Skeletal maturation and the location of the mandibular foramen within the ramus mandibulae

Purpose It is well documented that the mandible does not grow at a constant rate. There are significant correlations between the increase of mandibular size and cervical vertebral maturation. The peak growth velocity of the mandible occurs after the third stage of cervical vertebral maturation. The location of the mandibular foramen (MF) and its changes subsequent to growth are of great interest to clinicians as they relate to the anesthesia of the inferior alveolar nerve and to mandibular surgical procedures. Therefore, the aim of the present study was to assess the influence of the mandibular growth spurt on the location of the MF in various skeletal growth patterns. Methods Panoramic and lateral cephalometric radiographs of 98 (32 orthognathic, 50 retrognathic, 16 prognathic) patients before and after the growth peak were collected. For each subject, the maturational stage of the cervical vertebrae was defined on successive lateral cephalograms and the vertical and horizontal position of the MF was evaluated on two panoramic radiographs, one before and one after the growth peak. Results The MF-Post/MF-Ant ratio (MF distance to the posterior border of the ramus/MF distance to the anterior border of the ramus) significantly increased after the growth peak in orthognathic and retrognathic subjects ( P = 0.015 and 0.02, respectively). This ratio did not significantly increase in prognathic subjects ( P = 0.882). No statistically significant changes in the vertical position of the MF were found in the three groups after the growth spurt. Conclusion The horizontal position of the MF moves in an anterior direction in orthognathic and retrognathic subjects during the mandibular growth spurt. The vertical position of the mandibular foramen remains unchanged during this period.