Influência da Temperatura Pré-Polimerização e do Tempo de Fotoativação na Microinfiltração Marginal
Influence of pre-cure temperature and photo-activation time in the marginal microleakage
Torres, A.C.M.; Torres, C.R.G.; Araújo, M.A.M.
Rev. odontol. UNESP, vol.33, n4, p.163-168, 2004
Resumo
O objetivo deste estudo foi avaliar a influência da temperatura pré-polimerização e do tempo de fotoativação da resina composta na microinfiltração marginal. Para tal, 60 incisivos bovinos receberam preparos classe V na junção amelo-cementária e aplicação do sistema adesivo Prime & Bond NT (Dentsply), sendo restaurados com incremento único de Z250 (3M). Eles foram divididos em seis grupos de acordo com a temperatura e o tempo de fotoativação: G1 - o compósito foi resfriado a 5°C e fotoativado por 20 s; G2 - 5°C/40 s; G3 - o compósito foi mantido a temperatura ambiente de 24°C e fotoativado por 20 s; G4 - 24°C/40 s; G5 - o compósito foi aquecido a 54°C e fotoativado por 20 s; G6 - 54°C/40 s. Os dentes restaurados foram imersos em água destilada a 37°C por 24 horas e posteriormente receberam acabamento, polimento e 500 ciclos térmicos (5 e 55°C). A microinfiltração foi avaliada quantitativamente em milÃmetros pelo método do nitrato de prata seguido pela diafanização. Os dados foram submetidos a ANOVA paramétrica e teste de Tukey (α = 5%), obtendo-se um valor de p = 0,00. As médias (± desvio padrão) observadas para cada grupo foram: G6:1,7(± 1,0)a; G2:2,7(± 1,3)ab; G1:2,7(± 1,6)ab; G5:3,1(± 1,0)abc; G3:3,8(± 1,0)bc; G4:4,3(± 0,3)c. Os grupos acompanhados das mesmas letras não apresentam diferenças significantes. Pôde-se concluir que, utilizando 40 segundos de fotoativação, o aquecimento reduziu significativamente a microinfiltração em relação à temperatura ambiente, enquanto o resfriamento não produziu efeitos significantes. Utilizando 20 segundos de fotoativação, a variação de temperatura não exerceu efeitos significativos.
Palavras-chave
Infiltração dentária, resina composta, temperatura ambiente
Abstract
The aim of this study was to evaluate the influence of pre-cure temperature and photo-activation time in the microleakage of composite resin restorations. For such, 60 bovine incisor received class V preparations in the CEJ and application of the adhesive system Prime & Bond NT (Dentsply), being restored with a bulk increment of Z250 (3M). They were divided in six groups in agreement with the temperature and the time of photo-activation: G1 - the composite was cooled to 5°C and photo-activated by 20 s; G2 - 5°C/40 s; G3 - the composite was maintained to room temperature of 24°C and photo-activated by 20 s; G4 - 24°C/40 s; G5 - the composite was heated up to 54°C and photo-activated by 20 s; G6 - 54°C/40 s. The restored teeth were immersed in distilled water at 37°C/24 h and later they received the finish, polishing and 500 thermal cycles (5 and 55°C). The microleakage was evaluated quantitatively in mm by the silver nitrate method followed by clearing technique. The data were submitted to parametric ANOVA and Tukey´s test (a = 5%), being obtained a p value of 0,00. The mean (± Standard Dev) observed for each group were: G6:1,7(± 1,0)a; G2:2,7(± 1,3)ab; G1:2,7(± 1,6)ab; G5:3,1(± 1,0)abc; G3:3,8(± 1,0)bc; G4:4,3(± 0,3)c. Groups with same letters were no statistically different.We can conclude that using 40 s of photo-activation, the heating reduced significantly the microleakage in relation to room temperature, while the cooling didn’t produce significant effects. Using 20 s of photo-activation, the temperature variation didn’t showed significant effects.
Keywords
Dental leakage, composite resin, temperature
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