Dentin Permeability and Bactericidal Effects of MDPB-containing Cavity Disinfectant

Objectives: Previously, we reported that a cavity disinfectant containing an antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) demonstrated greater bactericidal effects than the commercially available chlorhexidine-containing disinfectant (Hirose et al., J Dent Res, 2016). In this study, to further investigate the effectiveness of this experimental cavity disinfectant, its penetration depth into dentinal tubules and the effects to kill bacteria in dentin were assessed by using a confocal laser scanning microscopy (CLSM).
Methods: The experimental cavity disinfectant (ACC), prepared by adding MDPB at 5% into 80% ethanol, and the commercial disinfectant containing 2% chlorhexidine (CPS; Consepsis, Ultradent) were used. Each solution with 0.07% Rhodamine B was applied to the dentin block obtained from the human coronal dentin, and the penetration depth was measured by observation using CLSM. Infected dentin model with bacterial invasion into dentinal tubules up to 50 µm was prepared by incubating the dentin block in Streptococcus mutans NCTC10449 suspension for 6 hours, and treated with each cavity disinfectant. After vertically fractured, the block was stained with LIVE/DEAD BacLight Bacterial Viability Kits and observed by CLSM to evaluate viability of bacteria in dentinal tubules.
Results: ACC penetrated into dentinal tubules beyond the bacterial invasion level, demonstrating significantly greater depth than CPS (p < 0.05, Tukey’s HSD test). CLSM observation with LIVE/DEAD staining confirmed that ACC could completely kill the bacteria in dentin, while the bactericidal effects of CPS were limited.
Conclusions: The experimental MDPB-cavity disinfectant was found to have greater dentin permeability and be more effective in killing bacteria in the dentinal tubules than the commercially available chlorhexidine-containing disinfectant.