Document Type : Original Article

Authors

1 Dept. of Operative Dentistry, School of Dentistry, Dental Research Center, Mashhad University of Medical Sciences, Mashhad, Iran

2 Dept. of Pharmasotics, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran

3 Dept. of Operative Dentistry, School of Dentistry, Hamadan University of Medical Sciences, Hamedan, Iran

Abstract

Statement of Problem: Free surface energy of substrate is an important factor for adhesion. High free surface energy results in increased wetness  and better adhesion.Purpose: The aim of the present study was to evaluate the effect of different  rinsing times after cutting with a suggested coolant on the free surface energy of the dentin.Methods and Material: In this in-vitro experimental study, 75 intact human premolar were randomly assigned into 5 groups: 1) Cut with water coolant, 5 seconds of rinse with water. 2) Cut with water coolant, 5 seconds of rinse with water, etch, rinse. 3) Cut with a suggested coolant (0.5 surfactant/HLB=7), 5 seconds of rinse with water. 4) Cut with a suggested coolant, 10 seconds of rinse with water, and 5) Cut with suggested coolant, 15 seconds of rinse with water. Free surface energy was measured by estimating the contact angle. The statistical analyses were performed using one-way ANOVA and Tukey tests.   Results: The surface energy means (dynes/cm) of groups 1 to 5 were 75.87, 46.00, 74.86, 72.64 and 70.05, respectively. The results of one-way ANOVA showed a significant difference among the five groups (p =0.000). The Tukey test showed that except groups 1 and 3 ( p =0.678), there was a significant difference in all the other groups ( p <0.05).Conclusion: Etching reduces the dentin surface energy. The surface free energy of the cut dentin with a surfactant as a coolant and then rinsing with water for 5 seconds is equal to dentin which is not etched.  Rinsing for more than 5 seconds (10 or 15 seconds) reduces the dentin surface energy.Key words: Smear layer, Surface-active agent, Surface free energy, dentin, surfactant