Effect of nicotine-free and nicotine-containing snus on plaque pH in vivo.

The aim was to investigate pH changes in plaque in vivo during the use of nicotine-free and nicotine-containing snus. The carbohydrate content of the products was also analysed. Ten subjects, all regular snus users, participated in an experimental crossover study, on eleven occasions with an interval of one week. Six nicotine-free and four nicotine-containing products, which are sold on the Swedish market, were included and a sucrose solution was used as a control. The subjects did not brush their teeth for three days before coming to the laboratory, without eating, drinking or using snus/smoking for two hours prior to the test. pH was measured at three approximal sites up to 45 min with the test product placed under the upper lip. The carbohydrate analysis showed that the nicotine-containing products contained only traces of glucose, fructose and sucrose (0.5-1%) and starch (approximately 1.5%). Some of the nicotine-free products contained up to 6.5% low-molecular-weight carbohydrates and 26.0% starch. The intraoral pH measurements showed that four nicotine-containing products increased the plaque pH, in contrast to three of the six nicotine-free products, which lowered the pH. These pH changes may have an effect on the caries risk, both positively and negatively, depending on which product is used.