Evaluation of an Adhesive Containing Calcium Salt of Acidic Monomers on Inhibition of Biofilm Formation of Bacteria Related to Root Caries

Root caries is a critical dental problem for the elderly people due to increased tooth retention and exposed root surfaces in aged society. The presence of a cariogenic biofilm and fermentable carbohydrates is the main etiologic factors. Streptococcus mutans, lactobacilli and Actinomyces spp. have been demonstrated to be associated with root caries. Currently, dental materials with multifunctional features have been combined into clinical adhesives. Calcium salt of acidic monomer (calcium salt of 4-methacryloxyethyl trimellitic acid or CMET) has been demonstrated to promote a significant remineralization and an adhesive containing CMET has been developed. However, there is no data regarding its antimicrobial potential. This study aimed to evaluate the property of an adhesive containing CMET and 10-methacryloyloxydecyl dihydrogen calcium phosphate (MDCP) on the biofilm formation of bacteria related to root caries. The adhesive was applied onto the flat-bottom surface of 96-well plate and LED light-cured. Then it was coated with sterile saliva at 37 °C for 60 min. The bacterial suspensions of 107 colony forming unit (CFU)/mL (Streptococcus mutans ATCC 25715, Lactobacillus casei ATCC 334 and Actinomyvces viscosus ATCC 19246) were added and incubated at 37°C in 5% CO2 atmosphere for 24 h to allow the biofilm formation. The amount of vital biofilm was determined by WST-8 Microbial Cell Counting Kit (Dojindo Molecular Technologies, USA). All tests were carried out in triplicate and repeated three times. Student’s t-test was employed for the statistical analysis. The significant suppressive effects were clearly noticed on S. mutans compared with a control. The percentage of biofilm reduction was nearly 65%. A 2% biofilm reduction was found on L. casei and A. viscosus, though no statistical significant decreases of biofilm were observed compared with a control. In conclusion, an adhesive containing calcium salt of acidic monomers could significantly inhibit biofilm formation of S. mutans. Using this adhesive can be beneficial for the prevention of root caries on the tooth surface.