Antibacterial Effects of an S-PRG Eluate on Polymicrobial Biofilms

Abstract

 Purpose: The removal of oral biofilm to prevent dental diseases and systemic conditions has been investigated in recent years. In environments where oral cleaning is difficult, such as during a disaster, biofilm increases susceptibility to pneumonia and infections, requiring a simpler and more effective means of oral care. The present study used polymicrobial biofilms from saliva to investigate the antibacterial effects of surface pre-reacted glass-ionomer (S-PRG) filler eluate on biofilm. The eluate contained fluoride and other ions (BO₃^3-, Na⁺, Sr²⁺, SiO₃^2-, and Al³⁺).
 Methods: S-PRG filler was suspended in distilled water, and the clear supernatant was used as the S-PRG eluate (110.5 ppmF). Buffered McBain 2005 culture medium prepared with this eluate was used for group S. Thereafter, buffered McBain 2005 was used to adjust 2-fold and 10-fold diluted culture containing S-PRG filler eluate (0.5S and 0.1S samples). For group F, NaF solutions with the same concentration of fluorides as that of S-PRG filler eluate, culture medium containing 2-fold and 10-fold diluted NaF (0.5F and 0.1F samples), were similarly created. These six solutions were used as test media. Buffered McBain 2005 medium was used as a standard medium for the control sample (Cont). A polymicrobial biofilm model was cultivated on glass plates in buffered McBain 2005 medium with stimulation saliva of one healthy subject and by continuous anaerobic culture for 24 h at 37°C. The media were refreshed at 10 h. Thereafter, anaerobic culture was performed using the test media from 24 hours until 48 hours following commencement of the experiment, to investigate the impact of S-PRG eluates. These media were refreshed at 34 h. In each sample, pH values were measured after 24, 34, and 48 h. The CFU count of each group was measured after 48 h. The data of pH and CFU were statistically analyzed (One-way ANOVA, Games-Howell test, p<0.05).
 Results: The pH value of S after 34 h was 6.8, and that of 0.5S was 6.4. After 48 h, the pH of S was 6.8, a significantly higher value than those of the other samples. CFU counts (CFU/ml) after 48 h were: S: 1.7×10⁷, 0.5S: 1.2×10⁸, F: 8.6×10⁷, and 0.5F: 2.3×10⁸. These values were significantly lower than that of Cont (5.8×10⁸). Group S showed significantly lower values compared to group F.
 Conclusion: Various kinds of ion contained in the S-PRG eluate affect biofilm, indicating the possibility that they can reduce live bacterial counts.