Dehydration imaging of dental fluorosis at 1950 nm

Dental fluorosis is an increasing problem in the U.S. due to excessive exposure to fluoride from the environment. Fluorosis causes hypomineralization of the enamel during tooth development and mild fluorosis is visible as faint white lines on the tooth surface while the most severe fluorosis can result in pitted surfaces. It is difficult to differentiate lesions due to fluorosis from those due to caries. Dental fluorosis appears with extremely high contrast at short wavelength infrared (SWIR) wavelengths of 1450 and 1960 nm coincident with higher water absorption. In this study reflectance measurements at 1450 and 1950 nm were used to monitor the dehydration dynamics of lesions due to fluorosis on extracted teeth. The dehydration dynamics were compared with the lesion structure that was measured with microCT. Sixteen extracted teeth with suspected fluorosis were imaged and microCT showed that the mean surface zone thickness was 118 ± 30 μm and the lesion depth was 284 ± 105 μm for the areas of fluorosis investigated. The dehydration dynamics of lesions due to fluorosis appeared most similar to those of arrested caries lesions. There was no significant correlation (P >0.05) of the intensity change and rate of the intensity change at 1450 or 1950 nm with either the lesion surface zone thickness or the lesion depth.