Dental discolouration after thermal treatment

Enamel and dentin discolouration have extrinsic and intrinsic origins. Possible causes include pigmented food or drink, caries, clinical chemical treatments, trauma and, high temperature. In the oral cavity, dental hard tissues can be heated when irradiated with high-intensity lasers. This paper, reports initial results on the discolouration of enamel and dentin induced by thermal treatment. The samples used in this work were bovine incisor teeth. Enamel and dentin discolouration were verified using microscopy and transmission spectroscopy. Thermal treatment was carried out at temperatures of 140 and 200 °C. The natural transparent aspect of the enamel became opaque after thermal treatment, it whitened following treatment at 140 °C, and turned completely opaque after treatment at 200 °C. With the same thermal treatment, dentin became light brown after treatment, at 140 °C, and the brown pattern was more evident after treatment at 200 °C. Although there is no conclusive evidence, non-enzymatic browning, collagen denaturation or oxidation of some chemical component of the dentin, may be intensified or produced by the thermal treatment. In enamel, water loss and the consequent increase in light scattering explain the observed opacity.