Introduction: The peer assessment rating (PAR) index was used to self-audit 4 years of completed pre-adjusted edgewise appliance cases treated by a single orthodontist in a government clinic. The objectives of this study were to evaluate orthodontic treatment standards and factors which may influence treatment outcomes and treatment time.
Methodology: Pre and post-treatment study models were scored using the PAR index by the author. 17 models were re-examined for intra-examiner reliability using intra-class correlation coefficient (ICC). ICC was excellent for pretreatment (0.96), post-treatment (0.98) and reduction in PAR (0.96) scores.
Results: There were 173 cases (51 males; 122 females) with mean age 17.6 (SD 5.75) years. Mean treatment time was 18.6 (SD 6.47) months with range between 5-40 months. There was no statistically significant difference between one-arch and two-arch cases and between routine and compromised cases. Treatment time in extraction cases (mean 19.5, SD 6.17) was significantly different (p=0.000) compared with non-extraction cases (mean 11.6, SD 4.10) although this accounted for 15% of the variation only (r=0.388). 76.3% cases were ‘greatly improved’, 22.0% ‘improved’ and 1.7% ‘worst/ no different’. Mean pretreatment, post-treatment and reduction in PAR score was 34.1(SD 9.68), 6.4 (SD 6.84) and 27.9 (SD 9.69) respectively. Mean percentage PAR score reduction was 82.0% (SD 1.96). Pretreatment (p=0.000), post-treatment (p=0.000) and reduction (p=0.489) in PAR scores was significantly different between routine and compromised cases. There was significant difference (p=0.000) between category of improvement and pretreatment scores but not with treatment time.
Conclusion: Severe malocclusions had larger reduction in PAR scores and required longer treatment time. Extraction cases took longer to complete and routine cases had better outcomes than compromised cases with severe skeletal discrepancy.