Aim: Fixed retention is the method of choice for permanent stabilization of the treatment outcome. In recent years, CAD/CAM techniques have been developed to produce retainers with high precision and tension-free fit. The aim of this retrospective study was to evaluate the suitability of a semi-industrial retainer manufacturing process (office-based construction, external laboratory manufacturing) in terms of positioning accuracy and post-treatment changes.
Materials and methods: The accuracy of 41 retainers that were digitally designed and produced from a titanium plate by water jet cutting was analyzed. The patient received the retainer through fixation with dental flosses, without using a transfer tray. We compared the position in the mouth after insertion with the virtual setup using 3D software for superimposition. Intraoral scans of 25 CAD/CAM retainers and 25 0.0175" hand-bent retainers were evaluated after one year of usage. We measured the width between the canines, the angle between the lateral incisors, and the angle of contact between the canines and the lateral incisors.
Results: The largest and significant positioning deviations occurred in the vertical position, whereas positional changes in the horizontal and sagittal were small. The CAD/CAM retainers and the hand-bent retainers showed similar and minimal post-treatment alterations, which were not statistically significant.
Conclusion: Semi-industrial CAD/CAM titanium retainers offer good positioning accuracy in the mandible even without a transfer tray. Increased deviations between planned and actual position only occur in the vertical plane. In addition, these retainers offer good retention properties with minimal posttreatment changes, making them suitable for permanent retention.
Keywords: Computer-aided design/computer-aided manufacturing retainer, fixed retention, long-term retention, multistranded retainer, orthodontic retainer, positioning accuracy, posttreatment changes, three-dimensional
