The assessment of pulp vitality is a crucial diagnostic procedure in the practice of endodontics. Conventionally, the dentist has relied on tests that depend on the patient’s perceived response to a stimulus as well as the dentist’s interpretation of that response. These methods include thermal stimulation (as in the case ofheat or cold application), electric stimulation or direct dentin stimulation (test cavity).
These tests fall short of the ideal pulp vitality testing on several criteria. Each of the methods described, tests only sensory nerve fibre response. Stimulation of nerve fibres is not the ideal method to determine vitality status. Several authors have stated that vascular supply and not innervation is the most accurate determinant for assessing pulp vitality. As a result, teeth that have temporarily or permanently lost their sensory function (e.g. teeth damaged by trauma. or teeth that have undergone orthognathic surgery) will be non responsive to these tests. However, they may have intact vasculatures . Moreover, the nervous tissue, being highly resistant to inflammation, may remain reactive long after the surrounding tissues have degenerated. Therefore, thermal and electric tests may give false positive response if only the pulp vasculature is damaged . Further, all these tests have the potential to produce an unpleasant and occasionally painful sensation and inaccurateresults may be obtained .
Recent attempts to develop a method for determination of pulpal circulation have involved the use of laser doppler flowmetry dual wavelength spectrophotometry and pulse oximetry. Although laser doppler flowmeter has met with some success in medical applications, its use in dentistry has been hampered by the sizeable expense, tack of reproducibility and sensitivity of the device to motion. Dual wavelength spectrophotometry has been examined only in the laboratory setting so far and only detects quantitatively the presence of haemoglobin and not the circulation ofblood .
Pulse oximeter is a non-invasive oxygen saturation monitoring device widely used in medical practice for recording blood oxygen saturation levels during the administration of intravenous anaesthesia through the use of finger, foot or ear probes. It was invented by Takuo Aoyagi, a biomedical engineer working for the Shimadm Corporation in Kyoto, Japan, in early 1970’s Pulse oximeter uses red and infrared wavelengths to transilluminate a tissue bed, detecting absorbance peaks due to pulsatle blood circulation and uses this information to calculate oxygen saturation and pulse rate It is the most commonly employed technique to measure oxygen saturation because of its ease and economy.
Different researchers have arrived at different conclusions regarding the efficacy of using pulse oximetry to diagnose pulp vitality. Schnettler and Wallac reported a correlation between pulp and systemic oxygen satiation readings using a modified ear pulse oximeter probe on a tooth. Thus, they recommended its use as a definitive pulp vitality tester. Kahan et al designed, built and tested a reflectance tooth probe using Biox 3740 oximeter. Pulse wave readings from the teeth were found to be synchronous with the finger probe but not consistently. They concluded that the accuracy of the commercial instrument was disappointing and in its present form, it was not considered to have predictable diagnostic value.
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