In addition, the position of the mental foramen was determined relative to the roots of the neighbouring teeth. This was assessed by defining regions of interest in the area of the first premolar, second premolar and first molar by extending the respective mesial and distal points of the cement-enamel junction caudally along the tooth axis. The position of the midpoint of the mental foramen was then determined in relation to these regions to determine its position relative to the roots (see Fig. 2).

SPSS 20.0 software (IBM) was used for statistical analysis. The medians, mean values, standard deviation and confidence intervals of all measurements (distance from the mandibular canal to the vestibular compact bone of the mandible and the position of the mental foramen) were calculated. Wilcoxon rank-sum test was used for comparing the means of all bone thickness measurements between men and women, the different age groups and the right and left sides of the mandible.