Biological Changes at the Tooth-Saliva Interface

studies showed that cementum exposed to the oral environment can calcify beyond the normal level. Evidence of exchange of mineral and organic components across the tooth-saliva interface became morpholog-ically detectable within a few weeks after thorough planing of cementum and root dentin. In recent years considerable interest has been centered on the enamel-saliva interface. Less effort has been devoted to the study of biological processes at the cementum-saliva interface, even though the opinion prevails that alterations do occur within and at the surface of cementum after its ex-posure to the oral cavity in periodontal disease and that these alterations interfere with healing after periodontal reattachment operations. Previous histological studies of alterations of cementum associated with pathologic con-ditions have been concerned mainly with quantitative changes, including resorp-tions,-3 fractures,4'5 and hypercementosis,6-9 although some study has been made of cementum caries using optical microscopyL0 and biophysical technics."'-15 Periodontal disease occasionally has been associated with altered permeability of the cementum,'6"17 decreased uptake of 32p,18 occurrence of cer-vical radiolucent areas,'9 changes in hardness of the cementum and underlying dentin,20'2' occurrence of brownish granules in histo-logic sections of exposed cementum and subjacent dentin, 22,23 and increased root surface roughness.24 Chemical analysis has indicated an in-creased mineral content of cementum that is exposed to the oral cavity because of ad