A retrospective study on the reasons for second molar extraction.

Objective: The reasons for second molar extraction include endodontics, periodontal disease, and impacted third molars. This retrospective study analyzed medical records and image examinations of patients who underwent second molar extraction to clarify the proportional distribution of different causes. Materials and methods: Medical records and imaging data of patients who underwent second molar extraction between January 1, 2020 and December 31, 2022 were systematically collected. Two senior dentists analyzed and recorded patient demographics, clinical diagnoses, and extraction causes. Inter-rater consistency was verified using Kappa testing. Results: A total of 1,818 valid cases were included with a mean age of 52.9 years (male: 864 cases; female: 954 cases). Endodontic factors accounted for 1,045 s molar extractions (57.43%) and periodontal factors contributed to 588 extractions (32.40%), both showing significant age-related correlations (p < 0.05). Impacted third molar factors led to 185 extractions (10.01%) with no significant age-dependent association (p > 0.05). Impacted third molars contributed to 13.97% of mandibular second molar extractions, while only 5.73% to maxillary second molar extractions. Conclusions: The main reasons for extracting second molars were endodontic factors, followed by periodontal factors, and impacted third molars. Advanced age was significantly associated with increased extraction risks attributable to both endodontic and periodontal disease. Impacted third molar-related factors accounted for a larger proportion in cases of mandibular second molar extractions.