An assessment of extraction versus nonextraction orthodontic treatment using the peer assessment rating (PAR) index

Abstract

The extraction of teeth for orthodontic purposes has always been a controversial subject in the specialty. The purpose of this study was to assess the outcome of orthodontic treatment in 100 patients treated with the extraction of four premolars and compare it with the outcome of 100 patients treated without extractions, using the peer assessment rating (PAR) index. Records were selected from 1,198 consecutively completed cases treated by a single provider (MGH) between 1981 and 1995. We chose the first 100 finished patients in each group (extraction and nonextraction) who were under the age of 16 and had no deciduous teeth at the start of treatment. The results of this study show that average treatment time for the extraction group was 29.7+/-6.1 months compared with 26.0+/-7.2 months for the nonextraction group. The extraction group had significantly higher initial PAR scores (T1-PAR ext = 30.01+/-8.20 vs. T1 PAR nonext = 25.21+/-8.55), with greater initial maxillary anterior crowding (PAR ext value = 6.05+/-3.85 vs. PAR nonext value = 4.21+/-2.90) and greater initial overjet (PAR ext value = 1.82+/-1.01 vs. PAR nonext value 1.28+/-1.04). All pretreatment differences were significant at the p < or = 0.0001 level. Although significantly different at the beginning of treatment, both groups were statistically identical at the end (PAR T2 ext = 6.18 + 3.04% reduction = 79.4% compared with PAR T2 nonext = 5.64 + 3.08% reduction = 77.6%). In conclusion, the results demonstrate that, given an additional 3 months of treatment, it is possible for an orthodontist to produce dento-occlusal relationships in extraction patients that are as good as those achieved in nonextraction cases.