|Year : 2011 | Volume
| Issue : 1 | Page : 14-21
Pulse oximetry and laser doppler flowmetry for diagnosis of pulpal vitality
Dakshita Joy Vaghela1, Ashish Amit Sinha2
1 Department of Conservative Dentistry and Endodontics, Kothiwal Dental College Research Centre and Hospital, Moradabad, India
2 Department of Pedodontics, Kothiwal Dental College Research Centre and Hospital, Moradabad, India
|Date of Web Publication||4-Mar-2011|
Dakshita Joy Vaghela
Department of Conservative Dentistry and Endodontics, Kothiwal Dental College Research Centre and Hospital, Moradabad
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The usual pulpal diagnostic instruments have been shown to be unreliable in diagnosing the pulpal status of the teeth following a traumatic injury, especially for teeth with immature root formation and open apex. Compounding the problem with these testing methods is that they all are very subjective, dependant on cooperation and understanding of the situation by the patient, which can lead to a further difficulty in cases involving young children. It is important to note that the usual pulp vitality tests provide information only about the presence or absence of nerve receptors in the pulp and not about the pulpal blood supply. Recent efforts for assessing pulpal circulation have involved the use of laser Doppler flowmetry and pulse oximetry. Though both methods are in their infancy and are not yet ready for general clinical applications, but hopefully before long, these technologies will become part of dentists' diagnostic armamentaria. The PubMed database search revealed that the reference list for Pulse Oximetry featured 2196 articles; in dentistry-121 articles and for Laser Doppler Flowmetry-932 articles and in dentistry-18 articles. A forward search was undertaken on selected articles, author names, and contemporary endodontic texts. A review is presented on the key developments in the arena of these pulp-tests to familiarize the modern dentists with the new advances in endodontic diagnosis.
Keywords: Endodontic diagnosis, laser Doppler flowmetry, pulp vitality, pulse oximetry, trauma
|How to cite this article:|
Vaghela DJ, Sinha AA. Pulse oximetry and laser doppler flowmetry for diagnosis of pulpal vitality. J Interdiscip Dentistry 2011;1:14-21
|How to cite this URL:|
Vaghela DJ, Sinha AA. Pulse oximetry and laser doppler flowmetry for diagnosis of pulpal vitality. J Interdiscip Dentistry [serial online] 2011 [cited 2020 Feb 28];1:14-21. Available from: http://www.jidonline.com/text.asp?2011/1/1/14/77191
The assessment of pulp vitality is a crucial diagnostic procedure in the practice of dentistry.  Pulp vitality test is crucial in monitoring the state of health of dental pulp, especially after traumatic injuries. The traditional pulp testing methods such as thermal and electrical depend on the innervation and often yield false positive and negative responses. In addition, each is a subjective test that depends on the patient's perceived response to a stimulus as well as the dentist's interpretation of that response.  The newer pulp testing devices, some of which are still in the developmental stage, detect the blood supply of the pulp and are considered to be more accurate and noninvasive. ,
| Pulse Oximetry|| |
The pulse oximeter is a noninvasive oxygen saturation monitoring device widely used in medical practice for recording blood oxygen saturation levels during the administration of intravenous anesthesia. This technique has been used to detect vascular integrity in the tooth. , Its wide acceptance in the medical field results from its ease of application and its capability of providing vital information about the patient's status. ,
In 1935 Carl Matthes built the first device to continuously measure blood oxygen saturation in vivo by transilluminating tissue. He used two wavelengths of light, one of which was sensitive to changes in oxygen saturation and the other, which was in the infra-red range, was used to compensate for changes in tissue thickness, hemoglobin content and light intensity. However, the device had limitations as it was difficult to calibrate and absolute values could not be obtained.
J.R. Squire in 1940 devised a technique of calibration by compressing tissue to eliminate the blood. This was later incorporated in the first generation of pulse oximeters used in the operating theatres.
In the early 1940s, Glen Millikan coined the term "oximeter" to describe a lightweight earpiece to detect the oxygen saturation of hemoglobin, for use in aviation research to investigate high altitude hypoxic problems. Soon, similar devices were used during anesthesia to detect episodes of arterial desaturation in patients.
An editorial in Anaesthesiology in 1951  concluded prophetically "on many occasions this instrument has detected anoxemia when observations of pulse, blood pressure, color of the patient and peripheral vascular tone have shown no abnormalities." This confirmed Comroe's classic work,  which emphasized the unreliability of cyanosis in detecting hypoxemia.
Millikan's ear oximeter was not calibrated. In order to overcome the problem of calibration, using Squire's concept, Earl Wood added a pneumatic cuff to measure the light increase when the ear was blanched.
In 1964, a surgeon, Robert Shaw, built a self-calibrating ear oximeter, which was marketed by Hewlett Packard in 1970 for use in physiology and cardiac catheterization laboratories.
Takuo Aayogi (1972) at the Nihon Kohden Corp. working on a dye dilution cardiac output monitor using a ear densitometer, found artifacts due to pulsatile flow. He noted that the washout curves were modified by pulsatile variations. While attempting to eliminate these variations, he discovered that the absorbency ratios of these pulsations at different wavelengths varied with the oxygen saturation. Thus, he could minimize the pulsatile component by balancing the red light signal with an infrared light signal where the dye had no absorption. As this compensation was dependent on oxygen saturation, he incorporated the technique of reducing noise in his signal to measure oxygen saturation. ,,
The subsequent development of light emitting diodes (LEDs), photo detectors and microprocessors further refined the technique and pulse oximeters were widely introduced into clinical practice. Modern pulse oximetry was born with the realization that pulsatile changes in light transmission through living tissues are due to alteration of the arterial blood volume in the tissue. Measurement of the pulsatile component would eliminate the variable absorption of light by bone, tissue, skin, pigment, etc. from analysis.
The most important premise of pulse oximetry, is that the only pulsatile absorbance between the light source and the photo detector is that of arterial blood. , Earlier studies by Schnettler and Wallace  reported a correlation between pulp and systemic oxygen saturation readings using a modified ear pulse oximeter probe on a tooth. They recommended its use as a definitive pulp vitality tester. Kahan et al.  designed, built, and tested a reflectance tooth probe by using a Biox 3740 oximeter (Ohmeda Louisville, CO). 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.  Gopikrishna et al.  developed a custom made pulse oximeter sensor holder for an existing Nellcor Oximax Dura-YD-YS multisite oxygen sensor (Tyco Healthcare group LP, Pleasanton, CA) and showed the utility of the pulse oximeter dental probe in assessment of human pulp vitality. They further evaluated the sensitivity, specificity, positive predictive value and negative predictive value of this device in comparison with thermal and electric pulp-testing methods and concluded that pulse oximeter is an objective and accurate method of assessing pulp vitality. ,
Because pulp vitality is purely the function of vasculature health, a vital pulp with an intact vasculature may test nonvital if only the nerve fibers are injured. This situation is commonly encountered in recently traumatized teeth. On the other hand, pulp fibres are more resistant to necrosis than the vascular tissue.  Therefore, thermal and electric tests may give a false-positive response if only the pulp vasculature is damaged.
In cases of trauma, teeth often do not respond to conventional pulp testing methods immediately after injury. This temporary loss of response is caused by injury, inflammation, pressure or tension on the nerve fibres in the apical area because of trauma.  Usually 1-8 weeks can lapse before a normal pulpal response can be elicited. However, greater observation periods may be required.  According to Ozcelik et al.,  early neuronal degeneration in cases of trauma is manifested as intramyelin edema, axonal swelling, and partial loss of myelin sheaths. Bhaskar and Rappaport  reported their clinical observation on 25 anterior teeth that had been traumatized and did not respond to conventional vitality tests. When the pulp chambers were opened, all revealed vital pulps. They concluded that conventional vitality tests are in reality sensitivity tests and have questionable predictive value of the vitality of the pulp tissue. For this reason, they recommended that endodontic therapy should be delayed in traumatized teeth and the affected pulp tissue should be considered vital unless apical radiolucencies or sinus tracts develop. A more accurate assessment of pulp vitality can be made by determining the presence of a functioning blood supply, thus allowing the healing potential to be evaluated at an earlier stage. Moreover, delay in diagnosis can lead to severe complications such as inflammatory root resorption.  Therefore, it is important to determine the status of pulp in such cases to evaluate the necessity for root canal treatment.
Principle and working
The principle is based on a modification of Beer Lambert's law, which relates the absorption of light by a solute to its concentration and optical properties at a given light wavelength. It also depends on the absorbance characteristics of hemoglobin in the red and infra-red range. , In the red region, oxyhemoglobin absorbs less light than deoxyhemoglobin and vice versa in the infrared region. ,
The system consists of a probe containing a diode that emits light in two wavelengths: red light of approximately 660 nm and infra-red light of approximately 940 nm. A silicon photo detector diode is placed on the opposing surfaces of the tooth, which is connected to a microprocessor. The probe is placed on the labial surface of the tooth crown and the sensor on the palatal surface. Ideal placement of the probe is in the middle third of the crown. If placed in the gingival third, disturbances from gingival circulation or any gingival trauma or bleeding will interfere with the readings, whereas incisally less pulp tissue is present for adequate detection of the pulse.
The critical requirement of using pulse oximeter in dentistry is as follows.
- Sensor should conform to the size, shape, and anatomical contours of teeth.
- Light-emitting diode sensor and the photoreceptor should be as parallel as possible to each other so that the photoreceptor sensor receives the light-emitted from LED.
The sensor holder should allow firm placement of the sensor onto the tooth to obtain accurate measurements [Figure 1]. 
|Figure 1: Working of a pulse oximeter. (a) LED-emitting red light at 660 nm. (b) LED emitting infrared light at 940 nm. (c) Photodetector. (d) Pulse oximeter monitor. (e) Pulse oximeter sensor. (f) Custom-made pulse oximeter sensor holder. HbO2, oxygenated hemoglobin; HbR, deoxygenated hemoglobin; SpO2, oxygen saturation of arterial blood|
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- Effective and objective method of evaluating dental pulp vitality.
- Useful in cases of impact injury where the blood supply remains intact but the nerve supply is damaged.
- Pulpal circulation can be detected independent of gingival circulation.
- Pulp pulse readings are reproducible.
- Smaller and cheaper commercial oximeters are now available for routine clinical use in an average dental office.
- Background absorption associated with venous blood and tissue constituents is not differentiated.
- Probes should be specific for the anatomy of a tooth as the oxygen saturation values from the teeth routinely register lower than the readings from the patient's finger. ,,
| Laser Doppler Flowmetry|| |
Pulp vitality implies that blood supply is present within the tissues. Hence, only a test that actually measures or assesses pulp blood flow can be called a vitality test., Laser Doppler flowmetry (LDF) is a noninvasive, painless, electro optical technique, which allows the semi-quantitative recording of pulpal blood flow. ,,,, It measures blood flow even in the very small blood vessels of the microvasculature. ,
Laser Doppler method was used by Yeh and Cummins  to estimate the velocity of red blood cells in capillaries. LDF was developed to assess blood flow in microvascular systems, e.g., in the retina, gut mesentery, renal cortex, and skin. [36-38] It has since been widely adopted for the measurement of blood flow especially in soft tissues. ,,,,,,,, This original technique utilized a light beam from a helium-neon (He-Ne) laser emitting at 632.8 nm, which, when scattered by moving red cells underwent a frequency shift according to the Doppler principle. A fraction of the light back-scattered from the illuminated area, shifted frequency in this way. This light was detected and processed to produce a signal that was a function of the red cell flux. This information was used as a measure of blood flow, the value being expressed as a percentage of full-scale deflection at a given gain. This method was adopted to monitor blood flow in intact teeth in animals , and in man. ,,,, Other wavelengths of semiconductor laser have also been used: 780 nm , and 780-820 nm. ,,, Zang et al.  demonstrated greatly improved results using forward scattering detection as opposed to conventional backward scattering detection.  These results were confirmed by Sasano.  Odor et al.  reported that the 810 nm wavelength showed good sensitivity but poor specificity and that the 633 nm wavelength showed good specificity but poor sensitivity. Nonlaser light (peak output at 576 nm) has also been used for the detection of pulpal perfusion.  In general, infrared light (780-810 nm) has a greater ability to penetrate enamel and dentine than shorter wavelength red light (632.8 nm).  LDF techniques are united in their validity for pulp vitality testing as they reflect vascular rather than nervous responsiveness.  Due to some of the inherent problems associated with this technology, Sasano et al.  considered it to be limited in its usefulness for human pulp vitality testing. The lasers used for LDF are usually at a low-power level of 1 or 2 mW and no reports on pulp injury by this method have been made. The other use of laser for diagnostics related to endodontics was the application of an excimer laser system emitting at 308 nm for residual tissue detection within the canals. ,,,
Principle and working
The technique depends on the Doppler principle whereby light from a laser diode incident on the tissue is scattered by moving RBCs and as a consequence, the frequency is broadened. The frequency broadened light, together with laser light scattered is photo detected and the resulting photocurrent processed to provide a blood flow measurement. LDF is an optical measuring method that enables the number and velocity of particles conveyed by a fluid flow to be measured. The particles (1-20 μm) must be big enough to scatter sufficient light for signal detection but small enough to follow the flow faithfully. ,,,,, The original technique used a light beam from a helium-neon (He-Ne) laser emitting at 632.8 nm. Other wavelengths of semi-conductor laser have also been used: 780 nm and 780-820 nm.  Laser light is transmitted to the dental pulp by means of a fibre optic probe placed against the tooth surface. Two equal-intensity beams (split from a single beam) intersect across the target area. The scattered light beams from moving red blood cells are frequency-shifted whilst those from the static tissue remain unshifted in frequency. The unshifted light is returned by an afferent fibre within the same probe to photodetectors in the flowmeter and the signal is produced. ,,, The LDF output signal or Flux can be simplified as a function of the product of red blood cells' concentration as well as their mean velocity.  It should be emphasized that the optical properties of a tooth change when the pulp becomes necrotic and this can produce changes in the LDF signal that are not due to differences in blood flow.  In fact, as red blood cells represent the vast majority of moving objects within the tooth measurement of the Doppler-shifted backscattered light serves as an index of PBF. LDF evaluates dynamic changes in blood flow by detecting blood cell movement in a small volume of tissue (about 1 mm 3 ).,, Most current laser Doppler devices give readout, in addition to the flux, in perfusion units (PUs).
If a wave with frequency ω is scattered from a moving particle with velocity v; the Doppler shift can be written as
where kI is the incident wave vector, ks is the wave vector of the scattered wave, and β is the angle between the velocity vector and the scattering vector, which is defined as (kI - ks) [Figure 2] and [Figure 3]. 
|Figure 2: Principle of laser Doppler flowmetry: red light is emitted from a light source; if the light beam is scattered-off of stationary tissue or cells, there is no shift in the light spectrum. If, however, the light hits a moving cell in a blood vessel there is a shift in the light spectrum of the scattered light according to the Doppler flowmetry|
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- Estimation of the pulpal vitality: the diagnosis of a tooth with a necrotic pulp may be difficult particularly when referred pain is present. In these situations, a suitable test and its precise interpretation are of paramount importance. 
- Pulp-testing in children: sensibility tests are not reliable in children, because they are subjective and rely upon patient's response. LDF is a suitable method for the measurement of PBF in deciduous incisors. 
- Periapical radiolucencies may have nonendodontic origins, so application of vitality tests, such as LDF can help in differential diagnosis of these radiographic views. 
- It monitors age related changes in PBF. Using this system, it has been shown that the hemodynamics in the human pulp is reduced with age. 
- Monitoring the effect of exercise on PBF. It has been indicated that PBF varies during exercise, with a mean percentage change of 38% from the level at rest.
- Monitoring of reactions to local and systemic pharmacological agents (including local anesthetic solutions). ,,
- Monitoring of reactions to electrical or thermal pulp stimulation. ,
- Monitoring reactions to orthodontic procedures.
- Measuring PBF after orthognathic surgery. Among patients who undergo a segmental maxillary osteotomy or Le fort I osteotomy, significant reduction in pulpal sensibility has been noted in teeth in the osteotomized segment or maxilla.
- Measuring of PBF after traumatic injuries: Traumatized teeth may have their innervations damaged and give a negative response to pulp tests although their blood circulation and thus their true vitality is functional. LDF is an accurate and objective technique for assessment of pulpal vitality in these teeth.
- Monitoring of revascularization of replanted teeth: LDF readings correctly predict the pulp status in vital vs nonvital teeth. 
Useful in young children whose responses are unreliable and its noninvasive nature helps to promote patient cooperation and acceptance. ,,
- Luxation injuries
- Too expensive a device for use in a dental office.
- The sensor should be maintained motionless and in constant contact with the tooth for accurate readings.
- The laser beam must interact with the moving cells within the pulpal vasculature. 
- It is generally agreed that LDF assessment for human teeth should be performed at 4 weeks following the initial trauma and repeated at regular intervals until 3 months.
- Blood pigments within a discolored tooth crown can also interfere with laser light transmission. Care must be taken to ensure that the false positive results are not obtained from the stimulation of supporting tissues. 
Comparative studies on pulp oximetry and laser Doppler flowmetry
Gopi Krishna et al. evaluated the efficacy of a custom-made pulse oximeter dental probe in comparison with the electrical and thermal tests for assessing pulp vitality. Sensitivity, specificity, negative predictive value, and positive predictive value for each test were calculated by comparing the test results with the actual pulpal status [Table 1] and [Table 2].
The results of the study showed that custom-made pulse oximeter dental probe is an effective, accurate, and objective method of evaluating pulp vitality. 
Gopi Krishna et al. compared the efficacy of a custom-made pulse oximeter dental probe with the electric pulp testing and thermal testing for measuring pulp vitality status of recently traumatized permanent teeth. Readings for pulp vitality for 17 recently traumatized maxillary incisors were taken with custom-made pulse oximeter dental probe (group 1), electrical pulp tester (group 2), and thermal testing (group 3) over a 6-month period. The proportion of recently traumatized teeth showing a positive responsiveness in thermal/electric pulp tests increased from no teeth showing responsiveness on day 0 to 29.4% teeth on the 28 th day, 82.35% of teeth at 2 months and 94.11% teeth at 3 months. However, pulse oximeter gave positive vitality readings that remained constant over the study period from day 0 to 6 months in all patients [Table 3]. 
|Table 3: The proportion of recently traumatized teeth showing positive response (in %) |
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Odor et al. investigated the pattern of light transmission through teeth of different species and examined laser light propagation within enamel from various animal sources. They concluded that light from a laser Doppler probe appeared to reach the dental pulp in all the species; however, in the mammals with smaller teeth, light may also have been able to reach the periodontium and thus the reflected signal may not be entirely of pulpal origin. 
| Conclusion|| |
The unreliability of testing tooth pulp nerve response is well-documented. When nervous sensations are inhibited or abolished in the tooth, for example, following trauma, tooth transplantation procedures or during a general anaesthetic, conventional tests are of little value. However, a method based on the vascular response of the pulp need not be restricted under such conditions. Recording the pulpal blood flow would be an objective assessment of the status of the pulpal blood circulation, a true indicator of pulp vitality. Optical devices that exploit the various absorbance properties of different substances within the dental pulp are being studied to determine pulsation and blood volume. They offer the advantages of being objective, noninvasive, and atraumatic testing modalities, which result in greater patient acceptance and cooperation. Currently, the significance and reliability of these methods are being studied. It is hoped that newer technology will enable a more thorough study of the pulpal vasculature and define its role in pulp vitality testing.
| References|| |
|1.||Noblett WC, Wilcox LR, Scamman F, Johnson WT, Diaz-Arnold A. Detection of pulpal circulation in vitro by pulse oximetry. J Endod 1996;22:1-5. |
|2.||Ehrmann EH. Pulp testers and pulp testing with particular reference to the use of dry ice. Aust Dent J 1977;22:272-9. |
|3.||Chambers IG. The role and methods of pulp testing in oral diagnosis: A review. Int Endod J 1982;15:1-15. |
|4.||Bhasker SN, Rapport HR. Dental vitality test and pulp status. JADA 1973;86:405-11. |
|5.||Schnettler JM, Wallace JA. Pulse oximetry as a diagnostic tool of pulpal vitality. J Endod 1991;17:488-90. |
|6.||Sigurdsson A. Pulpal diagnosis. Endod Topics 2003;5:12-25. |
|7.||Cohen S, Hargreaves KM. Pathways of the pulp. 9 th ed. St. Louis, Missouri 2006. |
|8.||Kamat V. Pulse oximetry. Ind J Anaesth 2002;46:261-8. |
|9.||Stephen RC, Slater HM, Johnson AL, Sekelj P. The oximeter-A technical aid for the anesthesiologist. Anesthesiology 1951;12:541-55. |
|10.||Comroe JH, Botelho S. The unreliability of cyanosis in the recognition of arterial hypoxemia. Am J Med Sc 1947;214:1-8. |
|11.||Jafarzadeh H, Rosenberg PA. Pulse oximetry: Review of a potential aid in endodontic diagnosis. J Endod 2009;35:329-33. |
|12.||Severinghaus JW, Honda Y. History of blood gas analysis. VII. Pulse oximetry. J Clin Monit 1987;3:135-8. |
|13.||Carlson KA, Jahr JS. A historical overview and update on pulse oximetry. Anesthesiol Rev 1993;20:173-81. |
|14.||Gopi Krishna V, Kandaswamy D, Gupta T. Assessment of the efficacy of indigeniously delevoped pulse oximeter dental sensor holder for pulp vitality testing. Indian J Dent Res 2006;17:111-3. |
|15.||Kahan RS, Gulabivala K, Snook M, Setchell DJ. Evaluation of a pulse oximeter and customized probe for pulp vitality testing. J Endod 1996;22:105-9. |
|16.||Gopikrishna V, Tinagupta K, Kandaswamy D. Evaluation of efficacy of a new custom-made pulse oximeter dental probe in comparison with the electrical and thermal tests for assessing pulp vitality. J Endod 2007;33:411-4. |
|17.||Gopikrishna V, Tinagupta K, Kandaswamy D. Comparison of electrical, thermal and pulse oximetry methods for assessing pulp vitality in recently traumatized teeth. J Endod 2007;33:531-5. |
|18.||Munshi AK, Hedge AM, Radhakrishnan S. Pulse oximetry: A diagnostic instrument in pulpal vitality testing. J Clin Pediatr Dent 2002;26:141-5. |
|19.||Pun Z, Trowbridge H, Bender IB, Rickoff B, Sorin S. Assessment of reliability of electrical and thermal pulp testing agents. J Endod 1986;12:301-5. |
|20.||Andreasen FM, Andreasen JO. Luxation injuries. In: Andreasen FM, Andreasen JO, editors. Textbook and Color Atlas of Traumatic Injuries to the teeth. 3 rd ed. Copenhagen: Munksgaard; 1994. p. 353-4. |
|21.||Andreasen FM, Andreasen JO. Crown fractures. In: Andreasen FM, Andreasen JO, editors. Textbook and Color Atlas of Traumatic Injuries to the teeth. 3 rd ed. Copenhagen: Munksgaard; 1994. p. 245. |
|22.||Ozcelik B, Kuraner T, Kendir B, Asan F. Histopathological evaluation of the dental pulps in crown fractured teeth. J Endod 2000;26:271-3. |
|23.||Tronstad L. Root resorption-etiology, terminology and clinical manifestations. Endod Dent Traumatol 1988;4:241-52. |
|24.||Wilson WC, Shapiro B. Preoperative hypoxia: The clinical spectrum and current oxygen monitoring methodology. In: Wilson WC, editor. Anesthesiology Clinics North America: Monitoring through clinical events. Vol. 19. Philadelphia: WB Saunders; 2001. p. 799-804. |
|25.||Goho C. Pulse oximetry evaluation of vitality in primary and immature permanent teeth. Pediatr Dent 1999;21:125-7. |
|26.||Samraj RV, Indira R, Srinivasan MR, Kumar A. Recent advances in pulp vitality testing. Endodontology 2003;15:14-19. |
|27.||Ingle JI, Heithersay GS, Hartwell GR, Goerig AC, Marshall FJ, Krasny RM, Frank AL, Gaum C. Endodontic diagnostic procedures. In: Ingle JI, Bakland LK, editors. Endodontics. 5 th ed. London: BC Decker Inc; 2002. p. 203-17. |
|28.||Berman LH, Hartwell GR. Diagnosis. In: Cohen S, Hargreaves KM, editors. Pathways of the Pulp. 9 th ed. St. Louis: Mosby; 2006. p. 16-20. |
|29.||Ramsay DS, Artun J, Bloomquist D. Orthognathic surgery and pulpal blood flow: A pilot study using laser Doppler flowmetry. J Oral Maxillofac Surg 1991;49:564-70. |
|30.||Ramsay DS, Artun J, Martinen SS. Reliability of pulpal blood-flow measurements utilizing laser Doppler flowmetry. J Dent Res 1991;70:1427-30. |
|31.||Mesaros SV, Trope M. Revascularization of traumatized teeth assessed by laser Doppler flowmetry: Case report. Endod Dent Traumatol 1997;13:24-30. |
|32.||Emshoff R, Kranewitter R, Norer B. Effect of Le Fort I osteotomy on maxillary tooth-type-related pulpal blood-flow characteristics. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:88-90. |
|33.||Emshoff R, Emshoff I, Moschen I, Strobl H. Laser Doppler flow measurements of pulpal blood flow and severity of dental injury. Int Endod J 2004;37:463-7. |
|34.||Yanpiset K, Vongsavan N, Sigurdsson A, Trope M. Efficacy of laser Doppler flowmetry for the diagnosis of revascularization of reimplanted immature dog teeth. Dent Traumatol 2001;17:63-70. |
|35.||Yeh Y, Cummins HZ. Localized fluid flow measurements with an He-Ne laser spectrometer. Appl Phys Lett 1964;4:176-8. |
|36.||Morikawa S, Lanz O, Johnson CC. Laser Doppler measurements of localized pulsatile fluid velocity. IEEE Trans Biomed Eng 1971;18:416-20. |
|37.||Riva C, Ross B, Benedek GB. Laser Doppler measurements of blood flow in capillary tubes and retinal arteries. Ophthalmol Invest 1972;11:936-44. |
|38.||Kimura Y, Wilder-Smith P, Matsumoto K. Lasers in endodontics: A review. Int Endod J 2000;33:173-85. |
|39.||Stern MD. In vivo evaluation of microcirculation by coherent light scattering. Nature 1975;254:56-8. |
|40.||Holloway GA Jr, Watkins DW. Laser Doppler measurement of cutaneous blood flow. The J Invest Dermatol 1977;69:306-9. |
|41.||Baab DA, Oberg PA, Holloway GA. Gingival blood flow measured with a laser Doppler flowmeter. J Periodontal Res 1986;21:73-85. |
|42.||Baab DA, Oberg PA. Laser Doppler measurement of gingival blood flow in dogs with increasing and decreasing inflammation. Arch Oral Biol 1987;32:551-5. |
|43.||Boutault F, Cadenat H, Hibert PJ. Evaluation of gingival microcirculation by a laser-Doppler flowmeter. Preliminary results. J Craniomaxillofac Surg 1989;17:105-9. |
|44.||Bystrova NK, Sidorov VV, Matrusov SG, Sadyrina EV, Chemens NK. Laser Doppler flowmetry as a method for evaluating the microwave radiation effect on cutaneous microcirculation. Crit Rev Biomed Eng 2001;29:549-56. |
|45.||Mayrovitz HN, Groseclose EE, Markov M, Pilla AA. Effects of permanent magnets on resting skin blood perfusionin healthy persons assessed by laser Doppler flowmetry and imaging. Bioelectromagnetics 2001;22:494-502. |
|46.||Raamat R, Jagomägi K, Kingisepp P. Simultaneous recording of fingertip skin blood flow changes by multiprobe laser Doppler flowmetry and frequency-corrected thermal clearance. Microvasc Res 2002;64:214-9. |
|47.||Sato M, Harada K, Okada Y, Omura K. Blood-flow change and recovery of sensibility in the maxillary dental pulp after a single-segment Le Fort I osteotomy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;95:660-4. |
|48.||Edwall B, Gazelius B, Berg JO, Edwall L, Hellander K, Olgart L. Blood flow changes in the dental pulp of the cat and rat measured simultaneously by laser Doppler flowmetry and local 125I clearance. Acta Physiol Scand 1987;131:81-91. |
|49.||Gazelius B, Edwall B, Olgart L, Lundberg JM, Hokfelt T, Fischer JA. Vasodilatory effects and coexistence of calcitonin gene-related peptide (CGRP) and substance P in sensory nerves of cat dental pulp. Acta Physiol Scand 1987;130:33-40. |
|50.||Gazelius B, Olgart L, Edwall B, Edwall L. Non-invasive recording of blood flow in human dental pulp. Endod Dent Traumatol 1986;2:219-21. |
|51.||Gazelius B, Olgart L, Edwall B. Restored vitality in luxated teeth assessed by laser Doppler flowmeter. Endod Dent Traumatol 1988;4:265-8. |
|52.||Olgart L, Gazelius B, Lindh-Stromberg U. Laser Doppler flowmetry in assessing vitality in luxated permanent teeth. Int Endod J 1988;21:300-6. |
|53.||Wilder-Smith PE. A new method for the noninvasive measurement of pulpal blood flow. Int Endod J 1988;21:307-12. |
|54.||Ingolfsson AE, Tronstad L, Hersh E, Riva CE. Efficacy of laser Doppler flowmetry in determining pulp vitality of human teeth. Endod Dent Traumatol 1994;10:83-7. |
|55.||Watson AD, Pitt Ford TR, McDonald F. Blood flow changes in the dental pulp during limited exercise measured by laser Doppler flowmetry. Int Endod J 1992;25:82-7. |
|56.||Zang DY, Millerd JE, Wilder-Smith PB, Arrastia AM. A novel laser Doppler flowmeter for pulpal blood flow measurements. Proceedings of the International Society for Optical Engineering 1996;2672:21-6. |
|57.||Vongsavan N, Matthews B. Some aspects of the use of laser Doppler flow meters for recording tissue blood flow. Exp Physiol 1993;78:1-14. |
|58.||Vongsavan N, Matthews B. Experiments in pigs on the sources of laser Doppler blood-flow signals recorded from teeth. Arch Oral Biol 1996;41:97-103. |
|59.||Hartmann A, Azerad J, Boucher Y. Environmental effects on laser Doppler pulpal blood-flow measurements in man. Arch Oral Biol 1996;41:333-9. |
|60.||Odor TM, Ford TR, McDonald F. Effect of probe design and bandwidth on laser Doppler readings from vital and root-filled teeth. Med Eng Phys 1996;18:359-64. |
|61.||Sasano T. Neural regulation of pulpal blood flow and pulp diagnosis. Tohoku Univ Dent J 1998;17:1-21. |
|62.||Odor TM, Pitt Ford TR, McDonald F. Effect of wavelength and bandwidth on the clinical reliability of laser Doppler recordings. Endod Dent Traumatol 1996;12:9-15. |
|63.||Diaz-Arnold AM, Wilcox LR, Arnold MA. Optical detection of pulpal blood. J Endod 1994;20:164-8. |
|64.||Tronstad L. Recent development in endodontic research. Scand J Dent Res 1992;100:52-9. |
|65.||Sasano T, Nakajima I, Shoji N, Satoh S, Sanjo D. Problems related to measurement of pulpal blood flow by means of laser Doppler flowmetry. Tohoku Univ Dent J 1997;16:32-6. |
|66.||Pini R, Salimbeni R, Vannini M, Cavalieri S, Barone R, Clauseries C. Laser dentistry: Root canal diagnostic technique based on ultraviolet-induced fluorescence spectroscopy. Lasers Surg Med 1989;9:358-61. |
|67.||Odor TM, Chandler NP, Watson TF, Ford TR, McDonald F. Laser light transmission in teeth: A study of the patterns in different species. Int Endod J 1999;32:296-302. |
|68.||Rajan V, Varghese B, Van Leeuwen TG, Steenbergen W. Review of methodological developments in Laser Doppler Flowmetry. Lasers Med Sc 2009; 24: 269-283. |
|69.||Durst F, Melling A, Whitelaw JH. Principles and Practice of Laser Doppler Anemometry. London: Academic Press; 1976. |
|70.||Durrani TS, Greated CA. Laser Systems in Flow Measurement. New York: Plenum; 1977. p. 147-63. |
|71.||Drain LE. The Laser Doppler Technique. New York, NY, USA: John Wiley Press; 1980. p. 36-52. |
|72.||Bonner RF, Nossal R. Principles of laser-Doppler flowmetry. In: Shepherd AP, Oberg PA, editors. Laser-Doppler Blood Flowmetry. New York: Springer-Verlag; 1990. p. 390-409. |
|73.||Albrecht HE, Damaschke N, Borys M, Tropea C. Laser Doppler and Phase Doppler Measurement Techniques. New York: Springer; 2003. p. 4-30. |
|74.||Musselwhite JM, Klitzman B, Maixner W, Burkes EJ Jr. Laser Doppler flowmetry: A clinical test of pulpal vitality. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;84:411-9. |
|75.||Gopikrishna V, Pradeep G, Venkateshbabu N. Assessment of pulp vitality: A review. Int J Paediatr Dent 2009;19:3-15. |
|76.||Roeykens H, Van Maele G, De Moor R, Martens L. Reliability of laser Doppler flowmetry in a 2-probe assessment of pulpal blood flow. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:742-8. |
|77.||Roebuck EM, Evans DJ, Stirrups D, Strang R. The effect of wavelength, bandwidth, and probe design and position on assessing the vitality of anterior teeth with laser Doppler flowmetry. Int J Paediatr Dent 2000;10:213-20. |
|78.||Rowe AH, Pitt Ford TR. The assessment of pulpal vitality. Int Endod J 1990;23:77-83. |
|79.||Soo-ampon S, Vongsavan N, Soo-ampon M, Chuckpaiwong S, Matthews B. The sources of laser Doppler blood-flow signals recorded from human teeth. Arch Oral Biol 2003;48:353-60. |
|80.||Oberg PA. Laser-Doppler flowmetry. Crit Rev Biomed Eng 1990;18:125-63. |
|81.||Ketabi M, Hirsch RS. The effects of local anesthetic containing adrenaline on gingival blood flow in smokers and non-smokers. J Clin Periodontol 1997;24:888-92. |
|82.||Perry DA, McDowell J, Goodis HE. Gingival microcirculation response to tooth brushing measured by laser Doppler flowmetry. J Periodontol 1997;68:990-5. |
|83.||Schmitt JM, Webber RL, Walker EC. Optical determination of dental pulp vitality. IEEE Trans Biomed Eng 1991;38:346-52. |
|84.||Fratkin RD, Kenny DJ, Johnston DH. Evaluation of a laser Doppler flowmeter to assess blood flow in human primary incisor teeth. Pediatr Dent 1999;21:53-6. |
|85.||Chandler NP, Love RM, Sundqvist G. Laser Doppler flowmetry: An aid in differential diagnosis of apical radiolucencies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:613-6. |
|86.||Ikawa M, Komatsu H, Ikawa K, Mayanagi H, Shimauchi H. Age-related changes in the human pulpal blood flow measured by laser Doppler flowmetry. Dent Traumatol 2003;19:36-40. |
|87.||Ahn J, Pogrel MA. The effects of 2% lidocaine with 1:100,000 epinephrine on pulpal and gingival blood flow. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:197-202. |
|88.||Ozturk M, Parker S, and Yilmaz D. Containing Different Proportions of 4% articaine HCl epinephrine HCL and Gingival blood supply and the Effects of Dental Laser Doppler Flowmetry Analysis Technique. Journal of Cumhuriyet University Dental Faculty 1998;1:19-23. |
|89.||Fernieini EM, Bennett JD, Silverman DG, Halaszynski TM. Hemodynamic assessment of local anesthetic administration by laser Doppler flowmetry. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;91:526-30. |
|90.||Raab WH, Magerl W, Müller H. Changes in dental blood flow following electrical tooth pulp stimulation-influences of capsaicin and guanethidine. Agents Actions 1988;25:237-9. |
|91.||Goodis HE, Winthrop V, White JM. Pulpal responses to cooling tooth temperatures. J Endod 2000;26:263-7. |
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]