Effect of premolar extractions on occlusal contacts and chewing efficiency: A case-control study

This study aimed to evaluate the effect of premolar extractions on masticatory performance and occlusal contact areas in patients who underwent orthodontic treatment with or without premolar extractions.

Seventy-five patients (aged 18-40 years), who had completed their treatment ≥6 months prior, were divided into groups: maxillary 2-premolar extractions (n = 22), 4-premolar extractions (n = 22), and nonextraction (n = 31). A control group of 31 individuals with no history of orthodontic treatment was also included. Posttreatment quality was assessed using plaster models evaluated according to the American Board of Orthodontics objective grading system (ABO-OGS). Intraoral scans obtained with the iTero Element 5D scanner (Align Technologies, San Jose, Calif) were analyzed in OrthoCAD (version 5.9.1.50; Align Technology, San Jose, Calif) to determine posterior occlusal contact areas (near and tight) at maximum intercuspation. Masticatory performance was evaluated using a gum chewing test. The chewed samples were scanned with a color desktop scanner, and color mixing was analyzed using ViewGum software (version 1.4; dHAL Kifissia, Greece).

Significant differences were found between groups in terms of age, gender, ABO-OGS scores, and occlusal contact areas (P <0.05), whereas masticatory performance did not differ significantly (P >0.05). No significant correlations were found between ABO-OGS scores and occlusal contact areas, masticatory performance, or the time since treatment the lasted. Similarly, masticatory performance showed no significant correlations with contact areas and posttreatment time. A positive correlation was found between occlusal contact areas and time since treatment lasted (near contact: r = 0.440; tight contact: r = 0.429).

Although differences in occlusal contact areas were observed, premolar extraction did not appear to negatively affect masticatory performance.