Pellicle Cleaning Ratio (PCR) Oral Care Product Stain Removal Testing

Pellicle cleaning ratio (PCR) testing for oral care product stain removal efficacy can support marketing claims or product development using human or bovine enamel samples can be applied to toothpastes or other dentifrices

The Pellicle Cleaning Ratio (PCR) test can be used to evaluate the stain removal performance of oral care dentifrices such as toothpaste or toothpowders. The consumers' desire for whiter teeth has driven the innovation of many new dentifrice products. If you are developing a new tooth stain removal product, then a robust, quick, reproducible test can help you to rank the stain removal capability of your formulation, guide further development or provide support for marketing claims.

Tooth stain build-up occurs when chromophores from food and drinks bind to the protein pellicle layer on the enamel surface. Dentifrices typically contain mild abrasives which help to remove stains during brushing and a PCR test is a means of comparing abrasivity against a reference abrasive agent or a benchmark product.

Our oral care product laboratory team routinely performs Pellicle Cleaning Ratio (PCR) testing to evaluate the stain removal performance of dentifrice products. To do this, bovine or human enamel slabs approximately 9mm square are embedded in plastic/acrylic blocks and stained with a mixture of tea, coffee, mucin, and iron chloride. The degree of stain is measured using a chromameter that records L*a*b* colour parameters and blocks (up to 16 per test cell) are stratified to test dentifrices and reference cells. Stained blocks are then brushed using an artificial brushing machine under specific conditions of load, speed, and duration, with slurries of the dentifrices made by mixing toothpaste or toothpowder with water. After brushing the L*a*b* parameters are re-measured and changes are calculated in terms of overall colour change (ΔE). Mean ΔE values for each dentifrice are calculated and compared to the reference abrasive thereby yielding a PCR value, which may fall into low, medium or high categories. PCR results can be statistically compared if required and are provided to the client in a reviewed and signed-off report.

For over 20 years our Clinical Research Services group has been bringing quality and safety to life as a trusted partner for developers and manufacturers of oral care products. We provide a one-source solution for in vitro studies providing robust data to support the efficacy of novel treatments.