Effects Of Er:YAG Laser And Acid Etching On Bond Strength Between Enamel/Dentin And Vita Markâ…¡ Blocks

Objective1. Observe the morphological changes of enamel and dentin surface after Er:YAG laser and acid etching.2. Compare the bond strength between enamel/dentin and VITA Mark II blocks after Er: YAG laser and acid etching.Method40human premolars extracted for orthodontic were chosen at department of oral surgery, stomatological hospital of Shanxi Medical University from September2010to September2011, grinding the mesial and distal surface of the each premolar, then get40enamel and dentin samples for3mm*3mm respectively. All the enamel and dentin samples randomly divided into four groups,10samples in each group:Group1, Er:YAG laser(60mj,2Hz); Group2, acid etching(35%phosphoric acid); Group3, Er:YAG laser combined with acid etching; Group4, acid etching combined with Er:YAG laser.2samples were chosen randomly from each group and observed the morphological changes of enamel and dentin with Scanning Electron Microscope(SEM),the other8samples of each group were bonded with VITA Mark II blocks by3M ESPE RelyX Unicem, and compare the bond strength between enamel/dentin and VITA Mark II blocks after bond strength test.ResultBoth enamel surface and dentin surface, the bond strength in the group of acid etching combined with Er:YAG laser showed the highest compared with other groups,and there was statistically significant difference with other groups(P<0.05). On the contrary, the group of Er:YAG laser combined with acid etchingshowed the lowest value. There was no statistically significant difference between the group of acid etching and Er:YAG laser (P>0.05), the bond strength of the two groups were in the middle of all the groups.ConclusionAcid etching combined with Er:YAG laser could significantly enhance the bond strength between enamel/dentin and VITA Mark II blocks.