Comparative evaluation of microleakage in occlusal and cervical part of cavitites prepared by Er:YAG laser and conventional method

The application of laser in dentistry has gained special attention in caries removal, cavity preparation and surface modification to obtain best adhesion of restorative materials to dental tissue. The aim of this study was to compare the microleakage of composite restoration in occlusal and cervical parts of cavities prepared by Er:YAG laser and diamond bur. 12 human caries free third molars were selected for this study. Then, the teeth were randomly divided in 2 groups of 6 in each. The class V cavities were prepared on both buccal and lingual side of each teeth by Er:YAG or diamond bur. After etching and bonding procedure, the cavities were restored by composite resin incrementally and light cured for 40 sec. All tooth surfaces were coated with two layers of nail varnish leaving 1mm wide border around restoration margins. Then, the samples were immersed in 2% methylene blue solution. After 24 hours, they were washed and dried. The samples were bisected longitudinally into two equal buccal and lingual halves. Then, samples were assessed by using a light microscope. The extent of dye penetration in occlusal and cervical part was analyzed by Kruskal-Wallis. There was no significant difference in 2 groups. Regardless of the method of cavity preparation (Er:YAG laser or diamond bur) the microleakage of class V cavities in cervical part was significantly more than those in occlusal part.