Resistance of bonded composite restorations to fracture of endodontically treated teeth.

The aim of this in vitro study was performed to evaluate the effect of dentin bonding agents and glass ionomer cement beneath composite restorations and its resistance to fracture of endodontically treated teeth. Fifty sound extracted maxillary teeth were selected; ten of them for controls and the remainder were modified with root canal treatment and a mesial occlusal distal (MOD) cavity preparation. The modified teeth were then divided into five groups: 1. Sound teeth 2. Prepared without restorations for control 3. Prepared and restored with Vitrebond (3M, USA), Singlebond (3M, USA), and Z100 (3M, USA) resin composite 4. Prepared and restored with Concise enamel bonding agent (3M, USA) and Z100 resin composite 5. Prepared and restored using Singlebond and Z100 composite resin The modified specimens were subjected to compressive load by an Instron machine until fracture occurred. Group 1 showed the highest resistance to compressive force followed by Groups 5, 3, 4, and 2, respectively. Statistical analysis using analysis of variance (ANOVA) and a t-test indicated significant difference between all groups. Use of a dentin bonding agent and composite resin increased the resistance of endodontically treated teeth to fracture.