Method: We used sixty extracted human teeth (third molars specifically) in a healthy condition. In each tooth two cavities were prepared in both buccal and lingual surface. Six groups were established randomly; each group consisted of twelve teeth. The specimens of each group were treated with hypochlorite at 5,25% and 2% chlorhexidine as a prior preparation for the restoration process. We used a fifth generation adhesive One step (Bisco) in all the groups, together with a previous total etching. The cavities were restored by incremental technique using Aellite A1 resin (Bisco) and photopolymerized with the lamps mentioned. Once the restorations were completed, six teeth of each group were tested to thermocycling (10,800 cycles). We looked for sudden temperature changes that can de tolerable in the oral cavity. Subsequently all groups were immersed in methylene blue for 24 hours. Finally all groups were subjected to microfiltration and then longitudinally sectioned for analysis and observation to the Scanning Electron Microscope (SEM).
Result: The results were subjected to ANOVA statistical analysis. It showed less microleakage values when using sodium hypochlorite, but no significant differences among the three types of lamps after thermocycling.
Conclusion: The groups tested with each lamp showed no significant differences in terms of microfiltration. However, after being subjected to thermocycling using both hypochlorite and chlorhexidine, we saw some major differences between the two substances when used for restorations. Chlorhexidine showed a better performance in the cervical surface while hypochlorite performed in a more efficient way in the occlusal surface.