Recent Studies on Nonspecific Aspects of Intraoral Adhesion

There is usually a high number of microorganisms present in the oral cavity, yet it takes some time for the first microorganisms to attach in vivo on clean solid surfaces. Similar patterns of microbiological adhesion can be observed in vitro and, conversely, in vivo attachment of non-biological colloidal particles occurs readily. This indicates that primary physical forces rather than biological specificities are responsible for initial adhesion of microorganisms and similarly shaped particles to teeth and restorations. Under physiological conditions, oral adhesive events are probably based on general types of physico-chemical interactions, and might be mainly controlled by the properties of the spontaneously adsorbed biological films that precede particle attachment. A variety of surface physico-chemical techniques, monitoring formation of biological films and attachment of biological, as well as nonbiological particles of colloidal dimensions both in vivo and in vitro on various solid surfaces, indicated that the formation of oral biological films proceeds at high speed and precedes particle attachment. Further, when different surfaces were clinically exposed to saliva and covered with such biological films, their significant original differences in surface properties could no longer be detected. Continuing differences in strength of particle adhesion to these surfaces must result, therefore, from differences in binding of the initial salivary films.