Patil Vathsala, Pai Keerthilatha M, Vineetha R, Rajagopal K V, Dkhar Winniecia
Department of Oral Medicine and Radiology, Manipal College of Dental Sciences, Manipal, Karnataka, India.
Department of Radio-Diagnosis, Kasturba Medical College, Manipal, Karnataka, India.
Contemp Clin Dent. 2019 Jan-Mar;10(1):93-98. doi: 10.4103/ccd.ccd_430_18.
Mandibular third molars are the most commonly impacted teeth, and their surgical removal can be associated with inferior alveolar nerve (IAN) injury. To avoid the deleterious complication of nerve injury on patients, a thorough visualization of IAN and its localization are essential.
The aims and objectives of this study were to evaluate the efficacy of two conventional localization techniques in determining the relationship of mandibular third molars to IAN and to assess its reliability in comparison with computed tomography (CT).
Panoramic radiograph (PR) was taken using Kodak 8000C Digital Panoramic and Cephalometric system. Intraoral periapical radiographs (IOPAs) were taken using Kodak 2200 Intraoral X-ray machine. CT scan images were taken using multidetector CT scans.
Two IOPAs (0° and -20° vertical angulation) and PR and CT scan images of thirty mandibular third molars were taken. Two combinations were used (i) a combination of two IOPAs and (ii) a combination of PR and IOPA (-20°). Tube-shift localization technique was applied to both these combinations to derive the relation between third molar and IAN canal as "in contact," "separate," "buccal," "lingual," and "in line with the apex" and the results were compared with CT images.
Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using SPSS software version 15.0.
The combination of PR and IOPA radiographs showed 14 teeth to be in contact with IAN. This gave a sensitivity of 100%, specificity of 94.1%, PPV of 92.9%, and a NPV of 100% in determining the relation as "in contact" or "separate." 78.3%, 85.7%, 94.7%, and 54.5% were the sensitivity, specificity, PPV, and NPV in localizing it as "buccal," "lingual," or "in line with apex." These results were better than that of the combination of the two IOPAs.
Localization using PR and IOPA could better deduce the relation between IAN and mandibular third molar.
下颌第三磨牙是最常见的阻生牙，其外科拔除可能与下牙槽神经（IAN）损伤有关。为避免神经损伤给患者带来有害并发症，全面观察IAN及其定位至关重要。
本研究的目的是评估两种传统定位技术在确定下颌第三磨牙与IAN关系方面的有效性，并与计算机断层扫描（CT）相比评估其可靠性。
使用柯达8000C数字全景和头影测量系统拍摄全景X线片（PR）。使用柯达2200口腔内X线机拍摄口腔内根尖片（IOPA）。使用多排探测器CT扫描获取CT扫描图像。
拍摄30颗下颌第三磨牙的两张IOPA片（垂直角度分别为0°和 -20°）、PR片和CT扫描图像。使用两种组合：（i）两张IOPA片的组合；（ii）PR片和IOPA片（-20°）的组合。对这两种组合均应用管移位定位技术，得出第三磨牙与IAN管之间的关系为“接触”“分离”“颊侧”“舌侧”和“与根尖平齐”，并将结果与CT图像进行比较。
使用SPSS 15.0软件计算敏感性、特异性、阳性预测值（PPV）和阴性预测值（NPV）。
PR片和IOPA片的组合显示14颗牙齿与IAN接触。在确定关系为“接触”或“分离”时，其敏感性为100%，特异性为94.1%，PPV为92.9%，NPV为100%。在将其定位为“颊侧”“舌侧”或“与根尖平齐”时，敏感性、特异性、PPV和NPV分别为78.3%、85.7%、94.7%和54.5%。这些结果优于两张IOPA片的组合。
使用PR片和IOPA片进行定位能够更好地推断IAN与下颌第三磨牙之间的关系。
