## 4 Discussion
These data are similar to those reported by other colleagues concerning different populations such as Hong Kong Chinese, British, Asian Indian and East African people (position III more prevalent than position IV) but different from Zimbabweans, Malawians and South Indians (position IV more prevalent than positions V and III) and from Nigerians and Kenyans (most common positions are II and III) [21]. Overall, these results show that there are significant differences among populations with different geographic origins (Table 4). Overall, our results confirm the conclusions of a recent meta-analysis by [PERSON] et al., according to which the most prevalent location for the mental foramen among the global population is mostly between the two premolars (between 50.4% and 61.95%) or apical to the second premolar (from 50.3% to 57.9%) [1]. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Position** & **I** & **II** & **III** & **IV** & **V** \\ \hline Italians (present study) & 6.0 & 6.5 & 40.0 & 14.5 & 1.0 \\ \hline East Africans & 0.3 & 7.6 & 57.9 & 31.5 & 0.0 \\ \hline British people & 0.0 & 9.1 & 59.1 & 31.8 & 0.0 \\ \hline Asian Indians & 0.0 & 6.2 & 75.4 & 19.2 & 0.0 \\ \hline Hong Kong Chinese & 0.0 & 21.0 & 51.0 & 24.0 & 4.0 \\ \hline Chinese & 0.0 & 21.0 & 59.0 & 19.0 & 1.0 \\ \hline Nigerians & 1.8 & 27.0 & 55.6 & 12.3 & 3.3 \\ \hline Kenyans & 0.0 & 31.9 & 56.1 & 12.1 & 0.0 \\ \hline Turks & 0.0 & 0.0 & 44.1 & 55.9 & 0.0 \\ \hline North Indians & 0.0 & 2.1 & 18.1 & 69.8 & 11.5 \\ \hline North Americans & 0.0 & 3.5 & 23.0 & 49.4 & 24.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Location (%) of the mental foramen in different populations (adapted from [PERSON] et al. [20]). The colors help to visualize the most frequent positions (green \(>\) yellow \(>\) orange \(>\) red \(>\) grey). Populations with similar distributions are placed next to each other. So far, most authors have considered only data such as the position of the MF and the presence of accessory mental foramina; however, only a few have evaluated the existence of correlations between metrical and morphological characteristics of the MF [7; 8; 9; 10; 11; 12; 20; 21; 22; 23]. Therefore, it is not easy to provide a unitary framework of the anatomical characteristics of the mental foramen [1]. For example, some authors took into consideration position and size without finding any significant correlation [9]. Also, our results did not find any correlation between metrical measurements and the position of the MF according to teeth and dental apices, thus suggesting that the above-mentioned parameters are independent of each other. Furthermore, a qualitative comparison of the metric data reported by different authors shows some variability regarding the dimensional parameters and the localization of the MF with respect to the mandibular edges--for example, within Indians (Table 9). In the future, these data could be subject to further analysis considering not only the inter-ethnic variability but also factors related to the different study techniques (dry jaws vs. CBCT) and the methods used for the measurements. On the other side, the present study found a significant correlation between the two diameters of the MF (height and width), both in males and in females: in addition, in females, depth shows a positive correlation with its distance from the inferior mandibular edge. The latter finding has particular importance in surgical practice, as it may help in predicting the depth of the MF in cases where anesthesia of the mental nerve is requested. In conclusion, the present study analyzed the correlation among different parameters useful for the localization of the MF: the results partially confirmed the existing literature; moreover, correlations between metrical measurements were found. The results of this study have important clinical implications for dental and maxillofacial surgery. First, our study confirms the existence of differences in the predominant localization of the mental foramen among different populations.