Dental pulp vitality measurement based on multiwavelength photoplethysmography

Observation of the intradental blood supply is important in cases of dental trauma, but difficult. As the methods used by dentists to measure pulp vitality are not very reliable, a dental pulp vitalometer based on fiberoptic reflectance measurement and measurement of the absorption of blood has been designed and built. In addition to the fiber optic probe and reflectance sensor electronics, the vitalometer includes a data acquisition card, a PC and data processing programs. The thick dentin and enamel layers and the small amount of blood in a tooth are major problems for optical measurement of its vitality, and scattered light from the enamel and the dentin surrounding the pulpa also causes a problem in measurements based on reflectance. These problems are assessed here by means of theoretical models and calculations. The advantage of reflectance measurement is that only one probe is used, which is easy to put against the tooth. Thus measurements are simple to make. Three wavelengths (560 nm, 650 nm, 850 nm) are used to measure photoplethysmographic signals, and these should allow the oxygen saturation of the blood in a tooth to be measured as well in the future. Series of measurements have been performed on vital and non-vital teeth by recording photoplethysmographic signals, using the vitalometer and using a commercial laser-Doppler instrument. Verifications of the laser-Doppler and vitalometer results are presented and deduced here.

[1]  J. Andreasen,et al.  Dental traumatology: quo vadis , 1990 .

[2]  K Oikarinen,et al.  Detection of pulse in oral mucosa and dental pulp by means of optical reflection method. , 1996, Endodontics & dental traumatology.

[3]  J. Featherstone,et al.  Nature of light scattering in dental enamel and dentin at visible and near-infrared wavelengths. , 1995, Applied optics.

[4]  J. J. Bosch,et al.  Theoretical model for the scattering of light by dentin and comparison with measurements. , 1993, Applied optics.

[5]  B. Wilson,et al.  Time resolved reflectance and transmittance for the non-invasive measurement of tissue optical properties. , 1989, Applied optics.

[6]  Gerhard J. Mueller,et al.  Infrared diaphanoscopy (IRD) and infrared fluoroscopic imaging (IRF) in biological tissue , 1993, Photonics West - Lasers and Applications in Science and Engineering.

[7]  A E Profio,et al.  Light transport in tissue. , 1989, Applied optics.

[8]  J. Schmitt,et al.  Optical determination of dental pulp vitality , 1991, IEEE Transactions on Biomedical Engineering.

[9]  Vladimir N. Grisimov,et al.  New optical effects in the human hard tooth tissues , 1990, Other Conferences.

[10]  B. Wilson,et al.  Diffusion equation representation of photon migration in tissue , 1991, 1991 IEEE MTT-S International Microwave Symposium Digest.

[11]  H Horiuchi,et al.  Optical characteristics of human extracted teeth and the possible application of photoplethysmography to the human pulp. , 1994, Archives of oral biology.

[12]  J B Gross,et al.  Principles of Pulse Oximetry: Theoretical and Practical Considerations , 1989, Anesthesia and analgesia.