Frequency of Orthodontic Extractions and Malocclusion-Related Factors in a University Setting During a 25-Year Period

Objectives :

The decision regarding orthodontic tooth extraction or dental arch expansion is an important yet challenging topic in orthodontic treatment planning. However, studies in this respect are limited In Iran. This study aimed to assess the frequency of orthodontic tooth extractions and the role of malocclusion-related factors that affect the frequency of orthodontic extractions in a university setting during 25 years.

Methods :

This descriptive retrospective study evaluated 1,222 records of patients who underwent fixed orthodontic treatment in Shahid Beheshti Dental School from 1994 to 2018. The frequency of tooth extraction, type of malocclusion, and age and gender of patients were analyzed by the Chi-square test. The correlation of quantitative and qualitative variables related to occlusion (overjet, overbite, space discrepancy, cross-bite, A point–nasion–B point angle, mandibular plane angle, canine relationship, molar relationship, and the Curve of Spee) with orthodontic extraction was analyzed by the binary logistic regression. All statistical analyses were performed by SPSS version 21.

Results :

The frequency of orthodontic extraction decreased from 1994 (74.5%) to 2018 (41.6%). The highest frequency of orthodontic extraction (60%) occurred in class II division I malocclusion cases. Frequency of orthodontic extraction in the age group of 12-20 years was significantly higher than in other age groups (P=0.003). The odds of orthodontic extraction increased by an increase in overjet (P=0.036) and in class II malocclusion cases (P=0.05), and decreased by an increase in overbite (P=0.020).

Conclusion:

 Tendency to orthodontic extraction has decreased in contemporary orthodontics in Shahid Beheshti Dental School. In addition to the degree of dental crowding, the decision regarding orthodontic extraction also depended on overjet, overbite, and type of malocclusion.