pH changes in dental plaque caused by sweetened, iron-containing liquid medicine

Five commercially available liquid iron medicines and a 5% aqueous sucrose solution were tested in a randomized cross-over study with six subjects at intervals of 3-4 d. The pH in plaque was measured in minute samples taken 5 min before and 5, 10, 20, and 40 min after oral intake of 10-ml volumes of the test solutions. The iron-containing medicines differed with respecto to pH (2.8-7.0), buffer capacity, viscosity, and iron content; two contained sorbitol (28 and 42%) and three sucrose (9, 17, and 47%). As expected, all sucrose-containing preparations produced a significant decrease in pH while no appreciable pH changes followed those with sorbitol. The pH readings after 5 min were affected by the sucrose content rather than the initial pH of the solutions. The decrease in pH was of shorter duration after exposure to the sucrose-containing iron medicines than after the 50% aqueous sucrose solution.