OBJECTIVETo investigate the relationship of the levels of proteins in parotid saliva, whole saliva and dental plaque fluid with caries susceptibility.

METHODSSixty-six of university students were selected as subjects, 39 in caries-free group (CF, DMFS = 0) and 27 in caries-susceptible group (CS, DMFS >/= 8 and DT >/= 3). Total protein concentration was detected with Lowry method. Protein compositions were separated with SDS-PAGE and alkaline electrophoresis. The gels were analyzed using an image evaluation system.

RESULTSTotal protein level in dental plaque fluid was about 10-fold higher than that in saliva. Whole saliva was closely related to dental plaque fluid in terms of proteins only in CF group (r = 0.804), but there was little relation in CS group. The proteins that occurred in all three fluids were 14 000, 66 000 and 76 000 proteins. The 14 000, 15 000 and 38 000 proteins level in dental plaque fluid and 14 000 protein level in whole saliva were significantly lower in CS group than in CF group.

CONCLUSIONSThe proteins of dental plaque fluid are influenced significantly by whole saliva in CF group. The results suggest some kinds of proteins in dental plaque fluid and in whole saliva might play important roles against caries.