2° Limiting the impact of caries at an early stage
3° Rehabilitation of the decayed teeth with further preventive care

In everyday clinical practice the distinction between secondary and tertiary prevention is unclear and they are therefore considered together in this section. Treating any carious lesions operatively will not prevent further disease and primary preventive measures (see section 3) must be continued.

4.1 Diagnosis of dental caries

In order to deliver effective prevention, accurate diagnosis and monitoring of lesions over time are required.

Early diagnosis of approximal enamel lesions is important as the majority of lesions in the outer half of enamel will take at least two years to progress into dentine⁵⁹ and progression is not inevitable. With intervention, lesion progression can be slowed, arrested or even reversed.^{60, 61, 62, 63, 64, 65} However, monitoring is important as in very caries-active individuals rapid progression can be seen. Evidence level Ib and III

Conventional clinical examinations for dental caries have a disappointingly poor sensitivity with the consequence that unaided visual diagnosis fails to detect many lesions, particularly those still at a stage amenable to preventive interventions. There is consequently a range of research underway seeking to identify diagnostic aids with high sensitivity and specificity which do not employ ionising radiation. Although the electrical and optical methods show promise and may lead to important breakthroughs in the near term, at present the use of dental radiography is still indicated.

In the diagnosis of caries in children, systematic review of the evidence, supported by expert opinion, shows that posterior bitewing radiographs are an essential adjunct to clinical examination.^{9, 66} An apparently increasing problem exists in detecting dentinal caries 'hidden' under an apparently sound occlusal surface. Radiographic examination has been shown to reveal these lesions,^{67, 68, 69} which may affect 10-15% of teenagers. However, no patient should be expected to receive additional radiation dose and risk as part of a course of dental treatment unless there is likely to be a benefit in terms of improved management of the patient. Evidence levels Ia, Ib and IV

A thorough clinical examination of clean, dried teeth should be carried out to assist caries diagnosis and to identify the patient's caries risk category prior to deciding whether to take a radiograph. This examination may include: transillumination flossing temporary separation of the teeth (e.g. with a wooden wedge or orthodontic separator).

Bitewing radiographs are recommended as an essential adjunct to a patient's first clinical examination.

The frequency of further radiographic examination should be determined by an assessment of the patient's caries risk (see Table 1).

For further details of selection criteria for dental radiography and optimal timing for recall intervals, see the Faculty of General Dental Practitioners guideline.⁹

4.2 Management of carious lesions

The management of carious lesions can be divided into three caries sites:

• occlusal caries
• approximal caries
• smooth surface caries.

The patterns of caries initiation and progression are different in each site, as are the management options.

4.2.1 Management of occlusal caries in children at high caries risk

Once a decision has been taken to initiate operative intervention, it has been shown that sealant restorations are as effective as amalgam restorations in managing small to moderate sized fissure caries^{70, 71, 72} and involve less tooth destruction.⁷² However, it must be appreciated that the fissure sealant component requires maintenance.^{70, 71, 72, 73} Using composite instead of glass ionomer improves sealant retention.^{73, 74} If amalgam is used as a filling material, any remaining fissures which are caries free should be fissure sealed in preference to "extension for prevention". ⁷⁵ Evidence level Ib

If only part of the fissure system is involved in small to moderate dentine lesions with limited extension, the treatment of choice is a composite sealant restoration.

If fissure caries extends clinically into dentine, the current treatment of choice is to remove the caries and place a restoration, rather than sealing over the caries.^{76, 77, 78} The evidence for the longevity of conventional restorations in this type of application is clear, although further studies with new materials and techniques are required. However, if caries is inadvertently covered by a fissure sealant which is then well maintained, the caries is very unlikely to progress.^{79, 80, 81, 82, 83} Evidence level Ib

If caries extends clinically into dentine, then carious dentine should be removed and the tooth restored.

For more extensive lesions still there is a wealth of evidence to support the use of well placed conventional amalgam fillings. Concerns about mercury related hazards have not been generally substantiated^{84, 85} and are offset by equivalent, although questionable, concerns about potential oestrogen depleting effects of resin monomers associated with the dental polymers that are the most popular alternative materials.^{86, 87} Evidence levels Ia, III and IV

Dental amalgam is an effective filling material which remains the treatment of choice in many clinical situations. There is no evidence that amalgam restorations are hazardous to the general health.

Current advice from the Department of Health is that amalgam fillings should not be used for pregnant women.⁸⁸

4.2.2 Management of approximal caries in children at high caries risk

Application of fluoride varnish can slow or arrest progression of approximal enamel lesions and therefore operative intervention is not indicated when lesions are at this stage of development.^{63, 64, 89} Evidence level Ib

Preventive care (e.g. topical fluoride varnish) rather than operative care is recommended when approximal caries is confined (radiographically or visually) to enamel.

Management strategies for lesions confined to the enamel should also include: twice daily use of a toothpaste containing at least 1000 ppm fluoride flossing dietary advice

For approximal lesions requiring restoration, a Class II approach should be used in preference to a tunnel preparation, which is technically very demanding and has been shown to have limited durability.^{90, 91} Composite resin is suitable for the restoration of small to moderate sized (not subjected to direct occlusal loading) Class II cavities in premolar teeth.⁹² Evidence level IIb

In an approximal lesion requiring restoration, a conventional Class II restoration should be placed in preference to a tunnel preparation.

4.2.3 Management of smooth surface caries in children at high caries risk

In free smooth surfaces, caries is easier to detect and manage.⁹³ The management strategy is the same as that for approximal lesions confined to enamel.

Management strategies for smooth surface (non-cavitated) lesions should include: twice-daily use of a toothpaste containing at least 1000 ppm fluoride plaque removal dietary advice (including the use of sugar free chewing gum, when acceptable)

4.3 Re-restoration

It is common to find a range of previous restorations in high risk patients. Restorations may fail for a number of reasons, including factors associated with the material or technique used or the operator's skill. However, for high caries-risk children, further decay is a particular problem. The margin between restoration and tooth tissue is a potential site for new decay, known as secondary or recurrent caries. More extensive lesions which continue to progress in spite of preventive care should be restored with an appropriate material depending on their degree of visibility.

However, the diagnosis of secondary caries is extremely difficult and there is a risk that large numbers of false diagnoses of secondary caries will lead to unwarranted replacement and re-replacement of fillings. Unnecessary replacement of fillings is deleterious to oral health and wastes scarce financial resources.^{94, 95, 96, 97, 98, 99, 100, 101} Evidence level IIa

The diagnosis of secondary caries is extremely difficult and clear evidence of involvement of active disease should be ascertained before replacing a restoration.

If only part of a restoration is judged to have failed, then consideration should be given to repairing rather than replacing it.