摘要:The purpose of this study was to evaluate the effects of thermocycling and Er:YAG laser conditioning on the microleakage of silorane, packable and nano-filled composites. 512 Class 2 cavities were prepared on 256 premolars. The teeth were assigned to 8 groups 1= Filtek Silorane, 2= Filtek Silorane with laser conditioning, 3= Aelite LS with acid conditioning, 4= Aelite LS with laser and acid conditioning, 5= Aelite LS with laser conditioning, 6= Filtek Supreme XT with acid conditioning, 7= Filtek Supreme XT with laser and acid conditioning, 8= Filtek Supreme XT with laser conditioning. Half of the samples in each group were thermally cycled. All specimens were immersed in basic fuchsine and evaluated with respect to microleakage. The data was analyzed statistically. Thermal cycling and laser conditioning increased microleakage of packable composite, Aelite LS. No effect of them was found in other restoratives. It was concluded that the Er:YAG laser conditioning should be selected according to the restorative material used.