目的 通过对锥形束CT（CBCT）图像进行回顾性研究，探究北京地区人群下颌第一磨牙独立远中舌根的发生率以及远中根分叉区的形态特征，为牙周诊疗提供依据。 方法 选取有双侧下颌第一磨牙存在的CBCT资料共401例，记录患者性别、是否存在独立远中舌根，统计其发生率。在存在远中根分叉的下颌第一磨牙CBCT图像中，测量并记录远中根分叉的根柱长度、远中根分叉开口的位置以及远中根分叉开口的角度。 结果 在401例CBCT图像资料中，下颌第一磨牙独立远中舌根的发生率在个体水平为33.2%，牙水平为26.8%。不同性别发生率无差异，右侧发生率更高。远中根柱长度为4.15 mm±1.02 mm，位置均偏舌侧，远中根分叉开口的角度为65.56°±11.56°，97.2%的远中根分叉开口较颊舌侧根分叉开口更偏根方。 结论 北京地区人群有较高的下颌第一磨牙远中舌根的发生率。下颌第一磨牙的远中根柱较颊舌侧根柱更长，根分叉开口位置偏舌侧，分叉角度较大。了解远中根分叉的形态有利于临床医师制定完善的诊疗方案。

Objective This retrospective study explored the incidence of independent distal-lingual root (DLR) in mandibular first molars and the morphologic features of distal furcations through cone beam computed tomography (CBCT) in Beijing population. Methods A total of 401 CBCT images of both mandibular first molars existed were included. The sex of the patients, the incidence of DLR, the distal root trunk length (DRT), the locations of distal furcation entrance (DFE), and the separation angle of distal furcation (ADF) were recorded. Results The incidence rates of DLR were 33.2% on the subject level and 26.8% on the tooth level. The incidence of DLR was not different between genders but was higher on the right sides. The DRT values were 4.15 mm±1.02 mm. The ADF was 65.56°±11.56°. The DFE was located lingually, and 97.2% DFE was located more apically than buccal/lingual furcations. Conclusion A high incidence of DLR was found in the Beijing population. The DRT was longer than buccal and lingual sites. The DFE was located lingually with a wide separation. Understanding the morphological features of distal furcation can help clinicians to make proper treatment plans.