| Objective The influence of Er:YAG laser with different parameters to remove the residual adhesive on the enamel surface on the rebonding of bracket was studied,and the comparison was made with sandblasting and silicon-ion universal grinding wheel commonly used in clinical practice,so as to provide a reference for the safe removal of adhesives and the guarantee of the rebonding effect in clinical practice.Methods A total of 85 healthy maxillary premolars extracted for orthodontic treatment were collected and selected from patients aged 13-25 years old in the Affiliated Stomatology Hospital of Anhui Medical University.After disinfection,they were randomly divided into 5 groups,A,B,C,D and E with 17 teeth in each group according to different methods of tooth surface adhesive removal.The Shear Bond Strength(SBS)of the initial bonding bracket was tested by universal testing machine after 24 h water bath.The adhesive surfaces were treated with Er:YAG laser of group A with power of 1.5W,Er:YAG laser of group B with power of 1.8W,Er:YAG laser of group C with power of 2.1W,sand blasting of group D and silicon-ion grinding wheel of group E respectively,and were rebonded with a new bracket.After 24 h water bath,universal testing machine was used to test the shear bonding strength of each group of bracket rebonding.Under Scanning Electron Microscope,the damage of the enamel surface after the removal of residual adhesives was evaluated,and under optical microscope,the Adhesive Residue Index(ARI)after the rebonding of the support groove was statistically evaluated.Finally,the data were sorted out and analyzed,and the SBS and ARI of each group were compared.SPSS26.0 was used for statistical analysis.The paired sample T-test was used to analyze the shear bond strength of the 5groups of samples after the initial bond and the re-bond,and the ANOVA(one-way variance analysis)and LSD-t test were used to compare the shear bond strength of the 5groups of samples after the re-bond.ARI scores of the two groups were analyzed for consistency,and a group of data was randomly selected for Kruskal-Wallis analysis.P< 0.05 was considered statistically significant.Results There was no significant difference in the initial shear bond strength(SBS)between the five groups(P>0.05),and the mean value was(13.82±3.28)MPa.The SBS of rebonding and primary bonding was compared within the group,and it was found that the shear strength of B and C laser groups(1.8W and 2.1W,respectively)was significantly increased after treatment(P<0.05).By comparing the rebonding SBS of the groups treated with different methods,it was found that the rebonding strength of the C laser group(power 2.1W)was higher than that of the other groups excluding group B and had statistical difference(P<0.05).The rebonding SBS of the B laser group was higher than that of the A laser group and the sandblasting group,and had statistical difference(P<0.05).There was no statistical difference in the rebonding SBS between A laser group(power 1.5W),sandblasting group and silicon-ion grinding wheel group(P>0.05).Scanning electron microscope(SEM)results showed that large amount of adhesive remained in laser group A,the adhesive was removed in laser group B and the enamel morphology was good,the enamel damage was serious in laser group C and sandblasting group,the silica ion group had a small amount of adhesive and the enamel structure was less damaged.Conclusion The rebonding shear strength obtained by Er:YAG laser treatment with1.8W and 2.1W was higher than that obtained by primary bonding,and higher than that obtained by other treatments.Scanning electron microscopy showed that 1.8W Er:YAG laser had less damage to the enamel structure and the least residual adhesive,while the other groups had different degrees of damage to the enamel or a large number of adhesive residues.It is recommended to use 1.8W Er:YAG laser to debond the enamel surface after the bracket falls off. |
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