Statistical analysis of parameters for the ramus, teeth, and biomechanical stress: A retrospective study

Abstract

ObjectiveTo explore the correlation between the anterior border absorption of the mandibular ramus and the occurrence of supernumerary teeth, along with the biomechanical stress. DesignThe 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. ResultsThe 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. ConclusionsBiomechanical 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.