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The caries process is the ubiquitous, natural metabolism in the biofilm that causes numerous fluctuations in pH. The interaction of this biofilm with the dental tissues may result in a caries lesion. However, lesion formation and progression can be controlled, particularly by disturbing plaque regularly with a fluoride containing toothpaste. This paradigm implies that everyone with teeth is at risk to lesion development. Treatment of caries is principally non-operative, involving plaque control, fluoride and a sensible diet. Operative dentistry repairs un-cleansable cavities and is part of plaque control. A diagnosis is a mental resting place on the way to a treatment decision. The relevant diagnostic features with respect to caries are lesion activity (active lesions require active management) and un-cleansable cavities. When teaching undergraduates, it is important that they are credited for the non-operative treatment of caries as well as for operative dentistry. This is equally important in dental practice where an appropriate skills mix of the dental team is required to deliver dental health cost-effectively. Training more dentists may be an expensive mistake as far as disease control is concerned. It is ironic that dentists make most money from operative care and specialist treatment when disease control could be delivered relatively cheaply. The key to dental health is regular and effective plaque control with a fluoride containing toothpaste, from cradle to grave.

The diagnosis of occlusal caries is an integral part of an epidemiologist's task, whether carrying out cross-sectional national caries prevalence surveys to assist with planning and the evaluation of service provision, or clinical trials of caries preventive agents. Similarly, the clinician also carries out this same overall diagnostic procedure in order to plan care for individual patients, although he/she will usually have access to improved facilities and diagnostic aids. This paper reviews the different problems now being encountered by both epidemiologists and clinicians in the face of changes in the presentation of the disease at this site and the qualifications which should now be appreciated when extrapolating from the results of surveys employing comparatively gross criteria. It explores recent developments in diagnostic aids and makes suggestions as to how further information might be obtained in future which would aid the valid comparison of diagnoses made by these two groups of dentists.

Objectives: the structural integrity and surface characteristics of dentine remaining after caries excavation may be relevant to the subsequent bonding of adhesive restorative materials to the prepared cavity. This in vitro investigation aimed to analyse the different surface characteristics of the dentine cavity floor created after preparation using five different mechanical and chemo-mechanical methods of excavation: hand excavation, slow-speed bur, sono-abrasion, air-abrasion and Carisolv™ gel. Methods: ten cavities were prepared using each excavation method in extracted teeth with occlusal carious lesions. Epoxy resin replicas of the 50 cavities were manufactured from silicone impressions and then analysed using secondary electron scanning electron microscopy (SEM) to ascertain the surface characteristics of the dentine at the cavity floor. Results and conclusions: results from the 50 cavities examined suggested that each alternative excavation technique produced a different and characteristic dentine surface. Carisolv™ gel was the only method examined that consistently removed the smear layer during excavation to leave exposed dentine tubules at the end of cavity preparation.

Validation of a diagnostic technique is important to establish whether it actually measures what it is purported to measure. However, the accuracy of the validation technique per se can influence the apparent accuracy of the diagnostic technique. Objectives: The aim of this study was to describe two alternative histological validating techniques for occlusal caries and to compare quantitative depth measurements of carious lesions taken using each method. Methods: Thirty sections (mean thickness 0.67mm) were cut to include two to four discrete sites in 10 freshly extracted teeth. The first histological validating technique used a microfocal X-ray unit to produce magnified high definition radiographic images of the sections or ‘macroradiographs’. An image analysis system was used to make quantitative measurements of the lesions (if present) with respect to the enamel-dentine junction (EDJ). The second validating technique used a confocal microscope to image beneath the cut surface of the section. Quantitative measurements were taken from the fluorescence images of both sides of each section and a mean depth measurement calculated. Results: Complete agreement was found between the two validating techniques for the subjective interpretation of the presence and extent of caries. A strong positive relationship was found between the two histological validating techniques for depth measurements made of dentine caries from the EDJ (r = 0.93, P < 0.001). Depth measurements made from the macroradiographs were greater than from the confocal fluorescence images (mean difference=0.41 mm). Conclusions: Both validating techniques enable the identification of sound sites, those with enamel caries and dentine caries. However, quantitative assessments made with each technique could result in disagreement.

This article describes some of the factors to be considered by the practitioner when prescribing bitewing radiographs in the diagnosis and management of dental caries and draws on the literature of a number of disciplines including restorative dentistry, cariology, epidemiology and oral radiology. It seems appropriate to re-assess current practice in the light of information on changes in the disease of dental caries, its behaviour and the way this behaviour may vary in high and low caries risk groups. The diagnostic potential of the bitewing examination appears, at present, to be unrivalled, but other diagnostic methods, such as fibreoptic transillumination and tooth separation, must also be considered. Some methods to minimize radiation doses and increase diagnostic yield are discussed. Current knowledge of prescribing patterns is reviewed and areas of ignorance are mentioned as findings from future research in these areas may influence decisions about when to use and re-use bitewing radiographs.

Microleakage may be defined as the passage of bacteria, fluids, molecules or ions between a cavity wall and the restorative material applied to it. Many techniques have been devised to test the cavity-sealing properties of restorations both in vitro and in vivo . These techniques include the use of dyes, radioactive isotopes, air pressure, bacteria, neutron activation analysis, artificial caries and scanning electron microscopy. Some form of thermal stressing has frequently been included in the experimental protocol. Research has shown that freshly packed amalgam restorations leak but that this leakage tends to decrease as fillings age. Cavity varnishes and liners reduce initial leakage of the material. Many of the tooth-coloured restorative materials in common use have been shown to leak. Acrylic restorations appear particularly susceptible to leakage after thermal stressing. There is some evidence that the newer composite materials may form a good cavity seal.