this application is directed to methods of assessing polymer deposition on dental surfaces using near infrared spectroscopy , providing a rapid and efficient method to screen for and identify optimal polymers for use in oral care formulations , near infra red absorption of a dental substrate is measured in the absence of a polymer under test , and subsequently of the test sample comprising the dental substrate contacted with the test polymer . after washing or rinsing the test sample near ir of it is determined again . the ir absorption of the test polymer itself is also measured . through the comparison of the three measurements , , and the degree of deposition and retention of the test polymer on the test sample is determined .