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| Author(s): |
Eduardo José Carvalho de Souza Júnior
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba |
| Defense date: | 2011-02-24 |
| Examining board members: |
Luis Alexandre Maffei Sartini Paulillo;
Rebeca Barroso Bezerra;
Flavio Henrique Baggio Aguiar
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| Advisor: | Luis Alexandre Maffei Sartini Paulillo |
| Abstract | |
The aim of this work was to: a) evaluate the effect of enamel selective enamel etching and LED curing units on dentin microtensile bond strength of Class I composite restorations; b) evaluate the effect of different LED light units and self-etch adhesives on the Knoop hardness profile (KHN) of Class I composite restorations; c) evaluate the gap formation before and after thermomechanical loading of Class I composite restorations photocured by LED and using different application protocols of self-etch adhesives systems. In experiment 1, ninety-six Class I cavities were made in human molars and restored with a microhybrid composite. For the restorative procedure, teeth were assigned in 12 groups (n=8) formed by the studied factors interactions, LED curing unit (Radii-Cal - RD, Flash Lite 1401 -FL and Ultra-Lume 5 - UL), self-etch adhesives (Clearfil SE Bond - CSE and Clearfil S3 Bond - S3) and selective enamel acid etching (with and without). After finishing and polishing approach, specimens were submitted to thermo-mechanical ageing and sticks were obtained from the bonding interface between adhesive and pulpal wall which were submitted to a microtensile load in a universal testing machine. After statistical analysis, (three-way ANOVA and Tukey test with ?=0.05) it was shown that the pre-etched enamel approach for Clearfil S3 decreased dentin bond strength while it did not affect the bond performance of Clearfil SE. Thus, the polywave LED promoted higher microtensile bond strength values for the two-step adhesive. When Clearfil S3 was used, the light curing units yielded similar dentin bond strength. In the experiment 2, 96 Class I cavities were prepared in the same way as the previous experiment. Teeth were assigned to 18 groups (n=8) by the interaction among the studied factors, LED curing source (RD, FL and UL), self-etch bond system (CSE and S3), depth (superficial, medium and deep). After the restorative procedure, specimens were submitted to thermo-mechanical ageing and then sectioned in the longitudinal direction for the Knoop hardness measurement in the different depths. Data were submitted to three-way ANOVA and Tukey test with a pre-set alpha of 0.05). The results showed that the third generation LED promoted similar KHN values to the single-peak ones and the superficial surface, in general, presented greater cure quality compared to the others surface depths. In the experiment 3, 192 third molars were used and Class I preparations were restored in the same way as the first study. Specimens were assigned to 12 groups (n=16) formed by the studied factors interaction, LED (RD, FL and UL), self-etch adhesives (CSE and S3), selective enamel acid etching (with and without) and before and after thermomechanical loading. After the restoration procedure, epoxy resin replicas were made and the marginal adaptation was analyzed in a scanning electron microscope (SEM). Then specimes were submitted to thermalmechanical loading and again, epoxy resin replicas were made and analyzed by SEM. After statistical analysis (Kruskal Wallis and Wilcoxon matched-pairs signed-ranks test, with a pre-set alpha of 0.05), it was shown that selective enamel etching yielded higher marginal integrity for S3, showing to be an efficient additional step for the bonding technique of this adhesive in Class I composite restorations. Also, the two-step self-etch adhesive gap formation was not influenced by the selective enamel etching, neither by the LED curing light (AU) | |
| FAPESP's process: | 09/03953-3 - Evaluation of light source and superficial treatment of cavosuperficial enamel on microtensile bond strength, Knoop microhardness and gap formation of self-etch adhesive sistems |
| Grantee: | Eduardo José Carvalho de Souza Junior |
| Support Opportunities: | Scholarships in Brazil - Master |