Mohammad Karim Soltani - Department of Orthodontics, Dental Faculty, Hamadan University of Medical Sciences, Hamadan, IR Iran
Sadegh Barkhori - Department of Orthodontics, Dental Faculty, Hamadan University of Medical Sciences, Hamadan, IR Iran
Yoones Alizadeh - Department of Mechanical Engineering, Amir Kabir University of Technology, Tehran, IR Iran
Farzaneh Golfeshan - Department of Orthodontics, Dental Faculty, Hamadan University of Medical Sciences, Hamadan, IR Iran

Background: Brackets’ debonding without any damage to the teeth is very important. Objectives: The aim of this study was to compare the debonding characteristics of the metal conventional and self-ligating brackets. Patients and Methods: ۶۹ maxillary premolars were randomly assigned in ۳ groups. Metal brackets of Damon, In Ovation and conventional systems were bonded to the teeth. The brackets were debonded with debonding pliers. Debonding strengths, adhesive remnant index, and enamel damage were evaluated. A Zwick model universal testing machine was used to measure debonding strengths. The debonding strength values were statistically analyzed by one-sided analysis of variance while the increase in the enamel crack numbers and length and the remained adhesive index were analyzed by chi-square test. Results: The means of the debonding strength in the brackets of in ovation, damon and conventional systems were ۱۵.۲۲, ۱۱.۴ and ۸.۶۷ MPa respectively. Significant differences were observed regarding debonding strength between three types of brackets (all: P < ۰.۰۰۱). After debonding of in ovation, damon and stainless steel brackets; the increased numbers of the enamel cracks were noted in ۲۶.۰۶%, ۲۱.۷۴% and ۱۷.۳۹% cases respectively. Also, the increased cracks lengths were demonstrated in ۴۷.۸۳%, ۳۹.۱۳%, and ۳۰.۴۳% cases. No significant differences were observed regarding the increase of the enamel cracks number and length and the amounts of residual adhesive on the teeth. Conclusions: The debonding characteristics of the metal self-ligating were comparable to the conventional brackets.

Debonding, Self, Ligating Brackets, Strength, Enamel Cracks