Influence of Core-Veneer Thickness Ratio on the Fracture Load and Failure Mode of Zirconia Crowns.

PURPOSE: To evaluate the influence of different core-veneer thickness (CVT) ratios on fracture loads and failure modes of zirconia crowns with or without thermomechanical cycling (TC). MATERIALS AND METHODS: Forty yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) cores were veneered with a pressable ceramic and divided into four groups (n = 10): group 1 - 1:3 CVT ratio (0.5-mm core, 1.5-mm veneer); group 2 - 1:1 CVT ratio (1.0-mm core, 1.0-mm veneer); groups 3 and 4 - identical to groups 1 and 2, respectively, except that they underwent TC (1,000,000 cycles with an 84-N load applied at a 4-Hz frequency, temperature cycling at 4°C, 37°C, and 55°C - 30 seconds each). Loads were applied axially to the central fossa of the crowns with a 1 mm/min crosshead speed at 200 N until failure. RESULTS: Two-way ANOVA showed that the crowns with a 1:3 CVT ratio had a lower mean fracture load than crowns with a 1:1 CVT ratio (group 1 = 1666.4 ± 466.4 N; group 2 = 2156.6 ± 472.3 N). TC had no effect on the fracture load for crowns with the same CVT ratio. The failures observed for the crowns in groups 1, 3, and 4 were fractures within the veneering ceramic, which exposed the core. The failure severity of fractures for group 2 was less extensive, characterized by chipping within the ceramic veneer. CONCLUSION: Crowns with a 1:1 CVT ratio had higher fracture load values and more conservative failures. TC had no effect on the fracture load of the ceramic crowns.

Effect of gender, experience, and value on color perception.

STATEMENT OF THE PROBLEM: Precise shade matching can be one of the most difficult tasks for the dentist and some variables may influence the process of shade comparison. PURPOSE OF THE STUDY: This study tested the differences in shade perception between genders, the influence of the observer's clinical experience, and the value of ceramics in correct shade selection. MATERIAL AND METHODS: A total of 45 women and 54 men compared 16 pairs of ceramic disks according to shades. The χ(2) and Fisher exact tests were used to analyze the results, adopting 5% as the level of statistical significance. An analysis of risk was also performed to evaluate the variables. RESULTS: The results indicated that there were statistical differences among gender, clinical experience, and shades in discriminating ceramics. CONCLUSIONS: Men and observers with more clinical experience were more successful in discriminating shades, although darker shades were selected more correctly than the lighter ones.

Natural teeth used as provisionals in immediate implant loading in the maxilla: a case report.

PURPOSE: The purpose of this article is to describe a clinical case in which the patient's natural teeth were extracted and used as provisionals immediately after the implants had been placed. PATIENT PRESENTATION: A 52-year-old woman was treated with implants at the 2 maxillary central incisors using osseotite-tapered certain implants (Biomet 3I Inc., Palm Beach Gardens, FL), length: 15 mm, diameter: 4.1 mm; and the extracted teeth were used as provisionals. RESULTS: After 4 months of using the temporary teeth, the treatment was concluded with the placement of 2 metal-free crowns on the implants and light polymerized resin on teeth 7 and 10. CONCLUSIONS: This work showed the possibility of using the patient's extracted teeth as provisional teeth during the period of osseointegration, preserving aesthetics and favoring gingival tissue healing with a correct emergence profile and maintenance of the gingival papillae.

Stress distribution in restorations with glass fiber and polyetheretherketone intraradicular posts: An in silico analysis.

This study evaluated stresses generated at maxillary central incisor (21) root restored with lithium disilicate crown (LDC), and glass fiber (GFP) or polyetheretherketone (PEEK) post. 3D models created by computed tomographic image (i-CAT Cone Beam 3D Dental Imaging System) reproduced maxillary central incisor. Each model had prosthetic LDCs (2.0 mm thick) cemented to GFP or PEEK posts with dual resin cement. Different loads were applied to each model (cervical, incisal, axial, middle). At maximum principal stress, PEEK showed higher stress than GFP in all loads, but with qualitative similarity. At minimum principal stress, PEEK and GFP showed qualitative and quantitative similarities, except axial load. Maxillary central incisor restored with GFP or PEEK and LDC presented, in general, similar stress intensity and distribution for main occlusal loads. Only two of sixteen occlusal loads tested (cervical for maximum principal; axial for minimum principal) showed significant quantitative difference.

Bond strength of self-adhesive resin cement to dentin using different adhesion protocols.

BACKGROUND: The treatment of dentin before the use of self-adhesive cements is still a crucial point to achieve the best bond strength values. The objective of this study was to evaluate the bond strength between dentin and composite resin using different adhesion strategies with self-adhesive resin cement. MATERIAL AND METHODS: Forty healthy third human molars were randomly divided into 4 groups (n = 10): CA (control); application of self-adhesive cement (Rely X U200, 3M ESPE), AD + CA: only application of conventional adhesive (Adper Single Bond 2, 3M ESPE) + self-adhesive cement, AC + AD + CA; conditioning with 37% phosphoric acid for 15 seconds + application of conventional adhesive + self-adhesive cement and AC + CA; conditioning with 37% phosphoric acid for 15s + self-adhesive cement. Blocks made of composite resin (Z250 XT, 3M ESPE) were cemented over dentin. The samples were stored for 24h in distilled water at 37ºC and then were sectioned on a metallographic cutter to obtain tooth picks with approximately 1.0 mm2 in cross section. A universal testing machine was used with a speed of 0.5 mm/min to test the microtensile bond strength,. The fracture patterns were classified as adhesive, cohesive and mixed failures. The data (MPa) were analyzed statistically by One-way ANOVA and Holm-Sidak test (α=5%). RESULTS: The AC + AD + CA and AC + CA groups had the highest averages, while the CA and AD + CA groups had the lowest bond strength values. Adhesive failure was prevalent in all groups. CONCLUSIONS: Conditioning with 37% phosphoric acid for 15s increases the adhesion of the self-adhesive resin cement to the dentin, regardless of the use of dental adhesive system. Key words:Resin cement, microtensile bond strength, acid conditioning.

Influence of the Multiple Layers Application and the Heating of Silane on the Bond Strength between Lithium Disilicate Ceramics and Resinous Cement.

OBJECTIVE: This study aimed to evaluate the bond strength between lithium disilicate ceramic and resinous cement when silane (Prosil, FGM) was applied in different amounts of layers under heating or not. MATERIALS AND METHODS: Sixty IPS E-max CAD ceramic (Ivoclar) was used. They were conditioned with 10% hydrofluoric acid for 20 seconds. The samples were distributed in six groups (n = 10): 1Sil, 1 layer of silane without heating; 1SilAq, 1 layer of silane with heating; 2Sil, 2 layers without heating; 2SilAq, 2 layers with heating; 3Sil, 3 layers without heating; and 3SilAq, 3 layers with heating. After each layer, a jet of cold air was applied for 20 seconds in groups 1Sil, 2Sil, 3Sil, and jet of hot air (50°C) in groups 1SilAq, 2SilAq, and 3SilAq. Subsequently, an adhesive layer was applied, and fourcylinders were made on the ceramic with a resin cement AllCemVeneer and photoactivated for 20 seconds. The samples were stored at 37°C for 24 hours and analyzed to the microshear test at EMIC. STATISTICAL ANALYSIS: Data were submitted to ANOVA and Tukey's test (α = 0.05). RESULTS: The results showed that there was no statistical interaction between the factors studied. The "heating" factor was not statistically significant; however, the "silane layers" factor showed differences between groups. The analysis of the results showed that the use of one (66%) or two layers (67%) of silane regardless of heating, produced higher values of bond strength, when compared with the group of three layers (62%). CONCLUSION: The use of silane with one or two layers provided a greater bond strength between lithium disilicate ceramic and resinous cement and that the heating did not influence the results.

Finite Element Analysis of Stress in Anterior Prosthetic Rehabilitation with Zirconia Implants with and without Cantilever.

OBJECTIVES: The aim of this study was to evaluate using finite element analysis (FEA), the stress distribution in prostheses (lithium disilicate crowns) on monotype zirconia implants with and without cantilever in the anterior region of the maxilla. MATERIALS AND METHODS: From a virtual reconstruction of bone model of the toothed maxilla from a computed tomography, three models (groups) were created: Zr (11-21)-implants placed in the area of 11 and 21 with cantilever; Zr (12-22)-implants placed in the area of 12 and 22 without cantilever; and Zr (11-22)-implants intercalated placed in the area of 11 and 22. In all models, monotype zirconia implant (4.1 × 12.0 mm) was used in single-body configuration. Lithium disilicate crowns were designed on the implants and pontics for all groups. A 150-N load was applied to the prostheses. The materials used were considered isotropic, homogeneous, and linearly elastic. FEA was performed to evaluate the maximum (tensile) and minimum (compressive) principal stresses in the implant, crowns, and bone tissue. Data were analyzed qualitatively and quantitatively. RESULTS: For all groups, the highest maximum principal stress occurred in the palatal cervical area of the implant, with the high values for the Zr (12-22) group and the low values for the Zr (11-21) group. The maximum principal stress was concentrated in the cervical palatal area of the crown, with the Zr (11-21) group presented the highest values and the Zr (12-22) group showed the lowest values. In the bone tissue all the groups presented similar values of maximum and minimal principal stress, with the palatal (maximum principal) and vestibular (minimum principal) close to the cervical of the implants the area with the highest concentration of stresses. CONCLUSIONS: The position of monotype zirconia implant did not interfere in the bone tissue stress, and the implants placed in the 11-21 present lower stress in implants and higher in the crown. The cantilever does not increase the stress in the implants, crown, and bone tissue.

Effect of Glass Fiber Post Adaptation on Push-Out Bond Strength to Root Dentin.

The aim of this study was to evaluate the effect of different glass fiber posts (GFPs) diameters on the push-out bond strength to dentin. Forty unirradicular human teeth were endodontically treated and used for cementation of GFPs (White Post DC, FGM) with different diameters (n=10): P1 - ø 1.6 mm coronal x 0.85 mm apical; P2 - ø 1.8 mm coronal x 1.05 mm apical; P5 - ø 1.4 mm coronal x 0.65 mm apical; and PC - customized post number 0.5 with composite resin (Tetric Ceram A2, Ivoclair Vivadent). All GFPs were cemented into the root canal using a dual-curing luting composite (Variolink II, Ivoclar Vivadent). One slice (1.7 mm) of each root third of cemented GFP (cervical, middle, and apical) was submitted to push-out testing. Failure modes of all specimens were classified as: adhesive failure between resin cement and post; adhesive failure between dentin and resin cement; cohesive failure within resin cement, post or dentin; and mixed failure. The data were analyzed with two-way ANOVA and Tukey's test (a=0.05). The highest bond strength values were presented for the P2 and PC groups. There was no statistically significant difference between the GFP thirds in each group. The groups P2, P5, and PC showed predominantly adhesive failure. For P1, the most prevalent type of failure was adhesive between resin cement and post. It may be concluded that a glass fiber post that is well adapted to the root canal presents higher bond strength values, regardless of GFP third.

Mechanical properties of experimental resin cements containing different photoinitiators and co-initiators.

AIM: The aim of this study was to evaluate the influence of different concentrations of two photoinitiators and one co-initiator on the flexural strength (FS) and elastic modulus (E) of experimental resin cements. MATERIALS AND METHODS: A mixture containing BisGMA, TEGDMA, and barium-aluminum-silicate (BaAlSi) and silanized colloidal silica (SiO2) filler particles was prepared with two photoinitiators, viz. camphorquinone (CQ) and bisacylphosphine oxide (BAPO). Dimethylaminoethyl methacrylate (DMAEMA) was used as co-initiator. Thirty groups (n=10) were formulated with different photoinitiator systems (CQ/DMAEMA and BAPO/DMAEMA) and concentrations (wt%) of photoinitiator and co-initiator. The photoactivation was carried out for 20 s with a light-emitting diode (LED, Bluephase, Ivoclar Vivadent) with irradiance of 1200 mW/cm2. The FS and E were obtained in a three-point bending test on a universal testing machine (0.5 mm/min). Data were subjected to the Kolmogorov-Smirnov normality test, followed by two-way ANOVA and Tukey's test (α=0.05). RESULTS: No polymerization occurred in the CQ groups without DMAEMA (0 wt%). DMAEMA 0.5 %wt and 1 %wt groups showed statistically similar FS and E results for CQ and BAPO, except for CQ 0.3 wt% (FS), CQ 0.9wt% (E) and BAPO 1.76 wt% (FS and E) for DMAEMA 0.5 %wt. No significant difference was found for FS and E values for different concentrations of photoinitiators, except for CQ 0.25 wt% (FS and E) and BAPO 0.25 wt% (E) that showed the lowest values. CONCLUSION: The wt% of the photoinitiators and co-initiator influenced the mechanical properties and the performance of CQ was dependent on the DMAEMA concentration. BAPO can be used as substitute for the conventional CQ/DMAEMA photoinitiator system.

Effect of Thermocycling, Teeth, and Polymerization Methods on Bond Strength Teeth-Denture Base.

OBJECTIVE: To evaluate the shear bond strength between different artificial teeth and denture base polymerized by two polymerization methods submitted to thermocycling. MATERIALS AND METHODS: Two acrylic resins were selected according to the polymerization method (water-bath and microwave), and four different artificial teeth (Biotone, Dentsply; Trilux, Vipi Dent; Premium 8, Heraeus Kulzer; Soluut PX, Yamahachi) were also tested. The polymerization of the acrylic resin was performed by using conventional cycle (8 h at 74°C) in water-bath and using two cycles (20 min at 270 W + 5 min at 360 W) by the microwave method. The shear bond strength was evaluated after 24 h of water storage at 37°C (immediately) and after the thermocycling test (5,000 cycles, 5-55°C). The shear bond strength (n=10) was performed using a universal testing machine (Instron 4411) at a crosshead speed of 1.0 mm/min. Modes of failures were classified as cohesive and adhesive. The data (MPa) were statistically analyzed by three-way ANOVA, and the mean values were compared by the Tukey test (α = 0.05). RESULTS: In general, the polymerization by microwave showed the highest shear bond strength values, and Trilux artificial teeth had the lowest bond strength values (p < 0.05). Thermocycling did not affect the shear bond strength (p < 0.05). There was a predominance of cohesive failures for all groups. CONCLUSIONS: The chemical composition of the artificial teeth affects the bond strength, and the microwave method is preferable to perform the acrylic resin polymerization.

Temporomandibular joint disorders as the only manifestation of juvenile idiopathic arthritis: a case report.

Juvenile idiopathic arthritis is a term used to include all chronic childhood arthritis of unknown etiology. It is characterized by chronic inflammation persisting for at least 6 weeks, beginning before 16 years of age. The characteristics present are chronic synovitis, arthralgia, impaired joint mobility in at least one joint, and erosion with destruction of cartilage and subchondral bone, that could be associated or not with systemic involvement, according to each subtype of the disease. During the pathologic process, the temporomandibular joint can be involved by the juvenile idiopathic arthritis, resulting in severe mandibular dysfunction, with higher frequency in female patients. Initially, these lesions can show minor alterations like flattening of the condyle, erosions, and evolve to severe lesions, like destruction of the head of the condyle. We report a case of male patient who had destruction of both condyles, as a result from juvenile idiopathic arthritis. Proposed mechanisms to explain the juvenile idiopathic arthritis was reviewed. In this report the patient did not have pain or inflammatory process, and the temporomandibular diseases was the only manifestation.

Conservative restorations combined with gingival zenith contour technique.

The symmetry, shape, contour, and size of teeth play an important role in the esthetics of the anterior maxillary region of the mouth. However, abnormalities in symmetry and contour can considerably influence the esthetic parameters. Consequently, rehabilitation performed in this region can be challenging and, frequently, multidisciplinary treatment planning that includes esthetics, function, structure, and biologic aspects is paramount. The high demand for esthetic rehabilitations has, therefore, allowed the effective use of minimally invasive techniques to obtain results that mimic natural teeth. This article presents a case report in which both esthetic and functional rehabilitation were obtained by recontouring the gingival zenith followed by placing ultraconservative porcelain veneers.

Influence of angulation and height of tooth preparation on the distribution of tensions in prosthetic crowns for upper central incisor: in silico analysis

Aim: it was to use tridimensional finite element analysis (FEA) to analyze the effect of height and angulation of prosthetic preparations on the distribution of stresses for lithium disilicate prosthetic crowns, the underlying resin cement, and the prosthetic preparation of a superior central incisor. Methods: a CAD modeling software, SolidWorks 2013, was used to generate three-dimensional virtual models comprising the dimensions of the preparation parameters. Three angles (6, 12 and 16 degrees) were simulated on the prepared walls and two wall heights were utilized (4 and 5 mm), for a total of six model groups according to the height and angulation of the walls. A vertical line in the Y-axis was used as a reference for determining the degrees of convergence (inclination of the preparations). The chamfer finish and preparation width were standardized for all groups. Results: the 4 mm preparations behaved more appropriately when the axial wall convergence was approximately 6 degrees. The 5 mm preparations required 12 degrees of angulation. In relation to resin cement, there was better stress distribution when the angle of incisal convergence was between 6 and 12 degrees. An increase to 16 degrees led to a considerable increase in peak stress at the preparation margin. Conclusion: it was concluded that the convergence of the axial walls of coronal preparations with 4 and 5 mm heights should be 6 and 12 degrees, respectively, to avoid high tension spikes in the underlying resin cement

Influence of cantilever position and implant connection in a zirconia custom implant-supported fixed partial prosthesis: in silico analysis / Influência da posição do cantilever e da conexão do implante em um modelo de zirconia de uma prótese parcial fixa implanto-suportada: análise in sílico

Introduction: A better tension distribution on implants and abutments in implant-supported fixed partial prosthesis is essential in the rehabilitation of posterior mandible area. Objective: To evaluate the influence of cantilever position and implant connection in a zircônia custom implant-supported fixed partial prosthesis using the 3-D finite element method. Material and method: Four models were made based on tomographic slices of the posterior mandible with a zirconia custom three-fixed screw-retained partial prosthesis. The investigated factors of the in silico study were: cantilever position (mesial or distal) and implant connection (external hexagon or morse taper). 100 N vertical load to premolar and 300 N to molar were used to simulate the occlusal force in each model to evaluate the distribution of stresses in implants, abutments, screws and cortical and cancellous bone. Result: The external hexagon (EH) connection showed higher cortical compression stress when compared to the morse taper (MT). For both connections, the molar cantilever position had the highest cortical compression. The maximum stress peak concentration was located at the cervical bone in contact with the threads of the first implant. The prosthetic and abutment screws associated with the molar cantilevers showed the highest stress concentration, especially with the EH connection. Conclusion: Morse taper implant connetions associated with a mesial cantilever showed a more favorable treatment option for posterior mandible rehabilitation.

Introdução: Uma melhor distribuição de tensão em implantes e mini-pilares em próteses parciais fixas implanto-suportadas é essencial na reabilitação em região posterior de mandíbula. Objetivo: Avaliar a influência da posição do cantilever e conexão do implante em uma prótese fixa de três elementos confeccionada totalmente em zircônia através do método de elementos finitos tridimensionais (MEF). Material e método: Foram confeccionados quatro modelos baseados em cortes tomográficos da região posterior da mandíbula com uma prótese parcial parafusada fixada em três fixações personalizadas de zircônia. Os fatores investigados do estudo in sílico foram: posição do cantilever (mesial ou distal) e conexão do implante (hexágono externo ou cone morse). Uma carga de 100 N para a região de pré-molares e de 300 N para a região de molares foi usada para simular a força oclusal em cada modelo para avaliação da distribuição de tensões nos implantes, mini pilares, parafusos e tecido ósseo cortical e medular. Resultado: A conexão hexágono externo apresentou maior concentração de tensão no osso cortical quando comparado ao cone morse. Para ambas conexões, o cantilever distal aumentou a tensão no osso cortical. O pico máximo de tensão foi localizado no osso cervical em contato com as primeiras roscas internas do primeiro implante. Os parafusos protéticos e dos mini-pilares associados ao cantilever distal apresentaram maior concentração de tensão, especialmente na conexão hexágono externo. Conclusão: Conexão do implante cone morse associada ao cantilever mesial apresentou uma opção de tratamento mais favorável para a reabilitação na região posterior de mandíbula.

Evaluation of dimensional stability and details reproduction of alginate molds storage in different times and temperature / Avaliação da estabilidade dimensional e reprodução de detalhes de moldes de alginatos armazenados por diferentes tempos e temperatura

Objective: The aim of this study was to evaluate dimensional stability and detail reproduction in alginate molds stored at different times and temperatures. Material and Methods: Three different commercially available alginates (Cavex Color Change, Jeltrate Plus and Hydrogum 5) were tested at four different times (0 - control, 1, 3 and 5 days) and two temperatures (25ºC and 37ºC) (n=5). The alginates were handled following the manufacturer's instructions. The impression procedures occurred in an environment with controlled room temperature (25ºC) and relative humidity (50±5%). A metallic model (ISO 1563:1990) was used to perform the impressions. The tray containing alginate remained on the metallic model under constant pressure (2 kgf) until the alginate gelation process. The molds were stored (different times and temperatures) and analyzed in stereomicroscope at 30x magnification and 0.5 µm accuracy (Olympus Measuring Microscope STM). The molds and the metallic model measurements were compared, and the data were statistically analyzed by Kolmogorov-Smirnov and three-way ANOVA tests, and the means were compared by Tukey test (5%). Results: The results showed no double interactions (p>0.05) and the different alginates presented statistically similar values of dimensional stability (p=0.102). However, 25ºC (temperature) and control group (time) showed the highest values of dimensional stability (p <0.05). Jeltrate Plus was the only material that presented inaccuracy in details reproduction. Conclusion: It is recommended that, for tested alginates, the stone casts should be poured immediately, even though the molds are dimensionally stable up to 5 days when stored at 25ºC.(AU)

Objetivo: O objetivo neste estudo foi avaliar a estabilidade dimensional e a reprodução de detalhes em moldes de alginatos armazenados em diferentes tempos e temperaturas. Material e Métodos: Foram testadas três diferentes marcas de alginato (Cavex ColorChange, Jeltrate Plus e Hydrogum 5), sendo que esses materiais foram armazenados por quatro diferentes tempos (0 - controle, 1, 3 e 5 dias) e duas diferentes temperaturas (25ºC e 37ºC) (n=5). Os alginatos foram manipulados seguindo as instruções do fabricante. A moldagem ocorreu em um ambiente com temperatura (25ºC) e umidade relativa (50±5%) controladas. Foi utilizado um modelo metálico (ISO 1563:1990) para a realização das moldagens. A moldeira contendo o alginato permaneceu sobre o modelo metálico sob pressão constante de 2 kgf até a geleificação do material. Em seguida, os moldes foram armazenados nos tempos e temperaturas testados, sendo posteriormente avaliados sob um microscópio comparador (Olympus Measuring Microscope STM) com precisão de 0,5 µm. As medidas dos moldes de alginato foram comparadas com as medidas do modelo metálico padrão, sendo os dados analisados estatisticamente pelos testes de Kolmogorov-Smirnov e ANOVA três fatores, sendo as médias foram comparadas pelo teste de Tukey (5%). Resultados: Os resultados mostraram nenhuma interação dupla (p>0,05), sendo que os diferentes alginatos apresentaram valores de estabilidade dimensional estatisticamente semelhantes entre si (p=0,102). Já a temperatura de 25ºC e o grupo controle (tempo) mostraram os maiores valores de estabilidade dimensional (p <0,05). O Jeltrate Plus foi o único material que apresentou imprecisão na reprodução de detalhes. Conclusão: Recomenda-se que os alginatos testados tenham os modelos de gesso vazados imediatamente, apesar dos moldes serem dimensionalmente estáveis até 5 dias desde que armazenados a 25ºC. (AU)

Evaluation of roughness and micromorphology of epoxy paint on cobalt-chromium alloy before and after thermal cycling.

It has been suggested that the epoxy paint used to coat metal substrates in industrial electrostatic painting applications could also be used to mask metal clasps in removable dental prostheses (RDP). The purpose of this study was to evaluate both the influence of thermal cycling and the in vitro roughness of a surface after application of epoxy paint, as well as to assess the micromorphology of a cobalt-chromium (CoCr) based metal structure. Sixty test specimens were fabricated from a CoCr alloy. The specimens were separated into three groups (n = 20) according to surface treatment: Group 1 (Pol) - polished with abrasive stone and rubbers; Group 2 (Pol+Epo) - polished and coated with epoxy paint; Group 3 (Epo) - air-abraded with aluminum oxide particles and coated with epoxy paint. The surface roughness was evaluated before and after 1000 thermal cycles (5°C and 50°C). The surface micromorphology was verified by scanning electron microscopy (SEM). The two-way repeated measures ANOVA showed significant differences among surface treatments (p < 0.0001), but no difference was found before and after thermal cycling (p = 0.6638). The CoCr-based metal alloy surfaces treated with epoxy paint (Groups 2 and 3) were rougher than the surfaces that were only polished (Group 1). Thermal cycling did not influence surface roughness, or lead to chipping or detachment of the epoxy paint.

Temporomandibular joint disorders as the only manifestation of juvenile idiopathic arthritis: a case report / Comprometimento da articulação temporomandibular como única manifestação da artrite idiopática juvenil: um relato de caso

ABSTRACT Juvenile idiopathic arthritis is a term used to include all chronic childhood arthritis of unknown etiology. It is characterized by chronic inflammation persisting for at least 6 weeks, beginning before 16 years of age. The characteristics present are chronic synovitis, arthralgia, impaired joint mobility in at least one joint, and erosion with destruction of cartilage and subchondral bone, that could be associated or not with systemic involvement, according to each subtype of the disease. During the pathologic process, the temporomandibular joint can be involved by the juvenile idiopathic arthritis, resulting in severe mandibular dysfunction, with higher frequency in female patients. Initially, these lesions can show minor alterations like flattening of the condyle, erosions, and evolve to severe lesions, like destruction of the head of the condyle. We report a case of male patient who had destruction of both condyles, as a result from juvenile idiopathic arthritis. Proposed mechanisms to explain the juvenile idiopathic arthritis was reviewed. In this report the patient did not have pain or inflammatory process, and the temporomandibular diseases was the only manifestation.

RESUMO Artrite idiopática juvenil é um termo usado para incluir toda artrite infantil crônica de etiologia desconhecida. É caracterizada por uma inflamação crônica, que persiste por pelo menos 6 semanas, com início antes dos 16 anos de idade. As características presentes são sinovite crônica, artralgia, mobilidade articular diminuída em pelo menos uma articulação, e erosão com destruição da cartilagem e do osso subcondral, podendo ser associada ou não com o envolvimento sistêmico, de acordo com cada subtipo da doença. Durante o processo patológico, a articulação temporomandibular pode ser envolvida pela artrite idiopática juvenil, resultando em disfunção mandibular severa, com maior frequência em pacientes do sexo feminino. Inicialmente, estas lesões podem mostrar pequenas alterações, como achatamento do côndilo e erosões, e evoluir para lesões graves, como a destruição da cabeça do côndilo. Relatou-se o caso de um paciente do sexo masculino, que apresentou destruição de ambos os côndilos, como resultado da artrite idiopática juvenil. Os mecanismos para explicar a artrite idiopática juvenil foram revisados na literatura. Neste relato de caso, o paciente não apresentou dor e nem processo inflamatório, sendo o comprometimento da articulação temporomandibular a única manifestação.

Dimensional accuracy of different impression techniques of partially edentulous mandibular arch / Precisão dimensional de diferentes técnicas de moldagem de uma mandíbula parcialmente edêntulo

ABSTRACT Objective: The purpose of this in vitro study was to assess and compare the dimensional accuracy of three impression techniques: 1-step putty/light-body, 2-step putty/light-body, and the monophase technique. Methods: A partially edentulous standard stainless steel mandibular arch cast with reference points on the teeth was used to make the impressions. The anteroposterior and transverse distances were measured. All impressions were made with a polyvinyl siloxane using stock metallic (1- and 2-step putty/light-body techniques) or acrylic resin (monophase technique) trays. The monophase impressions were made using a light-body material and the 1- and 2-step putty/light-body impressions with putty and light-body materials. After impression procedures, the accuracy of each technique was assessed measuring the stone casts (n = 5) poured from the impressions using a microscope at 30x magnification and at 0.5 µm accuracy. The data were analyzed statistically using 2-way ANOVA and Tukey's test (p<0.05). Results: Stone casts made by all techniques had significantly negative linear changes (shrinkage). The anteroposterior distances showed more dimensional changes than the transverse distances. The edentulous side showed more shrinkage than the anteroposterior side. Conclusion: No differences between the impression techniques were found, but significant dimensional changes were observed.

RESUMO Objetivo: Avaliar e comparar a precisão dimensional de três técnicas de moldagem: dupla mistura, reembasamento e moldeira individual. Métodos: Um modelo metálico inferior parcialmente edêntulo foi fabricado com pontos de referência nos dentes e usado para fazer as moldagens. As distâncias ântero-posteriores e transversais foram medidas. Todas as moldagens foram feitas com um silicone por adição utilizando moldeiras metálicas (técnicas da dupla mistura e reembasamento) ou de resina acrílica (técnica da moldeira individual). Na técnica da moldeira individual foi utilizado apenas o elastômero de viscosidade leve e nas técnicas da dupla mistura e reembasamento foram usados os elastômeros nas viscosidades denso e leve. Após os procedimentos de moldagem, a precisão dimensional de cada técnica de moldagem foi avaliada aferindo os modelos de gesso (n = 5) em um microscópio comparador com 30x de aumento e 0,5 µm de precisão. Os dados foram analisados estatisticamente por ANOVA dois fatores e teste de Tukey (p<0,05). Resultados: Os modelos de gesso feitos com todas as técnicas de moldagem apresentaram alterações lineares negativas (contração). As distâncias ântero-posteriores apresentaram maiores alterações dimensionais que as distâncias transversais. O lado parcialmente edêntulo teve maior contração que o lado ântero-posterior oposto. Conclusão: Não foram encontradas diferenças entre as técnicas de moldagem, mas foram observadas significantes alterações dimensionais.

Use of botulinum toxin type a in temporomandibular disorder / Utilização da toxina botulínica tipo a na disfunção temporomandibular

ABSTRACT Temporomandibular disorder (TMD) may be defined as a set of clinical scenarios involving the masticatory muscles, the temporomandibular joint (TMJ) and associated structures. Currently, 40 to 75% of the population has some sign of temporomandibular disorder, mainly pain located in the muscles of mastication in the pre-auricular region. The present clinical case was diagnosed as muscle temporomandibular disorder secondary to parafunction, as well as muscle hyperactivity due to surgical displacement of the left temporal muscle on two occasions, one for placement of aneurysm clips and the other for tumor excision from the supraorbital region on the left side. The patient sought medical and dental attention for 10 years due to constant headaches, tiredness and pain in the cheeks. The patient tried numerous bite-guards and pharmacological therapies to no avail. The American Academy of Orofacial Pain Questionnaire was applied combined with the Criteria for Research and Diagnostics (DRC) and a decision was made to use botulinum toxin type A in the masseter and temporalis muscles. An analog pain scale was applied over 90 days. Three days following the application of botulinum toxin type A, the patient reported a significant improvement with complete resolution of pain (level 0) after 90 days. At 12 weeks from starting treatment, facial muscle physiotherapy was introduced to strengthen the muscles of mastication and the patient remained pain-free, which allowed the preparation and adaptation of a snap-on prosthetic appliance. In conclusion, the use of botulinum toxin in patients with temporomandibular disorder should be considered as a viable therapeutic option.

RESUMO A desordem temporomandibular pode ser definida como um conjunto de distúrbios que envolvem os músculos mastigatórios, a articulação temporomandibular e estruturas associadas. Atualmente entre 40 a 75% da população apresenta algum sinal de desordem temporomandibular, sendo o mais frequente a dor, principalmente localizada nos músculos da mastigação e na região pré-auricular. O caso clínico apresentado foi diagnosticado como desordem temporomandibular muscular por parafunção, hiperatividade muscular antecedida por deslocamento do músculo temporal esquerdo para realização de duas cirurgias, uma para colocação de clips aneurismático e a outra para remoção de um tumor na região supraorbitária do lado esquerdo. A paciente procurou durante 10 anos ajuda médica e odontológica por sofrer com constantes dores de cabeça, cansaço, dor nas bochechas, usou inúmeras placas, medicamentos, porém o efeito desejado nunca fora alcançado. Frente ao histórico foi aplicado o questionário da Academia Americana de Dor Orofacial e o Critério de Pesquisa e Diagnóstico (RDC), e a conduta clinica adotada foi à aplicação de toxina botulínica tipo A nos músculos masseter e temporal. Foi aplicada uma escala de dor analógica ao longo de 90 dias. Já após 3 dias da aplicação da toxina botulínica tipo A, a paciente relatou melhora significativa chegando a nível 0 de dor após 90 dias. Após 12 semanas do início do tratamento, foram acrescidos exercícios para fortalecimento dos músculos da mastigação, sendo que a paciente continuava sem dor, permitindo desta forma a confecção e instalação de prótese tipo Snap-on. Desta forma, o emprego da toxina botulínica em pacientes com desordem temporomandibular deve ser considerado como uma boa opção terapêutica.

Relining effects on the push-out shear bond strength of glass fiber posts / Efeitos do reembasamento sobre a resistência ao cisalhamento por extrusão (push-out) de pinos de fibra de vidro

Introduction: The correct use of glass fiber posts in endodontically treated teeth is essential for the clinical success of restorative treatment. Objective: This study evaluated the push-out shear bond strength of relined (R) or non-relined (NR) glass fiber posts, cemented with self-adhesive resin cement [RelyXTM U100 (U100)] and conventional resin cement [RelyXTM ARC (ARC)]. Material and method: Sixty human single-rooted teeth were endodontically treated and divided into ARC-NR; U100-NR; ARC-R; U100-R groups. The teeth were sectioned into cervical, middle and apical thirds, and subjected to the push-out test. Bond strength was analyzed by the Friedman test; cement and post types were compared by the Mann Whitney test. The pattern of failures was evaluated with digital camera through images at 200x magnification, and was classified as adhesive (at the cement/dentin or cement/post interface), cohesive (cement or post), and mixed failures. Result: In ARC-NR, bond strength values were higher in the cervical third; in U100-NR and ARC-R they were similar between the thirds. In U100-R, in the cervical and middle thirds the bond strength values were similar, and there was lower value in the apical third. For non-relined glass fiber posts, the highest mean bond strength values were observed with self-adhesive resin cement. Whereas, relined posts cemented with conventional resin cement had stronger cement layer in comparison with non-relined fiber posts. Conclusion: The post relining technique was efficient in ARC-R. ARC-NR and U100-R showed improved bond strength in the cervical region of canal walls. The main failures were adhesive at the cement-post interface.

Introdução: O correto uso de pinos de fibra de vidro em dentes tratados endodonticamente é essencial para o sucesso clínico do tratamento restaurador. Objetivo: Esse estudo avaliou a resistência ao cisalhamento por extrusão (push-out) em pinos de fibra de vidro reembasados (R) ou não reembasados (NR), cimentados com cimento resinoso auto-adesivo [RelyXTM U100 (U100)] e cimento resinoso convencional [RelyXTM ARC (ARC)]. Material e método: Sessenta dentes humanos unirradiculares foram tratados endodonticamente e divididos nos grupos ARC-NR; U100-NR; ARC-R; U100-R. Os dentes foram seccionados nos terços cervical, médio e apical para serem submetidos ao teste de cisalhamento por extrusão (push-out). A resistência de união foi analisada pelo teste de Friedman; os tipos de cimento e de pinos foram comparados pelo teste de Mann Whitney. O padrão de falhas foi avaliado com câmera digital através de imagens em 200x de ampliação e foi classificado como falhas adesivas (na interface cimento/dentina ou cimento/pino), coesivas (cimento ou pino), e mistas. Resultado: No grupo ARC-NR, os valores de resistência de união foram maiores no terço cervical; os grupos U100-NR e ARC-R foram semelhantes entre os terços. No grupo U100-R, os valores de resistência de união foram semelhantes nos terços cervical e médio, e houve menor valor no terço apical. Para pinos de fibra de vidro não reembasados, a média mais alta dos valores de resistência de união foi com cimento resinoso auto-adesivo. Considera-se ainda que os pinos reembasados com cimento resinoso convencional tiveram camada de cimento mais forte em comparação com os pinos de fibra não reembasados. Conclusão: A técnica do pino reembasado foi eficiente no grupo ARC-R. Os grupos ARC-NR e U100-R mostraram melhor resistência de união na região cervical das paredes do canal radicular. As principais falhas foram adesivas na interface cimento-pino.