Affiliation:
1. Department of Orthodontics and Dentofacial Orthopaedics, Sri Ramachandra Dental College and Hospital, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
2. Private Practice Silver Smile Dental Specialists, Product Specialist Digant’s 3D Orthodontics, Rajkot, Gujarat, India
Abstract
Background: New technologies have paved the way for newer fabrication techniques, such as rapid prototyping, which has gained popularity in the fabrication of several orthodontic appliances including retainers. Aim: To evaluate the stability, survival time and periodontal health associated with vacuum-formed retainers (VFRs), bonded retainers (BRs) and rapid prototype retainers (RPRs) over a period of 12 months in retention. Study design: Prospective clinical study. Methods: A total of 72 participants completing fixed orthodontic treatment were allocated to the following three groups by the investigators based upon their initial malocclusion, compliant and preferences: VFR; BR; and RPR. The primary outcome was Little’s Irregularity Index (LII). Other stability parameters, including arch length (AL), inter-canine width (ICW) and inter-molar width (IMW), were also assessed immediately after debonding (T0) and 12 months (T2) after debonding. In addition, survival time, and calculus index and gingival index (GI) were assessed. Results: LII showed a significant difference ( P = 0.00) between the groups and was increased in the VFR group (0.18 ± 0.22 mm) compared to the BR (0.03 ± 0.05 mm) and RPR (0.01 ± 0.03 mm) groups but was not clinically significant. The mean survival time of maxillary retainers was longest for the RPR group (220.63 days; 95% confidence interval [CI] = 194.1–247.16) but there was no significant difference between the three groups ( P = 0.43). The mean survival time of mandibular retainers was higher and the same for the VFR and RPR groups (240 days; 95% CI = 240–240) and there was no significant difference between the three groups ( P = 0.38). The calculus index score ( P = 0.00) was statistically significant between the groups, with an increased score for the BR group (0.33 ± 0.27) compared to the VFR (0.07 ± 0.16) and RPR (0.13 ± 0.22) groups. Similarly, the GI score ( P = 0.02) was statistically significant between the groups and was increased in the BR group (0.01 ± 0.19) compared to the VFR (−0.15 ± 0.18) and RPR (−0.06 ± 0.15) groups. The increase in calculus index and GI scores for the BR group were not clinically significant. Conclusion: There were no clinically significant differences between the three retainer groups in terms of stability, periodontal health and time to failure.