The high interindividual variations of 'p' and 't' render the use of reference values problematic. Contrary to other craniofacial structures, neither age-related changes nor sexual dimorphism were found for 'p' and 't'. Any associations to antero-posterior cephalometric characteristics seem low.

INTRODUCTION The aim of this study was to compare treatment outcomes in university vs private practice settings with Class I patients using the American Board of Orthodontics Objective Grading System. METHODS A parent sample of 580 Class I patients treated with and without extractions of 4 first premolars was subjected to discriminant analysis to identify a borderline spectrum of 66 patients regarding the extraction modality. Of these patients, 34 were treated in private orthodontic practices, and 32 were treated in a university graduate orthodontic clinic. The treatment outcomes were evaluated using the 8 variables of the American Board of Orthodontics Objective Grading System. RESULTS The total scores ranged from 10 to 47 (mean, 25.44; SD, 9.8) for the university group and from 14 to 45 (mean, 25.94; SD, 7.7) for the private practice group. The university group achieved better scores for the variables of buccolingual inclination (mean difference, 2.28; 95% confidence interval [CI], 0.59, 3.98; P = 0.01) and marginal ridges (mean difference, 1.32; 95% CI, 0.28, 2.36; P = 0.01), and the private practice group achieved a better score for the variable of root angulation (mean difference, -0.65; 95% CI, -1.26, -0.03; P = 0.04). However, no statistically intergroup differences were found between the total American Board of Orthodontics Objective Grading System scores (mean difference, -0.5; 95% CI, -3.82, 4.82; P = 0.82). CONCLUSIONS Patients can receive similar quality of orthodontic treatment in a private practice and a university clinic. The orthodontists in the private practices were more successful in angulating the roots properly, whereas the orthodontic residents accomplished better torque control of the posterior segments and better marginal ridges. ABSTRACT Aim:The aims of this study were to compare treatment outcomes in university vs private practice, Class I patients, by using the American Board of Orthodontics objective grading system (ABO-OGS). Materials and Method:A parent sample of 580 Class I patients treated with or without extractions of four first premolars was subjected to discriminant analysis in order to identify a borderline spectrum of 66 patients regarding to the extraction modality. Of these patients, 34were treated in private orthodontic practices and 32 in a university graduate orthodontic clinic. The treatment outcomes were evaluated using the 8 variables of the ABO-OGS. Results:The total score ranged from 10 to 47 (mean, 25.44; SD 9.8) Conclusions:Patients can receive similar quality of orthodontic treatment in a private practice or in a university clinic. Orthodontists in a private practice were more successful in angulating the roots properly whereas orthodontic residents accomplished better torque control of the posterior segments and better marginal ridges.

No abstract