Relative significance of cellular and chemical remodeling of bones and teeth as revealed by radioactive isotopes

This presentation has dealt with the basic similarities and differences between skeletal and dental hard tissues. The structural basis for the biologic behavior peculiar to these various hard tissues has been discussed in the light of recent information gained from radioactive isotope studies. Teeth normally tend to be protected from the cellular type of remodeling to which bone is physiologically subjected in connection with functional adaptation and calcium withdrawal. However, teeth appear to share with bone a process of exchange or turnover of the chemical building blocks. Furthermore, the teeth are subject to a two-way traffic of various ions, both from within outward and from without inward. It is suggested that the relationship between the saliva and the enamel is similar in kind, even though not in magnitude, to that existing between connective tissue fluid and the other hard tissues-bone, cementum, and dentine. The possibility of withdrawal of ions after eruption has been suggested. In this connection, research on the teeth has been neglected as compared to research on bone, because the dental hard structures contribute, relatively little to the metabolic pool. However, the similarity in submicroscopic structure and microchemical composition between bones and teeth suggests that both are involved in metabolic interrelationship between tissue fluids and hard tissues. The significance of these interrelationships in the maintenance of dental health and in the susceptibility to dental pathology requires further study.