The main aim of the present observational study was to investigate whether synergisms can be identified when brushing teeth and chewing and whether a change in tooth brushing behaviour through the chewing process is possible. For this purpose, 65 sub-jects aged 20-33 years were included in the study. All subjects were informed in writing and verbally about the aim and procedure of the study. In a cross-over design, habitual toothbrushing was recorded on two consecutive dates before and after chewing gum or watching a landscape video and after an in-struction on toothbrushing systematics according to Rateitschak. In addition, the sub-jects were filmed for two minutes while chewing gum. The video analysis was carried out with the evaluation software INTERACT 18, where-by the parameters of brushing duration, frequency of changes and an index of system-atic behavior (TSI) were determined according to previous studies of our study group. Brushing frequency was a new parameter in the evaluation. A new coding scheme was introduced for the evaluation of chewing movement, which takes the chewing frequen-cy parameter into account. The results of the study show that brushing duration, frequency of changes and the TSI as established parameters of toothbrushing behavior are not influenced by motor or visual intervention. Similar applies to brushing frequency as a new examined parame-ter. Well-reproduced movement sequences were observed at several observation times, which indicates a strongly anchored brushing behavior. A very interesting result is that there appears to be a connection between the frequency of brushing and chewing. The linking of both frequencies suggests that both movement sequences are possibly controlled via common rhythm-giving brain areas. A one-off video instruction made the subjects' tooth-brushing behavior more systematic, but those who chewed gum were not able to implement the instruction better than those in the control group. These findings from the present work can provide the basis for the development of new strategies for changing tooth brushing behavior as part of individual and group prophy-laxis.