Influência dos procedimentos de clareamento dental na adesão de acessórios ortodônticos

• Autor(a) principal: Martins, Mariana Martins e
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14148
• topic: Orthodontics; Bleaching; Adhesion; Roughness; Microscopy; Ortodontia; Adesão; Clareamento; Rugosidade; Microscopia; Colagem dentária; Dentes - Clareamento; Microscopia eletrônica de varredura; Aspereza de superfície (Odontologia); CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA::ORTODONTIA

Elementary-chemical and morphological changes may occur in enamel surface by the use of bleaching agents, especially by the higher concentrations. The purpose of this research was to investigate the influence of 35% hydrogen peroxide on orthodontic bracket adhesion at zero hour, 24 hours, 7, 21 and 56 days after dental bleaching and investigate the alterations in enamel morphological structures. Bovine incisors were used in a total of 150, which 120 were prepared for adhesion test, adhesive remnant index (ARI) determination and roughness test. The 30 left were used for morphologic observation of bleached enamel in scan electron microscopy (SEM). The 35% hydrogen peroxide was used as a bleaching agent (Whiteness HP FGM) and the Transbond XT (3M Unitek) as a bonding agent. The Kruskal-Wallis and Mann-Whitney tests were applied for adhesion test and evaluation of ARI scores and the Student T test and ANOVA for roughness test, all adopting p < 0.05. The means of shear bond strength values were 7.47±2.18 MPa (control), 1.35±0.44 MPa (zero hour), 7.81±2.54 MPa (24 hours), 9.32±2.33 MPa (7 days), 7.31±2.20 MPa (21 days) e 6.67±1.77 MPa (56 days). Statiscally significant differences were observed between all the groups (p < 0.001) and were observed in the comparison of zero hour (p < 0.001) and 7 days (p < 0.027) with the control group and in the comparison of zero and 24 hours (p < 0.001). ARI scores (0, 1, 2 e 3) also showed statiscally differences between all the groups (p = 0.011) and at the comparison of all the experimental groups with the control: zero hour (p = 0.001), 24 hours (p = 0.009), 7 days (p = 0.018), 21 days (p<0.001) e 56 days (p = 0.004). In respect to the control group, the shear bond strength values became significantly lower when the bracket was bonded immediately after bleaching and quickly returned to control level in 24 hours. In 7 days became higher and recovered to normal values in the next weeks (21 and 56 days). Different patterns of enamel/adhesive/bracket fractures were observed in bleached enamel when ARI scores were analyzed. The control group showed a high frequency of 3 score (adhesive/bracket fracture) and none of zero score (adhesive fracture), the opposite behavior was observed in the experimental groups, with low frequency of 3 score and high of zero score. No statiscally differences were noted at roughness test and no effects on the surface morphology were observed in the dental enamel of all groups studied at SEM analysis.