Abstract Objective: To compare the clinical effect of two desensitizing agents used before the application of a bleaching gel based on 35% hydrogen peroxide (HP). Material and Methods: 30 patients were selected, and two desensitizing agents with different mechanisms of action were applied: Fluorine Neutral 2% (FN), which acts by blocking dentinal canaliculi while Potassium Nitrate 5% with 2% Sodium Fluoride (PN/SF) that acts in nerve transmission and blockade. Desensitizers were used before the application of 35% HP. For whitening, three clinical sessions were performed, with an interval of seven days, with three applications of the bleaching gel for 15 minutes, totaling 45 minutes/session. Tooth sensitivity (TS) was assessed with the numerical analog scale, and a spectrophotometer was used to obtain the color variation (ΔE). ΔE were submitted to ANOVA and Tukey test (p<0.05), and TS data were submitted to a two-way ANOVA analysis. Results: For sensitivity experience, the Tukey test indicated differences between PN/SF and the placebo I, but there was no statistically significant difference between FN and the placebo II. The TS was lower when the desensitizing gel was used during the bleaching procedure compared to after treatment, regardless of the desensitizing agents. Conclusion: PN/SF before in-office tooth bleaching can reduce TS intensity, and the use of desensitizing gel before bleaching did not affect the bleaching efficacy.

Resumo Introdução Com o intuito de se evitar as tensões geradas durante a contração de polimerização das resinas compostas, foram desenvolvidas as resinas compostas de baixa contração de polimerização. Objetivo Avaliar a resistência à microtração em cavidades classe I restauradas com tratamento ácido do ângulo cavo superficial e resina composta indicada para dentes posteriores. Material e método Foram selecionados 48 molares hígidos que foram divididos em 6 grupos (n=8), sendo que 3 desses tiveram o esmalte cavo superficial condicionado com ácido fosfórico a 35%. Os dentes foram restaurados com o sistema adesivo Clearfil SE Bond e as resinas compostas Filtek Z350 XT, Empress Direct e Charisma Diamond, fotoativadas por 40 segundos. Após 24 horas, os dentes foram levados para máquina de corte, na qual foram realizados cortes no sentido vestíbulo-lingual e no sentido mésio-distal obtendo – se palitos de 0,9×0,9 mm que foram levadas para a máquina de ensaio universal para a realização do teste de microtração. Para análise estatística foi realizado análise de variância e teste de Tuckey (p < 0,05). Resultado Não houve diferença estatística significante entre os grupos avaliados. Conclusão O condicionamento ácido do ângulo cavo superficial não influenciou no desempenho das restaurações provavelmente devido ao sistema adesivo utilizado.

Abstract Introduction To prevent the shrinkage stresses produced during polymerization, composite resins of low polymerization shrinkage were developed. Objective To evaluate the microtensile bond strength in class I cavities restored by acid-etching the cavosurface angle and with composite resins indicated for posterior teeth. Material and method 48 healthy molars were selected and divided into six groups (n = 8), considering that the cavosurface enamel of three groups was etched with 35% phosphoric acid. The teeth were restored with the Clearfil SE Bond adhesive system and Filtek Z350 XT, Empress Direct, and Charisma Diamond composite resins, which were light-cured for 40 seconds. After 24 hours, the teeth were taken to a cutting machine, which produced sections in the buccolingual and mesiodistal directions. This resulted in toothpicks of 0.9×0.9 mm that were taken to the universal testing machine for the microtensile bond strength test. Statistical analysis was performed with ANOVA and Tukey’s test (p < 0.05). Result There was no statistically significant difference between the groups evaluated. Conclusion Acid-etching the cavosurface angle did not affect the performance of restorations, probably due to the adhesive system used.

Abstract Objective To clinically assess the effect of desensitizing gels and dentifrices on the reduction in pain sensitivity and color variation during tooth bleaching. Methodology A total of 108 volunteers were randomly separated into the following groups of n=12: GT/S-glycerine and thickener/sucralose; NF/S-potassium nitrate and sodium fluoride/sucralose; NA/S-potassium nitrate and arginine/sucralose; GT/AC-glycerine and thickener/arginine and calcium carbonate; NF/AC-potassium nitrate and sodium fluoride/arginine and calcium carbonate; NA/AC-potassium nitrate and arginine/arginine and calcium carbonate; GT/PN-glycerine and thickener/potassium nitrate; NF/PN-potassium nitrate and sodium fluoride/potassium nitrate; and NA/PN-potassium nitrate and arginine/potassium nitrate. Sensitivity was assessed with the numerical analogue scale, and color variation (ΔE) was measured with a spectrophotometer. The sensitivity values obtained were subjected to a multivariate analysis of variance (MANOVA) and color variation values were subjected to a randomized analysis of variance (p<0.05). Results The NF/AC, NA/AC, NF/PN, and NA/PN groups presented lower sensitivity values and reduced sensitivity compared to those of the other groups throughout the clinical sessions. None of the groups showed sensitivity at the 24-week assessment. Statistically, no significant difference were observed in the color values among the groups four weeks after the beginning of bleaching (p=0.074). Additionally, the color assessment of all groups was statistically similar four weeks (p=0.084) and 24 weeks (p=0.118) after the beginning. Conclusion Our results indicate that adding NF/S, NA/S, NF/AC, and NA/AC desensitizers to tooth bleaching protocols reduces pain sensitivity without affecting its effectiveness.

The purpose of this study was to evaluate the fracture strength of roots that were prosthetically restored with metallic posts with or without any remaining coronal structure and with different finish lines. Sixty bovine incisors were sectioned below the cementoenamel junction, endodontically treated, and randomly divided into six experimental groups (n = 10) containing teeth with or without any remaining coronal structure, and with a beveled shoulder, a bevel, or a shoulder finish line design. The metallic posts were luted with dual-cured resin cement. The cores were made with composite resin, and metal crowns were cemented with zinc phosphate cement. The specimens were subjected to a tangential compressive load (135º angle) at a crosshead speed of 0.5 mm/min until failure, using a universal testing machine. The fracture strength data were analyzed using the ANOVA and LSMeans (least square means) tests (α= 0.05). The data indicated that the teeth with 2 mm of remaining coronal structure showed the highest fracture strength values when compared with the teeth without any remaining structure (p < 0.05). As to the different finish line designs, the highest fracture strength values were obtained for the beveled shoulder, followed by the bevel and then by the shoulder designs (p < 0.05). It may be concluded that, to increase fracture strength, a beveled shoulder and 2 mm of remaining coronal structure are the ideal conditions.

The aim of this in vitro study was to evaluate the susceptibility of a hybrid composite resin (Filtek Z250 - 3M ESPE) to staining, when light cured in four different modes and immersed in two different media. Composite resin specimens were randomly prepared and polymerized according to the experimental groups (conventional - 550 mW/cm² / 30 seconds; soft start - 300mW/cm² / 10 seconds + 550 mW/cm² / 20 seconds; high intensity - 1060 mW/cm² - 10 seconds; pulse delay - 550 mW/cm² - 1 seconds + 60 seconds of waiting time + 550 mW/cm² - 20 seconds) and immersed in one of two media (distilled water or absolute ethanol) for 24h. Next, the specimens were immersed in a 2% methylene blue solution for 12 hours. Afterwards, the specimens were washed and prepared for the spectrophotometric analysis. For statistical analysis, two-way ANOVA (4X2) and Tukey's test were performed on the data at 0.05 confidence level. Soft start showed the least staining, and was statistically different from the high intensity and pulse delay light curing modes (p<0.05). Conventional light curing unit did not show statistically significant differences from any other groups (p>0.05). There were no significant differences between the two immersion media (p>0.05). The soft start polymerization mode showed lower susceptibly of the composite resin to staining than high intensity and pulse delay, irrespective of the immersion medium.

O objetivo do trabalho foi avaliar a resistência à tração diametral (DTS) de compósitos submetidos a diferentes técnicas de polimerização. Foram testados quatro compósitos neste estudo: Targis (Ivoclar), Solidex (Shofu), Charisma (Heraeus-Kulzer) e Filtek Z250 (3M Espe). Foram confeccionados 64 corpos-de-prova cilíndricos, que foram divididos em 8 grupos de acordo com a técnica de polimerização (n = 8). Os compósitos indiretos (Targis e Solidex) foram polimerizados com seus respectivos sistemas de ativação (Targis Power e EDG-lux); Charisma e Filtek Z250 foram fotoativados com polimerização convencional (luz halógena) e, adicionalmente, com sistemas de polimerização adicional. Os corpos-de-prova foram armazenados em saliva artificial a 37°C por uma semana. Ensaio de DTS foi realizado em Máquina Universal de Ensaios Instron (0,5 mm/min). Os dados foram analisados estatisticamente pelos testes ANOVA e Duncan. Os resultados foram (MPa): Z250/EDG-lux: 69,04ª; Z250/Targis Power: 68,57ª; Z250/polimerização convencional: 60,75b; Charisma/Targis Power: 52,34c; Charisma/polimerização convencional: 49,17c; Charisma/EDG-lux: 47,98c; Solidex: 36,62d; Targis: 32,86d. Os resultados indicaram que o compósito Z250 polimerizado adicionalmente mostrou os maiores valores de DTS. O compósito Charisma não apresentou diferenças significativas quando foram comparadas diferentes técnicas de polimerização. Compósitos diretos apresentaram maiores valores de DTS que os compósitos indiretos.

The aim of this study was to evaluate the diametral tensile strength (DTS) of composite resins submitted to different curing techniques. Four composite resins were tested in this study: Targis (Ivoclar), Solidex (Shofu), Charisma (Heraeus-Kulzer) and Filtek Z250 (3M Espe). Sixty-four cylindrical specimens were prepared and divided into eight groups according to each polymerization technique (n = 8). The indirect composite resins (Targis and Solidex) were polymerized with their respective curing systems (Targis Power and EDG-lux); Charisma and Filtek Z250 were light-cured with conventional polymerization (halogen light) and additionally, with post-curing systems. Specimens were stored in artificial saliva at 37°C for one week. DTS tests were performed in a Universal Testing Machine (0.5 mm/min). The data were statistically analyzed by ANOVA and Duncan tests. The results were (MPa): Z250/EDG-lux: 69.04ª; Z250/Targis Power: 68.57ª; Z250/conventional polymerization: 60.75b; Charisma/Targis Power: 52.34c; Charisma/conventional polymerization: 49.17c; Charisma/EDG-lux: 47.98c; Solidex: 36.62d; Targis: 32.86d. The results reveal that the post-cured Z250 composite resin showed the highest DTS means. Charisma composite presented no significant differences when activation techniques were compared. Direct composite resins presented higher DTS values than indirect resins.

Fatores como o modo de ativação, a técnica restauradora e a configuração cavitária podem afetar a resistência adesiva à dentina. Este estudo avaliou os efeitos dos modos de ativação e das técnicas restauradoras na resistência de união compósito/dentina na parede vestibular de restaurações classe I. O esmalte oclusal dos dentes foi removido para expor uma superfície dentinária planificada. Cavidades oclusais (4 x 3 x 3 mm) foram preparadas em dentina. O adesivo Single Bond foi aplicado de acordo com as instruções do fabricante, e o compósito TPH Spectrum, inserido através de três diferentes técnicas: oblíqua incremental, horizontal incremental ou incremento único. O compósito foi ativado utilizando o método contínuo (600 mW/cm² por 40 s) ou "Soft-Start" (250 mW/cm² por 10 s + 600 mW/cm² por 30 s). O grupo controle foi obtido pela união somente à parede vestibular planificada (fator C = 1). Os dentes foram armazenados por 24 h em água a 37ºC e preparados para o ensaio de microtração (0,5 mm/min). Os espécimes apresentaram na secção transversal uma área de união de aproximadamente 0,8 mm². Os resultados foram analisados pela ANOVA (dois fatores), pelos testes de Tukey e Dunnett (alfa = 0,05). A técnica incremental seguida da ativação com ambas as formas de fotopolimerização produziu maiores valores de resistência de união que a técnica de incremento único (p < 0,05). A resistência de união sempre foi menor quando a restauração foi confeccionada em cavidade (p < 0,05), exceto quando foram utilizadas ativação com "Soft-Start" e técnicas incrementais. A resistência de união às paredes cavitárias é dependente da técnica de inserção e do modo de ativação da resina composta.

Factors such as light-curing mode, filling technique and cavity configuration may affect the bonding strength to dentin. This study evaluated the effect of irradiation mode and filling technique on resin/dentin bonding strength on the buccal wall of class I cavities in human teeth. Occlusal enamel was removed to expose a flat dentin surface. Occlusal cavities (4 x 3 x 3 mm) were prepared in dentin. The adhesive Single Bond was applied according to the manufacturer's instructions and TPH Spectrum composite resin was placed using the following: oblique incremental, horizontal incremental or bulk filling techniques. The composite resin was light-cured either by continuous (600 mW/cm² for 40 s) or Soft-Start (250 mW/cm² for 10 s + 600 mW/cm² for 30 s) modes. Specimens of the control group were obtained by bonding the material to the flat exposed buccal wall of the cavity (C-factor = 1). The teeth were stored in water at 37ºC for 24 h and prepared for microtensile testing. Bonded beams of approximately 0.8 mm² were obtained from the buccal wall and tested with a tension of 0.5 mm/min. Results were analyzed by two-way ANOVA, Tukey's test and Dunnett's test (alpha = 0.05). Incremental placement techniques with both irradiation modes produced higher bonding strength values than the bulk technique (p < 0.05). Bonding strength tested in the cavities had lower values than those obtained in flat dentin surfaces (control group) (p < 0.05), except for incremental fillings using stepped irradiation. Bonding strength to the cavity walls depends on the filling technique and on the irradiation mode of composite resins.

O objetivo deste estudo foi avaliar a influência de diferentes tratamentos de superfície na resistência de união de resinas compostas a um agente de fixação resinoso. Dois compósitos de laboratório, Solidex e Targis, e um compósito convencional, Filtek Z250, foram testados. Quarenta e oito blocos de resina composta (5.0 x 5.0 x 5.0mm) foram confeccionados através da técnica incremental, para cada compósito testado, e foram aleatoriamente divididos em 6 grupos. Os blocos foram submetidos a seis tratamentos de superfície: 1 - Controle, Lixa 600-SiC (C); 2 - Silanização (SI); 3 - Jateamento com Al2O3 50µm por 10 segundos (SA); 4 - Condicionamento com ácido fluorídrico por 60 segundos (HF); 5 - HF + SI; 6 - SA + SI. Blocos submetidos ao mesmo tratamento foram unidos com o agente de fixação resinoso Rely X. Uma carga de 500g foi aplicada por 5 minutos e as amostras foram fotoativadas por 40 segundos. Os blocos unidos foram seccionados em fatias de 0.9mm de espessura perpendicularmente à interface de união (n = 12). Foram realizadas constrições limitando a interface de união a 1mm e as amostras foram levadas para o ensaio de tração. As maiores médias de união foram obtidas para as amostras submetidas à aplicação do silano após o jateamento com Al2O3.

The purpose of this study was to evaluate the influence of different surface treatments on composite resin on the microtensile bond strength to a luting resin cement. Two laboratory composites for indirect restorations, Solidex and Targis, and a conventional composite, Filtek Z250, were tested. Forty-eight composite resin blocks (5.0 x 5.0 x 5.0mm) were incrementally manufactured, which were randomly divided into six groups, according to the surface treatments: 1- control, 600-grit SiC paper (C); 2- silane priming (SI); 3- sandblasting with 50 mm Al2O3 for 10s (SA); 4- etching with 10% hydrofluoric acid for 60 s (HF); 5- HF + SI; 6 - SA + SI. Composite blocks submitted to similar surface treatments were bonded together with the resin adhesive Single Bond and Rely X luting composite. A 500-g load was applied for 5 minutes and the samples were light-cured for 40s. The bonded blocks were serially sectioned into 3 slabs with 0.9mm of thickness perpendicularly to the bonded interface (n = 12). Slabs were trimmed to a dumbbell shape and tested in tension at 0.5mm/min. For all composites tested, the application of a silane primer after sandblasting provided the highest bond strength means.

O objetivo deste estudo foi avaliar o efeito de três tratamentos superficiais e dois sistemas adesivos na resistência ao cisalhamento de reparos em amálgama. Os resultados sugerem que os grupos reparados não apresentaram resistência de união semelhante ao amálgama intacto. Entre os grupos reparados com sistemas adesivos, valores superiores de resistência de união foram observados para os grupos que tiveram a superficie abrasionada com ponta diamanatada ou jateada. Os sistemas adesivos não apresentaram diferenças significativas na resistência ao cisalhamento quando comparados no mesmo tratamento superfical do amálgama.

The objective of this in vitro study was to evaluate the effect of three surface treatments and two adhesive systems on the shear bond strength of old and freshly placed amalgam. The results suggested that the intact amalgam showed a significantly higher strength than repaired groups and the strongest repaired specimens were made when the amalgam surfaces were roughened with a diamond bur or microetcher. The adhesive systems showed no significant differences on bond strength with the same superficial texture.