowest (621.01 ±138.08 MPa). Conclusions The flexural strength, microstructure, crystal phase, and grain size of the analyzed zirconia varied as per the sintering processing. The IPS e.max ZirCAD had the highest flexural strength (1057.41 ±150.54 MPa), followed by Prettau zirconia (864.18 ±118.21), with a statistically significant difference (P

Objective: This study aimed at evaluating the design and dimensions of five different brands of orthodontic mini-implants, as well as their influence on torsional fracture strength. Methods: Fifty mini-implants were divided into five groups corresponding to different manufactures (DEN, RMO, CON, NEO, SIN). Twenty-five mini-implants were subjected to fracture test by torsion in the neck and the tip, through arbors attached to a Universal Mechanical Testing Machine. The other 25 mini-implants were subjected to insertion torque test into blocks of pork ribs using a torquimeter and contra-angle handpiece mounted in a surgical motor. The shape of the active tip of the mini-implants was evaluated under microscopy. The non-parametric Friedman test and Snedecor’s F in analysis of variance (ANOVA) were used to evaluate the differences between groups. Results: The fracture torque of the neck ranged from 23.45 N.cm (DEN) to 34.82 N.cm (SIN), and of the tip ranged from 9.35 N.cm (CON) to 24.36 N.cm (NEO). Insertion torque values ranged from 6.6 N.cm (RMO) to 10.2 N.cm (NEO). The characteristics that most influenced the results were outer diameter, inner diameter, the ratio between internal and external diameters, and the existence of milling in the apical region of the mini-implant. Conclusions: The fracture torques were different for both the neck and the tip of the five types evaluated. NEO and SIN mini-implants showed the highest resistance to fracture of the neck and tip. The fracture torques of both tip and neck were higher than the torque required to insert mini-implants. RESUMO Objetivo: o objetivo do presente estudo foi avaliar o desenho e as medidas de cinco marcas diferentes de mini-implantes ortodônticos, e sua influência na resistência à fratura em torção. Métodos: cinquenta mini-implantes foram divididos em cinco grupos, correspondentes a diferentes fabricantes (DEN, Dentaurum; RMO, Rocky Mountain Orthodontics; CON, Conexão; NEO, Neodent; SIN, Sistema de Implantes Nacional). Vinte e cinco mini-implantes foram submetidos ao teste de fratura por torção no pescoço e na ponta, com mandris fixados a uma máquina universal de testes mecânicos. Os outros 25 mini-implantes foram submetidos ao teste de torque de inserção em blocos de costelas suínas, utilizando-se um torquímetro e um contra-ângulo montado em motor cirúrgico. O formato da ponta ativa dos mini-implantes foi avaliado por microscopia. O teste não-paramétrico de Friedman e o teste F de Snedecor na análise de variância (ANOVA) foram utilizados para avaliar as diferenças entre os grupos. Resultados: o torque de fratura do pescoço variou de 23,45 N.cm (DEN) a 34,82 N.cm (SIN); e o da ponta, entre 9,35 N.cm (CON) e 24,36 N.cm (NEO). O valor do torque de inserção variou de 6,6 N.cm (RMO) a 10,2 N.cm (NEO). As características que mais influenciaram os resultados foram: diâmetro externo, diâmetro interno, razão entre o diâmetro interno e o externo, e a presença de fresagem na região apical do mini-implante. Conclusões: os torques de fratura foram diferentes entre os cinco tipos avaliados, tanto no pescoço quanto na ponta. Os mini-implantes NEO e SIN foram os mais resistentes à fratura do pescoço e da ponta. Os torques de fratura tanto na ponta quanto no pescoço foram maiores do que o torque necessário para a inserção dos mini-implantes.

Over the last decades, much research has been done to improve the surface quality of dental implants, but there was no change in the materials used to manufacture the implants. The purpose of the present work is to compare the compressive strength and fatigue failure of dental implants made with a new material, nanocrystalline Ti grade 4 fabricated by Equal Channel Angular Pressing (ECAP) (Ti Hard) with a traditional material, microcrystalline Ti grade 4 (Ti G4). Machined screw-shaped implants with three different designs (Easy, Torq and Flash) made with the two materials were subjected to static and dynamic compressive loads. Implants made with Ti Hard showed higher static compressive strength (Easy: 889.9 ± 79.4 N, Flash: 588.9 ± 74.7 N, Torq: 498.3 ± 54.6 N) than implants made with TiG4 (Easy: 776.4 ± 74.5 N, Flash: 308.8 ± 15.2 N, Torq: 410.3 ± 25.2 N) and higher fatigue strength for 5 106 cycles (Easy: 400 N, Flash: 280 N, Torq: 260 N) than implants made with TiG4 (Easy: 300 N, Flash: 200 N, Torq: 200 N). The higher fatigue strength of nanocrystalline Ti G4 is attributed to a delay in crack initiation.

This work evaluated the mechanical strength and surface roughness of MgZn30Ca5ribbon manufactured via a melt spinning technique for applications in the biomedical field. Annealing was performed at 280°C. The inner side (in contact with the wheel) and the outer side (not in contact with the wheel) of the ribbons were mechanically evaluated using nanoindentation, and its surfaces were analyzed by an optical profilometer. Differential scanning calorimeter (DSC) and X-ray diffraction (XRD) analyses were also performed to identify the structure and devitrification of the magnesium metallic glass (MgMG). The nanohardness and elastic modulus increased after annealing (p 0.05). Although both sides of the ribbons showed different surface profiles (p

Introduction The goal of the present study was to evaluate the influence of surface grooves (peaks and valleys) resulting from machining during the manufacturing process of polished and unpolished nickel-titanium BR4C endodontic files on the fatigue life of the instruments. Methods Ten electropolished and 10 unpolished endodontic files were provided by the manufacturer. Specimens were from the same batch, but the unpolished instruments were removed from the production line before surface treatment. The instruments were evaluated with a profilometer to quantify the surface roughness on the working part of the instruments. Then the files were subjected to rotating bending fatigue tests. Results Analysis with the profilometer showed that surface grooves were deeper on the unpolished instruments compared with their electropolished counterparts. In the rotating bending fatigue test, the mean and standard deviation for the number of cycles until fracture (NCF) were greater for instruments with less pronounced grooves. Student t test revealed significant differences in all tests (P Conclusions The results from the present study showed that the depth of the surface grooves on the working part affected the NCF of the instruments tested; the smaller the groove depth, the greater the NCF.

The present work presents an experimental study on the behavior of ceramic tile rendering build on concrete block masonry walls loaded to compression failure. The walls were tested considering two different coating systems: a) direct application of adhesive mortar and lastly the ceramic tile; b) with cement plaster followed by the adhesive mortar and finally the ceramic tile. Four events were recorded: noise emission, plaster detachment, ceramic tile detachment and wall rupture. For both coating systems, the fracture loads were similar and ceramic tile detachment occurring at loads above expected service for residential buildings.

The objectives were to investigate the mechanical strength and biocompatibility of Mg2Ca2Gd and Mg1Ca2Nd (wt%) alloys developed for biomedical application as implantable bioabsorbable devices. Samples were implanted in New-Zealand rabbits tibia for 3, 6 and 8 weeks and compatibility analysis involved whole blood test, biochemistry, histopathology, histology, and radiographs. Refinement in grains were observed in Mg2Ca2Gd alloy; and Mg5Gd, Mg41Nd5, α-Mg and Mg2Ca phases were identified. Polarization curves revealed easier oxidation of Mg2Ca2Gd alloy, smaller values of corrosion rate and a higher polarization resistance of Mg1Ca2Nd. Adequate compatibility of both alloys was identified with pre-osteoblast stem cells. Red and white cells stayed compatible with reference ranges. Enzymes from liver and kidneys stayed at regular values and samples from kidneys and liver tissues presented similar organization to control animals. Histological displays from implantation sites disclosed well-structured tissues with evidences of bone cells activities compatible with the new bone tissues observed. Radiographs from tibias did not revealed relevant gas pockets. Mg2Ca2Gd alloy demonstrated faster degradation. Adequate biocompatibility was observed in Mg-Ca alloys with RE addition, being potential candidates for development of metallic implantable bioabsorbable devices. Refereed/Peer-reviewed