Pellicle Cleaning Ratio (PCR)

In vitro Pellicle Cleaning Ratio (PCR) Testing and evaluation of toothpaste stain removal from human or bovine enamel samples

The Pellicle Cleaning Ratio (PCR) can be used to evaluate stain removal performance of dentifrices such as toothpastes or toothpowders. 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 removed stains during brushing. The PCR test is a means of comparing abrasivity against a reference abrasive or benchmark products.

The consumer desire for whiter teeth has driven the appearance of many new dentifrice products on the market. A robust, quick, reproducible test is required that can rank stain removal capability and guide formulation development or provide support for marketing claims.

Our oral care laboratory team routinely performs Pellicle Cleaning Ratio (PCR) testing to evaluate stain removal performance of dentifrice products. 

Bovine enamel slabs approximately 9mm square are embedded in plastic/acrylic blocks and stained with a mixture of tea, coffee, mucin and iron chloride. 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 fully signed-off report.

For over 18 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 both in vitro studies and human trials providing robust data to support the efficacy and safety of novel treatments. 

Intertek Clinical Research Services (CRS) has a dedicated in vitro laboratory which conducts testing of all aspects of Oral Care products. 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.
Our team of laboratory scientists have a combined experience of over 30 years of testing oral care products and between them have degrees/PhD/MSc in Dentistry, Chemistry, Analytical Chemistry and Biological Sciences. They have also contributed to a variety of scientific papers in collaboration with many well-known clients and have presented posters at international scientific conferences.
Need help or have a question? +44 (0) 151 347 4810

Need help or have a question?

+44 (0) 151 347 4810
Wirral (UK):
+44 (0) 151 347 4810