Diagnostic methods for coronal caries in common use include visual inspection, tactile examination with a probe, bite-wing radiography, and often fiber-optic-transillumination (FOTI). Early diagnosis enables small lesions to be identified so that remineralization of lesions by preventive measures can be attempted; in clinical research, it may shorten the time for clinical trials. Quantitative methods may potentially decrease interexaminer variations and facilitate the determination of small progressions or regressions. This review discusses recent advances in the development of such methods, i.e., endoscopic methods, FOTI, light-scattering, laser fluorescence, ultraviolet illumination, penetration of dyes, iodide penetration, electrical resistance, ultrasonic imaging, and improved radiographic imaging techniques. Diagnosis of occlusal surfaces gains from the use of the electrical resistance method (preferable when the emphasis is on finding lesions) or radiography (when the emphasis is on identifying sound surfaces). Digitized radiography with simple contrast enhancement gives some further improvement. Quantitative methods are not yet proven to be good enough to measure small changes. Quantitative methods are not yet proven to be good enough to measure small changes. For occlusal surfaces, the electrical resistance method may be, but this has to be confirmed. For approximal surfaces, digitized radiography and fluorescent dye penetration have to be tested for clinical feasibility. It is concluded that there are many methods in development, but all require clinical testing, and many still need development before clinical use.
AN ELECTRICAL RESISTANCE METHOD FOR THE RAPID DETERMINATION OF THE MOISTURE CONTENT OF GRAIN