The Three－dimensional Finite Elements Analysis Of Different Rate Of Clinical Crown－root Of Maxillary Central Incisor

Objective: To constructing a three-dimensional(3-D) finite element model ofdifferent rate of clinical crown－root and width of marginal alveolar bone ofmaxillary central incisor and evaluate the date and distribution of stress in periodontalmembrane.Methods:(1) Choose a maxillary central incisor, get the images scanned by CTtechnique, transfer digital image by software Mimics and reconstruct a3-D model byreverse engineering software Geomagic,computer aid design program UG6. The3Dparametric model of different rate of clinical crown-root and width of marginalalveolar bone of maxillary central incisor including periodontal membrane andalveolar bone,was established in the UG software through its automated modeling.（2）Then the3-D parametric model was imported to Ansys Workbench software bybidirectional parameters transmitting between UG6and Ansys Workbench. Definedifferent parts with different Young’s moduluses and Poisson’s ratios, mesh themodel,and set the boundary restraints and constraints. Apply a force about120N onthe the edge1/3of the tooth45°tilted, set up3-D finite element model and evaluatethe date and distribution of stress in periodontal membrane and alveolar bone ofdifferent rate of clinical crown-root and width of marginal alveolar bone of maxillarycentral incisor.Results:(1) The3D parametric model was successfully established which hadprecise anatomical features. In the Design Exploration,the rate of clinical crown-rootand width of marginal alveolar bone were defined as input parameters,with the formerranging from1.1to2.5and the later from0.1mm to0.5mm.(2)When the width ofmarginal alveolar bone was0.3mm,the rate of clinical crown-root was changing, theregion of the maximum stress was on the cervix of the periodontal membrane andalveolar bone. When the rate of clinical crown-root was increasing, the area and date of the maximum stresses were increasing. When the rate of clinical crown-root reachat2.25, the Von Mises stress on the peridental membrane was26.8MPa which istwice of the normal one.(3)When the rate of clinical crown-root was1.8, the width ofmarginal alveolar bone the was decreasing, the area and date of the maximum stresseswere increasing,but the rangeability is comparative smaller than former.(4)Got3Dpictures used Ansys Workbench software to analyze,set as the goal of optimizing atthe same time,which can express any maximum Von Mises stress at the range ofdouble parameters and be the standard of damage pericementum tissues.Conclusion（:1）The3D parametric model of different rate of clinical crown-rootand width of marginal alveolar bone of maxillary central incisor was successfullyestablished by reverse engineering software which had precise anatomical features.（2）Double parameters were changing, the region of the maximum stress was on thecervix of the periodontal membrane and alveolar bone.（3）When the rate of cliniccrown-root reach at2.25, the Von Mises stresses on the peridental membrane weremore than the tolerance range of the normal one. The continued force was liable todamage pericementum tissues.（4）When the width of marginal alveolar bone the wasdecreasing, the rangeability is comparative smaller than former,so we should paymore attention to the damage of the rate of clinical crown-root in clinics.