Finite Element Analysis Of Mandibular First Premolar With Pulp Cavity Wall Defect Restored With Endocrowns

Oral health is closely ralated to life quality,which affects the external appearance,chewing,digestion as well as patient's mental health.Therefore,oral health has obtained more and more attention.In clinical,dentin wall defect caused by dental caries,trauma,severe wear and so on is a common problem.Ways to restore the defected tooth are multiple,it is of particular importance to determine the optimal method and to extend the life of the restored tooth as far as possible.In the condition of mandibular first premolar with different dentin defect forms,three methods are adopted frequently at present: The integral endocrowns restoration(IER);Flow resin for gingival wall lifting and endocrowns restoration(FRER);Ultrasonic resin for gingival wall lifting and endocrowns restoration(URER).For specific dentin defect form,what effects different restoration methods will have on the stress distribution of the restored tooth,and which restoration method will reach the optimal stress distribution state,relevant studies are not avalible.Restoration of this kind of defected tooth is mainly based on clinical experience.Finite element method is adopted in this paper to analyze this clinical problem,expecting to provide references for clinical design optimization and scheme selection.Based on CT images,finite element models of five types of dentin defect of mandibular first premolar and corresponding restorations were established with the use of Mimics,Geomagic,UG and Hypermesh software.The ABAQUS software was used to analyze the stress state of the restored teeth,which with different types of cavity wall defect and restored with different restoration methods described above.Merits and demerits of the methods in restoring specific cavity wall defect were analyzed comparatively as well.The main results are as follows:(1)The lateral force produced by mastication has a decisive influence on the restorative effects and life of the restored tooth,regardless of the restoreation method chosed and dentin wall forms.This suggests that the cusp inclination should be reduced as much as possible to reduce the adverse effect of lateral force on the restored tooth.(2)Restorative effects of IER will be improved in the presence of buccal dentin wall,and restorative effects of FRER?URER will be improved in the presence of distal dentin wall;(3)Regardless of forms of cavity wall defect,tooth restored with IER always obtains the optimal stress distribution state,followed by URER.FRER is the most unfavorable method to choose.