The investigation of the damage that occurs on enamel surface as a result of the removal of metal and different type ceramic brackets: An in vitro study

The aim of this study is to determine how the debonding process applied to remove fixed orthodontic applices at the end of active treatment affects the enamel surface. Our research includes 5 different study groups in which the enamel surface will be evaluated in vitro after the removal of 1 type of metal bracket and 4 different types of ceramic brackets from the tooth surface. 105 exracted premolar teeth are randomly divided into 5 groups. The roots of these teeth were embedded in acrylic blocks in groups of three, leaving the crowns outside. Master Series metal bracket was used for the samples in the first group (group A), monocrystalline Inspire Ice ceramic bracket for the samples in the second group (group B), silane coated monocrystalline Inspire Ice ceramic bracket for the samples in the third group (group C), polycrystalline Symetri ceramic bracket for the samples in the fourth group (group D), silane coated polycrystalline Symetri ceramic bracket for the samples in the fifth group (group E). All brackets were bonded using Transbond XT adhesive resin. SBS (shear bond strength) test was applied using universal test machine following the bonding procedure and shear bond strength values were noted in MPa unit. The amount of residual adhesives were determined by ARI scoring. After cleaning the tooth surfaces with a 12-blade tungsten carbide bur, the second SEM images were taken in order to determine the effect of debonding on the enamel surface, and the change in the number of enamel cracks and the length of the longest enamel crack were examined. Shapiro-Wilk test was used for testing the normality of the variable distribution, One Way ANOVA test was used for the comparisons between the groups and Pearson correlation analysis was used for testing the relationship between variables. Among all groups, the highest SBS value was found in the E group with 20.58 MPa in Symetri brackets with silane applied to the base. The lowest SBS value was found in the Master Series metal brackets with 9.46 MPa in group A. The highest ARI score was seen in group A. The changes observed in "Enamel Crack Number" and "Enamel Crack Length " from T0 to T1 were significantly lower (p<0,05) in groups A, B and C compared to Groups D and E. Keywords: Debonding; Enamel cracks; Ceramic bracket