A method for studying adherence of oral streptococci to solid surfaces.

The adherence of different streptococci to test pieces of glass, human enamel and whale dentin carried in the mouth or immersed in saliva or bacterial suspensions was studied by examining the number and frequency of microorganisms which were selectively desorbed by a standardized washing technique. The results obtained from in vivo and in vitro experiments were similar in principle. The proportion of streptococci obtained in the first washing resembled that found in the saliva, but with more vigorous washing the proportion of S. sanguis increased while that of S. salivarius decreased. This illustrates that different microorganisms can attach to solid surfaces with different strengths. The applicability of the method was tested by treating dentin surfaces with fluoride solutions and by incorporating sucrose in the test solution. The fluoride treatment reduced while the sucrose addition increased the number of streptococci which could be removed from the surfaces.