An older study examining the amount of dental plaque in subjects with varying frequencies of brushing their teeth and varying levels of ascorbic acid (Vitamin C).
Viewing brushing frequency-debris score relationships as influenced by ascorbic acid status (Figure 4) provides additional insights into plaque prevention and control. At all levels of brushing frequency, those with the better plasma AA levels exhibit cleaner teeth. In fact, the average debris score (0.92) for those who brush less than twice daily but have better vitamin C levels compares favorably with that of the poorer C subjects who brush twice or more daily (0.90 and 0.87).
Study full text in PDF here.