A dental system for cleaning a user's teeth and marginal gingiva with a drug solution includes a mouthpiece made for each user and having substantially the same shape as the teeth and the marginal gingiva of the user. The mouthpiece is designed to produce a gap between the mouthpiece and the teeth together with the marginal gingiva when placed to cover the teeth and the marginal gingiva of the user. The dental system also includes a drug solution supply unit and a drain unit, both connected to the mouthpiece, and a suction unit connected to the drain unit. The mouthpiece adheres to the marginal gingiva by a suction applied from the suction unit. The dental system cleans the teeth and the marginal gingiva with a stream of the drug solution flowing through the gap.