A mastication device designed for the evaluation of chewing gums

In vitro tooth whitening effect of two medicated chewing gums compared to a whitening gum and saliva

Background

Extrinsic staining of teeth may result from the deposition of a variety of pigments into or onto the tooth surface, which originate mainly from diet or from tobacco use. More recently, clinical studies have demonstrated the efficacy of some chewing gums in removing extrinsic tooth staining. The aim of this study was to assess the effectiveness of two nicotine medicated chewing gums (A and B) on stain removal in an in vitro experiment, when compared with a confectionary whitening chewing gum (C) and human saliva (D).

Methods

Bovine incisors were stained by alternating air exposure and immersion in a broth containing natural pigments such as coffee, tea and oral microorganisms for 10 days. Stained enamel samples were exposed to saliva alone or to the test chewing gums under conditions simulating human mastication. The coloration change of the enamel samples was measured using a spectrophotometer. Measurements were obtained for each specimen (average of three absorbances) using the L*a*b scale: lightness (L*), red-green (a) and yellow-blue (b).

Results

Medicated chewing gums (A and B) removed a greater amount of visible extrinsic stain, while the confectionary chewing gum with a whitening claim (C) had a milder whitening effect as evaluated by quantitative and qualitative assessment.

Conclusion

The tested Nicotine Replacement Therapy (NRT) chewing gums were more effective in the removal of the extrinsic tooth stain. This visible improvement in tooth whitening appearance could strengthen the smokers' motivation to quit smoking.

Apparatus for studying in vitro drug release from medicated chewing gums

An apparatus for in vitro drug release testing of medicated chewing gums has been developed and is described in detail. The effects on the drug release when varying critical instrumental settings such as the chewing stroke frequency, the distance between the chewing surfaces, the twisting movements of these surfaces and the temperature of the test medium have been thoroughly investigated. It has been shown that the drug release can be tuned to obtain suitable drug release profiles for a number of products: Nicorette((R)) and Nicotinell((R)) (active substance nicotine), Travvell((R)) (dimenhydrinate), V6((R)) (xylitol) and an experimental formulation containing meclizine. The main usage of the present apparatus should be within quality control but the present study has also shown that it may be employed within development pharmaceutics since useful in vivo/in vitro relationships may be obtained due to the versatile settings of the critical instrumental parameters.