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

The pellicle cleaning ratio (PCR) test can be used to evaluate the stain removal performance of oral care products and dentifrices such as toothpaste or toothpowders. Consumers' desire for whiter teeth has driven the innovation of many new dentifrice products in recent years with formulation research and development focussed on novel stain removal agents which have either a mechanical stain removal function or non-mechanical function. If you are developing a new tooth stain removal product, then a robust, rapid and reproducible pellicle cleaning ratio based laboratory test can help you to rank the stain removal capability of your formulations or ingredients and guide further development or support your marketing claims.

Tooth stain build-up occurs when chromophores from food and drinks bind to the protein pellicle on teeth enamel surfaces. 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 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. We are particularly adept in designing bespoke in vitro models to cater for your specific requirements. Intertek Clinical Research Services is licensed to handle and store human tissue under the Human Tissue Act 2004 and follows the principles outlined within the act as well as complying with local ethical guidelines.

Video: tooth whitening assessment

In Vitro Research Services for Oral Care Product Development