Postgraduate Program in Dentistry, Estácio de Sá University, Rio de Janeiro, Brazil.
Postgraduate Program in Dental Sciences, Christus University, Fortaleza, Brazil.
J Endod. 2019 May;45(5):538-542.e2. doi: 10.1016/j.joen.2019.01.004. Epub 2019 Mar 23.
Accidental damage to the inferior alveolar nerve is of concern during endodontic treatment of the posterior mandible teeth, and a careful evaluation of the relationship between the apices and the mandibular canal (MC) is mandatory to prevent iatrogenic complications. This study aimed to assess the distance between the root apices of posterior teeth and the MC and the bone density in such areas.
One thousand retrospective cone-beam computed tomographic scans were randomly selected from a private oral radiologic clinic database. The images were acquired with a limited field of view and analyzed by 2 evaluators who measured the shortest distance between the root apices and the upper cortical bone of the MC using Dental Slice software (Bioparts Biomedical Prototyping, Brasília, DF, Brazil). In addition, bone density was estimated using the tool "profile line of Hounsfield" and expressed in Hounsfield units.
The distal root of the right second molars was the closest to the MC (mean = 3.41 mm), and the right first premolar root was the farthest from the MC (mean = 5.87 mm), respectively. The root apices were closer to the MC in women than in men (P < .05). In 1.79% of the cases, the roots were in contact or invading the MC, whereas 8.35% of the root apices were close to the MC (<1.00 mm), and 89.85% were distant from the MC (>1.00 mm). In 85.55% of the cases, the bone was dense.
The results suggest that the risk of damage to the inferior alveolar nerve is higher for second molars, especially in female patients. The higher density of the adjacent bone may act as a protective factor against nerve damage arising from endodontic procedures.
在下颌后牙根管治疗过程中，下齿槽神经意外损伤令人担忧，因此必须仔细评估根尖与下颌管（MC）之间的关系，以防止医源性并发症。本研究旨在评估后牙根尖与 MC 之间的距离以及这些区域的骨密度。
从一家私人口腔放射诊所的数据库中随机选择了 1000 例回顾性锥形束 CT 扫描。使用有限视野采集图像，由 2 名评估员使用 Dental Slice 软件（巴西巴西利亚的 Bioparts Biomedical Prototyping）测量根尖与 MC 上皮质骨之间的最短距离来分析图像。此外，使用“Hounsfield 轮廓线”工具估计骨密度，并以亨氏单位表示。
右侧第二磨牙的远中根最接近 MC（平均值=3.41mm），而右侧第一前磨牙的根最远离 MC（平均值=5.87mm）。女性的根尖比男性更接近 MC（P<.05）。在 1.79%的病例中，根尖与 MC 接触或侵犯 MC，而 8.35%的根尖接近 MC（<1.00mm），89.85%的根尖远离 MC（>1.00mm）。在 85.55%的病例中，骨密度高。
结果表明，第二磨牙，尤其是女性患者，下牙槽神经损伤的风险更高。邻近骨密度较高可能是根管治疗引起神经损伤的保护因素。
