Study On The Effect Of Different Bracket Adhesives On The Enamel Microcracks Before And After Bonding

Objective: To compare the changes of enamel microcracks before and after bonding with different bracket adhesives.Methods: Ninety fresh premolar teeth were collected for orthodontic treatment.They were divided into two groups(45 in each group).The first group: obvious microcracks group(visible to the naked eyes under natural light),and the second group: weak microcracks group(invisible in natural light but visible under scanning electron microscope);each group was further divided into three groups(each group of 15): 3M light-cured adhesive group,3M chemically-cured adhesive group,control group.Scanning electron microscopy is used to measure their changes of length and width before and after debonding with different bracket adhesives.Results: In the obvious microcracks group: comparing its average width before debonding 3M chemical curing adhesive group and 3M light-cured adhesive group were different of statistical significance(P<0.05);There was no statistical significance of the average length of the microcracks before debonding between the two groups(P>0.05);The differences in width and length before and after treatment were statistically significant(P<0.05).In the weak microcracks group: the average width and length of microcracks were not statistically significant when comparing with 3M light-cured adhesive group and 3M chemically-cured adhesive group(P>0.05);The differences between the width and the length of the adhesive chemically-cured group before and after treatment with 3M light-cured adhesive group were statistically significant(P<0.05).Conclusion: The width and length of the enamel micro-crack group before and after removing brackets are both increased.Although 3M light-cured adhesive and 3M chemically-cured can both satisfy the requirements of adhesive strength of the enamel,3M chemical curing group has more damage to the tooth enamel after removing the brackets.Therefore,it is recommended to use 3M light-cured adhesive to meet the clinical requirements which can minimize its damage to the enamel surface.