An evaluation of shear bond strength of metal orthodontic brackets bonded with two different adhesives using a high intensity led curing unit at different curing times – An in vitro study

OBJECTIVES: To evaluate and compare the shear bond strength (SBS) and the residual adhesive left on metal orthodontic brackets bonded with Transbond XT and Bracepaste using a Woodpecker iLED curing unit (2500 mW/cm2) at different curing times. METHOD: According to curing time and composite type, ninety extracted human premolar teeth were divided into six groups, compromising 15 teeth per group. Metal brackets were bonded to the teeth with Transbond XT and Bracepaste, wgile the curing durations were at 6 seconds, 3 seconds, and 1 second, correspondingly. SBS was measured with a Hounsfield universal testing machine. Following bracket debonding, the surfaces were examined to assess the adhesive remnant index (ARI). RESULTS: A significant difference was found in the Shear Bond Strength of Transbond XT and Bracepaste cured for 6 seconds, 3 seconds, and 1 second (p < 0.001). Groups cured for 6 seconds exhibited the highest SBS, while those cured for 1 second demonstrated the lowest SBS. Also, a significant difference was noted in the quantity of adhesive left in the Transbond XT group, whereas no statistically significant difference was detected in the amount of adhesive remaining in the Bracepaste group. CONCLUSION: Shortening the curing duration leads to a reduction in shear bond strength (SBS), irrespective of utilizing a high-intensity LED light-curing device. Adequate SBS was accomplished with Transbond XT when cured for 6, 3, and 1 second, and with Bracepaste when cured for 6 and 3 seconds, employing a high-intensity LED curing light.