The purpose of this study was to evaluate whether the use of desensitizing dentifrices used 15 days prior to and after in-office tooth bleaching could eliminate or reduce tooth sensitivity. After institutional review board approval and informed consent, 45 subjects were selected and divided into 3 groups according to the dentifrice selected: Colgate Total (CT), Colgate Sensitive Pro-Relief (CS) or Sensodyne ProNamel (SP). The subjects used toothpaste and a toothbrush provided to them for 15 days prior to bleaching. They were then submitted to two in-office bleaching sessions (Whiteness HP Blue Calcium). Their tooth sensitivity was assessed using the Visual Analog Scale (VAS) for a week after each session. Their tooth shade alteration was measured with a Vitapan Classical shade guide to determine if the dentifrices could influence the effectiveness of the bleaching agent. The data were submitted to Wilcoxon, Kruskal-Wallis and Mann-Whitney tests (α = 0.05). The use of desensitizing dentifrices did not affect the bleaching efficacy. In regard to tooth sensitivity, there was a statistically significant difference between the results of the Control Group and Group T2 after the first session (p = 0.048). There was no statistically significant difference in the results for the other groups after the first session. In regard to the second session, there was no statistically significant difference in the results for all the groups. The use of a desensitizing dentifrice containing nitrate potassium reduced tooth sensitivity during the bleaching regimen. Dentifrices containing arginine and calcium carbonate did not reduce tooth sensitivity. Color change was not influenced by the dentifrices used

Este estudo comparou a resistência de união entre base de prótese e dentes de resina acrílica submetidos a 6 tratamentos de superfície. Noventa e seis espécimes foram feitos com dentes de poli(metilmetacrilato) unidos a uma resina para base de prótese polimerizada por energia de microondas. Os espécimes foram distribuídos em seis grupos (n=16) de acordo com o tratamento de superfície: CT - controle, superfície não alterada; MN - aplicação de monômero de metilmetacrilato; OA - jateamento com partículas de óxido de alumínio de 50 µm; BR - remoção do brilho superficial com broca esférica; PE - asperização com pedra abrasiva de óxido de alumínio e; CV - confecção de cavidade. Os grupos foram submetidos a uma carga compressiva em ângulo de 45 graus com o longo eixo dos dentes. Os resultados foram analisados por meio da ANOVA de um fator, seguido do teste de Scheffé (p<0,05). As médias de resistência (kgf) dos grupos foram: CT: 18,19 (7,14), MN: 18,34 (5,28), OA: 23,82 (5,40), BR: 23,30 (4,79), PE: 25,39 (7,80) e CV: 17,48 (7,17). Houve diferença estatisticamente significante apenas entre os grupos PE e CV (p=0,037997). Pode-se concluir que a asperização da base do dente com pedra abrasiva proporcionou a maior resistência de união, embora com diferença estatisticamente significante apenas em relação à confecção de uma cavidade na base do dente. Os demais tratamentos de superfície proporcionaram valores sem diferenças estatisticamente significativas.

The aim of this study was to compare the bond strength between acrylic denture base and teeth subjected to 6 surface treatments. Ninety-six specimens were made with poly(methylmethacrylate) teeth bonded to a microwave-polymerized acrylic denture base material. The specimens were distributed into 6 groups (n=16) according to surface treatments: CT - no treatment (control); MN - methylmethacrylate monomer etching; AO - 50-µm-particle aluminum oxide air abrasion; BR - glaze removal with a round bur; ST - surface grinding with an aluminum oxide abrasive stone; group CV - cavity preparation (diatorics). The control and surface-treated groups were subjected to a compressive load at 45º angle to the long axis of the teeth. Data were analyzed by one-way ANOVA, followed by Scheffé's test (p<0.05). Bond strength means and (SD) in kgf for groups were: CT: 18.19 (7.14), MN: 18.34 (5.28), AO: 23.82 (5.40), BR: 23.30 (4.79), ST: 25.39 (7.80) and CV: 17.48 (7.17). There was statistically significant difference (p=0.037997) only between ST and CV. In conclusion, ridge lap surface grinding with an aluminum oxide abrasive stone provided the highest bond strength, though it differed significantly only when compared to diatorics. The other surface treatments provided similar bond between the acrylic denture base and teeth.