Comparative assessment of the survival, stability and occlusal settling between two types of thermoplastic retainers: a prospective clinical trial

Introduction A controlled clinical trial was undertaken to compare the effectiveness of Vivera (R) and Duran (R) retainers with regard to the survival, stability and occlusal settling over the first 6 months of retention following the completion of clear aligner treatment. Methods Consenting participants who met the inclusion criteria were recruited from a single, metropolitan Melbourne orthodontic practice. The participants were divided according to their retainer type, Vivera (R) (n = 10) or Duran (R) (n = 14). Each retainer type was fabricated to a standardised design. Intra-oral scans were taken at the time of debond (T-0), at 3 months (T-2) and at 6 months (T-3). The participants wore their retainers full-time for the first 3 months and part-time for the remaining 3 months. The retainers were inspected at each review for damage that required replacement and failures were recorded in 'days from insert'. Patient reported failures were also recorded. Intra-oral scans were assessed for changes in incisor irregularity and the number of occlusal contacts and comparisons between the two retainer groups were investigated. The impact of full-time and part-time wear on occlusal settling was also assessed for each retainer type. Results Vivera (R) retainers showed a greater survival time in comparison to Duran (R) retainers, as no Vivera (R) failures were observed over the initial 6 months of retention. Both retainer groups showed similar results related to incisor stability and occlusal settling. Part-time wear resulted in increased posterior settling for both retainer types. Conclusion Vivera (R) retainers were as clinically effective as the Duran (R) retainer but exhibit a significantly higher survival rate. Part-time wear of full-coverage thermoplastic retainers appears to increase posterior settling.