Suppression of Periodontal Bacterial Interactions by Pre-reacted Glass Ionomer Filtrate

Objectives: Pre-reacted glass ionomer (S-PRG) filler particles are formed by an acid–base reaction between fluoroaluminosilicate glass and polyacrylic acid. S-PRG fillers are capable of fluoride release and recharge; several other ions (Al, B, Na, Si, Sr) can also be released from this material. We previously found that S-PRG filtrate suppresses a number of biological properties of Porphyromonas gingivalis. Given that periodontitis is a mixed infection involving several bacterial species, in this report, we evaluated the effect of S-PRG on bacterial interactions.
Methods: S-PRG filler was mixed with distilled water and shaken gently at room temperature for 24 h. The filler was removed by filtration, and the ion-containing filtrate was centrifuged to remove any residual insoluble material. P. gingivalis, Fusobacterium nucleatum, and Tannerella forsythia were cultivated anaerobically. Coaggregation and autoaggregation were examined by a visual assay and by measuring the optical density after deposition of bacteria. A sonicated extract of T. forsythia was added to the culture medium and growth of P. gingivalis was examined by monitoring turbidity. Then, the effect of adding S-PRG on suppression of growth enhancement was evaluated.
Results: The S-PRG filtrate reduced coaggregation between P. gingivalis and F. nucleatum but promoted autoaggregation of F. nucleatum. The sonicated extract of T. forsythia increased P. gingivalis growth, while the S-PRG filtrate suppressed this growth promotion.
Conclusions: Evidence has been brought that S-PRG filtrate, if used as an oral rinse, may reduce bacterial coaggregation thus hampering biofilm formation by different bacterial species. Moreover, its ability to increase autoaggregation may promote exclusion of bacteria from the oral cavity. Growth enhancement associated with infection by a mixture of bacteria is important in the progression of periodontitis; interestingly S-PRG filtrate could eliminate this phenomenon. This study suggests that S-PRG eluate may be of therapeutic interest against periodontitis.