Effect of salivary biofilm on the adherence of oral bacteria to bleached and non-bleached restorative material

Objective: The objective of this work was to examine the effect of in vitro salivary biofilm on the adherence of oral bacteria to bleached and non-bleached restorative material (Charisma®). Methods: Charisma® samples, prepared in silicon molds, were treated with either 10% carbamide peroxide (CP) or 10% hydrogen peroxide (HP). After incubation with the bleaching agent for a period of one, two or three days, the samples were coated with freshly collected human saliva. The adsorption pattern of the saliva to the restorative material was determined using gel electrophoresis coupled with computerized densitometry techniques. The amount of salivary proteins adsorbed onto the treated surfaces was measured using the Bradford method. Sucrose-dependent bacterial adhesion to the salivary-coated Charisma was tested using radio-labeled Streptococcus mutans, Streptococcus sobrinus and Actinomyces viscosus. Adhesion of each bacterium to surfaces pretreated with the bleaching agents was compared with saliva coated bleached surfaces. Results: The profile of salivary proteins adsorption followed a similar pattern in Charisma samples pretreated with either CP or HP or untreated samples. However, the total amount of salivary proteins adsorbed onto the samples decreased after bleaching with CP or HP. Salivary biofilm, coating the surface of the restorative material, significantly decreased sucrose-dependent adhesion of Streptococcus sobrinus and Streptococcus mutans to the bleached and non-bleached surfaces, compared to non-coated specimens (p < 0.05). Saliva had a minor effect on adhesion of Actinomyces viscosus. Significance: Our study demonstrates the importance of salivary biofilm in controlling adhesion of oral bacteria to restorative material pretreated with bleaching agents or untreated.