Efficiency in clinical trials of caries preventive agents and methods

The idea sequence of tests required to establish a caries prophylactic agent or procedure on a public health basis is described and a clear distinction is drawn between an experimental clinical trial, carried out under ideal conditions, and a community clinical trial carried out under real life conditions. Because of the artificial nature of an experimental clinical trial there are strict limitations placed on its objectives and the inferences that can be drawn from its results. Bearing these limitations in mind and using the data collected during a 3-year trial of a fluoride mouthrinse, two methods of improving the efficiency of experimental clinical trials of caries prophylactic agents are considered. Firstly, a reduction in length is suggested either by planning the trial to run for a shorter period in the first place or, alternatively, by stopping the trial when the criteria for success have been satisfied. Secondly, it is proposed that the number of subjects participating in the trial be reduced by excluding those whose contributions to the aims of the trial are likely to be low.