Effect of light attenuation through veneers on bond strength of adhesives with photoinitiator combinations.

This study aimed to evaluate the effect of light attenuation through ceramic veneers and resin cement on degree of conversion (DC), cohesive strength (CS), and microshear bond strength (µSBS) of experimental adhesive systems. Experimental etch-and-rinse and self-etch adhesives were combined with different ratios of camphorquinone (CQ) and diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiators: CQ-only; 3CQ:1TPO; 1CQ:1TPO; 1CQ:3TPO and TPO-only. Square-shaped ceramic veneer (IPS Empress Esthetic, Ivoclar Vivadent) (n = 10; 10mm long x 10mm wide x 0.5mm thick) and resin cement specimens (Variolink Esthetic LC, Ivoclar Vivadent) (n = 10; 10 mm long x 10 mm wide and 0.3 mm thick) were prepared. Light transmittance of a multiple-peak LED (Bluephase G2, Ivoclar Vivadent) was measured through restorative materials using a spectrometer (n = 5). Adhesive specimens were analyzed for DC, CS, and µSBS by light-curing the adhesive with or without (control) ceramic veneer, and with resin cement fixed to output region of the light-curing tip (n = 10). Data were submitted to ANOVA and Tukey's test (α = 0.05). Total light transmittance through the restorative materials was attenuated, and this attenuation was more evident for the violet spectrum. The DC for the TPO groups in ratios up to 1CQ:1TPO was similar to the control. 1CQ:3TPO showed lower values for CS. µSBS was reduced for all groups with light attenuation, but lower values were observed for 1CQ:3TPO and TPO-only. In conclusion, light transmission was reduced with interposed restorative materials. Adhesives combined with CQ and TPO up to 1CQ:1TPO showed greater cure efficiency and mechanical properties compared with a higher amount of TPO.

Auricular acupuncture in TMD - A sham-controlled, randomized, clinical trial.

This study evaluated the effect of auricular acupuncture (AA) on physical (PA) and emotional (EA) aspects of patients with temporomandibular disorders (TMDs) and compared the effect of AA with those of Sham and occlusal splints (OS). In accordance with the CONSORT guidelines, patients with TMDs were evaluated by axes I and II of the RDC-TMD. The patients were allocated among three groups: OS, Sham and AA; and followed for 8 weeks. Both intragroup and intergroup evaluation for quantitative variables were analyzed with ANOVA, one-way, followed by the Tukey test. Qualitative variables were analyzed with the Kruskal-Wallis, and Dunn tests (intergroup evaluation) and for intragroup analyses, the Friedman and Wilcoxon tests were applied. At the end of the experiment, the chi-squared test was applied to compare the three groups with respect to the number of variables that had shown improved scores. The adopted level of significance for all tests was α = 5%. Intragroup analysis showed that, in the Sham group, no improvement in performance was seen in either EA and significant was improvements in 5 variables for 9 for PA, while in the AA group, significant improvements were observed in 2 variables for EA and in 9 for PA. In the OS group at the end of this study, significant improvements were observed in 8 and 8 variables for EA and PA, respectively. The analysis of therapies used revealed that the number of variables exhibiting significantly improved outcomes after treatment was similar between the AA and OS groups, whereas the sham group showed statistically significant differences when compared with the other two groups. In conclusion, this study demonstrated that AA applied at a specific TMJ ear point was able to bring about improvements in patients with TMDs, with outcomes similar to those in patients treated with an OS. CLINICAL TRIAL REGISTRATION: RBR-69ynnw (Brazilian Registry of Clinical Trials).

Bond strength of different orthodontic brackets produced with different materials and fabrication methods / Resistência de união de bráquetes ortodônticos produzidos com diferentes materiais e métodos de fabricação

Objective: The aim of this study was to evaluate the effects of material and processing methods on the bond strength of orthodontic brackets. Material and Methods: Five types of brackets were tested: Conventional metallic (CM), metallic sandblasted (SB), ceramic (C), polycarbonate (PC), and metallic fabricated by melting injection molding (MIM). Shear bond strength (SBS) was conducted to check bond strength of the brackets bonded to bovine teeth (n=10/group), and tensile bond strength (TBS) (20 brackets/group) to check bracket retention to bonding material (n=20/group). Both, SBS and TBS were conducted with 1mm/min crosshead speed in a universal testing machine. Bond strength was calculated in Megapascal (MPa) based on force (N) and bracket area (mm 2). Data normality was verified, and One-way ANOVA was the statistical test with Tukey post-hoc (α=0.05). Results: SB and MIM presented higher SBS compared to C, PC, and CM (p<0.05). SB and MIM also presented significantly higher TBS compared to CM and PC (p<0.05). However, MIM was not different of C for TBS. Conclusion: The type of material and method of fabrication are determinant factors that affect bond strength of orthodontic brackets and melting injection molding (MIM) is a remarkable technology to improve brackets retention during the orthodontic treatment. (AU)

Objetivo: O objetivo deste estudo foi avaliar os efeitos dos materiais e métodos de processamento na resistência de união de bráquetes ortodônticos. Material e Métodos: Cinco tipos de bráquetes foram testados: Convencionais metálicos (CM), metálicos jateados (SB), cerâmico (C), policarbonato (PC), e metálico fabricado por injeção de metal fundido em molde (MIM). A resistência de união ao cisalhamento (SBS) foi conduzida para verificar a resistência de união dos bráquetes aderidos a dentes bonivos (n=10/grupo) e a resistência à tração (TBS) (20 bráquetes/grupo) para verificar a retenção do bráquete ao material adesivo (n=20/grupo). SBS e TBS foram conduzidas com relação carga/velocidade de 1mm/min em uma máquina de ensaios universal. A resistência de união foi calculada em Megapascal (MPa) com base na força (N) pela área do bráquete (mm 2). A normalidade dos dados e a estatística foi realizada utilizando One-way ANOVA e Tukey post-hoc (α=0.05). SB e MIM apresentaram os maiores valores de SBS comparados com C, PC e CM (p<0.05). Resultados: SB e MIM também apresentaram valores significativamente maiores de TBS comparados com CM e PC (p<0.05). Contudo, os valores de TBS para o grupo MIM não foram significativamente diferentes de C. Conclusão: O tipo de material e o método de fabricação são fatores determinantes que afetam a resistência de união de bráquetes ortodônticos e a injeção de metal fundido em molde (MIM) é uma tecnologia relevante para melhorar a retenção dos bráquetes durante o tratamento ortodôntico. (AU)

Effect of light attenuation through veneers on bond strength of adhesives with photoinitiator combinations

Abstract This study aimed to evaluate the effect of light attenuation through ceramic veneers and resin cement on degree of conversion (DC), cohesive strength (CS), and microshear bond strength (μSBS) of experimental adhesive systems. Experimental etch-and-rinse and self-etch adhesives were combined with different ratios of camphorquinone (CQ) and diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiators: CQ-only; 3CQ:1TPO; 1CQ:1TPO; 1CQ:3TPO and TPO-only. Square-shaped ceramic veneer (IPS Empress Esthetic, Ivoclar Vivadent) (n = 10; 10mm long x 10mm wide x 0.5mm thick) and resin cement specimens (Variolink Esthetic LC, Ivoclar Vivadent) (n = 10; 10 mm long x 10 mm wide and 0.3 mm thick) were prepared. Light transmittance of a multiple-peak LED (Bluephase G2, Ivoclar Vivadent) was measured through restorative materials using a spectrometer (n = 5). Adhesive specimens were analyzed for DC, CS, and μSBS by light-curing the adhesive with or without (control) ceramic veneer, and with resin cement fixed to output region of the light-curing tip (n = 10). Data were submitted to ANOVA and Tukey's test (α = 0.05). Total light transmittance through the restorative materials was attenuated, and this attenuation was more evident for the violet spectrum. The DC for the TPO groups in ratios up to 1CQ:1TPO was similar to the control. 1CQ:3TPO showed lower values for CS. μSBS was reduced for all groups with light attenuation, but lower values were observed for 1CQ:3TPO and TPO-only. In conclusion, light transmission was reduced with interposed restorative materials. Adhesives combined with CQ and TPO up to 1CQ:1TPO showed greater cure efficiency and mechanical properties compared with a higher amount of TPO.

Effect of commercial silanes on bond strength of resin cement to lithium disilicate ceramic / Efeito de silanos comerciais na resistência de união do cimento resinoso à cerâmica de dissilicato de lítio

The aim of this study was to evaluate the effect of different commercial silanes on microshear bond strength of resin cement to lithium disilicate ceramic. Twenty ceramic samples with 10 mm in length, 10 mm wide and 3 mm in thickness were fabricated, etched with 10% hydrofluoric acid for 20 seconds, and divided into 5 groups, according to the commercial silane applied: G1- RelyX Ceramic Primer (3M ESPE), G2- Angelus Silane, G3- Prosil (FGM), G4- Dentsply Silane (Dentsply) and G5- Bis-Silane (Bisco). Silanes were applied in accordance to manufacturers' recommendations. Addition silicone molds with 1 mm in thickness, 10 mm in diameter and 3 perforations with 1 mm in diameter each one, were placed on ceramic and filled with the resin cement RelyX ARC (3M ESPE) in all groups. Light activation was performed with LED Bluephase G2 (Ivoclar Vivadent) at 1200 mW/cm2, for 30 seconds. Samples were maintained in 100% humidity at 37°C for 24 hours and submitted to microshear test. The data (MPa) were submitted to one-way ANOVA and Tukey test (α=0.05). The results obtained for each group were: G1: 22.39±2.99; G2: 23.35±4.08; G3: 26.05±5.46; G4: 18.56±4.09; G5: 25.26±4.10. Statistical analysis showed significantly lower microshear bond strength for G4. Fracture pattern analysis showed predominance of adhesive failures in G1 and G2. G3 and G5 presented higher percentage of cohesive failures in ceramic, and G4 showed mixed, adhesive and cohesive fractures with similar percentages. It was concluded that different silanes showed influence on the lithium disilicate ceramic ­ resin cement bond strength

O objetivo neste estudo foi avaliar o efeito de diferentes silanos comerciais na resistência de união ao microcisalhamento do cimento resinoso à cerâmica de dissilicato de lítio. Foram confeccionadas 20 amostras de cerâmica (10mm de comprimento, 10mm de largura e 3mm de espessura), condicionadas com ácido fluorídrico a 10% por 20 segundos e divididas em 5 grupos, de acordo com o silano aplicado: G1- RelyX Ceramic Primer (3M ESPE), G2- Silano Angelus, G3-Prosil (FGM), G4- Silano Dentsply e G5-Bis-Silane (Bisco). Matrizes de silicone por adição (1 mm de espessura, 10 mm de diâmetro e 3 perfurações com 1 mm de diâmetro) foram colocadas sobre a cerâmica e preenchidas com cimento resinoso RelyX ARC (3M ESPE). A fotoativação foi realizada com LED Bluephase G2 (Ivoclar Vivadent) a 1200 mW/cm2, por 30 segundos. As amostras foram mantidas em 100% de umidade a 37°C por 24 horas e submetidas ao teste de microcisalhamento. Os dados (MPa) (G1: 22,39+2,99; G2: 23,35+4,08; G3: 26,05+5,46; G4: 18,56+ 4,09; G5: 25,26+4,10) foram submetidos a análise de variância e ao teste de Tukey (p<0,05). A análise estatística mostrou valor de resistência de união significantemente menor para G4. A análise do padrão de fratura mostrou predominância de falha adesiva para G1 e G2. G3 e G5 apresentaram maior porcentagem de falha coesiva em cerâmica, e o G4 apresentou fraturas mista, adesiva e coesiva em igual porcentagem. Concluiu-se que os diferentes silanos apresentaram influência na resistência de união do cimento resinoso à cerâmica de dissilicato de lítio

Solvent Degradation and Polymerization Shrinkage Reduction of Resin Composites Using Isobornyl Methacrylate.

The aim of this study was to use the isobornyl methacrylate (IBOMA) as a combining or substituent diluent monomer in the resin matrix of dental resin composites. Thus, the resin matrix was formulated with 60 wt% of BisGMA and 40 wt% of diluent monomers. TEGDMA as the only diluent monomer was used as control with 40 wt%, while total substitution of TEGDMA was done with 40 wt% of IBOMA. The combination of IBOMA and TEGDMA was done with 20 wt% of each monomer. To the resin matrix, 65 wt% of filler particles was added. Degree of conversion (DC) using FT-IR, flexural strength (FS), flexural modulus (FM), polymerization shrinkage by gap formation (GF), Knoop hardness (KH) and solvent degradation (SD) were evaluated. Data were analyzed using ANOVA and Tukey's test (α=0.05; b=0.2). The results showed that reducing or substituting TEGDMA using IBOMA did not affect the DC (0.085), FS (p=0.886) or FM (p=0.414). Also, when IBOMA was used, lower GF was found in comparison to the control containing only TEGDMA as the diluent monomer (p=0.032). However, even though all composites presented reduction in KH during the SD test, the combination of IBOMA and TEGDMA showed similar reduction in KHN in comparison to the control group (p=0.001), while the total substitution of TEGDMA with IBOMA decreased KHN after SD (p=0.041). Thus, the combination of IBOMA and TEGDMA seem to reduce SD and GF without affecting the properties of resin composites.

Discrepância de Bolton nas diferentes más oclusões e influência dos protocolos de extração / Bolton index in different malocclusions and extraction protocols influence

A obtenção de uma oclusão funcionalmente equilibrada é uma meta perseguida pelos ortodontistas, e um dos pré-requisitos para isso é a existência de proporcionalidade entre os tamanhos mésio-distais dos dentes superiores e inferiores. Com a intenção de localizar o excesso de massa dentária e dirigir a conduta clínica, a análise de Bolton estabelece proporções ideais para regiões anterior e total do arco dentário, evidenciando as discrepâncias. O objetivo deste estudo foi comparar a discrepância de Bolton entre as diferentes más oclusões sagitais e entre diferentes protocolos de extração de quatro pré-molares, avaliando a tendência de se promover discrepância de Bolton nos diferentes protocolos de extração específicos para a camuflagem das más oclusões. Em modelos de estudo de 86 pacientes, com média etária de 18,6 anos, sendo que 31 destes eram portadores de má oclusão de Classe I, 29 pacientes de Classe II e 26 de Classe III, mediu-se as discrepâncias de Bolton com a utilização de paquímetro. Comparou-se as médias dos diâmetros mésio-distais e suas proporções entre grupos de más oclusões, protocolos de extração e protocolos específicos para camuflagem, através da análise de variância. Não ocorreram diferenças estatísticas para discrepância anterior e total entre os grupos de más oclusões avaliados e entre os grupos de protocolos de extração. Com relação aos protocolos de extração para camuflagem, os pacientes Classe III tenderam a apresentar maior discrepância de Bolton às outras más oclusões. É válido considerar esses aspectos durante o plano de tratamento ortodôntico para que a finalização do mesmo não seja dificultada. (AU)

Obtaining a static and functionally balanced occlusion is a goal pursued by orthodontists, and one of pre requirements to it is the existence of proportionality between the mesial-distal sizes of upper and lower teeth. In order to locate the excess dental mass and direct clinical management, the Bolton analysis establishes ideal proportions for both anterior and total arch, highlighting the discrepancies. The objectives of this study were to compare the Bolton discrepancy between the malocclusions and between four premolars extraction protocols, and evaluate the tendency to promote Bolton discrepancy in different specific extraction protocols for camouflage of malocclusions. In plaster models of 86 patients, with a mean age of 18.6 years old, which 31 were suffering from malocclusion of Class I, 29 with Class II and 26 with Class III, it was measured Bolton discrepancies with the use of paquimeter. It was compared the mean values of mesiodistal diameters and their proportions between groups of malocclusion, extraction protocols, and specific protocols for camouflage, through the variance analysis. There were no statistical differences for anterior and total tooth size discrepancy between malocclusion groups and extraction protocols groups. Regarding the extraction protocols for camouflage, patients with Class III tended to show more Bolton discrepancy than other malocclusions. It is worth considering these aspects during orthodontic treatment plan for thereof completion won't be hampered.(AU)

Influência de desinfetantes bucais sobre a dureza de superfície de resinas para provisórios / Influence of oral disinfectant on surface hardness of acrylic resins for provisional restorations

As restaurações provisórias têm papel importante para diagnóstico e plano de tratamento em reabilitação com prótese fixa. Quando há necessidade de procedimentos cirúrgicos pré-protéticos, meios adicionais de controle de placa bacteriana devem ser indicados, mas pouco se sabe sobre os efeitos que podem produzir na superfície de restaurações provisórias. Proposição: este estudo teve como objetivo avaliar o efeito de dois enxaguatórios bucais na dureza de duas resinas usadas para confecção de provisórios protéticos. Material e Métodos: resina acrílica autopolimerizável poli(metil metacrilato) Dencrilay Speed e resina bisacrílica Protemp 4; dois enxaguatórios bucais, Periogard (digluconato de clorexidina 0,12%) e Oral-B sem álcool, tendo soro fisiológico como grupo controle. Foram confeccionadas 60 amostras, 30 para cada resina, as quais foram divididas em 6 grupos experimentais (n=10). As amostras foram imersas nas respectivas soluções para bochecho durante 10 minutos por dia, por um período de 30 dias. Após, foram submetidas a ensaios de microdureza utilizando o penetrador tipo Knoop. Resultados: a resina acrílica Dencrilay apresentou os maiores valores de dureza, no entanto apresentou redução na dureza quando imersa no enxaguatório Periogard. A resina bisacrílica Protemp 4 não apresentou diferença nos valores de microdureza de superfície quando imersa nas soluções utilizadas. Conclusão: a resina acrílica apresentou redução na dureza de superfície após imersão em solução de clorexidina 0,12%. Implicações clínicas: a resina bisacrílica, apesar de menor dureza, apresentaria superfície mais estável em meio bucal, mesmo com o uso diário de enxaguatórios bucais

Temporary restorations have important role for diagnosis and treatment plan in rehabilitation with fixed prosthesis element. When pre-prosthetic surgical procedures are required, additional means of controlling plaque must be indicated, but little is known about the effects it can produce on the surface of provisional prosthetic restorations. Purpose: To evaluate the effect of two mouthrinses on the hardness of two resins used in temporary restorations. Material and Method: Acrylic resin poly(methyl methacrylate) Dencrilay Speed and bisacrylic resin Protemp 4, two mouthrinses, Periogard (chlorhexidine digluconate 0.12 %) and Oral- B without alcohol and saline solution as control group. Sixty samples were prepared, 30 for each resin, which were divided into 6 groups (n = 10). The specimens were immersed in respective solutions for 10 minutes per day, for 30 days. Then, microhardness tests were performed using the Knoop indenter. Data were subjected to analysis of variance and Tukey's test, with a confidence interval of 95%. Results: Dencrilay acrylic resin had the highest values of hardness, however, it showed a reduction in hardness when immersed in the mounthrinse Periogard. The bisacrylic resin Protemp 4 showed no difference in the values of surface microhardness when immersed in the solutions used. Conclusion: The acrylic resin showed a reduction in surface hardness after immersion in 0.12% chlorhexidine solution. Clinical Implications: Bisacrylic resin, although less hard, would have a more stable surface in oral environment, even with the daily use of mouthrinses.

Immediate and 6-month Bond Strengths of Different Adhesives in the Oral Environment.

PURPOSE: To evaluate the microtensile bond strength (µTBS) of three adhesives to dentin after 1 week and 6 months in an oral environment. MATERIALS AND METHODS: Class I cavities were prepared in the third molars of 30 patients and randomized into 3 groups according to the following adhesives: Scotchbond Multi-Purpose (SM), Clearfil Protect Bond (CF), and Scotchbond Universal (UN). These molars were then subdivided into two groups according to the exposure time in the oral environment: one week (1W) and 6 months (6M). After the exposure time, the teeth were extracted, cut into beams, and submitted to the µTBS test. The data were analyzed using the Shapiro-Wilk test and two-way ANOVA followed by Tukey's post-hoc test with a significance level of 5%, and fracture modes were analyzed. RESULTS: The bond strengths in MPa (mean ± SD) were SM-1W: 39.5 ± 7.9; SM-6M: 29.7 ± 1.8; CF-1W: 30.5 ± 1.4; CF-6M: 28.6 ± 4.1; UN-1W: 30.6 ± 3.2; and UN-6M: 26.7 ± 2.0. The SM-1W group exhibited significantly increased µTBS compared with the other groups. After 6 months in the oral environment, a significant reduction of µTBS was only observed for the SM group, whereas similar bond strengths were observed for the other groups. SM-1W exhibited a predominance of mixed fractures, whereas the other groups showed a predominance of adhesive fractures. CONCLUSIONS: The adhesives which were applied in the self-etching mode maintained bond strength after six months in the oral environment. A reduction of µTBS was only observed for the three-step etch-and-rinse adhesive.