Acid-buffering effect of Toothpaste containing S-PRG Filler

Objective:

S-PRG filler, which has a 3-layer structure including a glass-ionomer phase, shows bioactive effects (formation of acid-resistant layer, strengthening of tooth structure, anti-plaque effect, dentin remineralization, etc.) derived from its ability to release various ion species, as reported by several studies. This study aimed to evaluate ion-releasing ability and acid buffering capacity of S-PRG filler-containing toothpaste.

Methods:

S-PRG filler-containing toothpaste (0.4g) and distilled water (40mL) were stirred (23ºC, 24h) to prepare test solution. Then hydrochloric acid solution (0.1mol/L) was pipetted into the test solution at regular intervals with 0.1mL each time, and pH change in the mixed solution was measured using a pH meter. Test toothpastes prepared with different contents of S-PRG filler (filler particle size/content) were: PRG3-5 (3µm/5wt%), PRG3-30 (3µm/30wt%); and PRG-0 (0wt% of S-PRG filler) as control. For comparison, Colgate (Col) and Crest (CR) were also used.

Prior to addition of acid solution, test solution was also subjected to elemental analysis of ion species released from S-PRG filler contained in test toothpastes using ICP atomic emission spectrometry and fluoride ion electrode method. Data were statistically analyzed (ANOVA, Tukey's, p<0.05).

Results:

There were 6 elements (Al, B, F, Na, Si, Sr) observed in the test solutions with S-PRG filler-containing toothpastes. They showed gradual decrease in the pH with the addition of acidic solution, keeping the pH within the neutral region. In contrast, the pH in PRG-0, Col and CR decreased sharply in the initial stages of addition of acidic solution, and then stabilized in the low pH region.

Conclusion:

Test results revealed that S-PRG filler-containing toothpaste has acid-buffering capacity to inhibit the pH of surrounding environment from shifting to the acidic region due to the presence of six ions released from S-PRG filler.