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.

评估下颌第三磨牙 (M3M) 阻生模式与其引起的病理的关联。在这项研究中，对转诊至上海徐汇区中心的 262 名患者（432 名受影响的 M3M）进行了回顾。病理包括冠周炎、下颌第二磨牙 (M2M) 龋齿和 M2M 远端牙周病理。检查了 M3M 的嵌塞模式和病理，同时评估了手术后的 M2M 结果。采用χ ²检验分析数据，p值<0.05被认为有统计学意义。冠周炎是所有患者的主要症状，而老年患者发生 M2M 远端龋齿和牙周病变的倾向增加。软组织阻生牙和垂直成角牙与冠周炎更相关（p  < 0.05）；深度较浅的近中角阻生牙发生 M2Ms 远端龋齿的风险更大 ( p  < 0.05)；相对较深位置的近中成角和水平阻生牙更有可能引起 M2Ms 远端牙周病变 ( p  < 0.05)。应考虑拔除垂直成角的软组织阻生牙，而可延迟拔除近中和水平成角或骨性阻生牙。