摘要目的:利用锥形束CT（CBCT）诊断37双生牙1例，并对其鉴别诊断、发生机制及CBCT在口腔颌面部疾病诊断中的价值进行分析。方法:对镇江市口腔医院2019年3月就诊的1例患者根据口腔临床检查、CBCT影像学检查进行诊断，对多生牙尖、融合牙、双生牙、结合牙等几种牙齿形态异常疾病的特点及鉴别要点结合文献进行分析。结果:CBCT检查见下颌牙列牙齿数目正常，37 牙根周围存在大面积低密度透射区；三维重建后见疑似多生牙与37牙根相融合；矢状面显示疑似多生牙位于37颊侧；轴向位置显示髓室底可见有三个明显的根管口；两者的牙本质是连通的；该疑似多生牙内有独立的牙髓腔，有清晰的根管，且在根中段与37远中根管融合成一个根管，矢状面显示呈“Y”型。CBCT显示37牙是一个融合根。结合口腔临床检查，确诊为左下颌第二磨牙双生牙。结论:CBCT是口腔疾病辅助检查非常重要的手段之一，在诊断牙齿形态异常上有显著的优势，可帮助临床医师作出正确的诊断、选择恰当的治疗方案，有一定的临床意义和创新性。

abstractsObjective:To report a case of germinated teeth of the left mandibular second molar diagnosed by cone-beam CT (CBCT), and to investigate its differential diagnosis, pathogenesis, and the application value of CBCT in the diagnosis of oral and maxillofacial diseases.Methods:One case of germinated teeth of the left mandibular second molar diagnosed according to oral general examination ad CBCT findings in Zhenjiang Stomatological Hospital, China in March, 2019 was included in this study. The characteristics and differential points of supernumerary cusp, fused teeth, geminated teeth and concresence of teeth were analyzed based on literatures.Results:CBCT examination showed that the number of mandibular dentition teeth was normal, there was a large area of low-density transmission area around the root of the left mandibular second molar. Three-dimensional reconstruction results revealed that the suspected supernumerary teeth were fused with the root of the left mandibular second molar. Sagittal projections showed that the suspected supernumerary teeth were located in the buccal side of the left mandibular second molar. Axial projections showed three separate root canal orifices at the level of pulp chamber floor, and the dentin of the two was connected. The suspected supernumerary teeth had an independent pulp cavity and a clear root canal, and fused with the distal root canal of the left mandibular second molar in the middle of the root to form a root canal. A "Y"-shaped structure was displayed on the sagittal projections. CBCT showed that the left mandibular second molar was a fused root. Based on oral clinical examination, the left mandibular second molar was confirmed to be a germinated tooth.Conclusion:CBCT is one of the most important means of oral auxiliary examination. It has significant advantages in the diagnosis of tooth abnormalities. It can help clinicians to make correct diagnosis and choose the appropriate treatment scheme. It has certain clinical significance and innovation.