Hidden caries is a term used to describe occlusal dentine caries that is missed on a visual examination, but is large enough and demineralised enough to be detected radiographically. The detection rate of such lesions will depend upon the prevalence of caries in the population and the frequency with which bitewing radiographic examinations are performed. Whether 'hidden caries' is a distinct clinical entity, reflecting a particular anatomical fissure topography or a different bacterial aetiology, is unknown. It is possible that an improved visual examination, with careful cleaning and drying of teeth, may improve occlusal caries detection to the point where 'hidden caries' no longer exists. However, this possibility has yet to be tested clinically and until it is, practising dentists would be wise to examine bitewing radiographs carefully for occlusal demineralisation. The authors would treat such hidden lesions by removing soft caries and placing sealant restorations.
At two recent international conferences (The European Organisation for Caries Research, 42nd ORCA meeting, Amsterdam, The Netherlands, 1995; Workshop on Understanding Dental Caries, Aarhus, Denmark, 1996) the term 'hidden caries' was used but caused some confusion amongst the academic dentists, researchers, clinicians and academic scientists present. Some questioned what constitutes 'hidden caries' while others denied its existence. This paper aims to clarify the term 'hidden caries', explain how the name originated and assess whether it is a discrete entity of relevance to the practising dentist.
The origin of the term 'hidden caries' Epidemiological surveys carried out between 1954 and 1981 have shown an unequivocal reduction in caries experience of children aged 8-15 years1. Whilst the reduction in smooth surface caries has been considerable, that of occlusal caries has been less marked' and occlusal caries now accounts for the majority of lesion^^-^. In the 1980s clinicians in the United Kingdom