Early detection of carious lesions increases the possibility of treatment without the need for surgical intervention. Optical coherence tomography (OCT) is an emerging three-dimensional imaging technique that has been successfully used in other medical fields, such as ophthalmology for optical biopsy, and is a prospective candidate for early caries detection. The technique is based on low coherence interferometry and is advantageous in that it is non-invasive, does not use ionizing radiation, and can render three-dimensional images. A brief history of the development of this technique and its principles are discussed in this paper. There have been numerous studies on caries detection, which were mostly in vitro or ex vivo experiments. Through these studies, the feasibility of OCT for caries detection was confirmed. However, further research should be performed, including in vivo studies of OCT applications, in order to prove the clinical usefulness of this technique. In addition, some technological problems must be resolved in the near future to allow for the use of OCT in everyday practice.

Caries remains prevalent throughout modern society and is the main disease in the field of dentistry. Although studies of this disease have used diverse methodology, recently, X-ray microtomography has gained popularity as a non-destructive, 3-dimensional (3D) analytical technique, and has several advantages over the conventional methods. According to X-ray source, it is classified as monochromatic or polychromatic with the latter being more widely used due to the high cost of the monochromatic source despite some advantages. The determination of mineral density profiles based on changes in X-ray attenuation is the principle of this method and calibration and image processing procedures are needed for the better image and reproducible measurements. Using this tool, 3D reconstruction is also possible and it enables to visualize the internal structures of dental caries. With the advances in the computer technology, more diverse applications are being studied, such automated caries assessment algorithms.