Development of long-term antimicrobial poly(methyl methacrylate) by incorporating mesoporous silica nanocarriers.

Objective: Poly(methyl methacrylate) (PMMA) used as removable denture bases or orthodontic appliances has relatively poor antimicrobial properties, which accelerate oral infection and induce unfavorable odors. Mesoporous silica nanoparticles (MSNs) have been highlighted as a potential additive to overcome this issue because of their drug-loading capacity. Here, we present the long-term antimicrobial effect of MSN-incorporated PMMA with drug-loading capacity.

Methods: After the MSNs were characterized, MSN incorporation into chemically activated PMMA (0.5, 1, 2.5 or 5wt%) relative to the methyl methacrylate powder by mass was fabricated into a rectangular specimen (1.4×3.0×19.0mm) for a 3-point flexural test at a speed of 1mm/min or a disk (∅=11.5mm and d=1.5mm) for investigation of its antimicrobial effects.

Results: A typical spherical morphology with a well-ordered mesoporous structure of the MSNs was visualized and is beneficial for loading drugs and combining in matrixes. Among the tested levels of MSN incorporation in PMMA (0.5, 1, 2.5 or 5wt%), only 5wt% decreased the flexural strength (p<0.05), whereas the flexural modulus was not significantly decreased (p>0.05). The surface roughness and surface energy were increased with 2.5wt% or 5wt% incorporation. An anti-adherent effect against Candida albicans and Streptococcus oralis after 1h of attachment was only observed with 2.5 and 5wt% incorporation compared to a lack of MSNs (p<0.05). A long-term antimicrobial effect was observed for 2 weeks with 2.5wt% MSN-incorporated PMMA when amphotericin B was loaded into the MSNs on the PMMA surface.

Significance: The long-term antimicrobial performance after loading amphotericin B into the MSN-incorporated PMMA suggests the potential clinical usefulness of MSN-incorporated PMMA resin.