RESUMO Objetivo Analisar a rugosidade superficial e a estabilidade da cor da resina composta após tratamento de superfície com os discos de óxido de alumínio e posterior exposição à fita clareadora Advanced Teeth Whitening Strips. Métodos Foram confeccionados 20 corpos de prova do restaurador universal Filtek Z350XT (3M®), estes, foram submetidos ao clareamento caseiro por 30 minutos diários durante 14 dias. Utilizou-se um rugosímetro de precisão para verificação da rugosidade através de 3 leituras aleatórias no mesmo sentido em cada amostra, e para estabilidade de cor foi utilizado o sistema CIELAB (valores L*, a*, b*), através do espectofotômetro (MINOLTA CR-321, Japão). As leituras coletadas possibilitaram o cálculo das médias dos corpos de prova e a média de cada grupo. Em seguida, os dados foram submetidos a tratamento estatístico pela análise de variância ANOVA. O nível de significância estabelecido foi de 5% (p≤0,05). Resultados a rugosidade não sofreu grandes variações numéricas e também não houve diferença estatisticamente significantes entre as médias obtidas em relação a rugosidade superficial da resina composta (p=0,44). Contudo, verificou-se que houve diferenças estatisticamente significantes entre as medias obtidas em relação à estabilidade de cor da resina composta, com p= 0,007. Conclusão As fitas pré-contornadas contendo peróxido de hidrogênio a 6% não provocam efeito adverso significantes sobre a rugosidade da resina Z350XT (3M®). Contudo, também concluímos que, de acordo com a análise de estabilidade de cor realizada, poderá haver indicação da substituição das restaurações após o tratamento clareador devido à alteração na coloração das mesmas.

ABSTRACT Objective to analyze the surface roughness and color stability of the composite resin after surface treatment with the aluminum oxide discs and subsequent exposure to the Advanced Teeth Whitening Strips. Methods 20 specimens of the Filtek Z350XT restorer (3M®) were prepared and daily subjected to home bleaching for 30 minutes during 14 days. A precision rugosimeter was used in order to verify the roughness by means of 3 random readings in the same direction in each sample. For color stability the CIELAB system (L*, a*, b* values) was used through the spectrophotometer (MINOLTA CR -321, Japan). The means of the test specimens as well as the mean of each group were calculated using the random readings. Data statistical analysis were performed by ANOVA- analysis of variance. The level of significance was set at 5% (p ≤ 0.05). Results Roughness did not present great numerical variations. No statistically significant difference between the means obtained concerning the surface roughness of the composite resin with p = 0.44 was observed. However, it was found that there was a statistically significant difference between the means obtained in relation to the color stability of the composite resin, p=0. 007. Conclusion It was concluded that pre-contoured strips containing 6% hydrogen peroxide do not have a significant adverse effect on the roughness of Z350XT (3M®) resin. However, it was also concluded that according to the color stability analysis performed, there may be an indication of the restoration replacement after the bleaching treatment, due to their color change.

OBJECTIVE: Using strain gauge (SG) analysis, the aim of this in vitro study was quantify the strain development during the fixation of three-unit screw implant-supported fixed partial dentures, varying the types of implant-abutment joints and the type of prosthetic coping. The hypotheses were that the type of hexagonal connection would generate different microstrains and the type of copings would produce similar microstrains after prosthetic screws had been tightened onto microunit abutments. MATERIALS AND METHODS: Three dental implants with external (EH) and internal (IH) hexagonal configurations were inserted into two polyurethane blocks. Microunit abutments were screwed onto their respective implant groups, applying a torque of 20 Ncm. Machined Co-Cr copings (M) and plastic prosthetic copings (P) were screwed onto the abutments, which received standard wax patterns. The wax patterns were cast in Co-Cr alloy (n=5), forming four groups: G1) EH/M; G2) EH/P; G3) IH/M and G4) IH/P. Four SGs were bonded onto the surface of the block tangentially to the implants, SG 1 mesially to implant 1, SG 2 and SG 3 mesially and distally to implant 2, respectively, and SG 4 distally to implant 3. The superstructure's occlusal screws were tightened onto microunit abutments with 10 Ncm torque using a manual torque driver. The magnitude of microstrain on each SG was recorded in units of microstrain (µε). The data were analyzed statistically by ANOVA and Tukey's test (p<0.05). RESULTS: Microstrain values of each group were: G1= 338.1±223.0 µε; G2= 363.9±190.9 µε; G3= 415.1±53.5 IE; G4= 363.9±190.9 µε. No statistically signifcant difference was found between EH and IH, regardless of the type of copings (p>0.05). The hypotheses were partially accepted. CONCLUSIONS: It was concluded that the type of hexagonal connection and coping presented similar mechanical behavior under tightening conditions.