This study was conducted to investigate the optimal management interval in 33 healthy adults by observing changes in oral health on the basis of the plaque control index and gingival index. When plaque control score was compared according to the period, it was found that oral hygiene management was the best in the fourth visit (p0.05). The questionnairesurvey showed, that the optimal management interval was 1, 3, and 6 months. As a result, with the effective management interval for the preventive management program focused on professional mechanical tooth cleaning, which was administered weekly, the maximum ability for oral hygiene management was attained at the fourth visit. The effective management period was 1 month. The use of a phase contrast microscope and the calculation of the evaluation index for oral hygiene management could influence the motivation to improve oral hygiene management.