| Wedge-shaped defect is an abrasion that caused by long-term abrasion in tooth cervical.It often is wedge shape.It is well-known to be prevalent in oral.Its defect by two planes intersect and become,the surface is hard and smooth, edge tidy,Normally,the tooth isecru,sometimes can have degree differs shading.Often occurs on premolar, especially the first premolar,Along with the age,the greater the wedge-shaped defect trend and more serious.Clinically,there are two kinds of treatment wedge-shaped defect methods, desensitization and filling ,Filling is the best therapy way and being used commonly.At present,the issue is still discuss as to the cavity form of wedge-shaped defect preparation during the treatment process therapy.In this study,we analyzed the influence of wedge-shaped defect retention form of restoration on stress distribution in tooth using three-dimensional finite element method and the consequence would provide useful data for clinical treatment.Objective:Three-dimensional finite element method applied research in different ways of wedge-shaped teeth defect filling equivalent stress and displacement, wedge-shaped teeth defect for the clinical treatment of repair, provide biomechanical evidence.Methods:Through the spiral CT scan technology, using Ansys software such as Mimics to construct a three-dimensional finite-element model of the maxillary first premolar molar. Spiral CT scanning was used to obtain the morphological pictures of the maxillary first premolar molar.Photoshop ware used to improve the definition and contrast of the pictures which was saved as BMP.Mimics software was used to form the primary three-dimensional finite element models.And import the three-dimensional finite element models in MSC.MARC software to establish models of the tooth.Maxillary molar respectively established before the first wedge-shaped defect, concave of wedge-shaped teeth defect repair, box of wedge-shaped teeth defect repair, complex pointlike hole wedge-shaped teeth defect repair the three-dimensional finite element model, the simulation of two loading method occlusion, comparison and analysis of different ways of retention wedge-shaped teeth defect filling the overall effect. Results:(1)Established a direct,complete three-dimensional finite element model of the maxillary first premolar molar.The model was fit for biomechanics analysis.(2)Different ways of treatment of filling defect, wedge-shaped teeth body tissue to stress level has certain effect. With a box of wedge-shaped teeth defect repair the maximum equivalent stress retention, concave shape of repair, composite pointlike hole type wedge-shaped teeth defect repair equivalent stress. Three methods are not filling treatment than wedge-shaped teeth defect equivalent stress.In the restored models, the maximum stresses of pour concave, box, the plaque-forming hole technique restorations were 5.0113Mpa, 5.0240Mpa, and 4.7747 Mpa;the minimum stresses were 0.99187MPa,0.99396MPa,0.94488MPa.Conclusion:(1)This research established four three-dimensional finite element models of a maxillary first premolar with wedge-shaped defect restored by different techniques respectively.The model established by this way was of high accuracy,similarity and comparability.(2)After the wedge-shaped with filling defect in the way of closely related.Different ways of treatment retention filling wedge-shaped defect,there are some influence on stress level of teeth organization.With box retention form wedge-shaped teeth defect repair the maximum equivalent stress,Pour concave retention form repair take second place. Composite plaque-forming hole type wedge-shaped teeth defect repair equivalent stress is the smallest.Equivalent stress of three repair methods are all smaller than an unfilled treatment wedge-shaped teeth defect.In vertical load,the stress distribution trends of each model defect area are since teeth in vitro surface to the medullary cavity side increase.The restored effect of the plaque-forming hole technigue is the best among the three techniques. |
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