Comparison of survival rate and duration of maxillary and mandibular lingual bonded retainers – a retrospective cohort study

Background: This study aimed to evaluate the survival rates of maxillary and mandibular lingual bonded retainers fabricated from coaxial wire. It also analyzed the impact of operator experience, as well as patients’ inherent and treatment-related factors, including age, sex, malocclusion, and the number of teeth bonded, on their survival rates. Methods: This study comprised a sample size of 300 participants. The records of patients with maxillary and mandibular lingual bonded retainers were retrospectively analyzed during a five-year follow-up period to assess retainer survival, types of failure, and the timing of those failures. Descriptive statistics were calculated, Cox regression analysis was employed to assess possible predictors of retainer survival, while the Kaplan-Meier survival curve was used for assessment of the survival function. Results: Survival rates for maxillary and mandibular lingual bonded retainers were 39.8% and 66.3%, respectively, over a mean observation period of 60 months. Survival regression analysis showed that the risk of retainer failure in the mandible was 0.43 times lower compared to the maxilla. Additionally, the risk of retainer failure was 1.61 times higher when second premolars were included in the retainer, while it was 0.7 times lower when placed by a fourth-year resident. Conclusions: The maxillary lingual bonded retainers exhibited a significantly higher failure rate than the mandibular lingual bonded retainers. Survival rates were lower with less experienced operators and in longer-span retainers, especially those extending to the second premolars. Clinical trial number: Not applicable.