Abstract: Early dental caries detection is carried out by a method that combines optical coherence tomography (OCT) and Raman spectroscopy to provide morphological information and biochemical specificity for detecting and characterizing incipient carious lesions found in extracted human teeth. OCT imaging of tooth samples demonstrated increased light back-scattering intensity at sites of carious lesions as compared to the sound enamel. Raman microspectroscopy and fibre-optic based Raman spectroscopy are used to characterize the caries further by detecting demineralization-induced alterations of enamel crystallite morphology and/or orientation. OCT imaging is useful for screening carious sites and determining lesion depth, with Raman spectroscopy providing biochemical confirmation of caries. The combination is incorporated into a common probe operable without movement to scan the tooth surface and to provide an output for the dentist.

Abstract: The present invention provides an apparatus for etching a substrate, comprising: a container; a substrate support disposed in the container; a rotation actuator attached to the substrate support; and a fluid delivery assembly disposed in the container to deliver an etchant to a peripheral portion of a substrate disposed on the substrate support. Preferably, the substrate support comprises a vacuum chuck and the fluid delivery assembly comprises one or more nozzles. The invention also provide a method for etching a substrate, comprising: rotating a substrate positioned on a rotatable substrate support; and delivering an etchant to a peripheral portion of the substrate. Preferably, the substrate is rotated at between about 100 rpm and about 1000 rpm, and the etchant is delivered in a direction that is substantially tangent to the peripheral portion of the substrate at an incident angle between about 0 degrees and about 45 degrees from a surface of substrate.