A dental instrument and method for imaging the three-dimensional topography of one or more teeth in the oral cavity of an individual is provided. The instrument includes a probe insertable into the oral cavity to receive the image of these surfaces which can then be processed. Combined with the probe is an auxiliary which projects an air stream toward the surface to be imaged by the probe and acts to evaporate and remove from these surfaces a liquid film coating formed by saliva and other fluids present in the oral cavity, to render these surfaces dry and to enhance their reflectivity and in doing so, provide clearer images.