Effectiveness of modifications to preadjusted appliance prescriptions based on racial dental characteristics assessed by the ABO Cast-Radiograph Evaluation: A propensity score matching study

BACKGROUND: Because racial discrepancies in dental characteristics are known to exist, designing preadjusted appliances according to racial normal occlusion data would be expected to improve treatment results. However, whether modifications based on racial characteristics can improve treatment outcomes in the clinic remains to be investigated. METHODS: To study the influence of prescription type on treatment outcomes, 91 patients treated with Chinese or Roth prescription appliances were selected as an initial sample. Two groups of patients were selected by propensity score matching (1:1) to limit the effects of confounding factors, including age, sex, case complexity, and extraction plan. Discrepancy Index and cervical vertebral maturation values were used to quantify case complexity and patient age, respectively. After matching, the final sample of 60 patients consisted of two groups of 30 patients each: group 1 had been treated with a Chinese prescription appliance and group 2 had been treated with a Roth prescription appliance. ABO casts and radiograph evaluation (CR-Eval) and lateral cephalograms were utilized to compare the treatment outcomes of the two groups. RESULTS: The total ABO scores of groups 1 and 2 were 22.03 and 23.87, respectively. There were no significant differences between the two groups in total ABO score or in seven other sub-scores; however, there was a significant difference between the two groups in mandibular canine alignment score. CONCLUSIONS: There are no significant differences in overall treatment outcomes between the Chinese and Roth prescription appliances. The Chinese prescription yielded better alignment results in the mandibular canine for Chinese patients.