Bond Performance of Universal Adhesives with Different Application Times

Objectives: This study determined the effect of adhesive application time in different etching modes on enamel and dentin bond performance of universal adhesives.
Methods: Five commercially available and an experimental universal adhesives were used: Adhese Universal (AU), Clearfil Universal Bond Quick (CQ), G-Premio Bond (GP), Scotchbond Universal (SU), Tokuyama Universal Bond (TU), and one experimental universal adhesive from 3M ESPE (EU, ADH-XTE). Bovine enamel and dentin specimens were divided into four groups of ten for each adhesive. Shear bond strengths were determined after the following surface treatments: 1) self-etch (SE) mode with immediate air-blowing after adhesive application (IA), 2) self-etch mode with prolonged application time (PA), 3) Etch & rinse (ER) mode with IA, and 4) ER mode with PA. Bonded specimens were subjected to SBS testing after 24 h water storage.
Results: For enamel SBS, significantly higher SBS values were obtained with ER mode than with SE mode regardless of the application time or type of adhesive. For dentin SBS, AU, SU, and EU for which the instructions require longer application times, showed significantly lower SBS values in IA than in PA in both etching modes. Representative SBS values in SE mode are shown in the table below.
Conclusions: Reduced application time appears acceptable for universal adhesives that are designed for air-blow immediately after adhesive application regardless of the etching mode or tooth substrate.