Comparative evaluation of shear bond strength and surface enamel loss of three orthodontic adhesives bonded to metal brackets

Background and Objectives: Attachments with sufficient bond strengths and a low failure rate are required for a fixed orthodontic appliance to be successful. For bonding brackets to enamel surfaces, a variety of adhesives have been employed and optimal color and shade match of composite resins and teeth, make identification of adhesive–tooth interface difficult and complete removal of adhesive remnants may not be easily achieved. Color-change light-cured composites were recently introduced to the orthodontic market to enhance differentiation of adhesive and enamel. The objective of this study is to compare the shear bond strength, adhesive remnant index and enamel loss while debonding between two color changing adhesive with a conventional orthodontic adhesive. Methods: 120 human maxillary teeth freshly extracted was collected and stored. Then specimen was randomly divided into three groups and bonded accordingly. Among 40 samples prepared in each group, 20 samples were taken for shear bond test. Remaining 20 samples was debonded manually by using a debonding plier. The debonded tooth surfaces of 20 samples were examined under stereomicroscope of 10x magnification to assess residual adhesive on tooth surface and site of bond failure using Adhesive remnant index. The debonded bracket base of 20 samples was examined under Scanning Electron Microscope and Energy dispersive X ray spectroscopy to detect calcium and phosphorus. Result and Discussion: There was no statistically significant difference between the shear bond strength of Grengloo and Transbond Plus color changing adhesives. Energy dispersive X ray spectroscopy analysis showed a significantly high amount of elemental Calcium (Ca) and Phosphorous (P) on Transbond Plus. There were significant differences found in enamel loss by color changing adhesives. Significant result was found between shear bond strength of color changing adhesive and Transbond XT conventional adhesive. Conclusion: Metal brackets bonded with color changing adhesives have shown good shear bond strength with minimal enamel loss with Grengloo. Transbond plus showed significantly high amount of elemental Calcium (Ca) and Phosphorous (P).