Maglione Michele, Costantinides Fulvia, Bazzocchi Gabriele
MD, DDS, MSc, Associate Professor, Unit of Oral Surgery, School of Dental Sciences, Department of Medical Sciences, Surgery and Health, Trieste, Italy.
DDS, MSC, Adjunct Professor, Unit of Oral Surgery, School of Dental Sciences, Department of Medical Sciences, Surgery and Health, Trieste, Italy.
J Clin Exp Dent. 2015 Apr 1;7(2):e224-31. doi: 10.4317/jced.51984. eCollection 2015 Apr.
Neurological involvement is a serious complication associated to the surgical removal of impacted mandibular third molars and the radiological investigation is the first mandatory step to assess the risk of a possible post-operative injury to the inferior alveolar nerve (IAN). The aim of this study was to introduce a new radiological classification that could be normally used in clinical practice to assess the relationship between an impacted third molar and mandibular canal on cone beam CT (CBCT) images.
CBCT images of 80 patients (133 mandibular third molars) were independently studied by three members of the surgical team to draw a classification that could describe all the possible relationships between third molar and IAN on the cross-sectional images. Subsequently, the study population was subdivided according to this classification. The SPSS software, version 15.0 (SPSS® Inc., Chicago, Illinois, USA) was used for the statistical analysis.
Eight different classes were proposed (classes 0-7) and six of them (classes 1-6) were subdivided in two subtypes (subtypes A-B). The distribution of classes showed a prevalence of buccal or apical course of the mandibular canal followed by lingual position and inter-radicular one. No differences have resulted in terms of anatomic relationship between males and females apart from a higher risk of real contact without corticalization of the canal when the IAN had a lingual course for female group. Younger patients showed an increased rate of direct contact with a reduced calibre of the canal and/or without corticalization.
The use of this classification could be a valid support in clinical practice to obtain a common language among operators in order to define the possible relationships between an impacted third molar and the mandibular canal on CBCT images. Key words:CBCT, classification, inferior alveolar nerve, third molars.
神经损伤是下颌阻生第三磨牙拔除术的一种严重并发症，而影像学检查是评估下牙槽神经（IAN）术后可能损伤风险的首要必要步骤。本研究的目的是引入一种新的影像学分类方法，该方法可在临床实践中常规用于评估锥形束CT（CBCT）图像上阻生第三磨牙与下颌管之间的关系。
手术团队的三名成员独立研究了80例患者（133颗下颌第三磨牙）的CBCT图像，以得出一种能够描述横断面图像上第三磨牙与IAN之间所有可能关系的分类方法。随后，根据该分类对研究人群进行细分。使用SPSS 15.0软件（美国伊利诺伊州芝加哥市SPSS公司）进行统计分析。
提出了八种不同的分类（0 - 7类），其中六种（1 - 6类）又细分为两个亚型（A - B亚型）。分类分布显示下颌管颊侧或根尖走行最为常见，其次是舌侧位置和根间走行。除女性组IAN为舌侧走行时，下颌管无皮质骨化的实际接触风险较高外，男女在解剖关系方面未发现差异。年轻患者直接接触的发生率增加，且下颌管管径减小和/或无皮质骨化。
在临床实践中使用这种分类方法可为操作人员提供一种通用语言，以便在CBCT图像上定义阻生第三磨牙与下颌管之间的可能关系，从而提供有效的支持。关键词：CBCT、分类、下牙槽神经、第三磨牙。
