THE EFFECT OF DIFFERENT DEBONDING TECHNIQUES ON THE ENAMEL SURFACE - AN IN-VITRO QUALITATIVE STUDY

The purpose of this in vitro study was to evaluate the enamel surface structure subjected to various techniques of debonding orthodontic att achments and to develop a technique for residual adhesive removal that restores the enamel surface as closely as possible to its pretreatmen t condition without introducing iatrogenic damage. Enamel surface stru cture was examined with a scanning electron microscope before bonding of twin metal brackets to 60 previously extracted premolars with two h eavily filled composite resins. Two groups, each consisting of 30 teet h, were equally subdivided into 10 subgroups. The first three subgroup s were used to compare the efficacy of three bracket removing instrume nts. Since there were no differences in the debonding properties betwe en the two resins, the two groups were combined. In this way, each sub group (n = 6) could be used for a more meaningful comparison. On the b asis of the results of this comparison, the bracket removing instrumen t that produced the most consistent separation at the bracket-adhesive interface was used in the remainder of the study. After appliance rem oval, the teeth were again examined microscopically and photographed, and seven different procedures for residual resin removal were compare d. After resin removal, the final polished enamel surface was followed by microscopic evaluation. Results of this study show the bracket rem oving plier produced the most consistent separation at the bracket-adh esive interface, leaving the enamel surface intact. Carbide burs at hi gh speed and air coolant proved to be efficient in residual resin remo val, but when used alone, failed to produce a satisfactory enamel surf ace. After the removal of residual resin, graded medium, fine, and sup erfine Sof-Lex finishing disks (Unitek Corp., Monrovia, Calif.) produc ed surfaces that could be readily restored satisfactorily after receiv ing a final polish with a rubber cup and Zircate paste.