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 site 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 with the respective adhesive according to the manufacturers' instructions. Each specimen was debonded using an Instron Universal Testing Machine at a crosshead 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-cured composites had a higher shear bond strength than the RMGIC. The adhesive-remnant scores were similar for the composites with the mean values at about 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 from the composites and indicated that all of the adhesive remained on the tooth with a distinct impression of the bracket.