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News Bulletin : ADA News Bulletin August 2011
18 AUGUST 2011 desensitising agents These can be roughly divided into in-office and take-home categories: In-office • Calcium hydroxide: this method of desensitising is only of historical interest; it consists of the application of a calcium hydroxide paste and burnishing it with a wooden stick or rubber tip. The mode of action is unclear, but it was suggested by Bal et al. (1999) that the high pH provokes protein coagulation in the tubules, leading to their closure and to a decrease in the hydraulic conductance of dentine. • Fluoride varnishes: the most commonly used product is 5% neutral sodium fluoride (e.g., Duraphat, Clinpro White Varnish). The mode of action is through occlusion of tubules by the formation of calcium fluoride. Other fluoride compounds which have been used in the treatment of hypersensitivity are amine fluoride, stannous fluoride and titanium tetrafluoride. • Fluoride iontophoresis: this method uses a small electrical charge to deliver fluoride deeper into dentine. It is mentioned in this report only for the readers’ interest as the product is not available on the local market. The application tray can be used with 1.23% acidulated phosphate fluoride (APF) or 2% sodium fluoride (NaF) gels (www.fluorinex-active.com). • Desensitising polishing paste: the active ingredients are calcium carbonate and arginine. Similar to calcium hydroxide, the paste works best when it is burnished onto the tooth surface with a rubber cup, running at slow speed. • Placement of physical barriers: where lesions are shallow, a layer of a dentine bonding agent can be used to cover the affected areas, while more advanced lesions can be successfully restored using glass-ionomer or resin modified glass-ionomer cements. One product containing both resin and glutaraldehyde has been shown to be somewhat effective against dentine hypersensitivity. The manufacturer claims that the glutaraldehyde leads to precipitation of serum albumin in the tubules. • Lasers: a review of four different types of lasers used to reduce dentine hypersensitivity indicated highly variable rates of success. Take-home • Toothpaste: there is a range of toothpastes designed for hypersensitivity relief; these can contain strontium chloride, strontium acetate, potassium chloride and arginine and calcium carbonate. The proposed mode of action of potassium is by blocking nerve transmission while strontium, calcium and arginine act by the occlusion of dentine tubules. • Stannous fluoride: this ingredient is effective in management of dentine hypersensitivity and also useful in caries prevention, reduction of plaque formation and gingivitis and suppression of breath malodour. The mechanism of action for stannous fluoride appears to be the creation of a calcific barrier via induction of high mineral content. One study reported the development of a tin-rich surface forming in vitro and in situ after a two-week application of 0.4% stannous fluoride gel. It has also been proposed that stannous ions may precipitate into a large enough mass to sufficiently inhibit the hydrodynamics of tubule fluid. • Oxalate salts: compounds containing oxalate salts have also been shown to produce relief from the symptoms of dentinal hypersensitivity. Commercially available preparations more commonly include potassium oxalate or ferric oxalate, both of which have been shown to provide effective reduction in sensitivity. • Calcium phosphopeptide-amorphous calcium phosphate (CPP-ACP): there is evidence to show that CPP-ACP has a clinical application in the management of dentine hypersensitivity by enhancing surface mineralisation and tubule occlusion. COnCLUSIOn The diagnosis and management of dentine hypersensitivity can be a difficult clinical challenge and requires a systematic approach. Patients will have variable levels of tolerance and any management strategies must take into consideration the multifactorial nature of the condition. Hien Ngo On behalf of the Dental Instruments Materials and Equipment Committee Fig 1. Hypersensitive area difficult to visualise. Fig 2. Mild acid etching (2s) enables visualisation of lesion. committee report
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