The importance of methodology in the evaluation of pulp reactions

Studies of pulp reactions to restorative materials are the final arbiter of the acceptability of the material for clinical use. The techniques commonly employed suffer from the occurrence of artefacts which may lead to incorrect conclusions being drawn. Many of these errors can be avoided by strict adherence to methodology in the choice and processing of specimens and in the interpretation of histological findings. Attention is drawn to the lack of correlation between clinical symptoms and histological appearances. The effects of specimen preparation, including fixation and demineralization are discussed in relation to both the pulp and its surrounding dentine. The advantages and disadvantages of using young teeth in preference to those from older individuals and of carious as against intact teeth are set out. The application of results in tests on animal teeth to the human situation is shown to be unreliable because of differences in composition and reaction time. Methods of inducing inflammatory changes in normal pulps are described and the possibility of using other criteria for the investigation of pulp reactions is explored.