Computerized occlusal analysis of Essix and Hawley retainers used during the retention phase: a controlled clinical trial

Aim The aim of this study was to evaluate the occlusal force distribution (OFD), individual tooth force (ITF), and occlusal surface area (OSA) of Essix and Hawley retainers, using T-Scan III (Tekscan Inc., South Boston, MA, USA) analysis. Materials and methods A total of 35 subjects were randomly assigned to one of the retention groups following fixed orthodontic treatment. While 18 of these subjects were provided with Essix retainers, 17 were given Hawley retainers. Computerized occlusal analysis of the patients' dentitions was performed using T-Scan III. The evaluations were made after debonding (T0) and at month 3 (T1), month 6 (T2) and 1 year (T3) after the retention phase. Results The changes in OFD were significant only in the Hawley group for the left/right half jaws and the right posterior quadrants when comparing the T2-T3 time interval. Also, the differences between the groups were significant only for the left half jaw for the T0-T2 time interval and for the right half jaw when comparing the T0-T2 and the T2-T3 time intervals. The changes in ITF were insignificant within groups, but significant between the groups for tooth 11 and 22. Although there was an increase observed in OSA for both groups, the difference between the groups was insignificant. However, the OSA increase in the Essix group for the left/right anterior quadrants was significant only for the T0-T2 and the T0-T3 time intervals, while in both groups, for the posterior left quadrant, the OSA was insignificant only for the T0-T1 time interval. Conclusions Although OSA increased when using both retention appliances, OFD did not change.