Objective: To explore the correlation between the anterior border absorption of the mandibular ramus and the occurrence of supernumerary teeth, along with the biomechanical stress.
Design: The bone mass of mandibular ramus was evaluated on CBCT images by bone mass analysis. In addition, the number of supernumerary teeth and corresponding anatomical positions were recorded.
Results: The CBCT images of 5100 patients were analyzed. Along with eruption of mandibular permanent molars in sequence, the width of the ramus increased from 29.02 mm to 36.02 mm (P < 0.001). The proportion of the width from the nerve canal to the anterior border of the ramus in the whole ramus decreased from 52.51% to 43.79% (P < 0.001). Meanwhile, among the 5100 participants, 278 supernumerary teeth were identified in 209 patients (4.1%). The predilection loci were close to the regions of central incisors (72.66%) in the maxilla and of the premolars (11.51%) in the mandible.
Conclusions: Biomechanical stress, mainly pressure during tooth development, was the internal force of anterior border absorption of the mandibular ramus. The release of pressure after tooth eruption is a possible reason for the occurrence of supernumerary teeth.
Keywords: Dental biomechanical stress analysis; Mandible; Supernumerary; Tooth; Tooth Eruption.
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