Skeletal and dental effects of tooth-borne versus hybrid devices for mandibular symphyseal distraction osteogenesis

Objective: To evaluate and compare, retrospectively, the skeletal and dental effects of mandibular symphyseal distraction osteogenesis (MSDO) achieved through the use of tooth-borne versus hybrid distractors.Materials and Methods:Pretreatment (T1), predistraction (T2), postdistraction (T3), and posttreatment (T4) orthodontic records were collected and analyzed for 47 patients (20 tooth-borne, 27 hybrid). At each time point, records included intraoral photographs, study models, postero-anterior cephalometric radiographs, and lateral cephalometric radiographs. Submental vertex radiographs were taken at T2, T3, and T4. Changes in a total of 18 measurements were analyzed to compare patients undergoing tooth-borne versus hybrid distraction.Results:The cumulative effects of orthodontics and MSDO produced similar gains in measured arch widths, with a decreased irregularity index in both groups (P > .05). However, there were differences in the timing during which the expansion was achieved. The hybrid distractor group gained space during the distraction phase of treatment. The tooth-borne group showed greater gains during pre- and postdistraction orthodontics. Comparisons of intercanine and interbone marker widths demonstrated a more parallel separation of bone during distraction with the hybrid distractor (P < .001). Distraction with the tooth-borne distractor was disproportionate, with greater separation of the canines in alveolar bone than of the bone markers in basal bone. During postdistraction orthodontics, the tooth-borne distractor group showed statistically greater increases in measurements.Conclusion:Both skeletal and dental expansion was achieved with both appliances. Greater skeletal expansion was achieved with a hybrid distractor. Greater dental expansion was achieved with a tooth-borne distractor.