Novel Crown Cement Containing Antibacterial Monomer and Calcium Phosphate Nanoparticles

Objectives: Plaque accumulation at the crown/tooth interface is asignificant issue that can lead to caries formation, and subsequently the failure of the restoration. Therefore, the objective of this study were to: (1) develop a novel crown cement containing dimethylaminohexadecyl methacrylate(DMAHDM) and nano-sized amorphous calcium phosphate(NACP) for caries-inhibition, and (2) investigate mechanical, physical properties, and biofilm growth.
Methods: DMAHDM was synthesized via a modified Menschutkin reaction. NACP was made using a spray-drying technique. Novel crowncement was formulated using pyromellitic glycerol dimethacrylate and ethoxylated bisphenol-A dimethacrylate monomers(PEHB) at filler:matrix mass ratio of 45:55. Five resin cements were developed: (1) 45%glass fillers as an experimental control, (2) 25%NACP; (3) 25%NACP+3%DMAHDM; (4) 25%NACP+4%DMAHDM; (5) 25%NACP+5%DMAHDM. The mechanical and physical properties were assessed via dentin shear bond strength, film thickness, and flexural strength. To assess the antibacterial properties, 48-h S. mutansbiofilms were grown over the cement surface and the colony-forming units (CFUs) and the metabolic activities. The Kolmogorov-Smirnov test was used to test the normality, and one-way analysis of variance (ANOVA) was conducted to analyze the results.


Results: Adding 25%NACP, 5%DMAHDM createdthe highest film thickness(45.8±3.1mm) compared to the control(19.8±2.7mm)(P=<0.05), however, it is in an agreement with the ISO recommendations.The dentin shear bond strength values were comparable to the control (8.2±2.9MPa)(P=>0.05), and the highest value observed with the 25%NACP+3%DMAHDM group (11.2±3.4MPa). The flexural strength values of the experimental groups were comparable to the control (74.2±2.8MPa)(P=>0.05) except for 25%NACP+5%DMAHDM group (67.7±5.9MPa)(P=<0.05). Incorporating 3, 4, and 5%DMAHDM with NACP fillers reduced the CFUs and metabolic activities of the S. mutans biofilm.
Conclusions: The incorporation of NACP and DMAHDM into crown cement demonstrated strong antibacterial properties with clinically acceptable mechanical properties. This new nanostructured bioactive crown cement is promising to suppress caries and reduce failure rates of crown restorations.