Bioactive caries-preventing effects of mineral ions released from surface pre-reacted glass-ionomer (S-PRG) filler on oral biofilm

Abstract

Objective

The bioactive caries-preventing effects of mineral ions released from surface pre-reacted glass-ionomer (S-PRG) filler on oral biofilm were estimated by analyzing the depth-specific density of Streptococcus mutans and Streptococcus sanguinis.

Design

Ten participants wore in situ plaque-generating enamel slab devices on their upper molars to form biofilm for 5 days. Filtrates were prepared from prophylaxis paste slurries containing S-PRG filler, whereas paste without the filler served as the control. The devices were alternately immersed in sucrose solution three times and in the experimental or control filtrate twice each day. Two biofilm samples taken from each device were separated into 6–9 layered fractions (100 μm each) by serial sectioning. One sample was used for extraction of genomic DNA. The gene sequences encoding D-alanine:D-alanine ligases were amplified using universal and species-specific primers. Borate, aluminum, silicate, and strontium concentrations were determined using thicker sections of the other sample, correcting for biomass volume estimated by the area measurement of stained thinner sections.

Results

The ratios of S. mutans to S. sanguinis in the outer, middle, and inner layers were 0.0359, 0.0254 and 0.0157 for the experimental biofilm and 0.046, 0.0325 and 0.0255 for control biofilm, respectively. The ratio in the whole layer was significantly lower in the experimental biofilm than control biofilm. Strontium and aluminum concentrations in the experimental biofilm were 114- to 146-fold and 2.74- to 4.48-fold higher compared with control biofilm. respectively.

Conclusions

These results suggest that S-PRG filler has bioactive caries-preventing effects on oral biofilm.