Evaluating the effect of dentin surface pretreatment on the static contact angle of a drop of a bonding agent: an in vitro study

Introduction: The aim of this study was to investigate the effect of dentinal pretreatment on the static contact angle of a bonding agent as a measure of dentin surface wettability. Materials &Methods: Twenty mid-coronal dentin surfaces were prepared and randomly allocated to four groups (n=5) according to the priming solutions. All segments were etched with 35% phosphoric acid gel for 15 s, rinsed for 30 s and dried. Each group was rehydrated with 10 &micro;L of distilled water, 0.2 % chlorhexidine, 70% ethanol and 5.25% Sodium Hypochlorite respectively and the excess solution was removed after 60 sec using an absorbent paper. Using a micro syringe, a droplet of the Adper Single Bond 2 was placed on each prepared surface. Then the profile and the static contact angle of the droplet were analyzed with a video-based optical contact angle measuring system. The statistical analysis was performed using One-way ANOVA and Dunnett&rsquo;s t tests (p<0.05). Results: There was a statistically significant difference between the water and sodium hypochlorite groups which indicates the negative effect sodium hypochlorite may have on dentinal surface energy. (p=0.013). The differences between the water and ethanol groups (p=0.168) and between the water and chlorhexidine groups (p=0.665) were not significant. Conclusion: The use of 5.25% sodium hypochlorite as a priming solution in bonding procedure is not recommended. There is no improvement in dentinal surface wettability by using 70% ethanol or 0.2% chlorhexidine instead of water and the recommendation for use of any of the two should be based on other long-term or short-term effects they may have on the bonding procedure.