Infiltration of antibacterial dentine bonding agents into root caries

OBJECTIVES: The UK population is ageing and retaining more natural teeth into later life. There is hence an increase in the incidence of dental diseases such as root caries in this generation. Classical treatment of root caries involved removal of carious tissue and replacement with an adhesive restoration. A novel treatment proposes using an antimicrobial dentine bonding agent to infiltrate the carious dentine layer, as a minimally invasive, conservative procedure. The antibacterial agent MDPB (MethacryloxyDodecyl-Pyridinium Bromide) has previously been shown to be active against bacteria found in carious lesions. This study examines the extent to which the bonding agent can infiltrate the natural carious lesion, therefore allowing access to the infected dentine layer. METHOD: Six extracted teeth with root caries were gently cleaned with a prophylaxis brush, stored in saline and tested within one week of extraction. Rhodamine B was added to the primer and bond of an experimental resin bonding agent (Clearfil ABF incorporating MDPB, Kuraray Medical Inc., Japan), prior to these being applied to the surface of the carious lesions according to the manufacturers instructions. The teeth were longitudinally sectioned and examined with confocal and light microscopes. The depth of resin infiltration and extent of carious lesion were measured. RESULTS: Depth of resin infiltration (mean=0.64, s.d.=0.13) was closely related (p=0.73) to the dark stained dentine layer (mean=0.67, s.d.=0.26), which is associated with the caries infected dentine layer. CONCLUSION: Infiltration of natural root surface carious lesions by the antimicrobial dentine bonding agent incorporating MDPB was sufficient to enable the antimicrobial agent to contact infected areas, and therefore may offer potential for minimally invasive treatment of root caries.