Viii PREFACE 



either some organic coating or a different crystal structure of tlie 

 denticles, or both. 



In addition to such potential protection of the inorganic phase 

 against demineralization, other factors appear to control the en- 

 zymatic breakdown of the underlying organic framework. Observa- 

 tions on the action of collagenase suggest that the amorphous 

 ground substance may serve as a protective coating wliich could 

 modifv the coUagenolytic activity. The pertinence of this concept 

 in dissolution of bones and teeth has not been fully established. The 

 very same substance, presumably an acid mucopolysaccharide, has 

 been thought to be involved in the process of calcification ( see Cal- 

 cification in Biological Systems). The two concepts could conceiv- 

 ably be reconciled, however, were one for the moment simply to 

 suggest that the ground substance serves a stabilizing function. 



When all is said and done, it will appear that the weakest link in 

 our present fundamental understanding of the mechanisms involved 

 in dissolution of mineralized structures relates to the specific chem- 

 ical agents located in immediate juxtaposition to the dissolving sur- 

 faces. Whereas the living culprits of destruction generally can be 

 identified at the "scene of the crime" — be they gastropods, mollusks, 

 sponges, algae, fungi, osteoclasts, or bacteria — the precise micro- 

 environments in which these biological systems operate present 

 great difficulties in research and consequently certain differences in 

 . interpretation. 



It is hoped that this volume may serve as a springboard for fur- 

 ther research on hard tissue biology throughout the animal king- 

 dom, especially at the relatively unexplored level of molecular 

 biology. 



REmAR F. SOGNNAES, Editof 



Program Chairman and 

 Retiring Secretary, 

 AAAS Section on Dentistry 

 September, 1963 



