コンポジットレジン製CAD/CAM冠の破断荷重値に及ぼす犬歯傾斜と合着剤の影響

Effects of Cuspal Inclination and Luting Agent on Fracture Load Values in Composite Resin CAD/CAM Crowns.

抄録

本研究の目的は，犬歯の傾斜がコンポジットレジン製CAD/CAMクラウンの破断荷重値に影響を与えるか否かを検討することである．2歯咬頭の下顎第一小臼歯を治療するために，支台歯とCAD/CAM冠を準備した．CAD/CAM冠は，1）主応力線が圧子との2点接触部から支台歯の咬合面まで放射状に分布するもの（タイプI），2）主応力線が支台歯の咬合面の外側を通るもの（タイプII，III）であるように設計された．CAD/CAM冠は，2種類のレジン・セメントとポリカルボキシレート・セメントを用いてアバットメントに装着された．万能試験機を用いて破断荷重を測定した．タイプIのCAD/CAM冠が最も高い平均破壊荷重値を示し，次いでタイプII，タイプIIIの順となり，すべてのタイプで有意差が認められた（p＜0.05）．使用した合着剤（レジンまたはポリカルボキシレートセメント）は破断荷重値に影響を与えなかった．Type IIとType IIIでは，スーパーボンドとハイボンドで破断荷重に有意差が認められた（p＜0.05）．

The purpose of this study was to evaluate whether change in cuspal inclination influences the fracture load values of composite resin computer-aided design/computer-aided manufacturing (CAD/CAM) crowns. Abutment teeth and CAD/CAM crowns were prepared as they would be for treating a mandibular first premolar with two cusps. The CAD/CAM crowns were designed so that 1) the principal stress lines would be radially distributed from the two points of contact with the indenter to the occlusal area of the abutment (Type I), or 2) the principal stress lines would pass outside the occlusal area of the abutment (Types II and III). The CAD/CAM crowns were mounted on the abutments using one of two types of resin or polycarboxylate cement. Fracture load values were measured using a universal tester. The Type I CAD/CAM crowns exhibited the highest mean fracture load value, followed by the Type II crowns and then the Type III crowns, with significant differences seen between all types (p<0.05). The luting agent used (resin or polycarboxylate cement) showed no effect on the fracture load value. With the Type II and Type III crowns, significant differences in the fracture load value were observed between the Super-Bond and Hy-Bond polycarboxylate cement groups (p<0.05).