Background:Data on the role of dental plaque in the transmission of Helicobacter pylorihave varied. Furthermore, there has been few reports on the relationship between dental plaque control and H. pyloriinfection of gastric mucosa. The purpose of this study was to elucidate this potential relationship. Methods:The 13C urea breath test was conducted on 56 subjects who received dental plaque control and 51 subjects who did not. Results:The prevalence of H. pyloriin the gastric mucosa was 19.64% in patients who received dental plaque control, which was significantly lower than in those without dental plaque control (84.31%). Conclusion:Long‐term professional dental plaque control was associated with less gastric reinfection by H. pylori, suggesting that dental plaque control may help to prevent H. pylori‐induced gastric disease or reinfection.