Optimal and practicable designs for measuring plaque pH-profiles.

Abstract

The shape of the plaque pH-profile after consumption of a food item determines the food's potential caries risk. This and related facts have caused an increased interest in measurements of plaque pH-profiles during the last decade. A standard design for these measurements is to take equally spaced observations over a certain period of time. The theory of optimal experimental design gives methods for positioning the measurements of a pH-profile in an optimized way. The objective is to minimize the effort given a desired precision of the estimated profile characteristic or to maximize the precision given the number of measurements. We show that a reduction in the number of measurements up to 50 per cent or a respective improvement in precision of the estimates as compared to standardly applied designs is possible. This implies less inconvenience for the subjects and better compliance with the needs of investigation. Our study is intended to demonstrate the applicability of the theory of optimal experimental design which has the potential to improve the efficiency of medical research.