A device for determining a contour of a dental treatment area during treatment thereof includes a laser beam guidance system and an imaging system. The laser beam guidance system can guide a laser beam and, optionally, a scanning light to a dental treatment area, and the imaging system, which can include an adjustable focus image sensor, can obtain an image of the dental treatment area based on light rays reflected therefrom. The device also includes a computation system to compute a contour, e.g., a 2D contour, of a surface of the dental treatment area based on the image obtained by the imaging system and, optionally, geometries of one or more components of the laser beam guidance system and/or optical components associated with the imaging system.