Welcome to the Glass Age

50 cream or taking a sip from a hot cup of coffee, for many the pain is chronic and needs treatment. The pain is thought to be caused by exposed tubules in our dentine (Figure 3.7b). Our teeth are covered by hard enamel, underneath which is the dentine. Enamel and dentine are very similar to bone, in that they contain calcium phosphate mineral and collagen, and the tubules in the dentine lead to the nerves in the pulp chamber in the heart of the tooth. Early toothpaste for hypersensitivity delivered anaesthetics during brushing, but now toothpastes have been developed that can occlude the tubules by promoting formation of new calcium phosphate mineral. This occurs because the bioactive glass dissolves in saliva, releasing calcium and phosphate [11]. As saliva is already rich in calcium phosphate, saturation occurs, and this natural mineral is deposited on the surface of the teeth (Figure 3.7c,d). The first bioactive glass to be used in toothpaste was the 45S5 Bioglass composition. As fluoride is known to be greatly beneficial for remineralising Figure 3.7. (a) Photograph of Sensodyne Repair and Protect toothpaste packaging, which contains NovaMin ® , fine Bioglass particules; and (b-e) scanning electron microscopy images of tooth dentin [11] (bar = 1 μm): (b) untreated, (c) immediately after application of Bioglass in artificial saliva; (d) 24 h after Bioglass application; (e) 5 days after application. Source: (a) Julian R. Jones; (b-e) modified from Earl et al. [11].