Preferential affinity of oral bacteria for homologous salivary films on dental materials.

Freshly isolated strains of Streptococcus mutans from saliva of two test subjects were tested for adhesion to various dental gold alloys and one brand of luting cement. The materials were covered with pellicle derived from one or the other of the two subjects. In "crossover" experiments it was consistently found that S. mutans adhered in greater numbers to pellicles of homologous origin. This preference for the homologous pellicle appeared to vary among the materials tested as substrates; also, the total number of organisms adhering varied among the materials. Moreover, different isolates varied in their affinity for the materials and showed a varying degree of dependence on homologous pellicle for adherence. In vitro plaque formation of mixed oral flora on pellicle-coated dental casting gold alloy were also more abundant on homologous pellicles as compared with heterologous ones. The results support the view that biologically specific mechanisms contribute to the adhesion of bacteria to dental restorative materials, and to the build-up of a bacterial plaque on these materials.