In this paper, we described the intelligent toothbrush system which is capable of monitoring three-dimensional brushing motion of toothbrush and analyzing brushing regions based on sensor signals measured from built-in accelerometer and magnetic sensors. In order to evaluate the efficacy of the proposed toothbrush system, we performed two experiments. First, all subjects are asked to brush their teeth freely without any restrictions, and brushing motions were recorded and evaluated for the time duration of each possible brushing regions. Then, all subjects were received toothbrushing instruction(TBI) and encouraged to follow basic TBI for a week. Second, subjects were asked to brush their teeth freely again. Data from previously performed experiments are compared with time durations of each brushing region. The result shows that time distributions of each regions in the second experiment became more uniform than the first brushing. The ratios of time distributions of each brushing regions is increased, and the overall toothbrushing times increased from 107 sec to 225 sec (p<0.01). It manifests that the proposed smart toothbrush system lead subjects to have a good brushing habits and improved oral hygiene. And more quantitative analysis to evaluate the efficacy of brushing education with smart toothbrush would be useful for clinical application.