Askari, Marjan; Williams, Robert E., D.M.D., M.A.; Barron, Thomas (2012)
      Introduction: This is a pilot study utilizing CBCT to compare cases treated with either the Damon System or conventional mechanics. The primary purpose of this study was to evaluate changes in dental and skeletal arch width and length. The secondary purpose was to evaluate differences between the three CBCT views (3D coordinate, sectional, and volume views). Methods: Eleven Patients (18 years of age or older) with moderate to severe crowding who had both pre- and post-treatment CBCTs and were treated with non-extraction, either with conventional edgewise appliances or with a self-ligating Damon system were retrospectively selected from two orthodontic practices. The arch length, inter-occlusal, inter-apical, inter-buccal and inter-lingual alveolar crest arch widths, and the bucco-lingual angulation for canine, premolars and first molars were measured. Different CBCT views were evaluated by first measuring the interocclusal distances of the respective teeth in the coronal section and the volume views. These measurements were compared with those gathered previously using the 3D coordinate system. A paired t-test, an independent t-test, and an ANOVA were used for statistical analysis. Results: Both non-extraction treatment modalities resulted in interocclusal arch width expansion in both the maxilla and the mandible. The overall expansion of arches in the Damon treated cases, was statistically greater than in the conventionally treated cases. Maxillary and mandibular arch lengths were increased but not significantly in both groups. There were no statistically significant differences between the three different CBCT views. Conclusion: Both the Damon and conventional systems resulted in increased arch width and length, but the Damon system caused significantly more overall arch expansion. There was less tipping of the teeth during arch expansion in the conventional system. The ratio of crown to root movement in the conventional system versus Damon group in the maxilla was approximately 1:1 versus 3:1 and in the mandible 3.6:1 versus 6:1. Using the 3D coordinate systems to evaluate the interocclusal points in CBCT yields the most exact measurements but the volume and sectional views provide accurate measurements of arch length and arch width.