A Study on Abutment Forms and materials of Restorations utilizing Adhesion

本研究的目的是通过三维有限元方法评估利用粘连的试验性基牙形式临床应用的可能性。参照拔除的上颌第一前磨牙建立有限元模型。3种无轴向基牙模型：Form 1：咬合面缩小1.5 mm，Form 2和Form 3：牙冠垂直于牙轴，距中心沟2 mm(Form 2)或4 mm(Form 3)。修复体由树脂复合体、烤瓷和金基合金3种材料制成。形态4：基牙形态同形态3，修复材料为瓷质+树脂复合体(咬合面为1.5 mm厚的瓷质，牙体为树脂复合体)。修复体通过粘结剂树脂粘结到基牙上。在颊尖脊中心施加500N的垂直载荷。利用有限元分析软件Ansys/Structual 5.6(Ansys，Inc.)对胶粘剂的应力分布进行了求解，结果表明，即使加载500N，胶粘剂中的应力也小于胶粘剂的抗压强度和拉伸强度。结果表明，这些实验基牙形态在临床上有一定的实用价值，有必要选择适合每种基牙形态的修复材料。

The aim of this study was to evaluate the possibility for clinical use of experimental abutment forms utilizing adhesion by means of the three-dimensional finite element method (FEM). The FEM models were created referring to the extracted human maxillary first premolar. Three experimental abutment forms, which had no axial wall, were as follows ; Form1 : Occlusal surface was reduced by 1.5mm, Form2 and 3 : The crown was cut perpendicularly to tooth axis at a distance of 2mm (Form 2) or 4mm (Form3) from central groove. The restorations were made from the 3types of materials, resin composite, porcelain and Gold base alloy. Form 4 : Abutment form was same as Form 3, and the restoration was made from porcelain and resin composite (occlusal surface was made from porcelain by 1.5 mm thickness and body was made from resin composite.). Restorations were bonded to the abutments by an adhesive resin. A vertical load of 500N was applied to the center of buccal cusp ridge. The stress distribution was solved by means of the ANSYS/Structual 5.6 (ANSYS, Inc).The stress in the adhesives was smaller than compressive strength and tensile strength of the adhesive resin, even if 500N was loaded. It was indicated that these experimental abutment tooth forms were useful in clinic and it is necessary to choose the restorative material suitable for each abutment form.