ORCID ID
Graduation Date
Fall 12-18-2026
Document Type
Thesis
Degree Name
Master of Science (MS)
Programs
Medical Sciences Interdepartmental Area
First Advisor
Sumit Yadav
Second Advisor
Vaibhav Gandhi
Third Advisor
Sangamesh Kumbar
Fourth Advisor
Peter Giannini,
Fifth Advisor
Benjamin H Kwok
Abstract
Introduction: Retention in orthodontics is a critical phase of care intended to preserve tooth alignment and occlusal relationships achieved during the treatment. Fixed and removable retainers are widely used, but their longevity and patterns of failure vary. Objectives: To evaluate survival and first documented failure of maxillary and mandibular fixed and removable retainers; compare failure patterns among arches and modalities; identify factors associated with failure; and characterize recurrent fixed-retainer failure. Hypothesis: Retainer survival and failure would vary according to retention modality, dental arch, and selected patient- and treatment-related characteristics. Results: Of 1,574 screened records, 1,253 patients met eligibility criteria. The cohort included 495 males (39.5%) and 758 females (60.5%), with a mean age at treatment initiation of 17.47 years and mean active-treatment duration of 25.21 months. First documented failure occurred in 191 of 858 maxillary fixed retainers (22.3%), 189 of 973 mandibular fixed retainers (19.4%), 66 of 741 maxillary removable retainers (8.9%), and 25 of 472 mandibular removable retainers (5.3%). Kaplan-Meier analysis demonstrated progressive decline in failure-free survival, with fixed retainers showing higher documented failure proportions than removable retainers. In multivariable Cox regression, deep bite increased the hazard of maxillary fixed-retainer failure (HR, 1.77; 95% CI, 1.38-2.28; P< 0.001). Longer active-treatment duration was associated with fixed-retainer failure in both arches (HR per month, 1.02; 95% CI, 1.01-1.03; P< 0.001 for each). Most fixed-retainer failures were segmental: v
129 of 191 maxillary failures (67.5%) and 134 of 189 mandibular failures (70.9%). Among 201 patients with follow-up after an initial fixed-retainer failure, 68 (33.8%) experienced a second documented break. Conclusion: Retainer failure was time-dependent and multifactorial. Fixed retainers had higher documented first-failure proportions than removable retainers, with maxillary fixed retainers showing the least favorable survival profile. Deep overbite and prolonged active orthodontic treatment were independently associated with an elevated hazard of fixed-retainer failure. These findings support individualized retention planning and long-term surveillance.
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Recommended Citation
Hansraj, Varun, "Survival and Failure Patterns of Fixed and Removable Orthodontic Retainers: A Retrospective Cohort Study" (2026). Theses & Dissertations. 1111.
https://digitalcommons.unmc.edu/etd/1111