SALIVA MEDIATED ADHERENCE, AGGREGATION AND PREVALENCE IN DENTAL PLAQUE OF STREPTOCOCCUS-MUTANS, STREPTOCOCCUS-SANGUIS AND ACTINOMYCES SPP IN YOUNG AND ELDERLY HUMANS

Salivary components in the pellicle mediate bacterial adherence to the tooth. Such components may also aggregate bacteria in saliva and prev ent them becoming established in dental plaque. In the present study, the adherence and aggregation of Streptococcus mutans strain Ingbritt, S. sanguis strain 10556 and Actinomyces viscosus strain 19246 mediate d by parotid and whole saliva from groups of young and elderly people were examined. Significant differences were found between test strains , salivary secretions and age groups. S. sanguis 10556 and A. viscosus 19246 generally adhered more strongly than S. mutans Ingbritt, which adhered better to pellicles from parotid saliva than from whole saliva . Strain 19246 bound in higher numbers to parotid saliva pellicles fro m elderly compared to young individuals. Strain 10556 adhered better t o whole saliva than parotid saliva pellicles, and the difference was s ignificant among the young individuals, indicating reduced adherence a bility in elderly whole saliva. The streptococci were aggregated by pa rotid and whole saliva, and S. sanguis aggregation was less with whole saliva from the elderly than from the young participants. Besides a c orrelation between whole saliva aggregation of S. mutans and proportio ns of bacteria in plaque, no correlations were found for the individua l binding properties of saliva and prevalence of bacteria in vivo. How ever, the level of saliva-mediated adherence in vitro was in the follo wing order: S. mutans < Actinomyces S. sanguis, which corresponded to their isolation frequency in plaque. These findings emphasize the impo rtance of initial adherence to salivary receptors in bacterial coloniz ation on teeth. Further studies are needed to reveal if individual pat terns in the ill vitro binding characteristics of saliva lead to varia tion of colonization in vivo. (C) 1997 Elsevier Science Ltd.