A comparison of shear bond strengths of three visible light-cured orthodontic adhesives

The purpose of this study was to evaluate the shear bond strength and the s ite of bond failure for 2 visible light-cured composites (Transbond XT and Enlight) and a resin-modified glass ionomer cement (RMGIC; Fuji Ortho LC). Seventy-five extracted human premolars were collected and randomly divided into 3 test Groups. Brackets were bonded to the teeth in each test group wi th the respective adhesive according to the manufacturers' instructions. Ea ch specimen was debonded using an Instron Universal Testing Machine at a cr osshead speed of 0.1 mm/min. The mode of bond failure was observed by using light microscopy. The results of this study demonstrated that the light-cu red composites had a higher shear bond strength than the RMGIC. The adhesiv e-remnant scores were similar for the composites with the mean values at ab out 2, which indicates that more than half of the adhesive remained on the tooth. The RMGIC had a mean score of 3, which was significantly different f rom the composites and indicated that all of the adhesive remained on the t ooth with a distinct impression of the bracket.