Calcium-Polyphosphate Submicroparticles (CaPP) Improvement Effect of the Experimental Bleaching Gels' Chemical and Cellular-Viability Properties.

The aim of this research was to develop and characterize the chemical and cellular-viability properties of an experimental high-concentration bleaching gel (35 wt%-H 2 O 2 ) containing calcium-polyphosphate particles (CaPP) at two concentrations (0.5 wt% and 1.5 wt%). The CaPP submicroparticles were synthesized by coprecipitation, keeping a Ca:P ratio of 2:1. The CaPP morphology, size, and chemical and crystal profiles were characterized through scanning and transmission electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction, respectively. The assessed bleaching gels were experimental (without CaPP); 0.5% CaPP; 1.5% CaPP; and commercial. The gels' pH values and H 2 O 2 concentrations (iodometric titration) were determined. The odontoblast-like cell viability after a gel's exposure was assessed by the MTT assay. The pH and H 2 O 2 concentration were compared through a repeated-measures analysis of variance (ANOVA) and a Tukey's test and the cell viability through a one-way ANOVA and a Tukey's test using a GraphPad Prism (α < 0.05). The CaPP particles were spherical (with Ca and P, 135.7 ± 80.95 nm size) and amorphous. The H 2 O 2 concentration decreased in all groups after mixing ( p < 0.001). The 0.5% CaPP resulted in more-stable pH levels and higher viability levels than the experimental one ( p < 0.05). The successful incorporation of CaPP had a positive impact on the bleaching gel's chemical and cellular-viability properties when compared to the experimental gel without these particles.