The traditional method of detecting caries signs is by visual inspection of dental surfaces, with the aid of a bright light and dental mirror, if necessary, to see the teeth from all angles. Reflecting light onto the mouth mirror also can be done to search for dark shadows that could indicate dentine lesions.
While the use of a dental probe continues to be controversial, it is extremely helpful when used correctly and judiciously. A dental probe can be used to remove plaque that may be covering lesion, and when the blunt side of the probe is used, it can help remove biofilm to check for signs of demineralisation and to assess the surface roughness of a lesion. Studies show that gentle probing does not disrupt the surface integrity of non-cavitated lesions, while vigorous poking can cause irreversible damage to the surface of a developing lesion.8,9 The accuracy of caries detection does not increase if probing is used. A probe is unnecessary if visual inspection detects a cavity.7During a visual–tactile examination, the dentist or dental therapist will also use a 3:1 syringe to blast air on to the tooth, which makes it easier to see some lesions.2
Other tools used in visual–tactile examination may include magnifying devices to look at teeth, or orthodontic elastic separators to separate teeth over the course of 2 to 3 days for a closer look between teeth prone to caries lesions. Fiber-optic transillumination is also sometimes used. This is a method by which visible light is emitted through the tooth using an intense light source. If the transmitted light reveals a shadow, this may indicate a carious lesion.2,4