To evaluate the associations of impaction patterns of mandibular third molars (M3Ms) with pathologies caused by them. In this study, 262 patients with 432 impacted M3Ms who referred in Shanghai Xuhui District Center were reviewed. The pathologies include pericoronitis, mandibular second molar (M2M) caries, and M2M distal periodontal pathology. The impaction patterns of M3Ms and the pathologies were examined, while the M2M outcomes after surgeries were evaluated. A χ2 test was used to analyze the data, with a p value of <0.05 being considered statistically significant. Pericoronitis was the major symptom in all patients, whereas the propensities of M2M distal caries and periodontal pathologies increased in older patients. Soft tissue impacted and vertically angulated teeth were more associated with pericoronitis ( p < 0.05); mesio-angular impacted teeth in less deep positions had greater risks of M2Ms distal caries ( p < 0.05); mesio-angular and horizontal impacted teeth in relative deep positions were more likely to cause M2Ms distal periodontal pathologies ( p < 0.05). Extractions of soft tissue impacted teeth in vertical angulations should be considered, while removals of mesially and horizontally angulated or bony impacted teeth could be delayed.

Background To evaluate the associations of impaction patterns of mandibular third molars (M3Ms) with pathologies caused by them. Methods In this study, 262 patients with 432 impacted M3Ms were included. The pathologies include pericoronitis, mandibular second molar (M2M) caries, and M2M distal periodontal pathology. The impaction patterns of M3Ms and the pathologies were examined, and the M2Ms outcomes after the surgeries were evaluated. χ2 test was used to analyze the data and a P value of <0.05 was considered statistically significant. Results Pericoronitis was the major symptom in all patients, whereas the propensities of M2M distal caries and periodontal pathologies increased in older patients. Soft tissue impacted and vertically angulated teeth were more associated with the pericoronitis (p <0.05); Mesio-angular impacted teeth in less deep positions had greater risks of M2Ms distal caries (p <0.05); Mesio-angular and horizontal impacted teeth in relative deep positions were more likely to cause M2Ms distal periodontal pathologies (p <0.05). Conclusions Extractions of soft tissue impacted teeth in vertical angulations should be considered. While removals of mesially and horizontally angulated or bony impacted teeth could be delayed.