The shape of the plaque pH-profile after consumption of a food item de
termines the food's potential caries risk. This and related facts have
caused an increased interest in measurements of plaque pH-profiles du
ring the last decade. A standard design for these measurements is to t
ake equally spaced observations over a certain period of time, The the
ory of optimal experimental design gives methods for positioning the m
easurements of a pH-profile in an optimized way, The objective is to m
inimize the effort given a desired precision of the estimated profile
characteristic or to maximize the precision given the number of measur
ements, We show that a reduction in the number of measurements up to 5
0 per cent or a respective improvement in precision of the estimates a
s compared to standardly applied designs is possible, This implies les
s inconvenience for the subjects and better compliance with the needs
of investigation, Our study is intended to demonstrate the applicabili
ty of the theory of optimal experimental design which has the potentia
l to improve the efficiency of medical research.