抄録
Distribution of Neisseria, Rothia and streptococci in the early stages of dental plaque was studied on 6 adult subjects. The dental plaque was collected from the surface of the upper incisor at 0, 1, 4 and 12 hours after thoroughly brushing the teeth.
Although marked individual differences were observed, Streptococcus was the most predominant and Rothia was also nearly the same as Streptococcus. Neisseria was less in number. The mean distribution of Neisseria was 9.2% (at 0 hour), 11.3% (at 1 hour), 1.8% (at 4 hours) and 3.5% (at 12 hours) and showed a decreasing trend with the passing of time. Streptococci and Rothia showed approximately the same values in all plaque samples.
The distribution of the streptococcal species was studied. S. faecalis could not be found in all of the plaque samples. S. milleri and S. salivarius were infrequently found and the latter was considered to be the contamination of saliva. S. mutans was also of the minor group in the early surface plaque. S. milior and S. sanguis were the most predominant species in all stages of the plaque.
With regard to the growth rate of the 3 genera, the streptococci were the highest, reaching the stationary phase in 12 hours. Rothia showed a longer lag-phase but the final growth rate was nearly the same as the streptococci. Neisseria showed the slowest growth, the lag phase continuing up to 20 hours.
The process of initiation and maturation of the plaque were discussed in relation to the growth rate and adhesion capacity.
