PROTEOGLYCANS ATTHEBONE-IMPLANT INTERFACE M.M. Klingerl*

Thewidespread success ofclinical implantology stems frombone's ability toformrigid, load-bearing connections totitanium andcertain bioactive coatings. Adhesive biomolecules intheextracellular matrix arepresumably responsible for muchofthestrength andstability ofthese junctures. Histochemical andspectroscopic analyses ofretrievals havebeensup- plemented bystudies ofosteoblastic cells cultured onimplant materials andoftheadsorption ofbiomolecules totitanium pcowder. These datahaveoften beeninterpreted tosuggest that proteoglycans permeate athin, collagen-free zoneatthemost intimate contact points withimplant surfaces. This conclusion hasimportant implications for thedevelopment ofsurface mod- ifications toenhance osseointegration. Theevidence forproteoglycans attheinterface, however, issomewhat less thancom- pelling duetothelack ofspecificity ofcertain histochemical techniques andtopossible sectioning artifacts. Withthis caveat inmind, wehavedevised aworking modeltoexplain certain observations ofimplant interfaces inlight oftheknownphysical andbiological properties ofboneproteoglycans. This modelproposes that titanium surfaces accelerate osseointegration by causing therapid degradation ofahyaluronan meshwork formed aspart ofthewound-healing response. Itfurther suggests that theadhesive strength ofthethin, collagen-free zoneisprovided byabilayer ofdecorin proteoglycans heldintight asso- ciation bytheir overlapping glycosaminoglycan chains.