Post-retention assessment of the transverse dimension in Class I crowding alignment utilizing the Damon System-A pilot study

This study was conducted to evaluate the short-term post-retention stability of the transverse dimension in patients with Class I malocclusion treated with the Damon System. Nine females and seven males with average pre-treatment crowding, −1.9 ± 2.1 mm in the maxilla and −2.2 ± 1.6 mm in the mandible were evaluated. Subjects were 12.4 ± 1.5 years at pre-treatment, 15.3 ± 0.9 years at post-treatment, and 19.7 ± 1.2 years at post-retention. They were retained for an average of 2.1 ± 0.9 years, followed by no retention for an average of 2.3 ± 0.9 years. Models and cephalograms of all three stages were measured and the data were analyzed in SPSS. Treatment produced statistically significant increases in transverse arch dimensions (maxillary arch 2.0-5.6 mm and mandibular arch 2.4-4.6 mm), all of which were greater than expected for untreated controls. There were significant post-retention decreases in arch width, often less than expected for untreated controls. Relapse was less than 35.4% and 26% in the maxillary and mandibular arch, respectively. In conclusion, Damon treatment produced significant net gains in arch width, especially in the mandibular arch. Occlusal settling occurred following active treatment causing significant improvement in post-treatment outcomes.