1. A method of capturing a digital dental image, comprising: illuminating a dental region of interest (ROI) using light sources; capturing reflectance images by receiving light reflected from ROI in narrow wavelength bands; processing captured reflectance images to determine relative tHb concentration and its oxygenation level using at least a wavelength band that includes an isobestic wavelength for absorption coefficients of oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb), wherein the processing includes generating reflectance intensity ratios, including an isobestic intensity from the captured reflectance images, in combination, to determine the relative tHb concentration and its oxygenation level; identifying selected areas of interest (AOI) within the dental ROI having selected pixel image characteristics of both hemoglobin's total concentration and oxygenation level; and displaying, storing, or transmitting the identified AOI within the dental RO.