Co-adhesion and removal of adhering bacteria from salivary pellicles by three different modes of brushing

This study compares removal of pairs of co-adhering and non-co-adhering oral actinomyces and streptococci by hand, electric and sonic brushing from salivary pellicles. In addition, re-deposition of a co-adhering and non-co-adhering streptococcal strain to brushed pellicles was studied. First, actinomyces were allowed to adhere to a pellicle in a flow chamber, after which streptococci suspended in saliva were perfused through the chamber at 33 C. Pellicles with adhering bacterial pairs were brushed and the number of bacteria remaining determined. Whereas sonic brushing removed nearly all adhering bacteria, greater numbers of larger aggregates of the co-adhering pair, involving Streptococcus oralis J22, were left behind after hand and electric brushing than of the non-co-adhering pair with Streptococcus sanguis PK1889. Re-deposition of streptococci to electrically and sonically brushed pellicles, however, was two-fold higher for the co-adhering pair than for the non-co-adhering pair. This demonstrates a role for co-adhesion in de novo plaque formation. Removal by the three different modes of brushing was not affected by the presence of fluoride, indicating that fluoride is not able to disrupt calcium bridges between co-adhering pairs. In contrast, in the presence of lactose only small aggregates of co-adhering pair were left behind.