Accuracy evaluation of bracket repositioning by indirect bonding: hard acrylic CAD/CAM versus soft one-layer silicone trays, an in vitro study

Abstract : OBJECTIVES:Rapid development of digital technologies and 3D printing provide new tools for orthodontic indirect bonding. The purpose of this in vitro study is to evaluate the clinical acceptability of hard CAD/CAM indirect bonding tray.MATERIAL AND METHODS:Ten soft silicone transfer trays and ten hard CAD/CAM trays were produced, and 200 brackets were placed on them. The brackets were then transferred to twenty stereolithography -printed models by indirect bonding. These models were scanned and digitally compared with the reference model by three-dimensional superimpositions (GOM software). The linear and angular measurements were collected and analyzed.RESULTS:For the CAD/CAM trays, 100% of the mesiodistal, vertical, and transverse measurements of incisors were within the clinically acceptable range of the American Board of Orthodontists (ABO) standards. More specifically, the clinically acceptable linear measurements were between 97 and 100% for silicone trays while they were between 89 and 100% for CAD/CAM trays. The clinically acceptable angular measurements varied between 87 and 100% for the silicone trays and between 79 and 100% for the CAD/CAM trays. Silicone trays were more precise than CAD/CAM trays. The difference was significant for all linear and angular measurements.CONCLUSIONS:While the CAD/CAM group shows clinically acceptable results according to the ABO, silicone remains to be more precise than CAD/CAM for transfer trays and is therefore still the reference.CLINICAL RELEVANCE:We demonstrate here that the orthodontic indirect bondings, whether they are realized using silicone transfer trays or CAD/CAM trays, are clinically acceptable in terms of the repositioning accuracy of brackets.