# Fluoride Content, Availability, and Stability in a Propolis-Based Dentifrice

## TL;DR

This study tested how stable fluoride in a propolis-based toothpaste remains over two years.

## Contribution

The study provides new data on fluoride stability in a dentifrice containing Brazilian red propolis over a 24-month period.

## Key findings

- Total fluoride decreased from 1500 μg/g to 763.5–1083.1 μg/g after 24 months.
- Soluble and ionizable fluoride levels also declined significantly after 24 months.
- Fluoride remained relatively stable for the first 12 months of storage.

## Abstract

Purpose: This study aims to verify the stability of different types of fluoride in a dentifrice containing Brazilian red propolis (BRP).

Methods: The dentifrice formulation was developed with calcium carbonate (CaCO3) and sodium monofluorophosphate (MFP) (patent INPI BR1020170110974). Nominal fluoride content was 1500 μg/g. Batches of five lots were selected and analyzed for 2 consecutive years (fresh, with 12 and 24 months). Dentifrices from each tube were analyzed in duplicate using an ion-specific electrode (ISE). The concentrations of fluoride (total fluoride [TF], total soluble fluoride [TSF], and ionizable fluoride [IF]) were determined, and the results were expressed in ppm F (μgF/g).

Results: After 12 months of aging, the samples showed TF concentration ranging from 1198.9 ± 26.9 to 1443.6 ± 33.4 ppm F, TSF ranging from 869.6 ± 105.5 to 965.8 ± 149.8 ppm F, and IF ranging from 223.5 ± 14.8 to 269.7 ± 10.1 ppm F. After 24 months of aging, the samples showed TF concentration ranging from 763.5 ± 73.2 to 1083.1 ± 32.4 ppm F, TSF ranging from 552.3 ± 39.9 to 758.4 ± 141.1 ppm F, and IF ranging from 102.2 ± 4.0 to 174.7 ± 4.9 ppm F.

Conclusion: Soluble fluoride remained relatively stable until 12 months of aging; however, at 24 months of aging, the concentration reduced.