Methods: Single-blind clinical trial with a control group on children 8 - 9 years of high caries status (DMT-R + dmt-r ≥ 3) in Nguyen Van Tran primary school, Binh Chanh district, Ho Chi Minh City: 153 students for the test group (using chewing gum containing xylitol 4 times daily, each time with 2 tablets chewed for at least 5 minutes, without tooth brushing at least 1 hour after chewing up) and 147 students for the control group (without chewing).