Objective: The aim of this study was to investigate whether the CAD/CAM brackets could provide enough bonding force as much as that of the conventional bracket, by comparing the debonding forces and shear bond strength (SBS) of 4 different customized bracket systems.
Method: A total of 30 extracted human upper premolars were divided into 5 groups of bonding the brackets which were (1) a labial conventional bracket; (2) a lingual self-ligating customized bracket; (3) a casted gold alloy lingual customized bracket; (4) a labial self-ligating milled customized bracket; (5) a labial customized resin based metal bracket. The debonding force was measured with an Instron universal testing machine and the bonding area was measured with 3D digital scanner. The SBS was calculated by divide the debonding force by bonding area.
Result: The mean debonding force were 62.7N (standard deviation [SD] 12.7), 196.9 N (SD 82.8), 127.2 N (SD 71.0), 104.5 N (SD 92.5) and 135.0 N (SD 83.2) for group 1, 2, 3, 4 and 5. The mean SBS were 6.7 MPa (SD 1.4), 6.1 MPa (SD 2.6), 3.6 MPa (SD 2.1), 10.2 MPa (SD 9.07) and 11.5 MPa (SD 7.2) for group 1, 2, 3, 4 and 5. Group 2, and 5 showed significantly higher debonding force than that of conventional bracket (P<0.05).
Conclusion: CAD/CAM bracket systems showed large deviation of debonding force due to variability of bracket design. However, all the CAD/CAM brackets provided similar or higher debonding force compared with conventional bracket.
Acknowledgement: This research was supported by a grant (17172MFDS366) from Ministry of Food and Drug Safety in 2017.