OCT pinpoints hard-to-find tooth enamel cracks

Tooth enamel, the thin outer covering of the tooth that protects teeth against their daily use, is the toughest tissue present in the human body. But despite its toughness, enamel can wear away from acidic foods and beverages, sugary diets, and stress, for example, causing cracking that can lead to cavities or tooth decay.

Of course, finding enamel cracks using conventional methods such as x-rays can be difficult, especially if there is some sort of restoration present. What's more, these methods are not all that sensitive. Recognizing this, researchers from Tokyo Medical and Dental University (Tokyo, Japan) performed a study using swept-source optical coherence tomography (SS-OCT) imaging to cross-sectionally detect enamel cracks.¹

SS-OCT sweeps the near-infrared wavelength spectrum at a 30 kHz rate over a span of 110 nm centered at 1330 nm. In the study, the researchers evaluated 20 extracted human teeth using SS-OCT, applying the imaging technique to locations where the presence of an enamel crack was suspected. To validate their findings, the teeth were then sectioned with a diamond saw and directly viewed under a confocal laser scanning microscope (CLSM).

Using SS-OCT, the presence and extent of enamel cracks were clearly visualized on images based on backscattering signals, and the extension of enamel cracks beyond the dentinoenamel junction also could be confirmed, say the researchers. In addition, the results correlated well with those from the CLSM.

1. K. Imai, Y. Shimada, A. Sadr, Y. Sumi, and J. Yagami, J. Endont., 38, 9, 1269–1274 (September 2012).