OBJECTIVE The aim of the study was to evaluate the change of plaque pH after chewing 2 kinds of gums. METHODS The investigation consisted of 8 healthy subjects (aged 23-27 years, 4 males and 4 females) who refrained from toothbrushing for 24 hours before the test. The pH of dental plaque was measured using a Beetrode pH microelectrode before and after sucrose challenge with a 10% sucrose solutions at 5, 10, 15, 20 minutes as the baseline data. One week later the pH of dental plaque was measured again before the rinse and then the subjects rinsed with a 10% sucrose solutions. After 1 minute the sugar-free chewing gum was given and started to chew for 5, 10, 15, 20 minutes. The pH of dental plaque was measured at the same time on the non-chewing side. One week later the same test was carried out but the chewing gum was changed to tea polyphenol gum. Dental plaque pH value were analyzed by one-way ANOVA and SNK using SPSS 10.0 software package. RESULTS Compared with the baseline chewed either tea polyphenol gum or sugar-free gum could increase the plaque pH recovery due to the sucrose rinsing challenge and it could maintain the dental plaque pH above the resting value. There was no statistically significant difference between tea polyphenol gum and sugar-free gum (P>0.05). CONCLUSIONS Both gums can increase the plaque pH and decrease the risk of caries.