Effect of Nd

Abstract

Recurrent caries is one of the most common problems subsequent to tooth restorative procedures. The majority of researchers believe that microleakage is the main reason for recurrent caries, and pulpal inflammation and necrosis. Problems associated with microleakage worsen due to failure to remove infected tooth structure. Considering the importance of disinfecting dentin after cavity preparation and the possible effect of disinfecting agents on induction of various reactions between the tooth structure and the adhesive restorative material, the aim of the present study was to evaluate microleakage of composite resin restorations after disinfecting the prepared dentin surface with Nd:YAG and Diode lasers and photodynamic therapy. Materials and methods: In this in vitro study 96 sound bovine teeth were randomly divided into 4 groups of 24 based on the disinfection method used after standard class V cavities were prepared on buccal surfaces: Group 1: Nd:YAG laser; Group 2: Diode laser; Group 3: photodynamic therapy; and Group 4: the control. Two specimens from each group prepared for SEM analysis. Self-etch Clearfil SE Bond bonding agent was applied according to manufacturers instructions. All the cavities were restored with Z100 composite resin using the bulky technique and light-cured for 40 seconds at a light intensity of 400 mW/cm2 using a halogen light-caring unit. The samples were stored in distilled water at 37C and then thermocycled. The periphery of the restorations was covered with nail varnish and the samples were immersed in 0.5% basic fuchsin for 24 hours at room temperature. Then the samples were longitudinally sectioned through the center of the restoration using a diamond disk at low speed under water spray; microleakage of occlusal and gingival margins was evaluated under a stereomicroscope at 25. Data was analyzed with Kruskal-Wallis and Wilcoxon signed-rank tests at p<0.05. Results: There were no significant differences in the microleakage of occlusal and gingival margins between the groups under study (p>0.05). Wilcoxon signed-rank test did not show any significant differences in microleakage between the occlusal and gingival margins in the Nd:YAG laser group (p>0.05). In the other groups, microleakage at gingival margins was significantly higher than that at the occlusal margins (p<0.05). Conclusion: Nd:YAG and Diode lasers and photodynamic therapy can be used to disinfect cavity preparations before composite resin restorations, without any negative effects on microleakage.