Clinical relevance of antimicrobial testing results for dental restorative materials

The antimicrobial activity of restorative materials is clinically relevant because all dental materials are subject to an environment containing bacteria. This study aimed to investigate the use of 2 methodologies referred to in the literature to assess antimicrobial properties of restorative materials and investigate whether material properties alter results of these traditional methodologies.

A number of dental restorative materials - namely, Chemfil Superior®, Spectrum®, Heliobond®, Ionoseal®, Dyract Extra®, Smart Dentin Replacement (SDR®) and Biodentine® - were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectroscopy and pH analysis. Antimicrobial activity was assessed using agar diffusion and biofilm accumulation tests. Key factors affecting results were assessed using analysis of covariance.

Biodentine after immediate mixing and Ionoseal aged for 6 weeks resulted in an inhibition zone, while significantly higher McFarland readings were observed in the presence of barium when using materials Ionoseal, Dyract and SDR at 24-hour aging. Through analysis of covariance it was shown that material properties affected methodology results.

Properties of materials affect results of antimicrobial testing, but this may not directly reflect the antimicrobial potential of the material in question. Careful choice of methodology and interpretation of results is important.