2 Clinical need and practice
2.1 Tooth decay (dental caries) is a chronic disease that can result in the localised and progressive demineralisation (loss of mineral content) of the hard surfaces of the tooth. It is a multistage process initiated by the local accumulation of cariogenic bacteria on the hard surfaces of the tooth. Cariogenic bacteria metabolise dietary carbohydrates to produce plaque acids, which cause demineralisation of the tooth enamel (non-cavitated dental caries). Without successful treatment, the demineralisation can extend into the dentine and eventually into the pulp (cavitated dental caries). Common symptoms of untreated cavitated dental caries are significant pain and discomfort, which can lead to disturbances in eating and loss of sleep.
2.2 The progression of dental caries is a slow process in most people; at current levels of consumption of fermentable carbohydrates and fluoride exposure, most enamel lesions take more than 2 years to cavitate. A number of variables can affect progression time and the progression of dental caries may be more rapid in deciduous teeth because they are less well mineralised.
2.3 The type of dental caries can be classified by its location: pit and fissure caries occurs in the pits (small depressions) and fissures (small grooves) of the occlusal (biting) surface of teeth, the palatal surfaces of the upper molars and the vestibular surface of the lower molars. Caries can also occur between the surfaces of adjoining contact areas of adjacent teeth. Root caries occurs in the area between the tooth and the receding gum. Primary dental caries is decay on a previously sound natural tooth. Secondary dental caries is decay at the margin of a restoration (filling); this often necessitates replacement of the filling (re-restoration).
2.4 Carious lesions are first identified on the basis of clinical visual examination. Various techniques are used to diagnose and monitor progression or reversal of dental caries, although none have been well validated. In addition to visual examination and probing, X-rays and digital radiography can be used to estimate the depth of lesions or to identify lesions that are 'hidden' on visual examination. Lesions can be classed as soft, leathery or hard. Lesions that are progressing are classified as 'active' and those that have stopped progressing are described as 'arrested'. This distinction is clinically important because arrested lesions do not require any further preventive interventions.
2.5 Adults in the UK have an average of 1.5 decayed or unsound teeth, and 55 per cent have one or more decayed or unsound teeth (Adult Dental Survey 1998). Despite a reduction in the mean number of decayed, missing and filled teeth over the past 25 years, there are still many people with significant dental caries, which is often linked to socioeconomic factors. Forty three percent of 5-year-olds and 57% of 8-year-olds have obvious tooth decay in deciduous teeth, and between 52% and 77% of children aged 8 to 15 years have obvious tooth decay in permanent teeth (Dental Health Survey of Children 2003). Root caries usually begins between the ages of 30 and 40 years and is most prevalent in elderly people.
2.6 The treatment of dental caries depends on the severity of the lesion at presentation (whether or not it is cavitated) and on its location. People undergoing dental treatment routinely should receive instructions on good oral hygiene and dietary advice to reduce the consumption of fermentable carbohydrates. After treatment, the activity status of dental caries lesions is assessed at follow-up visits to determine whether further preventive treatment is necessary.
2.7 Water fluoridation and topical fluoride delivery – in the form of toothpastes, mouth rinses, gels and varnishes – are the mainstay in the management of dental caries. The effectiveness of fluoride has been established by randomised controlled trials and summarised recently in a series of systematic reviews produced by members of the Cochrane Collaboration.
2.8 Non-cavitated pit and fissure caries is currently managed by removing plaque and treating with topical fluorides (for example, toothpaste and mouth rinse) and pit and fissure sealants where appropriate.
2.9 Cavitated pit and fissure caries is currently managed by removing plaque and tooth decay (using drills or air abrasion) and restorative treatment with a composite resin, glass-ionomer cement or amalgam. Amalgam is commonly used for filling posterior permanent teeth. The average lifetime of a restoration is about 8 years, although it varies with the size of the restorations.
2.10 Non-cavitated root caries is currently managed by removing plaque and treating with topical fluorides (for example, toothpaste and mouth rinse), which may be sufficient to prevent progression where the tooth is accessible to cleaning.
2.11 The management of cavitated root caries involves removing plaque and treating with fluoride. Restorative treatment with glass ionomer cements or resin-based fillings may be required.