174 McKernan/Dailly: The Relationship between Swelling of Hard Tissues Collagen 



would suggest that the "extra" cross-links are responsible for the structural acid 

 stability of both bone and dentine collagens. The nature of these cross-links has yet 

 to be elucidated but current information on the role of hexoses in cross-linking 

 collagen and their stability to oxidation suggest that such structures are likely to be 

 involved. 



Summary 



1. The swelling behaviour of purified bone collagen and corium collagen has been 

 investigated under both acid and alkaline conditions. 



2. In alkali both collagens show progressive swelling increases with time and, in 

 the case of bone collagen, there is a simultaneous release of phosphorus. In acid 

 solution no release of phosphorus was observed for bone collagen and no swelling 

 occurred. In contrast, corium collagen swelled by a factor of approximately 700Vo 

 under the same conditions. 



3. The results are consistent with the presence of acid-stable, alkali-labile cross- 

 links in bone collagen but not to the participation of phosphate cross-links in the acid 

 stability. 



4. The presence of additional, unidentified, cross-links which may well be common 

 to both dentine and bone collagens is proposed. 



Acknowledgments 

 The authors wish to express their gratitude to the Directors of British Glues and 

 Chemicals Ltd. for permission to publish this paper. 



References 



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