S-Space College of Dentistry/School of Dentistry (치과대학/치의학대학원) Dept. of Dentistry (치의학과) Theses (Master's Degree_치의학과)
하악 제3대구치와 하치조신경의 해부학적 위치에 대한 연구
Anatomical study of inferior alveolar nerve and mandibular third molar
- 치의학대학원 치의학과
- Issue Date
- 서울대학교 대학원
- 학위논문 (석사)-- 서울대학교 치의학대학원 : 치의학과, 2015. 2. 서병무.
- Extraction of third molar is the most common minor surgery in dental care, with various reasons. The extraction of the third molar has a risk of the complications that can occur inevitably in the extraction process. Especially the possible risk of inferior alveolar nerve (IAN) damage, the mandibular third molar (M3) extraction procedure is discouraged in local dental clinic.
The purpose of this study is to check the anatomical position of IAN in conjunction with the mandibular third molar with computerized tomography (CT) scan.
Subjects included in this study are the patients who want to pull out their third molar to the same surgeon and took panoramic radiographs with CT scan, in Seoul National University Dental Hospital from September 2009 to December 2013. Total 651 patients with 1077 of M3s were included in this study because the roots of M3 were superimposed in panoramic radiographs. Panoramic radiographs and cone beam CT or reformatted localized CT data were investigated to evaluate the risk of IAN. In addition, after extraction, complications were confirmed by review of the chart of the patient. Among total 1077 mandibular third molars, actual contacted M3s with IAN confirmed on CT scan was 824. Additionally, high risk group was defined in case of intruding of root into IAN canal or compression of IAN with its root. These high risk cases composed of 310 teeth. The number of extracted teeth among subject 1077 M3s was 677. Among these, high risk teeth were only 138. In the same period, regardless of CT taking, total number of surgical extractions of mandibular M3 was 1188.
Symptoms of IAN damage, which contains all of minor sensory deprivation were identified in 8 cases (0.67%) from all of 1188 M3 surgical extractions. Interestingly, all IAN damage cases were confirmed that M3 roots and IAN are contacted in CT scan. Symptoms lasting over 6 months were found in 3 cases (0.25%). In other aspect, incidences of IAN damage in extracted high risk cases (138 cases) increased to 5.8% and 2.17% respectively. Although the contact of M3 root and IAN is related with nerve damage as a consequence of tooth extraction, the incidence is too low to conclude as causal factor with statistical significance. We can take advantage from CT image to avoid IAN complication, and patients are given warning regarding high risk for IAN damage when IAN contacts with root of third molar. Therefore some patients were not undergone third molar extraction in high risk cases. This is one of the effectiveness of the CT image to help reduce IAN complication of this study.