Occlusal contact area changes with different retention protocols: 1-year follow-up

Abstract

The purpose of this study was to evaluate the occlusal contact area and cast-radiograph evaluation (CRE) score changes in patients with 3 different retention protocols after a 1-year retention period. A total of 90 patients with acceptable final occlusion according to American Board of Orthodontics CRE were equally divided into 3 groups according to the retention protocol: upper bonded retainer and lower Essix or bonded retainer (Essix group); upper bonded retainer and Hawley or lower bonded retainer (Hawley group); and upper bonded retainer and lower bonded retainer (bonded retainer group). Digital models were used to assess occlusal contact area changes after a 1-year retention period. The follow-up occlusion models were assessed with the American Board of Orthodontics CRE. Occlusal contact areas increased significantly in the Hawley and bonded retainer groups for all teeth except incisors. The bonded retainer group showed the greatest amount of settling, but differences with the Hawley group were not statistically significant. However, statistically significant decreases in occlusal contact areas were recorded for the Essix group except for incisors. A decrease of CRE scores was seen in the Hawley group, whereas a statistically significant increase was recorded in the Essix group. Both Hawley and bonded retainers allowed settling of the occlusion during the retention phase, whereas the Essix retainer did not allow relative vertical movement of the posterior teeth. The Hawley group showed improvement in the total CRE score, whereas the Essix group showed worsening.