Changes in occlusal surface area and occlusal force distribution following the wear of vacuum-formed, hawley and bonded retainers: A controlled clinical trial.

To evaluate the changes in occlusal surface area (OSA) and occlusal force distribution (OFD) following the wear of Vacuum-formed (VFR), Hawley (HR) and Bonded (BR) retainers, using T-Scan III. A total of 60 subjects using three different maxillary and mandibular orthodontic retainers, VFR (n:20), HR (n:20) and BR (n:20), were included in this study. The changes in OSA and OFD were evaluated using the T-Scan III. The evaluations were made 2 hours after debonding orthodontic appliances (T0) and in the 3rd (T1) and 6th (T2) months of the retention phase. For left (LDA), right (RDA) and posterior dental arches (PDA), intragroup comparison of OSA showed significant increase in the VFR and HR groups at T1-T2 and T0-T2 time intervals and in the BR group at T0-T1 and T0-T2 time intervals. For the anterior dental arch (ADA), only the increase in the HR group at T0-T1 and T0-T2 time intervals was found significant. When compared between the groups, the changes between HR and BR groups detected at T1-T2 time interval for the RDA and at T0-T1 and T0-T2 time intervals for the ADA were found significant. Intragroup comparison of OFD displayed significant changes only in the BR group. At T0-T1 time interval, the decrease in the ADA and the increase in the PDA were found significant. Also, intergroup OFD comparison exhibited significant differences between HR and BR groups at T0-T1 time interval for ADA and PDA. Although no significant differences were found between the VFR group, the increase in OSA occurred faster in the PDA in the BR group, whereas in the ADA it was significant only in the HR group.