Composition of plaque and saliva following use of an alpha-tricalcium-phosphate-containing chewing gum and a subsequent sucrose challenge

Previous studies demonstrated that the chewing of a 2.5% (mass fraction) al pha-tricalcium-phosphate-fortified (alpha-TCP) experimental chewing gum rel eased sufficient calcium and phosphate to eliminate any fall in the tooth m ineral saturation of plaque fluid after a sucrose rinse (Vogel et al., 1998 ). In contrast, the chewing of a conventional sugar-free gum did not elimin ate this decrease in saturation. The purpose of this study was to examine i f the release of ions from plaque calcium-phosphate pools induced by this g um could provide protection during subsequent exposure to cariogenic condit ions. Fourteen subjects accumulated plaque for 48 hrs, fasted overnight, ch ewed a control or experimental gum for 15 min, and subsequently rinsed 1 mi n with a mass fraction 10% sucrose solution. Before gum chewing, and at 7 m in and 15 min afterward, whole plaque, plaque fluid, and salivary samples w ere obtained and analyzed by micro-analytical techniques. Additional sample s were collected and analyzed at 25 min (7 min after the sucrose rinse). Al though the results confirmed the deposition of large amounts of calcium and phosphates in plaque seen in the previous study, only a small increase was seen in plaque-fluid-free calcium and phosphate before sucrose administrat ion. This suggests that few of the mineral ions were mobilized under non-ca riogenic conditions. However, 7 min after the sucrose rinsing, an increase in these concentrations was seen which, based on hydroxyapatite ion activit y product calculations, indicated a decrease in the driving force for demin eralization compared with that seen with the control gum. These results sug gest that the chewing of the experimental gum deposits a labile mineral res ervoir in plaque that can resist a subsequent cariogenic challenge.