## 3 Results
### Inferior Alveolar Nerve (IAN) Injury  
Of the 4708 patients who underwent surgical extraction, 31 (0.658%) complained of nerve damage. Among them, 30 patients complained of symptoms of IAN injury, and 1 patient complained of symptoms of lingual nerve injury. In 30 patients with IAN injury, they were administered 50 mg of vitamint twice a day, 21.96 mg of adenosine triphosphate disodium trihydrate twice a day for 2 weeks, and 30 mg of prednisolone once daily for 12 days with a step down of 5 mg every 2 days. A total of 21 of 30 patients had resolved the symptoms of nerve injury and 9 patients complained of persistent nerve injury. The risk factors of IAN injury were analyzed with impaction pattern, panoramic signs, and CBCT driving pathway except for lingual nerve injury caused by the anesthesia needle. IAN injury was significantly correlated with gender and age (Tables 11 and 12). \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **CT Contact** & **Without CT** & **Total (\%)** & **\(p\) Value** \\  & **(\%)** & **Contact (\%)** & & \\ \hline Root darkening & 2334 (71.8) & 876 (28.2) & 3110 (100.0) & \multirow{2}{*}{\(p\) \(<\) 0.001 \({}^{*}\)} \\ Without root darkening & 4049 (56.2) & 3151 (43.8) & 7200 (100.0) & \\ Root deflection & 664 (67.1) & 325 (32.9) & 989 (100.0) & \\ Without root deflection & 5619 (60.3) & 3702 (39.7) & 9321 (100.0) & \\ Root narrowing & 332 (64.5) & 183 (35.5) & 515 (100.0) & \\ Without root narrowing & 5951 (60.8) & 3844 (39.2) & 9795 (100.0) & \\ Dark line of root & 1021 (61.1) & 651 (38.9) & 1672 (100.0) & \\ Without dark line of root & 5262 (60.9) & 3376 (39.1) & 8638 (100.0) & \\ Interruption of IAN & 1944 (76.3) & 604 (23.7) & 2548 (100.0) & \\ Without interruption of IAN & 4339 (55.9) & 3423 (44.1) & 7762 (100.0) & \\ IAN diversion & 474 (89.6) & 55 (10.4) & 529 (100.0) & \\ Without IAN diversion & 5809 (59.4) & 3972 (40.6) & 9781 (100.0) & \\ IAN narrowing & 319 (83.5) & 63 (16.5) & 382 (100.0) & \\ Without IAN narrowing & 5964 (60.1) & 3964 (39.9) & 9928 (100.0) & \\ \hline \hline \end{tabular} \({}^{*}\)Statistical significance \(p\) \(<\) 0.05, [PERSON]’s chi-square test.  
\end{table} 
Table 7: Association between panoramic signs and contact in cone beam computed tomography (CBCT). \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Lingual Cortical Bone** & **No Lingual Bone** & **Total (\%)** & **\(p\) Value** \\  & **Fenestration (\%)** & **Fenestration (\%)** & **Total (\%)** & **\(p\) Value** \\ \hline Dark line of root & 796 (47.6) & 876 (52.4) & 1672 (100.0) & \\ Without dark & 634 (7.3) & 8004 (92.7) & 8638 (100.0) & \multirow{2}{*}{\(p\) \(<\) 0.001 \({}^{*}\)} \\ line of root & 1430 (13.9) & 8880 (86.1) & 10,310 (100.0) & \\ \hline \hline \end{tabular} \({}^{*}\)Statistical significance \(p\) \(<\) 0.05, [PERSON]’s chi-square test.  
\end{table} 
Table 8: Association between a dark line of root in panoramic view and lingual cortical bone fenestration in cone beam computed tomography (CBCT). In the Pell and Gregory classification, Classes A, B, and C were found to be correlated with nerve injury, and Classes I, II, and III were not correlated (Table 13). There was a significant correlation with inferior alveolar nerve injury in cases where the roots became dark at the IAN area (\(p\) = 0.018) and diversion of the inferior alveolar nerve at the root area (\(p\) = 0.041) (Table 14). Finally, there was no significant correlation between the driving pathway of the IAN and the IAN injury in CBCT. However, when the IAN showed a lingual pathway and narrowing at the same time, there was a significant correlation with IAN injury (Table 15).