The Veneer/Core Thickness About The Strength And Fatigue Of All-ceramic Crown Based On Isight Design Gateway

The finite element method can analyze the geometric shape of prosthesis and thecomplexity of the oral environment and multi-physics problems, it has the advantages ofhigh efficiency、accurate、 low cost advantages and has been widely applied in the field oforal restoration. However the present finite element study of prosthodontics has someshortcomings：first of all,the load is loaded only point-load or area-load into the prosthesis,ignoring the nonlinear contact state and the coupling relationship between the prosthesisand jaw teeth, linear hypothesis that it is not actual situation, will inevitably influence theaccuracy of the results. The traditional finite element method established the model for thenon-parametric model, but when the conditions change, we need reverse engineering tomodeling、spend a lot of manpower and material resources, and reduce the efficiency.Isight Design Gateway provides a suite of tools to execute simulation-based designprocesses in a visual and flexible way. These tools allow you to set up and manage varioussoftware components utilized by the design process, and the rapid integration of theseapplications and Isight’s ability to automate their execution greatly accelerates the evaluation of product design alternatives. Abaqus is one of the world’s most advancedlarge-scale general finite element software, it can analyze mechanical problems ofcomplex、 control large solution scale and analysis of nonlinear mechanics,it reachesworld leading level. the nonlinear analysis can accurately simulate the restoration andchewing on jaw nonlinear contact state and coupling relationship.Therefore the purpose of this paper is to consider the condition of contactnonlinearity, using Abaqus nonlinear finite element algorithm, compared five groups ofveneer/core thickness ratio using the conventional finite element method and the IsightDesign Gateway analysis of all-ceramic crown thickness influence on the strength andfatigue, the study can lay a foundation for traditional nonlinear finite element method andIsight Design Gateway for the field of application in oral prosthesis.The whole studies were divided into two parts:Part Ⅰ: traditional nonlinear finite element method.Axisymmetric finite element models with different veneer/core thickness ratio ofall-ceramic crown of mandibular first molar（1:4、1:2、1:1、2:1、4:1,respectively）was established in the software of Pro/E, The finite element model are analyzed thestrength and fatigue using traditional nonlinear finite element method using Abaqus andFe–safe.Part Ⅱ: Isight Design Gateway method.Isight Design Gateway can rapidly integrate finite element software including Pro/E、Abaqus and Fe-safe; parameterized modeling of IPS E.max press all-ceramic crown ofmandibular first molar finite element model was established, occlusal core thickness (O)and axial core thickness (A) as a parameter (ParameterP), O and A ranged from0.2mm to1.3mm. the maximum principal stress(Mps) in crown was set as objectivefunction(OBJ),Isight Design Gateway can automately analysis the strength and fatigue ofall-ceramic crown, Optimum design was carried by observing how A and O affect theOBJ, probe life of all-ceramic crown.The experimental results：Study one， the maximum principal stress of all-ceramic lied core ceramic concentrated in the interface of cement and core under the load area;The maximumprincipal stress of veneer existed on the surface of the crown, particularly around theplaces the ball contacted;As the load increased,the maximum principal stress of porcelainand core ceramic did.The biggest fracture strength of the five different veneer/corethickness ratio was1:4according to the optimization theory.Study two，we can conclude the same failure vulnerable place that is on the surfaceof the veneer, particularly under the places the ball contacted in all five models; thenonlinear relationship between different veneer/core thickness ratio on all-ceramic crownfailure cycles:1:4＞1:2＞1:1＞4:1＞2:1; the fatigue longest lifetime of the five differentveneer/core thickness ratio was1:4,while the shortest one of the five different veneer/core thickness ratio was2:1.Study three，there is an interaction affect between O and A, and they work togetherto affect Mps;but O has the greatest affect, impact value up to94.5%; when O is greaterthan0.75mm, the maximum principal stress is a less one when O was0.2mm, A was0.36mm; when O is less than0.35mm, Mps has a larger value; When O is less than0.35mm, the maximum principal stress of all ceramic crown is bigger, when O is greaterthan0.75mm, the maximum principal stress is less stress; O and A influence each otherand mutual influence of maximum principal stress of all-ceramic crown; axial corethickness ranged from1.2mm to1.3mm and occlusal core thickness ranged from0.91mmto1.09mm are the combination with optimal.Study four， with the increase of occlusal core thickness,fatigue lifetime ofall-ceramic crowns is rising firstly then falling; with the increase of axial core thickness,fatigue lifetime of all-ceramic crowns is falling; there is an interaction affect between Oand A, and they work together to affect fatigue lifetime;but O has the greatest affect,impact value up to66%;the fatigue longest lifetime was0.793～1.09mm of occlusal corethickness、0.71～1.3mm of axial core thickness; the fatigue shortest was0.2mm～0.43mmof occlusal core thickness、0.2mm～0.42mm of axial core thickness.Conclusion:Biomechanically, a optimal design of all-ceramic crown on strength and fatigue using traditional non-linear finite element analysis and Isight Design Gateway， occlusal corethickness of IPS e.max press ranged from0.91mm to1.09mm and axial core thicknessranged from1.2mm to1.3mm, the fatigue longest lifetime was0.793～1.09mm ofocclusal core thickness、0.71～1.3mm of axial core thickness. The experiment optimized theall-ceramic crown strength and fatigue lay a foundation for the nonlinear finite element method andIsight Design Gateway in the dental fields.