Yang V, Zhu Y, Curtis D et al. Thermal Imaging of Root Caries In Vivo. J Dent Res 2020; DOI: 10.1177/0022034520951157.

New technology may measure the extent of remineralisation of root caries lesions.

The diagnosis of active root caries is subjective, depending on judgements of colour, texture, appearance, cavitation and proximity to the gingival margin. No reliable relationship between appearance and activity has been identified. Radiography is also unreliable.

The heat of vaporisation from a tooth surface can be measured by thermal imaging systems. Water retention in dentine increases with demineralisation. The heat of vaporisation of water from the tooth surface produces a large drop in temperature, which differs between sound or remineralised dentine and actively carious dentine. In this study, the mean loss of heat from 30 lesions diagnosed clinically as active was four times greater than sound dentine or arrested lesions. The technology is 'cheap' (not defined) and the temperature changes can be monitored in real time at the chairside. In future, it may be possible to measure the effects of remineralisation interventions on individual lesions.