Evaluation of Ca-P coatings in animal experiments: importance of study design

During the last decennium the research on oral implants has increased considerably. A lot of different implant materials and types have been tested, but differences in study design and evaluation criteria make comparison of the results difficult. The purpose of this paper is to discuss surgical, statistical, and histological methods for testing and evaluating the biocompatibility of oral implants. Many formulas are available for calculating the required group size. The paper describes how such calculations can be used for the evaluation of implants and reviews the preferred surgical techniques. The control of various external influences that can contribute to the variability in obtained data are discussed. After implantation, the implants with their surrounding tissues are retrieved and subjected to histological evaluation. Currently, because of technical limitations, light microscopical sectioning is still the preferred preparation technique. After sectioning, quantitative analysis has to be performed. The parameters that can be evaluated are described. Finally, the use and potential of the described techniques are demonstrated with two examples.