A comparative evaluation of effect of three drying methods of post preparation on bond strength using hydrophilic bonding agents

Purpose: The purpose of this study was to evaluate the effect of different drying methods of the post space on dentin bonding in composite core build-up method by using hydrophilic and hydrophobic agents. Methods: Total 30 caries-free incisors and premolars were endodontically treated for post and core build up. After drying each post space using three drying methods (air drying, paper-point drying, or ethanol drying, which involves filling the space with 99.5 vol% ethanol followed by air drying) A dual-cure one-step self-etching adhesive system bonding agent (Prime and Bond universal™, Universal Adhesive) was coated in to the canals and filled with dual-cure resin composite. The bonded specimens were sectioned into square beams of approximately 1 mm square for microtensile bond strength (mTBS) testing. mTBS were analyzed using Scheffé multiple comparison. Results: The mTBS significantly decreased in the order of ethanol drying, paper-point drying, and air drying (air drying/ethanol drying: p < 0.001, air drying/paper- point drying: p = 0.048, ethanol drying/paper-point drying: p = 0.032). There were significant differences among the three drying methods (airdrying/ethanoldrying: p < 0.001). Similar tendencies were clearly observed with hydrophobic agents. But as compared to hydrophobic agent, hydrophilic shows higher strength. Conclusions: Ethanol drying was found to be an effective method for direct resin composite core build-up, as compared with two other methods, in terms of less residual liquid, less gap formation, and higher bond strength as compared to hydrophobic bonding agents.