Predoctoral student, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia.
Senior Lecturer, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia.
J Prosthet Dent. 2018 Aug;120(2):210-213. doi: 10.1016/j.prosdent.2017.10.019. Epub 2018 Mar 15.
The inferior alveolar nerve (IAN) frequently loops backward before exiting from the mental foramen and spreads several millimeters medially to the foramen. Implant placement in this area may damage the nerve if the anterior loop area is not carefully identified in a radiographic or computed tomography (CT) evaluation.
The purpose of this observational study was to measure the prevalence of the presence of the anterior loop and to estimate sex and ethnicity-related variations in anterior loop length in the Malaysian population.
A total of 100 cone beam computed tomography (CBCT) Digital Imaging and Communications in Medicine (DICOM) files were selected from a pool of 810 ongoing or completed patients in 3 different ethnic groups: Malay (33), Indian (33), and Chinese (34). The DICOM data were imported into commercial software. The IAN was traced with software along with the anterior loop and part of the incisive nerve. The vertical length of the nerve was estimated from the canal to the opening of the mental foramen from the cross-sectional view and translated to the panoramic view. Measurement was made from this point to the most anterior point of the anterior loop by following the trajectory of the nerve and was repeated on the opposite side. A 2-way mixed analysis of variance (ANOVA) test was carried out to evaluate the sex- and ethnicity-related variations (α=.05).
The anterior loop was present in 94% of the 100 participants. Overall anterior loop length (AnLL) ranged between 0.73 and 7.99 mm with a mean length of 3.69 ±1.75 mm on the left side and 3.85 ±1.73 mm on the right side. Among all participants, no statistically significant differences were found between the left and right sides of the mandible (P=.379). Overall, no significant main effect of ethnicity (P=.869) or sex (P=.576) was found on AnLL measurements. Also, with multiple comparisons, no significant effect was found between each pair of ethnic groups. Men in all 3 ethnic groups had greater AnLL than women.
The anterior loop was present in 94% of the 100 participants among the 3 major ethnic groups of Malaysia. Overall AnLL ranged between 0.73 and 7.99 mm and mean lengths of 3.69 ±1.75 mm on the left side and 3.85 ±1.73 mm on the right side, with no significant ethnicity- or sex-related variations.
下牙槽神经（IAN）在离开颏孔前经常向后弯曲，并向内侧延伸数毫米至孔。如果在影像学或计算机断层扫描（CT）评估中不仔细识别前环区域，在该区域植入可能会损伤神经。
本观察性研究的目的是测量前环存在的发生率，并估计马来西亚人群中前环长度的性别和种族相关差异。
从 3 个不同种族（马来人 33 人、印度人 33 人、中国人 34 人）的 810 名正在进行或已完成的患者中，共选择了 100 个锥形束 CT（CBCT）数字成像和通信（DICOM）文件。将 DICOM 数据导入商业软件。用软件追踪 IAN 及其前环和部分切牙神经。从横断面估计神经的垂直长度，从管腔到颏孔开口，并转换为全景视图。从这个点到前环最前点的测量是通过跟随神经的轨迹进行的，并在对侧重复进行。采用 2 因素混合方差（ANOVA）检验（α=.05）评估性别和种族相关差异。
100 名参与者中，前环存在于 94%的参与者中。总体而言，前环长度（AnLL）在 0.73 至 7.99mm 之间，左侧平均长度为 3.69±1.75mm，右侧平均长度为 3.85±1.73mm。在所有参与者中，下颌骨左侧和右侧之间无统计学差异（P=.379）。总体上，种族（P=.869）或性别（P=.576）对 AnLL 测量无显著主要影响。此外，通过多重比较，在每个种族组之间没有发现显著的影响。所有 3 个种族的男性的 AnLL 均大于女性。
在马来西亚的 3 个主要种族群体中，100 名参与者中有 94%存在前环。总体而言，AnLL 在 0.73 至 7.99mm 之间，左侧平均长度为 3.69±1.75mm，右侧平均长度为 3.85±1.73mm，无显著的种族或性别相关差异。
