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

BMC Oral Health BioMed Central Research article Open Access In vitro tooth whitening effect of two medicated chewing gums compared to a whitening gum and saliva Michael Moore1, Nathalie Hasler-Nguyen*2 and Geoffrey Saroea3 Address: 1Health Science Research Center, Indiana University – Purdue University Fort Wayne, 2101 Coliseum Blvd East Fort Wayne, USA, 2Department of Preclinical Development, Novartis Consumer Health, Rte Etraz, Nyon, Switzerland and 3Department of Medical Affairs, Novartis Consumer Health, Argentia Road, Mississauga L5N 2X7, Canada Email: Michael Moore - ; Nathalie Hasler-Nguyen* - ; Geoffrey Saroea - * Corresponding author Published: 11 August 2008 BMC Oral Health 2008, 8:23 doi:10.1186/1472-6831-8-23 Received: 12 March 2008 Accepted: 11 August 2008 This article is available from: http://www.biomedcentral.com/1472-6831/8/23 © 2008 Moore et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract 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. Background An attractive smile and healthy looking teeth reflect well being and quality of life for the majority of people [1]. The natural color of a permanent tooth is determined by the enamel translucency enabling the underlying dentine color to be visible. Enamel acts as a filter for dentine by the way light passes through to the dentine and as the light is reflected back by the dentine, which is the tooth color visually perceived [2]. This color can be quantified with a spectrophotometer using the L*a*b* color scale, which measures lightness for L*, red-green color range for a* and yellow-blue range for b*. Coloration of teeth is due to extrinsic stains, which lie on the surface of the tooth and within the acquired pellicle, while intrinsic Page 1 of 7 (page number not for citation purposes) BMC Oral Health 2008, 8:23 stains lie within the dental tissues [3]. The aesthetic effects created by both types of discoloration are issues, which are dealt with by the dentist. Most intrinsic stain cannot readily be removed, but can be masked by restorative techniques, or by chemical means such as peroxide. On the opposite, extrinsic staining can often be removed by simple mechanical actions [3]. Home care procedures that remove extrinsic stain, are focused on dentifrice and toothbrushes. More recently, some chewing gums with a tooth whitening claim have been launched with clinical studies supporting their efficacy in removing extrinsic tooth stains [4]. Chewing gum has also been used to deliver therapeutic agents such as nicotine for smoking cessation therapy [5]. The aim of this in vitro method described by Kleber [6] was to evaluate the extrinsic stain removal capabilities of two medicated chewing-gums containing nicotine, one confectionary chewing-gum with a tooth whitening claim and formulation, against a non chewing-gum negative control using only human saliva. Methods Products The experimental chewing gums were provided by the sponsor in coded packaging, which is equivalent to blind test samples. http://www.biomedcentral.com/1472-6831/8/23 using a water slurry of GK1072 calcined kaolin (median particle size = 1.2 microns) on a cotton cloth. The finished specimen was examined under a dissecting microscope and discarded if surface imperfections were observed. In order to render the polished tooth surfaces more similar to natural teeth and promote the formation of stain on the enamel, the specimens were etched for 60 seconds in 0.2 M HCl followed by a final etch with 1% phytic acid for 60 seconds. The specimens were then rinsed with deionized water and attached to the staining apparatus. Tooth staining apparatus The tooth staining apparatus as shown in Fig. 1 was designed to provide alternate immersion into the staining broth and air-drying of the specimens. This instrument was made in house. Tooth staining broth preparation The staining broth was prepared by adding 1.02 g of instant coffee, 1.02 g of instant tea, and 0.75 g of gastric mucin to 250 ml of sterilized trypticase soy broth [6]. Approximately 50 ml of a 24-hour Micrococcus luteus culture, which is a stain inducing bacteria found in the oral cavity was also added to the stain broth to promote and The tested products were two nicotine replacement therapy (NRT) brands, Nicotinell Mint coated chewing gum with 2 mg nicotine (chewing gum A; Novartis Consumer Health) and Nicotinell Thrive Mint chewing gum with 2 mg nicotine (chewing gum B; Novartis Consumer Health). The differences between the two gums are that chewing gum A has a 60% higher calcium carbonate content and a different Mint flavor base than chewing B. A confectionary chewing gum with a tooth whitening claim, V6 White Strong Mint (chewing gum C; Fertin), containing carbamide and xylitol but not polyphosphates was used as positive control. Preparation of enamel specimen Four mm squares of dental enamel from bovine permanent incisors, which are a representative model for human teeth [7], were cut using a diamond cutting disk. Using a mold, an enamel square measuring 4 mm × 4 mm, was embedded in clear polyester casting resin to provide a 1.5 cm square block with the tooth enamel labial surface exposed. The top surface of the polyester blo (...truncated)