Risk factors for orthodontic fixed retention failure in the upper and lower jaw: A retrospective controlled study.

OBJECTIVE: To investigate the potential correlation between fixed orthodontic retention failure and several patient- and treatment-related factors.

METHODS: Patients finishing treatment with fixed appliances between 2016 and 2017 were retrospectively included in this study. Those not showing fixed retention failure were considered as control group. Patients with fixed retention failure were considered as the experimental group. Additionally, patients with failure of fixed retainers in the period of June 2019 to March 2021 were prospectively identified and included in the experimental group. The location of the first retention failure, sex, pretreatment dental occlusion, facial characteristics, posttreatment dental occlusion, treatment approach and presence of oral habits were compared between groups before and after treatment separately by using a Fisher exact test and a Mann-Whitney U test.

RESULTS: 206 patients with fixed retention failure were included, 169 in the lower and 74 in the upper jaw. Significant correlations were observed between retention failure in the lower jaw and lower arch length discrepancy ( p = 0.010), post-treatment growth pattern ( p = 0.041), nail biting ( p < 0.001) and abnormal tongue function ( p = 0.002). Retention failure in the upper jaw was more frequent in patients with IPR in the lower jaw ( p = 0.005) and abnormal tongue function ( p = 0.021).

CONCLUSIONS: This study suggests a correlation between fixed retention failure and parafunctional habits, such as nail biting and abnormal tongue function. Prospective studies with larger study populations could further confirm these results.