## 4 Discussion  
If the OPG is interpreted correctly, numerous signs may help clinicians to predict the wisdom tooth position decreasing the risk of injury to the IAN. Sometimes, the signs are \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{2}{c}{**Mean Distance (Mean \(\pm\) SD) in Millimeter**} & **Sig.** \\ \hline
**Total Group (\(n=228\))** & \multicolumn{2}{c}{\(-\)**1.09 \(\pm\) 1.5 mm**} & \\ \hline Group & C-group (0 \(\pm\) 1.6) (\(n=96\)) & D-group (\(-1.89\)\(\pm\) 1.26) (\(n=132\)) & **\textless{0.001 }*** \\ \hline Pathological Sign in D-group & Yes (\(-0.22\)\(\pm\) 1.54 mm) (\(n=11\)) & No (\(-2.04\)\(\pm\) 1.12) (\(n=121\)) & **\textless{0.001 }*** \\ \hline Javta-apical Radiolucency (JAR) & & (0.77 \(\pm\) 0.84 mm) (\(n=4\)) & Not detectable \\ \hline Inferior Alveolar Nerve (IAN) impaction & & (0.81 \(\pm\) 0.44 mm) (\(n=10\)) & Not detectable \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mean distance across the study groups. SD = standard deviation, Sig = statistical significance using One-way ANOVA and T-test. *= \(p\) value with significance level. Figure 2: A graphic representation of the distribution of patients with impaction of the root in the lingual cortical bone of at least 1 mm (in black) in D-group (84.85%, 112/132) and C-group (14.58%, 14/96). confirmed by CBCT and the risk of complications during or after surgery is too high so that a coronectomy technique is recommended [16; 17]. Complications after third molar extractions are reported to be more frequent than complications for other teeth extractions, particularly for wound infection and loss of sensibility [18]. A correct pre-surgical planning and a proper knowledge of the teeth's position and its contact with other anatomic structures could prevent these complications reducing the incidence, particularly of nerve damage, for these reasons CBCT may help surgeons because it is a [19; 20]. When the third molar root is impacted into the cortical portion of the lingual side of the inferior jaw, the incidence of complications may increase such as the lingual nerve could be damaged, the portion of the root impacted in the bone could fracture and/or even the lingual cortical bone may fracture [21]. According to the results of the present study, the root is more frequently positioned near the lingual portion of the bone or in direct contact with it when the OPG shows a band like radiolucent area corresponding to the apical portion of the inferior third molar root with an odds ratio of 32.8 (Figure 3) confuting the null hypothesis proposed. The distance between these two structures in the control group is in line with other studies [12; 22; 23]. Still, a radiolucent area does not always correspond to the proximity between root and cortical lingual bone. For these reasons, CBCT may be useful to verify the anatomic position of the third molar (Figure 4). The stratification of patients in the D-group (with a dark sign in OPG) was performed using CBCT to make a differential diagnosis and help clinicians to have as much information as possible OPG classifying subjects with no sign of pathologies that could explain the radiolucent area in the apical portion of the root of the inferior wisdom tooth, and subjects with possible pathologies. Figure 3: Patient 180122 with a Y-sign corresponding to wisdom tooth 3.8 in the OPG. This radiolucency in \"Y-sign\" occurs because if the third molar root is positioned in proximity with the cortical bone, in fact, we could name this sign as \"Periapical Band-Like Radiolucent Sign\" possible due to its periodontal ligament impacts the lingual plate and the bone in that slight area resorbs. When this is visible in OPG, the probability to have a closeness between root and lingual cortical bone is extremely high. After the stratification of the D-group according to the presence of Pathology (Yes) or not (No), the results significantly showed that, in 90.91% of suspected dark areas, third molar roots are close to the lingual cortical bone if there are no other pathologies.