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法（FEM）来评估利用粘连的实验基台形式在临床应用的可能性。以拔除的人类上颌第一前磨牙为对象建立有限元模型。三种不设轴墙的试验桥台形式如下：表1：咬合面缩小1.5mm；表2、表3：离中心槽2mm（表2）或4mm（表3），将冠垂直于牙轴切割。修复体由树脂复合材料、陶瓷和金基合金3种材料制成。表4：基台形式与表3相同，修复体为瓷树脂复合材料（咬合面为1.5 mm厚的瓷，体为树脂复合材料）。修复体通过粘接树脂粘接在基台上。在颊尖脊中心处施加500N的垂直载荷。采用ANSYS/ structual5.6 （ANSYS, Inc .）软件求解应力分布。即使加载500N，胶粘剂中的应力也小于胶粘剂树脂的抗压强度和抗拉强度。结果表明，这些试验性基牙形态在临床应用中是有价值的，有必要根据不同的基牙形态选择合适的修复材料。

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.