Evaluation of Adjacent Tooth Movement Following Compromised First Permanent Molar Extraction in Mixed Dentition

Abstract

This study aimed to evaluate the vertical, horizontal, and angular changes in the second premolars and molars following extraction of the first permanent molar (FPM) in growing patients. A panoramic radiographic analysis was conducted on 38 mixed dentition cases from 32 patients treated between 2013 and 2022 at the Department of Pediatric Dentistry, Pusan National University Dental Hospital. In the maxilla, second molars on the extraction side exhibited horizontal mesial movement of 5.9 mm (mesial crown) and 4.5 mm (distal crown), along with vertical eruption of 7.4 mm and 10.0 mm at the mesial and distal cemento-enamel junction (CEJ). Angular changes in the maxillary second molar averaged 23.9° during mesial tipping. The mean angle of the distal tip of the second premolars was 5.5°. In the mandible, second molars demonstrated greater horizontal mesial movement (10.1 mm mesial, 10.4 mm distal) and less vertical eruption than that in the maxilla (4.1 mm mesial, 3.5 mm distal at the CEJ). No significant angular changes were observed in the mandibular second molars, whereas the second premolars were tipped distally by 8.7°. Interarch comparisons revealed significant mesial movement of the second molars in the mandible, and greater vertical eruption and angular changes in the maxilla. The mesial movement of the mandibular second molar exhibited a statistically significant inverse correlation with the dental age at extraction. These findings provide quantitative data for treatment planning following early FPM extraction in mixed dentition.