Streptococcus sanguis and streptococcus salivarius in early plaque formation on plastic films

The presence of Strep.sanguis and Strep, salivarius during early plaque formation on plastic films has been studied in humans. The numbers of other cultivable bacteria were also evaluated. In 12 adults with clinically healthy gingiva, a thin transparent plastic film was applied to the buccal surface of one of the premolars in either the upper or the lower jaw. The films were left in place for different time intervals, from 10 seconds to 240 minutes. Samples for bacteriologic analysis were taken from a defined area of each film located just coronally to the gingival margin. At each time interval, a saliva sample was also taken from each individual. The various samples, showed bacterial growth at each time interval. Immediately after salivary contamination of the films, Strep, sanguis, predominated over Strep, salivarius while in the corresponding saliva samples these proportions were reversed. During the experimental period of 240 minutes the presence of Strep. sanguis on the film increased with increasing time, while the corresponding figures for Strep, salivarius were low. The film technique used seemed to provide an adequate method for studies of early plaque formation.