Full text
| |
| Author(s): |
Marcelo Tavares de Oliveira
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Piracicaba, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba |
| Defense date: | 2009-09-03 |
| Examining board members: |
Marcelo Giannini;
Aldo Brugnera Junior;
Patricia Nobrega Rodrigues Pereira;
Patricia Moreira de Freitas;
Mario Fernando de Goes
|
| Advisor: | Marcelo Giannini |
| Abstract | |
The use of alternative techniques for cavity preparation is more common nowadays. Among these technologies, laser is the target of a great number of studies. The objectives of this study were to evaluate the effects of different parameters of dentin irradiation with Er:YAG laser on the adhesive procedures and their consequences over the substrate and resin dentin interface. Procedures were performed over flat dentin surfaces of human third molars bonded to three different adhesive systems ((Single Bond 2 - 3M ESPE, Clearfil Protect Bond - Kuraray Medical Inc. e Clearfil Tri-S Bond - Kuraray Medical Inc.). The evaluation tests were: dentin permeability, microtensile bond strengths, durability and the analysis of the ultra-structure using transmission electron microscope (TEM) and confocal laser scanning microscope (CSLM). Dentin permeability data and microtensile bond strength data were analyzed with one-way ANOVA and three-way ANOVA, respectively. Tukey test was used to point out differences among the tested groups. The significance level was fixed at 5%. Results showed a significative reduction on the dentin permeability and the 120mJ/4Hz parameter promoted the greatest reduction. For the microtensile bond strength test, this study showed that the irradiation with Er:YAG laser reduce the bond strength values at the baseline. After six months all groups became similar. Furthermore, self-etching systems were less affected by the Er:YAG laser irradiation. The two-step self-etching system seemed the more stable over time. TEM and CLSM images showed the hybrid-layer formation for all adhesive tested. The hybrid-layers had different thicknesses when the adhesive systems were bonded to abraded dentin. The observation of a uniform and well defined hybrid-layer was not possible when the adhesive systems were bonded to laser irradiated dentin, regardless of the used parameter. According to the data presented, dentin irradiation with Er:YAG laser reduce the permeability of the substrate, interfering on the bonding strength to dentin at the baseline, however, after six months laser irradiated groups were similar to control groups. Microscope analysis revealed that hybrid layer formation was irregular and non-uniform when dentin was laser irradiated. (AU) | |