Comparison of Extraction and Non-extraction Orthodontic Treatment using the Objective Grading System

Statement of Problem: The extraction versus non-extraction debate is almost as old as the advent of orthodontic practice and up to now, this dilemma remains. Recently, the American Board of Orthodontics (ABO) has developed a method by the name of Objective Grading System (OGS) in order to evaluate the results of orthodontic treatment. The aim of the present study was to evaluate and compare the patients’ final occlusion after extraction and non-extraction therapy using the OGS. Sixty sex-matched cases with an age range of 15-20 year old were selected and evenly divided into 2 groups as follows: 30 patients were treated by extraction of 4 premolars and 30 received a non-extraction treatment. All patients had class 1 malocclusion before treatment and were well treated with the standard edgewise system in a private clinic. With the aid of an ABO measuring gauge, 8 parameters of occlusion were measured 3 times, each. Reproducibility of the measurements were evaluated by use of the Phi correlation coefficient and the total OGS scores between the two groups were compared using Levene`s test and Student t- test with the significant level at 95%. The mean OSG scores were significantly more negative in the non–extraction group (-6.58  8.63) as compared to the extraction group (-28.65  6.67, p < 0.004). Acceptable occlusion was observed in 73.4% of the extraction and 43.4% of the non-extraction cases. In this study according to the ABO grading system (OGS), the final occlusion of patients treated with extraction seemed more acceptable than non-extracted cases.