The effects of erupting mandibular 3 molar on the dental arch: A FEM study

Abstract

Role ofErupting Mandibular 3 molars as a cause of incisor crowding in the lower arch continues to be controversial. The relation between 3 molar and dental crowding has not been established. To determine the area of stress distribution and tooth displacement during eruption of mandibular 3 molar in mesioangular and horizontal impaction. Three dimensional finite element models were generated based on computed tomography scan data. From computed tomographic scans of a human mandible two additional finite element models were generated: a mandibular model with mesioangular impaction and second model with horizontal impaction. To investigate the stress distribution to the mandible, and tooth displacement eruptive force of 10 grams was applied.High concentration of stresses was seen at the inferior border of the mandible and lowest concentration of stress was present at symphysis for both the models. The tooth displacement for both mesio-angular and horizontal impaction caused mesial tilting of all the teeth i.e. from 2 molar to central incisor; with greatest tilting of 2 molar. Along the vertical plane, there was extrusion seen with 2 molar with mesio-angular impaction and extrusion in 2 molar and 1 molar with horizontal impaction And all the teeth exhibited buccal flaring in case of both impaction. There is significant level of tooth displacement from 2 molar towards the incisors. These changes occurring along the dental arch must be taken into consideration while planning for prophylactic extraction of third molars.