Changes in the distribution of occlusal forces in the course of the orthodontic retention phase

Abstract

Purpose Aim of the present study was to assess the relative distribution of occlusal forces after orthodontic treatment and during the first 3 months of the retention phase using a computerized occlusal analysis system (T-Scan, Tekscan Inc., Norwood, MA, USA). Materials and methods A total of 52 patients were included in this prospective cohort study and underwent analysis of occlusal forces on the level of tooth, jaw-half, and -quadrant during a 3-month period. Furthermore, differences between three retention protocols (group I: removable appliances in both jaws; group II: fixed 3–3 lingual retainers in both jaws; group III: removable appliance in the maxilla and fixed 3–3 lingual retainer in mandible) were assessed with Wilcoxon signed-rank tests at 5%. Results Directly after debonding, measured forces distribution were similar to published references for untreated samples. In the following, no significant difference was found between retention protocols II and III with regard to the asymmetry of the anterior occlusal forces. Both groups maintained an asymmetric force distribution in the anterior segment during the study period. There was also no difference between groups II and III in the distribution of occlusal forces for the posterior segments. Both retention concepts kept the symmetrical distribution of occlusal forces stable over the observation period. The retention concept of group I demonstrated a symmetrical distribution of occlusal forces in the anterior segment after debonding and this remained stable during the 3‑month period. In the posterior segment, no improvement of the initially asymmetric masticatory force distribution could be observed. Conclusions All three studied retention protocols showed stability in retaining their original symmetrical or asymmetrical occlusal force distribution posteriorly/anteriorly during the 3‑month observation period. Therefore, an even distribution of occlusal forces should be the aim of the finishing phase, as no relative benefit of any single retention scheme in terms of post-debond improvement during the retention phase was seen.

T scan – A review on an occlusal indicator in dentistry

“…The T-Scan device can also be a helpful tool for monitoring patients and determining whether a relapse has occurred. 25,26 F Fritz et al, 27 assessed the comparative dispersal of occlusal loads after orthodontic management and throughout the initial 3 months of the retention stage using a high-tech occlusal exploration co-ordination. The goal of the last phase should be an equitable distribution of occlusal loads because T Scan did not show any qualified benefits for any retention plan in terms of post-debond improvement throughout the retention phase.…”