Adherence of chewing gum to dental restorative materials

To describe a method whereby chewing gum tackiness can be measured.

The chewing gum used for the experiment was V6 (Freshmint). Paladur denture base material, Silux Plus, P-50 and Heliomolar resin composites and Luxalloy amalgam were used. Squared specimens (15 x 15 x 2 mm) composed of the polymerized materials tested or set amalgam were made with a mold. As gold specimen, a gold-plated brass specimen was used, having the same dimension as specified above. A tooth enamel specimen (5 x 5 mm) was made out of flat ground human enamel from an incisor. All specimens were stored for more than 7 days in water before use, and wet ground on paper No 320 immediately before testing. The adhesion was measured by a balance equipped with a recorder and a bottom attachment, to which a chain was mounted. The end of the chain was attached to a quadratic brass plate, to which one of the above described specimen was glued by cyanoacrylate. Another brass plate, with an attached specimen of the same material, was mounted in a small vise in such way that the two specimens were parallel with and facing each other. A motor drive enabled parallel removal of the two plates from each other. The gum was chewed approximately 1 second between bites and for various periods of time. It was then pressed between the two parallel squares (mentioned above) of restorative materials or enamel, reaching a final distance of 1 mm between the plates and occupying the entire space between the plates. The study was carried out at 36 degrees C, and the two plates were wetted with fresh saliva or water immediately before placement of the chewing gum. Excess liquid was removed after the wetting, leaving a thin film. The maximal force during parallel removal of the two plates from each other was recorded. The measurements were performed eight times in each group, and the mean adhesion per surface area and SD was expressed as mN/mm(2). The measurements were repeated for some of the groups. The significance of differences between each group was tested by Newman-Keul's Multiple Range Test at a 5% level of significance.

Adherence of chewing gum to dental restorative materials and enamel was found to decrease as follows: denture base material > resin composites = silver amalgam > gold > human enamel. The adhesion was dependent on gum base and not on the sweetening additives and reached a maximum after about 2 minutes' chewing.