Orthodontic Extraction Rates by Age at First Visit

Objectives: To sample the distribution of mixed dentition and adult dentition orthodontic extraction rates of patients in various age groups within the practice of a board certified orthodontist. Methods: A random sample of 396 patients was drawn retrospectively from post-treatment records in the private practice of a single academic orthodontist. 6 cut points for chronological age at first visit were defined using criteria of clinical relevance. Patients were categorized by age group and dentition stage (mixed or permanent) at first visit. Mixed dentition patients were further sub-grouped into those treated immediately and those whose treatment the clinician deferred until the eruption of the full permanent dentition. The incidence of extraction within each category was tallied. Results: In this practice, which is strongly oriented toward early treatment, 1/3 of all patients were first seen between the ages of 7.5 and 9.5 years and 216 patients (55% of the sample) presented in the mixed dentition. Of these, 138 received early treatment and 78 (36%) were treated in the permanent dentition. Extraction rates for patients who were first seen before the age of 9.5 were 19% but rose to more than 40% among patients whose first visit occurred after their 12^th birthday (Statistical significance by Chi², P<0.001).

Conclusion: In this practice, the ability to evaluate patients early appears to be very strongly associated with a reduced number of extractions in the permanent dentition.