1 Assistant Professor, Department of Orthodontics, Dental School, Babol University of Medical Sciences, Iran
Aim: Light cure composites are routinely used to attach orthodontic brackets, so bond strength and cure time must be considered. Ilowever, the disadvantages of the conventional halogen apparatus include heat and lengthy composite curing. Therefore, the purpose of this study was to compare shear bond strength of orthodontic brackets composite cured by plasma arc (PAC), conventional halogen (QTII), light- emitting diode (LED) and self-cure.
Materials and Methods: In this in vitro study, sixty premolar teeth extracted for orthodontic purposes from patients tinder 18 years of age were collected and divided into four equal groups. In the first group, the brackets were bonded by self-cure composite. In the second, third, and fourth groups, they were bonded by halogen, LED and plasma arc, respectively. The samples were thcrmocycicd and finally the force required for brackt failure was measured. Shear bond strength was obtained by dividing the exerted force by the bracket base surface. AR1 (Adhesive Remnant Index) and EDI(Enamel Detachment index) were also evaluated. Data were analyzed by ANOVA followed by TUKEY test.
Results: Average shear bond strengths were 14.7±5.4 MPa in the self—cure group, 14.6±5.3 MPa in the halogen group, 14.7±4.5 MPa in the LED group, and 14.2±5 MPa in the plasma group. There were no significant differences among the groups. EDI and AR1 did not differ between the light-cure and self-cure groups.
Conclusion: No significant difference was observed in shear bond strength among different methods of composite curing. Therefore, despite the high cost of plasma arc, it is recommended in order to reduce operation time.