title: Survival time comparison between Hawley and clear overlay retainers: a randomized trial.
abstract: The objectives of this study were to compare the survival time of the Hawley retainer (HR) and the clear overlay retainer (COR) over one-year follow-up and to analyze risk factors contributing to their breakage. In this randomized, controlled clinical trial, we assigned 120 adolescent patients to receive either the HR or the COR. All specific data on breakage dates, the reasons for breakage, and the broken parts of the retainers were recorded. A survival analysis was used to describe retainer survival over time. No significant differences were observed in survival times between the 2 groups for either the maxillary retainer (p = 0.254) or the mandibular retainer (p = 0.188). Both retainers tended to fracture, but the fracture locations were different. The findings indicate that clinicians should avoid increasing buccal root torque and reinforce the retainer base plates. Breakage rates may not influence the choice of retainer (Trial Registration number is ChiCTR-TRC-00000055).
authors.affiliation: Department of Orthodontics, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, People's Republic of China.
authors.forename: J
authors.initials: J
authors.lastname: Sun
authors.forename: Y C
authors.initials: YC
authors.lastname: Yu
authors.forename: M Y
authors.initials: MY
authors.lastname: Liu
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.forename: H W
authors.initials: HW
authors.lastname: Li
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Zhou
authors.forename: D
authors.initials: D
authors.lastname: Ao
authors.forename: R
authors.initials: R
authors.lastname: Tao
authors.forename: W L
authors.initials: WL
authors.lastname: Lai
mesh_terms: D000293:Adolescent; D016009:Chi-Square Distribution; D002648:Child; D004311:Double-Blind Method; D004868:Equipment Failure; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D018704:Orthodontic Retainers; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018709:Statistics, Nonparametric