Numerical Simulation Of The Functional Remodeling Of The Anterior Alveolar Bone

The alveolar bone is the most active bone in metabolism of the systemicbone tissue. Periodontal disease, physiological atrophy and other reasons canlead to the reduction of alveolar bone height, changes of density and attachmentloss of the periodontal ligament, so that the periodontal and the alveolar boneremodeling will change in the bite force. Sensors in the bone can measure theinternal load and activate the bone cells to make the bone grow or resorb. Thisphenomenon is called bone remodeling, which is associated mainly with densityand/or geometry changes.The molecular biology and clinical studies have revealed the mechanismand laws of the alveolar bone remodeling, but it is difficult to predict or quantifythe process and results of bone remodeling. However, the FEA modelestablished with geometry and density information of the periodontal tissue,though using numerical simulation of the conversion process, could predictpossible converted results of the alveolar bone. The results will be helpful toform the basis of diagnosis and treatment planning in periodontics.In this study, a FEA model of the maxillary central incisor with the parodontium was established, and the model consist of the density and geometry.In order to fully exploit potential of the bone remodeling model, the newmathematical model for bone remodeling was implemented into the commercialfinite element (FE) software ABAQUS. By using user material subroutine(UMAT) of ABAQUS and the simulation software MATLAB Toolbox,diversification of density and geometric of the maxillary central incisor alveolarbone was researched under the different bite loading. This model will be helpfulto analyze teeth alveolar bone remodeling process and predict results ofalterations.In this study, include the following four-part experiment:1. Establishment of the three-dimensional finite element model of maxillarycentral incisors and periodontal tissueSelect one off due to trauma, normal anatomy, and maxillary centralincisors as a modeling basis; Micro CT scan to30μm thick, the datas of DICOMformat to import Mimics software; three-dimensional surface morphology ofthe central incisors was obtained and STL format is saved. Use of surfacedressing on the generated model in Geomagic Studio11.0converted to NURBSsurfaces. The datas of NURBS surfaces was imported to UG NX6,Three-dimensional solid model with the root outer surface to build theperiodontal ligament organization (0.2mm), the outer cortical bone (2mm) andthe inner chancellors bone. to generate the finite element model in the ABAQUSfinite element analysis software.2. Establishment of the remodeling model to the anterior alveolar boneFinite element based on strain energy density (SED), bone remodelingtheory combining with the development of finite element analysis softwareAbaqus UMAT and simulation software MATLAB toolbox, to established remodeling model reflecting the maxillary alveolar bone density and bone tissuemorphology.3. Effect of bite force and duration of action on alveolar bone remodelingThe methods of the second experiment was used to further establish therelationship between the alveolar bone density changes and the time increment.By simulating the different loading and alveolar bone density changes on24months, it is anticipated that the laws of the alveolar bone density changes canbe quantiic ationally represented under the different loading.4. Morphology simulation of the maxillary central incisor alveolar boneremodelingThe simulation software MATLAB toolbox was established on the basis ofthe third Experiment, the reconstructed alveolar bone density information wasconsidered as a criterion to alter at the model morphology, and then the nextstage of the conversion process would be simulated. It can be used to analyse theinfluencing factors of the morphological changes and successfully achieve thesimulation of the histological changes in the process of alveolar boneremodeling.The results shown that:1. In this paper, the geometry of the finite element model is similar to thenatural teeth and periodontal tissues, which can betterly simulate the loadingstate of the maxillary incisors and periodontal tissue and lay a goodfoundation.2. Finite element is combined with bone remodeling theory based on strainenergy density (SED), with the development of finite element analysissoftware Abaqus UMAT and simulation software MATLAB toolbox, toestablishthe remodeling model, reflecting the maxillary alveolar bone density and bone tissue morphology.3. With the increase of the physiology loading, the pressure stress on thebuccal cervical margin increased gradually while the density decreasedgradually. The cortical bone was lower than its initial density1.74g/cm3,whichwas1.74-1.63g/cm3. The density of cancellous bone was0.90-0.77g/cm3,which was lower than its initial density0.90g/cm3. The lingual cervical marginwas under tensile stress which also increased with loading, the density has nosignificant change. When the loading achieve to120N, the density of corticalbone is1.74-1.73g/cm3. No significant change was found in the cancellousbone.4. The mineral density of the buccal and lingual cortical bone was mainlyconcentrated in the region of the neck edge, the mineral density buccal andlingual cortical bone in the first three months is relatively stable. When the loadwas60N, the alveolar buccal and lingual cortical bone density on4-24monthsincreased slowly. When the load is70N-150N, the density of the cortical bone ofthe r buccal and lingual regions on the first three months undergo the stableperiod, and then the density increasing stage, along with the increasing load,showing the trend of density values faster decreasingConclusions1. The fnite element method is combined with SED bone remodeling theory,which is used to analyses density and shape changes of the alveolar boneremodeling process under the different bite force. The findings show that themethods and techniques are feasible, and the simulation results are similar to theclinical conditions,which can provide a new method for the study of periodontaltissue remodeling.2. When the natural teeth bear too large bite force, the compressive stress and tensile stress are formed in the buccal and lingual region, the strain energyof the corresponding regions are high, which can cause the reduction of thealveolar bone density.3. The mineral density of the buccal and lingual cortical bone is mainlyconcentrated in the neck edge of the area; when the bite force is60N and70N,maxillary anterior alveolar bone density tends to a steady state on24month, andthe alveolar bone morphology have no change. When the load is greater than80N at the neck edge of the area, the density of the buccal and lingual alveolarbone is increased with the load and time increasing, showing a trend whichfirstly increase and then decrease, in addition, the cortical bone also shows avisible absorption.4. When the alveoar bone withstands large external load, The buccal andlingual of the alveoar bone were resorbed. Load the greater the absorption of thealveolar bone appear sooner and more alveolar bone height reduction.