The bleaching effect of office bleaching agents containing S-PRG filler evaluated by pH value and electron spin resonance.

Objectives: Surface reaction-type pre-reacted glass-ionomer (S-PRG) filler releases six types of ions with a neutralizing ability. This study evaluated the effect of S-PRG filler incorporation in an HO-based bleaching material on the bleaching efficacy, pH, and reaction state.

Materials And Methods: The experimental bleaching material was formulated by the addition of 5% or 10% S-PRG fillers to the powder part. The stained bovine teeth were treated with the prepared bleaching paste. Commission internationale de l'éclairage (CIE) L*a*b* color space values were recorded before and after bleaching, and the color difference (ΔE) and whiteness index (WI) were calculated. Moreover, the used bleaching formulations were assessed for their pH values and reaction state by evaluating the oxidation state of manganese (Mn) using electron spin resonance (ESR).

Results: The results of ΔE and WI showed that the addition of S-PRG filler increased the bleaching effect, but there was no significant difference between the groups with 5% and 10% S-PRG filler. A significant increase in pH in S-PRG filler groups (5% pH 6.7, 10% pH 6.8) was found compared to the 0% group (pH 4.8). ESR measurements showed that the signal emitted from Mn decreased over time. The S-PRG filler groups showed a significantly higher reduction in Mn compared to the 0% group, with no significant difference between the 5% and 10% S-PRG groups.

Conclusions: S-PRG filler addition resulted in improved bleaching efficacy, higher reaction rate, and pH values that are close to neutral.

Clinical Relevance: S-PRG filler addition may be effective on the bleaching outcome of HO-based materials.