Objective:

The aim of this study was to compare the clinical effectiveness of Essix and Hawley retainers during the retention period.

Methods:

A total of 30 subjects whose fixed orthodontic treatment results were evaluated according to the American Board of Orthodontics Phase III Objective Grading system were included in this study. After the removal of orthodontic attachments, the study participants were equally divided into two retention protocols: upper-lower Essix and upper-lower Hawley. The subjects were instructed to wear their retainers full time for 6 months, except during meals, and during nights only for 6 months. The clinical effectiveness of the retainers was evaluated according to the overjet, overbite, maxillary, and mandibular intercanine widths, intermolar widths, arch lengths, irregularity indexes, and lateral cephalometric measurements. All dental model and lateral cephalometric measurements were performed by the same investigator during three periods: pre-treatment, post-treatment, and post-retention.

Results:

The overjet, overbite, maxillary, and mandibular intercanine widths; intermolar widths; and arch lengths and lateral cephalometric measurements were not statistically significantly different between the groups and identified time periods. Although the maxillary and mandibular irregularity indexes increased from the post-treatment to post-retention periods, the difference was not statistically significant. Pre-treatment, post-treatment, and post-retention lateral cephalometric measurements were not statistically significantly different between and within the groups.

Conclusion:

According to the results of a repeated-measures analysis of variance with two factors, and although an increase was found in the maxillary and mandibular irregularity indexes, the clinical effectiveness of Essix and Hawley retainers was found to be similar during the retention period.

Keywords: Orthodontic treatment, retention, Essix, Hawley, relapse