Optical determination of dental pulp vitality

The feasibility of employing photoplethysmography and pulse oximetry to assess the status of blood circulation in dental pulp was explored. A simple photometer that measures diffuse light transmission at 575 nm was built to record tooth plethysmograms and the ability to distinguish the vital from the surgically devitalized teeth of a dog using plethysmography was demonstrated. As an extension of the photoplethysmographic technique, red-infrared pulse oximetry applied to the measurement of the oxygen saturation (SO ₂) of blood in the pulp was examined using an in vitro test setup. Results suggest that the measurement of relative SO ₂ changes is feasible, but standard dual-wavelength pulse oximetry does not allow determination of SO ₂ independent of tooth geometry and sensor placement. Practical issues concerning the design of an optical vitalometer capable of reliably detecting the tooth pulp plethysmogram are discussed.