Evaluation of the dental effects of a modified Pendulum appliance

Non-compliant molar distalization mechanics are a common feature in contemporary orthodontics that still deserves further study. Objectives: to evaluate the magnitude of changes in distal crown tipping and anchorage loss by the incorporation of uprighting bends into the distalizing spring arms of a pendulum appliance from the beginning of treatment. Methods: Cephalometric radiographs and dental casts were obtained on 22 patients (mean age 12 yr 11 mo). All Patients met the following criteria: use of the modified pendulum appliance (15-25° uprighting bends incorporated from the beginning of treatment) as the first phase of orthodontic treatment for distalization of the maxillary first molars, maxillary first and second bicuspids erupted or partially erupted, non-extraction treatment plan, good quality cephalometric radiographs, no other molar distalization procedure performed during the observation period (average treatment time 7 mo 2 weeks +/- 4 weeks). Student t tests and Pearson’s correlation test were conducted to analyze the data. Results: Cephalometric and model data were obtained for each one of the patients before and after appliance removal. The following results were obtained: excessive distal crown tipping of the maxillary first molars was reduced to only 5 degrees (p<0.0001) by the modification introduced into the appliance. Anterior anchorage loss and increments in overjet and overbite were no greater that comparable previously published data. Conclusions: Stability and prevention of anchorage loss in the posterior segment for subsequent treatment with fixed appliances is paramount. It is therefore, not unreasonable to assume that by incorporating uprighting bends into the design of the pendulum appliance from the beginning of treatment, we can greatly minimize excessive distal crown tipping and facilitate future fixed orthodontic treatment. The more bodily the molars are moved distally (as opposed to tipping), the less posterior anchorage loss.