An In-Depth Analysis of Borderline Class I Malocclusions in Caucasian Patients at the University of Maryland

Abstract

Problem: To determine if a group of experienced clinicians determines there to be equal numbers of extraction and nonextraction treatments planned when evaluating borderline Class I malocclusions in Caucasian patients, and second, to determine the variables that are most important in the diagnosis and evidence-based treatment planning of these cases. Methods: All Caucasian patients treated in the University of Maryland, Baltimore Orthodontic Graduate Clinic having completed initial orthodontic records over a three-year period were evaluated for the presence of a borderline Class I Malocclusion. Of the initial 180 subjects, 15 were statistically determined to be borderline and were subsequently subjected to analysis by 11 orthodontic faculty members. The cases were then evaluated for those variables determined to be indicative of borderline Class I malocclusions in Caucasian patients based on stepwise forward logistic regression. Results: There was no significant difference between the treatment plan recommended and the 50/50 treatment expected for borderline cases (X2=0.055, p = 0.8153), although extraction treatment was slightly more likely to be chosen by those surveyed (50.9%) than non-extraction treatment (49.1%). As determined through logistic regression, the four most significant variables were the mandibular intercanine measurement and maxillary crowding, (both study model variables), followed by the cephalometric Z-angle and the upper lip to E-plane measurement. Conclusions: The results of the first stage of this study, which evaluated the percentage of extraction and non-extraction cases planned by faculty members when evaluating borderline Class I malocclusions in Caucasian patients, found that there was no significant difference in the percentage of extraction and non- extraction treatments planned The most common extraction pattern was the extraction of all four first bicuspids (44.1%). The results of the second stage of the study identified cephalometric and study model variables that were indicators of borderline Class I malocclusions in Caucasian patients. The four variables with the highest B value significance levels were identified through logistic regression to be the mandibular intercanine width and maxillary arch crowding, followed by the Z-angle and the upper lip to E-plane measurement.