Influência da irradiação com laser nd:yag associado ao flúor nos valores de resistência de união de sistemas adesivos às dentinas sadia e cariada

• Ano de defesa: 2006
• Autor(a) principal: Paranhos, Maria Paula Gandolfi
• Orientador(a): Burnett Junior, Luiz Henrique
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: ODONTOLOGIA; LASER - ODONTOLOGIA; FLÚOR (ODONTOLOGIA); DENTINA; DENTÍSTICA; ADESIVOS DENTÁRIOS
• Link de acesso: http://hdl.handle.net/10923/541

This study evaluated, in vitro, the microtensile bond strength of two adhesive systems (Single Bond/3M-ESPE and Clearfil SE Bond/Kuraray) to caries affected and normal dentin, with or without previous treatment with Nd:YAG laser or Nd:YAG laser associated to fluoride. Dentin surfaces were exposed from 60 human third molars. Teeth were divided into 12 groups, where groups 1-6 were submitted to pH cycling for artificial caries and groups 7-12 remained with normal dentin. Dentinal surfaces received three different treatments: laser Nd:YAG irradiation (60 mJ, 15 Hz and 0. 9 W) for 1 min; laser Nd:YAG irradiation associated to fluoride in gel; and no treatment (controls). Twelve teeth, treated as mentioned above, were analyzed by SEM, Energy Dispersive Spectroscopy (EDS) and microhardness. In experimental groups, adhesive systems were applied according to manufacturers’ instructions and composite resin restorations (Filtek Z250/3M-ESPE) were made incrementally. After storage in distilled water for 24 h and 37° C, teeth were sectioned serially in both x and y directions and sticks with adhesive area of 0. 8 mm2 were obtained (25 per group). The sticks were measured and submitted to the microtensile bond strength test in an Universal Testing Machine (EMIC DL) in a 0. 5 mm/min crosshead speed. Failure mode was analyzed in SEM and in Fractographical analysis. According to general linear model univariate (GLM) and Tukey (p < 0. 05), the highest mean bond strengths were obtained in groups of normal dentin treated with Clearfil SE Bond (40. 65 MPa) and Single Bond (34. 2 MPa) according to manufacturers’ instructions. The results showed that the presence of caries affected dentin significantly decreased the mean bond strengths of the 2 adhesives systems. Laser irradiation of dentin also decreased the bond strengths of teeth treated with Clearfil SE Bond. Moreover, laser irradiation associated to fluoride also decreased the bond strength values of the 2 adhesive systems. However, caries affected dentin had better results with this association when compared to normal dentin. Mixed failure was the most common mode of failure in this study. SEM analysis showed irregularities and porosities in dentin after Nd:YAG laser irradiation due to melting and re-crystallization of this surface. Normal dentin showed closed dentinal tubules after laser irradiation and caries affected dentin showed clearer dentinal tubules because of the re-establishment of peritubular dentin.