Effects of Er:YAG laser on bond strength between dentin and blocks

Objective To observe the bond strength between dentin and VITA MarkⅡblocks after Er:YAG laser.Methods Thirty human premolars extracted were chosen,grinding the mesial and distal surface of each premolar,then get 30 dentin samples for 3 mm×3 mm respectively.All the dentin samples were randomly divided into four groups,10 samples in each group:Group 1,Er:YAG laser(60mj,2Hz);Group two,acid etching(35% phosphoric acid);Group 3,acid etching combined with Er:YAG laser.2 samples were randomly chosen from each group and observe the morphological changes of dentin with SEM;the other 8 samples of each group were bonded with VITA MarkⅡblocks by 3M ESPE RelyX Unicem.Compare the bond strength between dentin and VITA MarkⅡblocks after bond strength test.Result The bond strength in the group of acid etching combined with Er:YAG laser showed the highest(20.4504),and there was statistically significant difference with the other groups(P0.001).There was no statistically significant difference between the group of acid etching(15.2624)and Er:YAG laser(15.2360).Conclusion Acid etching combined with Er:YAG laser could significantly enhance the bond strength between dentin and VITA MarkⅡblocks.