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News Bulletin : ADA News Bulletin August 2011
16 AUGUST 2011 Dentine hypersensitivity is a common condition in which individuals experience brief episodes of sharp, well-localised pain when their teeth are exposed to common stimuli such as cold water, air currents and touch. The pain is sharp in nature but short in duration and is often described by patients as annoying but bearable. This condition is becoming more common as the population ages and people retain their natural teeth longer. In this brief report, the basic anatomic and physiological mechanisms responsible for sensitivity are reviewed and the commonly available treatments are described that have been developed to treat tooth hypersensitivity. This article is provided only as a guide for clinicians, and individual patient needs must be assessed prior to any treatment decisions. PREvALEnCE Clinical reports suggest that the prevalence of dentine hypersensitivity ranges from 10–20%, with a peak in patients aged between 20 and 40 years old, even though the condition can be found in teenagers and patients in their 70s. Females may have a higher prevalence than males and this could be accounted for by differences in diet and oral hygiene habits. In the maxilla, the most common location is anterior to the first premolar, while in the mandible the first molar and premolars are more commonly affected. AETIOLOGy Dentine hypersensitivity is the symptomatic manifestation of significant dental problems, such as erosive wear and other forms of non-carious tooth structure loss. Often, the loss of enamel and cementum can be traced back to a combination of erosion, abrasion and possibly abfraction. In older patients, dentine hypersensitivity is often associated with root surface exposure due to gingival recession; however, in younger patients, the lesions may be surrounded by enamel with no exposed root surfaces. Clinically, the condition is frequently the consequence of salivary dysfunction, aggressive oral hygiene practices and diets rich in acids. A number of case-control studies has shown that intrinsic and extrinsic acids are the primary aetiological factors and their erosive effect is accelerated in those patients who lack the protection of healthy saliva. dIAGnOSIS Effective management of dentine hypersensitivity requires proper identification of the contributing factors through history taking, examination and saliva analysis. A survey of dental practitioners showed that few dentists consider diet analysis during management of this condition. Enamel in the cervical area of the tooth is thin and this area is frequently the first to manifest the symptoms of hypersensitivity due to the loss of this enamel and exposure of the underlying dentine. In the early stages, dentine exposure can be difficult to identify (Fig 1) other than by air blast or tactile exploration. The use of a two-second acid etch can be used to reveal the area of exposed dentine (Fig 2). The intact border of enamel along the gingival margin is a typical feature of the early lesions, which is due to the acid neutralising and protective capacity of gingival crevicular fluid. MECHAnISMS Of PAIn TRAnSMISSIOn As the intra-dentinal nerve fibres are confined to the pre-dentine zone, it is most likely that dentine hypersensitivity is evoked by indirect stimulations. The three major theories on the mechanism of pain transmission in dentine are: • dentinal receptor theory: the odontoblast has a sensory function; • transducer theory: the nerve impulses in the pulp are modulated through the liberation of polypetides from the odontoblasts, when these are injured; • hydrodynamic theory: when a stimulus is applied to the outer dentine surface, there is a displacement of fluid in the dentinal tubules, giving rise to a mechanical stimulation of the nerve receptors at the pulpo-dentinal border. The diameter of the tubule is also very important, as the rate of fluid flow is dependent on the tubule diameter. If the tubule diameter doubles, the fluid flow may increase by as much as 16 times. MAnAGEMEnT The first principle in managing multi-factorial and chronic conditions is to relieve the symptoms and to address the aetiological factors which are specific to individuals. Patients should be led through a tiered management program of progressively more intensive treatments. The first step is the removal of contributory factors and habits, to be followed by the use of desensitising agents, which can be applied in-office or by the patient as part of their daily home care. The currently available products and methods aim at either occluding the dentine tubules or preventing sensory nerve transmission. Dentine Hypersensitivity committee report
ADA News Bulletin July 2011
ADA News Bulletin September 2011