Dental Pulp Testing: A Review

Dental pulp testing is a useful and essential diagnostic aid in endodontics. Pulp sensibility tests include thermal and electric tests, which extrapolate pulp health from sensory response. Whilst pulp sensibility tests are the most commonly used in clinical practice, they are not without limitations and shortcomings. Pulp vitality tests attempt to examine the presence of pulp blood flow, as this is viewed as a better measure of true health than sensibility. Laser Doppler flowmetry and pulse oximetry are examples of vitality tests. Whilst the prospect is promising, there are still many practical issues that need to be addressed before vitality tests can replace sensibility tests as the standard clinical pulp diagnostic test. With all pulp tests, the results need to be carefully interpreted and closely scrutinised as false results can lead to misdiagnosis which can then lead to incorrect, inappropriate, or unnecessary treatment.

Related papers:

title: Pulp testers and pulp testing with particular reference to the use of dry ice.
abstract: Pulp testing is mandatory before any operative procedures, invaluable in the diagnosis of pain and is an essential adjunct in the interpretation of radiolucent areas. Methods of pulp testing are reviewed and the use of dry ice for this purpose is discussed in detail. Limitations of pulp testing are considered. Vitality tests are of only limited use in traumatized teeth. The results are only qualitative and not quantitative.

title: Dental vitality tests and pulp status.
abstract: Clinical observations were made on 25 anterior teeth that had been traumatized and did not respond to the conventional vitality tests. Examination of the pulp chambers revealed that all the teeth had vital pulps. Radiographs taken at various times after the trauma showed narrowing of root canals. Whereas the pulp tissue acquires its vitality from its blood supply, the nerves provide it only with sensitivity. Since the conventional vitality test establishes only the status of the nerve, the response can be negative and yet the pulp tissue may be vital. It is recommended that in traumatized teeth endodontic therapy should be delayed and the affected pulpal tissue considered vital. If apical radiolucent regions develop, endodontic therapy can be instituted.

title: Reversible and irreversible painful pulpitides: diagnosis and treatment.
abstract: The foregoing clinical evidence indicates that when pain is severe, or when mild to moderate pain is present with a previous history of pain in the aching tooth, with or without periapical radiolucency, the tooth is in the IRPP category. Treatment dictates endodontic therapy or extraction. On the other hand, when clinical evidence indicates that the pain is mild or moderate with no previous history of pain, normal pulp vitality, and there is no positive percussion sign, the pulp is in the RPP category. Treatment dictates indirect or direct pulp capping in teeth with or without periapical radiolucency. The success rate favours teeth with no periapical radiolucency, 98%; in teeth with periapical radiolucency the success rate is less favorable, 43%. Efforts should be made to maintain pulp vitality. Endodontic therapy can always be done, if in time the pulp develops necrosis.

title: A clinical classification of the status of the pulp and the root canal system.
abstract: Many different classification systems have been advocated for pulp diseases. However, most of them are based on histopathological findings rather than clinical findings which leads to confusion since there is little correlation between them. Most classifications mix clinical and histological terms resulting in misleading terminology and diagnoses. This in turn leads to further confusion and uncertainty in clinical practice when a rational treatment plan needs to be established in order to manage a specific pathological entity. A simple, yet practical classification of pulp diseases which uses terminology related to clinical findings is proposed. This classification will help clinicians understand the progressive nature of the pulp disease processes and direct them to the most appropriate and conservative treatment strategy for each condition. With a comprehensive knowledge of the pathophysiology of pain and inflammation in the pulp tissues, clinicians may accomplish this task with confidence.

title: Relationship of patient complaints and signs to histopathologic diagnosis of pulpal condition.
abstract: The correlation between the histopathologic examination of pulp biopsy specimens and patients' complaints and signs was investigated. The sensitivity, specificity and reliability of each complaint and sign, and the characteristics of pain that are associated with treatable and untreatable pulp states is proposed. Pulp specimens were obtained from teeth that required endodontic treatment. Clinical data were recorded to identify each patient's complaints. The pulp specimens were processed and the histopathologic diagnoses were categorised and correlated with the patients' complaints. Of the 240 cases, 100 (41.7%) were diagnosed as atrophic pulp or pulposis; 4 (1.7%) as acute pulpitis; 64 (26.7%) as transitional stage; 56 (23.3%) as chronic pulpitis, and 16 (6.7%) as acute pulpitis superimposed on a chronic pulpitis. Results showed that previous pain (p < 0.05), spontaneous pain (p < 0.01), and prolonged pain on cold stimuli (p < 0.05), were significantly more frequent in the patients with chronic pulpitis compared to those with pulposis or transitional stage. We concluded that clinicians must consider the sensitivity and specificity of patient complaints and signs in order to perform a diagnosis based upon clinical evidence.

title: Diagnostic acuity versus negligence.
abstract: This is not a challenge to one’s diagnostic ability, but rather a narrative of one man’s astute diagnostic acumen versus a team of dentists who proved disastrously negligent over a period of years. The first was Dr. Bernard H. Poliak, who practiced general dentistry in Palm Springs, California, from 1946 until his death in 1996. Bernie was a superb dentist and numbered among his patients ex presidents of the United States and their wives, as well as CEOs of the nation’s leading industries, and many luminaries from the motion picture colony. Every one, from servant girl to president, was treated the same in his office. In addition to being a skilled restorative dentist, he did all the endodontics required by his patients. He was a life-long member of the American Association of Endodontists and attended every annual meeting. The story starts one New Year’s Eve when Dr. Poliak was called at his home by Ambassador Walter Annenberg. One of his guests, Miss Elizabeth Taylor, was suffering a terrible toothache. “Was there something Dr. Poliak could do for her?” “Let me speak to Miss Taylor, please. How severe do you believe the pain to be? That bad! Would you do something for me please? Would you please rinse some ice water around that side of your mouth and tell me what happens? You’re saying that the pain disappeared immediately? Now you’re saying the pain is slowly coming back? Would you please ask Ambassador Annenberg to bring you to my office at once? I’ll meet you there.” (Poliak BH, personal communication, September, 1975). At the office, Dr. Poliak used hot and cold testing to determine exactly which tooth was involved, radiographed the area, anesthetized the tooth, and removed the pulp. The next day Miss Taylor reported complete relief and graciously thanked Dr. Poliak for his efforts—simple testing and definitive treatment. On another occasion, Dr. Poliak was called upon to administer to another famous patient, Moss Hart, the distinguished American playwright. In this instance, Mrs. Hart (Kitty Carlisle), called Dr. Poliak at four o’clock in the morning reporting that Moss had an absolutely excruciating toothache, it had awakened him suddenly and he was pacing the floor, holding his left jaw in pain. “Does he have pain anywhere else?” “No, just his jaw!” “Tell him to quit pacing, to sit down, and I’ll be right there.” (Poliak BH, personal communication, September, 1975). At the Hart home he used the same simple test for advanced acute pulpalgia that he suggested to Elizabeth Taylor—ice water swished around the affected side. In this case there was no relief from the pain. Suspecting a heart attack, Dr. Poliak knew he had to get the patient to the hospital without frightening him. (There was no 911 at that time.) He said he wanted to “conduct some other tests there.” Mrs. Hart went out to get the car and Bernie conducted Mr. Hart out to the front lawn while he went on to turn his car around. Looking back he saw Hart fall to the ground. He rushed to him and started CPR, but it was too late. Moss Hart died on his front lawn. Here again, simple testing and astute knowledge led to a correct diagnosis—but too late! In marked contrast to Dr. Poliak’s abilities is the sad story of five dentists: one a general practitioner, one a board-qualified (but not boarded) prosthodontist, and three board-qualified (but not boarded) endodontists. The endodontists were all trained in the same graduate program. In this case, the patient, a woman trial lawyer, started with the general dentist for whom she soon developed a lack of confidence. She requested her full-mouth radiographs and transferred to the prosthodontist. Using these original films, which by now were over a year old, he outlined a restorative prescription that included root canal therapy, crowns, and bridges. His first action was to refer her to an endodontist with the request to retreat two canals in the lower left first molar. Even the third canal appeared to have a questionable periradicular lesion.) He subsequently crowned the tooth. The endodontist did as he was requested, but both dentists ignored the peculiar bony lesion, glaringly apparent in the radiographs, immediately mesial to the molar and involving the premolar region. Over a period of years the prosthodontist continued his restoration, including a bridge that fell out twice. Finally, the lower left premolar lesion had grown to be noticeable by the patient, just swelling, mind you, but no pain, inflammatory redness, or loss of function. At this point the prosthodontist took his first radiograph of the region and referred the patient back to the original endodontist. This man was not in the office that day, but his partner examined the patient and recommended root canal treatment for the lower left second premolar in the center of the lesion. The patient was unhappy with the substitute endodontist and chose one of her own, closer to home. Once again, the third endodontist took a radiograph, declared the lesion a periapical abscess, and recommended a root canal filling, even though the JOURNAL OF ENDODONTICS Printed in U.S.A.

title: Pulpal injury: pathology, diagnosis and periodontal reactions.
abstract: Diagnosis of pulpal disease can be difficult due to the lack of diagnostic signs and symptoms available to the practitioner. An understanding of the possible underlying pathological processes, combined with an exact assessment of the pain history, and appropriate clinical tests, should aid the practitioner in determining the nature of pulpal inflammation, and differentiating it from dentine sensitivity and cracked teeth. The responses of the pulp to traumatic injury to the periodontal membrane (PDM) require special consideration, particularly with respect to the assessment of pulp vitality, and the determination of cases requiring pulp extirpation in order to avoid inflammatory root resorption. Although the pulp is relatively isolated from the rest of the dentoalveolar complex by a dentine/cementum barrier, it is important to remember that it can communicate with the PDM through apical and lateral foramina, and areas of damaged cementum. Hence, it is a priority to both preserve the integrity of the cemental layer in cases of traumatic injury and periodontal disease, and to prevent the inflammation and resorption associated with periapical lesions by accurate diagnosis of irreversible pulpitis and pulp necrosis, followed by appropriate endodontic debridement procedures.

title: Pulp-dentin biology in restorative dentistry. Part 4: Dental caries--characteristics of lesions and pulpal reactions.
abstract: The infectious disease dental caries results in lesions that may affect enamel, dentin, pulp, and cementum. If a caries lesion has progressed to the stage at which it requires restorative intervention, it is important that the clinician understand the tissue changes in the dentin that are likely to have taken place during lesion development. Until the present, no major distinction between the restorative treatment of active (rapidly progressing) and arrested (slowly progressing) lesions has been made, despite the fact that the two conditions exhibit major differences in tissue changes in the pulp-dentin complex. Intratubular changes and tertiary dentin formation will affect the outcome of the restorative treatment. In unaffected dentin and in rapidly progressing lesions, permeable tubules persist, and when the preparation of carious teeth results in the opening of unaffected dentin, greater care must be taken in all phases of the restorative procedures than if the dentin is impermeable. An active, deep lesion can be changed to an arrested lesion by a two-step excavation approach. Optimal assessment of the prevailing clinical conditions can only be made on the basis of thorough knowledge of the biology of the pulp-dentin organ.

title: Correlation of clinical pain symptoms with histopathological changes of the dental pulp: a review.
abstract: Pulpalgia is strong and often throbbing and it can start and stop spontaneously. When evoked, pain in pulpitis outlasts the stimulus. The pain is difficult to localise and often radiates to other parts of the face. But the pain symptoms vary. There are cases of severe pulpitis progressing to abscess formation and even necrosis without any symptoms (silent pulpitis). In some cases slight pulpal inflammatory changes will cause severe pain. It seems that correlation between clinical symptoms and histopathological condition of the pulp is not clear. Pulpal inflammatory changes may cause hypersensitivity of the intradental nerves. Vasodilation, increased vascular permeability and extravasation will cause increased intrapulpal pressure. This could spontaneously activate the pulpal nerves. The increased pressure will selectively activate the C-fibres while blocking the A-fibres which are more vulnerable to hypoxia. This would explain the change in pain symptoms during progress of pulpitis to dull type of pain. Some of the inflammatory mediators can excite the pulpal nerves while others even have an analgesic effect. Some of the exogenous compounds (bacterial metabolites and substances released during the breakdown of dentine) induce nerve activity in the pulp while others have a depressing effect. The net effect will probably depend on the relative proportions and concentrations of these substances in the pulp. This would also explain the variability of pain symptoms in pulpitis. Also the condition of dentine with blocked or patent dentinal tubules is important. If the substances with depressive effect are predominantly in greater proportions and concentrations, and if the dentinal tubules are blocked, this could be the case of "silent pulpitis".

title: Assessment of reliability of electrical and thermal pulp testing agents.
abstract: The reliability of several pulp testing agents was compared in intact human premolar teeth. The electric pulp tester, CO 2 snow and dichlorodifluoromethane were found to be more dependable than ethyl chloride and ice in producing a positive response. However, in young patients the electric pulp test was less reliable than CO 2 snow and dichlorodifluoromethane but more reliable than ethyl chloride and ice. The thermal agents were also compared for their ability to decrease intrapulpal temperature in vitro. The rate of temperature decrease was greater when CO 2 snow or dichlorodifluoromethane were applied to the tooth than in the case of either ethyl chloride or ice.

title: Standardization of a test for dental sensitivity to cold.
abstract: T hc relation of thermal sensitivity to pathologic changes in the pulp has been of interest to t.he diagnost.ician for a long t.imc. Attcmpt,s to clarify this pmhhn have been hampered by the fact that there is 11o standard reliable, and practical method for measuring sensitivity to cithcr cold or heat. The objectives of our study were to dcterminc whether, by using a simple cone! of kc as ;I. testing agent, (1) there might be a. relat.ionship between t.hc length of time thca colt1 stimulus was a.pplietl and the t.hclrmal reactivity of the. tooth, (2) a rc4ationship could bc established between t.hc sensitivity elicit.etl by such a test and the scnsit.ivitv noted b,v the patient whila eating cold foods in a routine manner, and (3) a consistent response by a patient to the same stimulus applictl 011 different clays coultl 1~ obtainetl.

title: Comparison of carbon dioxide versus refrigerant spray to determine pulpal responsiveness.
abstract: There is little evidence for which cold delivery method is most accurate in determining pulp responsiveness. This study compared carbon dioxide dry ice sticks (CO2) versus refrigerant spray (RS) to generate a patient response from different types of teeth restored to varying degrees. Fifteen human patients were selected. In each quadrant, three teeth were identified and the restoration type recorded. Blindfolded patients were randomly tested with either CO2 or RS in a crossover design at two different sessions. Responsiveness was recorded as yes/no and the interval (in seconds) from application to response was determined. Results showed that (a) CO2 and RS were equivalent in producing a pulpal response regardless of tooth and presence of restoration, and (b) CO2 took significantly (p < 0.05) longer to evoke a response than RS using paired t tests. In conclusion, RS and CO2 were equivalent in determining pulpal responsiveness, but the elicited response from RS was faster.

title: Cold testing through full-coverage restorations.
abstract: Endodontic diagnosis often requires thermal testing through porcelain fused-to-metal (PFM) and all-ceramic restorations. The purpose of this study was to measure and compare the temperature change during thermal testing by three commonly used methods occurring at the pulp-dentin junction (PDJ) of nonrestored teeth and teeth restored with full coverage restorations made of PFM, all-porcelain, or gold. The methods used to produce a thermal change were (a) an ice stick, (b) 1,1,1,2-tetrafluoroethane (TFE), and (c) carbon dioxide snow. A thermocouple measured temperature changes occurring at the PDJ in 10 extracted premolars when thermal tested by each method over a period of 30 seconds. Temperature reduction was also measured for the same samples restored with full gold crowns, PFM, and Empress crowns. Results showed intact premolars and those restored with PFM or all-ceramic restorations to respond similarly to thermal testing. In these teeth, TFE produced a significantly greater temperature decrease than carbon dioxide snow between 10 and 25 seconds (p < 0.05). In conclusion, application of TFE on a saturated #2 cotton pellet was the most effective method for producing a temperature reduction at the PDJ of intact teeth and those restored with gold, PFM, and all-porcelain when testing for less than 15 seconds.

title: In vitro effects of ice, skin refrigerant, and CO2 snow on intrapulpal temperature.
abstract: Ice, skin refrigerant, and CO 2 snow, three cold tests, were compared for their ability to decrease intrapulpal temperatures in vitro. A five-second CO 2 snow application resulted in a statistically greater decrease than ice or skin refrigerant in both noncarious and in crowned teeth. Although the amount of temperature change a pulp can withstand is not known, the 4 to 8 F decrease produced by the CO 2 snow did not seem extreme. Temperature transfer between teeth in proximal contact was relatively insignificant. The advantages of CO 2 snow are discussed.

title: Evaluation of the effects of carbon dioxide used as a pulpal test. Part 2. In vivo effect on canine enamel and pulpal tissues.
abstract: Carbon dioxide snow was used to test the teeth of two dogs for periods of 5, 15, 60, and 120 s. Using the scanning electron microscope and histological evaluation, the cold could not be shown to have affected the surface of the enamel or to have caused pulpal damage.

title: Effects of thermal vitality tests on human dental pulp.
abstract: Experiments were conducted to determine the effects of thermal pulp testing agents on the human dental pulp. Histological evaluation of the pulps of premolar teeth to which heated gutta-percha had been applied for up to 10 s revealed no evidence of injury. Teeth to which carbon dioxide (CO 2 ) snow was applied for as long as 5 min were found to have structurally intact pulps. When the thermal testing agents were applied to teeth in vitro, temperature in the region of the pulpodentinal junction did not reach noxious levels. This study indicates that assessment of tooth vitality with either heated gutta-percha or CO 2 snow does not jeopardize the health of the pulp.

title: Pulp lability and repair; effect of restorative procedures.
abstract: An ever-increasing body of knowledge provides strong evidence that any alteration in the homeostasis of the dental pulp environment elicits a response directly commensurate with the intensity of the physiologic assault. The intrapulpal response is evident within the cells, the vascular apparatus, and the ground substance. Heat production (elevation of intrapulpal temperature) results in the most constantly reproducible changes in the pulp. All other factors being equal, the production of heat within the pulp may be singled out as the most severe stress which restorative procedures impart to the pulp.

title: Adult pulpal diagnosis. I. Evaluation of the positive and negative responses to cold and electrical pulp tests.
abstract: This study investigated the positive and negative responses of 1488 teeth in 60 patients to two electric pulp testers and a cold thermal pulp test. Three subgroups of known pulpless or pulpally diseased teeth (teeth receiving root canal therapy, teeth with root canal fillings, or teeth with confirmed associated apical radiolucencies) were identified and their responses evaluated separately. Testing was performed on two tooth surfaces, the facio-occlusal and faciocervical, and on all restorations. The gingival tissue of each patient also was tested using both electrical tests. The primary findings were: (a) teeth not responding to cold and either not responding or responding at readings greater than the tissue response to electrical had a high probability of being in the known pulpless or pulpally diseased subgroups; (b) the only false positive responses to cold in the three subgroups were in multirooted teeth with probable vital tissue remaining in at least one canal; and (c) in the three subgroups, if the false positive responses to electrical that responded at levels higher than the patient's tissue response were considered to be negative responses, the difference in false positives between cold and electrical became not statistically significant (p = 0.07).

title: Simplified approach to use of electrical pulp tester.
abstract: : The routine use of gloves as a barrier technique is recommended by the American Dental Association and the Centers for Disease Control. The use of the electrical pulp tester necessitates that the dentist contact the patient's skin or mucosa to complete the circuit. A technique is presented that simplifies the operation of the electrical pulp tester by the dentist wearing gloves. Advantages of this method include a sound barrier technique, an enhanced psychological benefit to the dentist, and an abatement in discomfort for the patient.

title: Using the electric pulp tester with gloves: a simplified approach.
abstract: A method is presented which simplifies the use of the electric pulp tester for the dentist who routinely wears gloves in practice. Advantages of this method include a reduction in patient apprehension as well as a possible decrease in discomfort for the patient.

title: Electronic and Clinical Comparison of Pulp Testers
abstract: Electronic and clinical comparisons of three commercially available pulp testers were investigated using oscilloscopes and a clinical trial. The three devices varied in wave-form characteristics and showed statistically significant differences in patient responses.

title: Variables associated with electric pulp testing.
abstract: A modern electronic pulp tester is evaluated in both the laboratory and clinical situations. Different electrode media are tested and compared to results obtained without any electrode media. Contact pads are also evaluated and found to add another variable to electric pulp testing. Several technique variables were introduced and found to have a significant effect on transmission of the stimulus to the tooth.

title: Probe placement during electric pulp-testing procedures.
abstract: Electrode placement sites during electric pulp-testing procedures on the crown of a tooth were evaluated in a laboratory setting using thirty-one extracted teeth, an oscilloscope, and a new electric pulp tester (Digital Analytical Pulp Tester). This study showed that the lowest resistance occurred on the occlusal two-thirds electrode sites of the labial or buccal surfaces of maxillary incisors and premolars. More specifically, the middle-third electrode sites of the incisors and the occlusal-third electrode sites of the premolars were shown to have the least resistance. The electrode placement area on the crown where the pulp nerve is first excited to threshold must be identified to avoid false-positive stimulation of surrounding periodontal nerves. This will decrease nerve damage and ensure the patient's cooperation and acceptance.

title: A preliminary evaluation of the effects of electrical pulp testers on dogs with artificial pacemakers.
abstract: Four pulp testers were used to evaluate their interference with a pacemaker implanted in a dog and the effect of electrical current leaks on the pacemaker. The use of artificial pacemakers in patients with heart disease has created a special type of patient management problem for dentists. The application of electrical currents to such patients by the use of pulp testers, desensitizing equipment, electrosurgical instruments and so forth, as well as current leaks from other electrical equipment, can interfere with pacemaker function and may constitute a serious health hazard. Dentists should be aware of the effects of the application of electrical current to their patients.

title: The pacemaker patient in the dental surgery.
abstract: Most electrical equipment used in dentistry has been shown to interfere with cardiac pacemaker function. Various dental instruments were tested in a crude experimental simulation of the body's resistance and it was found (out of five instruments tested) that the dental diathermy was the only one to affect pacemaker function.

title: Selective interference with pacemaker activity by electrical dental devices.
abstract: We sought to determine whether electromagnetic interference with cardiac pacemakers occurs during the operation of contemporary electrical dental equipment.



Fourteen electrical dental devices were tested in vitro for their ability to interfere with the function of two Medtronics cardiac pacemakers (one a dual-chamber, bipolar Thera 7942 pacemaker, the other a single-chamber, unipolar Minix 8340 pacemaker). Atrial and ventricular pacemaker output and electrocardiographic activity were monitored by means of telemetry with the use of a Medtronics 9760/90 programmer.



Atrial and ventricular pacing were inhibited by electromagnetic interference produced by the electrosurgical unit up to a distance of 10 cm, by the ultrasonic bath cleaner up to 30 cm, and by the magnetorestrictive ultrasonic scalers up to 37.5 cm. In contrast, operation of the amalgamator, electric pulp tester, composite curing light, dental handpieces, electric toothbrush, microwave oven, dental chair and light, ENAC ultrasonic instrument, radiography unit, and sonic scaler did not alter pacing rate or rhythm.



These results suggest that certain electrosurgical and ultrasonic instruments may produce deleterious effects in medically fragile patients with cardiac pacemakers.

title: Safety of electronic apex locators and pulp testers in patients with implanted cardiac pacemakers or cardioverter/defibrillators.
abstract: The purpose of this study was to determine if electronic apex locators (EAL) or electric pulp testers (EPT) interfere with the function of implanted cardiac pacemakers (ICP) or cardioverter/defibrillators (ICD). Twenty-seven patients with ICPs or ICDs had continuous electrocardiogram monitoring and device interrogation to detect interferences during the use of two types of EALs and one EPT. No interferences were detected by any ICP or ICD. In six patients, with intermittent pacing, a significant increase in pacing was observed during EAL/EPT stimulation (p < 0.05). Examination of RR intervals (a measure of intrinsic heart rate) demonstrated significantly longer RR intervals (slower intrinsic heart rate) during EAL/EPT stimulation (p < 0.05). Evaluation of the electrocardiograms for each patient failed to show any abnormalities in pacing during testing. These findings led us to conclude that the increased pacing frequency observed was related to a slower intrinsic heart rate and not electrical interference with the cardiac devices. In conclusion, the two EALs and one EPT used in this study did not interfere with the functioning of any of the cardiac devices tested.

title: Influence of maturation status and tooth type of permanent teeth upon electrometric and thermal pulp testing.
abstract: The threshold values of developing teeth were determined for two commonly used electrometric pulp testers (Siemens Sirotest and Bofors Pulp Tester) and a new thermal test based on carbon dioxide snow (Odontotest). The teeth examined were divided into 7 stages according to maturation status. This study showed that teeth in Stages 3-5, i.e. until completion of root formation, show an increased electrometric threshold value. The Siemens tester appeared to be equal to the Bofors tester with regard to reliability. The Odontotest was the most reliable method examined, giving a consistent positive response in all examined teeth.

title: Pulpal pain diagnosis--a review.
abstract: Evidence gathered from our studies and the work of others appears to support the presence of two distinct nerve pain pathways in the dental pulp, represented by fast conducting A-delta and slow conducting C-fibers. Each of these types of fibers has different pain characteristics: A-delta fibers evoke a rapid, sharp, lancinating pain reaction, and C-fibers cause a slow, dull, crawling pain. Pain response thresholds vary in different regions of the tooth, and thermal, osmotic, ionic, and electric stimuli involve different mechanisms to provoke nerve excitation of the dental pulp. Evidence also points to the fact that the incidence of pain increases as the histopathosis worsens. On interrogation, patients who manifest severe or referred pain almost always give a previous history of pain in the tooth with the ache. Eighty percent of patients who give a previous history of pain manifest histopathologic evidence of chronic partial pulpitis with partial necrosis, the untreatable category, for which endodontics or extraction is indicated. The other 20% exhibit histopathosis of the pulp with slight inflammation to chronic partial pulpitis without necrosis, a treatable category. Clinically, one can determine the degree of pulp histopathosis by asking the patient about a previous history of pain in the involved tooth. This history of previous pain adds another dimension in diagnosis for the clinician as to whether the painful pulpitis is reversible. This information also aids in referred pain localization.

title: Transient apical breakdown and its relation to color and sensibility changes after luxation injuries to teeth.
abstract: In examining a population of 637 luxated permanent teeth, it was found that 27 teeth (4.2%) demonstrated apical breakdown in the form of either a pronounced radiolucency which appeared spontaneously some time after injury, or a persistent expansion of the periodontal ligament space (PDL) over an extended interval after injury, which at later follow-up controls had either returned to normal without further radiographic change or was accompanied by surface resorption and/or pulp canal obliteration without intervening treatment. Two of the 27 teeth demonstrated radiographic change alone, while the remaining 25 demonstrated color and/or electrometric sensibility-changes as well. Twenty-three teeth had fully-formed roots whose apices were either closed or half-closed at the time of injury. Five had roots which were fully formed, but with an open apex; the remaining tooth had three-quarter root formation. The injuries were moderate, the majority being extrusion or lateral luxation, affecting both pulpal and periodontal structures. Based on clinical findings, the following hypothesis is proposed: Transient apical breakdown appears to be a phenomenon linked to the repair processes in the traumatized pulp or pulp and periodontium of luxated mature teeth which returns to normal when repair is complete. Whether this is related to a transitory infection and/ or removal of necrotic traumatized tissue cannot be evaluated from the material available.

title: The reliability of electric pulp test after concussion injury.
abstract: Traumatic injuries to teeth present a difficult diagnostic problem with respect to determining the vitality of the affected teeth. Conventionally, a latency period of 4 to 6 weeks is proposed as the amount of time required for the return of a positive electric pulp test (EPT) response; however, this has been based on empirical data. The purpose of this study was to 1) determine a time frame during which a return of a reliable response to EPT may be measured, and 2) correlate this time frame with pulpal vascular changes that occur after traumatic injuries. Four canines from each of nine ferrets were used for this experiment (18 traumatized and 18 control teeth). A reproducible concussion injury was devised by releasing a known weight at a constant height above the facial surface of the experimental teeth. The EPT response was confirmed by the use of an EMG muscle recorder. Animals were killed at 24, 48 and 72 h and 6, 12 and 28 days after the injury and the teeth analyzed histologically. The histological sections showed an absence of inflammatory cells in both groups; however, according to the NIH image system, an increase in the number of vessels was detected in the experimental group when compared to the controls. In a majority of the cases, a positive response to the EPT returned within 12 days post concussion injury and as early as 10 days. In addition, a significant vascular change was accompanied with the loss of the EPT response. This study provided a reliable method by which concussion injuries may be studied using an animal model.

title: Efficacy of laser Doppler flowmetry in determining pulp vitality of human teeth.
abstract: The aim of this study was to examine if laser Doppler flowmetry (LDF) could aid in distinguishing teeth with necrotic pulps from vital teeth and if so, which configuration of 5 experimental probes would give the best results. Each probe had 3 fibers arranged in a triangle. One fiber carried the laser light to the pulp tissue and 2 fibers carried the back-scattered light to the detector giving the output signal. The distance between the 3 fibers in the triangular arrangement in each probe was 250, 500, 800, 1000, and 1500 microns. A special rubber-base splint was used to hold the probe in place on the buccal surface of the tested teeth. Eleven anterior teeth with clinically diagnosed necrotic pulp were measured with the LDF method and the results compared to contralateral teeth with vital pulp. For the sake of comparison, 10 pairs of anterior teeth with vital pulps in 10 patients were tested as well. The LDF signals were fed into an analog printer and a lap-top computer where all calculations were done. With the LDF method, the output signals from the teeth with necrotic pulps were significantly lower with all 5 probes than the output signals from the contralateral vital teeth. On average, the signal was 42.7% lower from the teeth with necrotic pulps than from the vital teeth. Four of 11 teeth with necrotic pulp gave a positive response to an electrical pulp tester (EPT). The results suggested that the probe with the smallest separation of fibers was the most sensitive in distinguishing necrotic pulps from vital ones.

title: The optimum placement-site of the electrode in electric pulp testing of the 12 anterior teeth.
abstract: The present study of 2,387 recordings of 12 anterior teeth in 53 patients indicates that the incisal edge is the optimal placement-site for the electric pulp tester to determine the lowest response threshold. The results show significant individual variations in the lowest threshold responses of the cervical-third, middle-third, incisal one-third, and incisal edge sites on a tooth, with a confidence level of 99%, according to the analysis of variance. The maxillary teeth gave a higher response threshold than the mandibular teeth and different types of teeth (canines and incisors) had statistically significant different response thresholds. The application of the electric pulp tester to the incisal-edge region with exposed dentin produced the most significant decrease in the threshold response.

title: Revascularization of traumatized teeth assessed by laser Doppler flowmetry: case report.
abstract: Infection of the pulp space in addition to the attachment damage of a traumatic injury to a tooth, results in serious complications and often tooth loss. Therefore, the prevention or treatment of root canal infection is a major consideration in these cases. In immature teeth, revascularization of a necrotic pulp is possible and highly desirable. Unfortunately, current sensitivity tests are poor indicators of revascularization, with the result that many pulps are removed unnecessarily. Laser Doppler flowmetry is an objective test of the presence of moving red blood cells within a tissue, which has been reported to be effective in the detection of tooth pulp vitality as well. A case is presented where an eight year old child severely luxated both maxillary central incisors. While only one of the incisors was weakly responsive to CO2 ice at 76 days after replantation, the laser Doppler flowmeter indicated that revascularization was occurring in both teeth at a much earlier time. Because of the laser Doppler readings, endodontic treatment was not initiated and the teeth developed normally.

title: Pulpal blood flow assessed by laser Doppler flowmetry in a tooth with a horizontal root fracture.
abstract: Horizontal root fractures of both maxillary central incisors were diagnosed radiographically; neither responded to electric pulp testing nor to cold testing. The pulp of the right incisor was necrotic, whereas the pulpal status of the left incisor was uncertain. Pulpal blood flow of the teeth was measured with laser Doppler flowmetry. The blood flow of the left central incisor was 4.0. Eight months after the injury, a local anesthetic with a vasoconstrictor was administered to confirm pulp vitality. The blood flow of the tooth was decreased to 51% of the preanesthesia value after the local anesthesia. At 19 months after the injury, it responded to both the electric pulp test and cold test. Laser Doppler flowmetry is a noninvasive method of evaluating the blood flow status in human teeth, and it may provide a clinically reliable method of assessing pulpal vitality.

title: A two-probe laser Doppler flowmetry assessment as an exclusive diagnostic device in a long-term follow-up of traumatised teeth: a case report.
abstract: The reliability of laser Doppler flowmetry in a two-probe assessment of pulpal blood flow is well known. The purpose of this case report was to determine its use as an exclusive and reliable tool for tooth vitality diagnosis in a long-term follow-up. As a result of a traumatic injury to a 24-year-old Caucasian female, tooth pulp vitality was studied in six maxillary front teeth over 30 weeks using two-probe laser Doppler flowmetry and current sensitivity tests. A similar assessment was repeated after 228 weeks. Confronted with an alveolar bone fracture with a tooth in the fracture line, one intrusion and several luxated teeth, current sensitivity tests are found not to be as reliable indicators of revascularisation, as significant results are obtained later (7 weeks) than using laser Doppler flowmetry tests (1 week). A pathway with ischaemia (3 weeks), hyperaemia (7 weeks) and restored blood supply in the pulp measured by laser Doppler flowmetry tests was found and avoided endodontic treatment. Teeth vascularisation evolved normally (228 weeks). Despite a strong indication in all sensitivity tests for endodontic treatment, the use of laser Doppler flowmetry tests was clear, more reliable than sensitivity tests and exclusive, as denervation was postponed and pulp vascularisation evident.

title: Laser Doppler flowmetry for monitoring traumatized teeth.
abstract: Laser Doppler Flowmetry (LDF) has been shown to be valuable in monitoring revascularization of immature incisors following severe dental trauma. Several investigators have demonstrated the ability of LDF to record blood flow signals from vital tooth pulps. In this case report, LDF was used for a 7-year-old child patient following a severe luxation of tooth #9. During follow-up examinations the traumatized tooth was unresponsive to traditional vitality testing during the first 6 months; however, LDF indicated that revascularization had occurred much sooner. Until recently, CO2 ice has been the most effective method for sensitivity testing in trauma cases such as presented here. In this case, LDF gave us the assurance that we could defer invasive care during a critical time period when root canal therapy might have been initiated for this child patient.

title: Use of laser Doppler flowmetry to predict vitality of luxated or avulsed permanent teeth.
abstract: Splinting of traumatically displaced or avulsed permanent teeth has been described as an effective modality in the treatment of patients with dental injuries. The purpose of this study was to investigate whether laser Doppler flowmetry (LDF) measurements of pulpal blood flow (PBF) and/or dental injury type may predict treatment outcome of splinting of permanent maxillary incisors.



The study comprised 64 patients undergoing dental trauma splinting, who were characterized by the presence of a single permanent maxillary incisor affected by a subluxation, luxation, or avulsion type injury. Perfusion units (PU) were taken in 2 sessions, on the day of splint removal (6 weeks after trauma; session I) and 12 weeks after splint removal (session II). At each session, when an injured permanent maxillary central incisor was recorded, the respective contralateral homologous tooth was used as a control. An adverse outcome occurring 36 weeks after splint removal was defined as the presence of "periapical radiolucency and/or grey discoloration." A multiple logistic regression analysis was used to compute the odds ratio for session-related PBF characteristics and dental injury type for adverse outcome (n=22) versus nonadverse outcome (n=42).



There was a significant increase in PBF values from session I to session II (P=.047) for teeth without an adverse outcome, whereas teeth affected by an adverse outcome showed a significant decrease in PBF values (P=.001). PBF measurements did not change over time for the control group of contralateral incisors (P=.185). For the outcome criterion of "presence of periapical radiolucency and/or grey discoloration," there was a significant association between the treatment outcome groups and the variables of dental injury type (P=.049), session-related PBF difference (P=.000), and session II-related PBF level (P=.000). Significant increase in risk of an adverse outcome occurred with a session-related PBF difference (PBF(Session I) - PBF(Session II)) of >/=0 PU (8.6 odds ratio) (P=.014), and a session II-related PBF level of </=2.8 PU (20.2 odds ratio) (P=.030).



The data suggest the LDF test to be a valuable diagnostic adjunct for luxated teeth showing signs of adverse outcomes. Predictive modeling may provide clinicians with the opportunity to identify "at-risk" teeth early and initiate specific treatments.

title: Assessing revascularization of avulsed permanent maxillary incisors by laser Doppler flowmetry.
abstract: Laser Doppler flowmetry, or LDF, is a noninvasive method used to assess pulpal blood flow, or PBF. Dental avulsion is associated with loss of pulpal sensitivity. The authors conducted this study to assess whether LDF could be used to detect revascularization of replanted teeth.



The authors used LDF to assess the PBF values of avulsed permanent maxillary incisors treated using replantation and splinting in 17 subjects. They took measurements at four sessions: on the day of splint removal and at 12 weeks, 24 weeks and 36 weeks after splint removal. Five vital control teeth and five nonvital control teeth were used to assess the background signal. At 36 weeks, the authors determined clinically and radiographically whether revascularization had occurred.



LDF readings correctly predicted the pulp status in 88.2 percent of the readings. Of the readings for vital teeth, 100 percent were correct, and of the readings for nonvital teeth, 80 percent were correct. Univariate analysis of variance demonstrated that in revascularized teeth, the PBF value increased significantly from splint removal to week 12 after splint removal and from week 24 to week 36 after splint removal. In the teeth that failed to revascularize, the PBF value dropped significantly from week 24 to week 36 after splint removal.



The results of this study suggest that LDF accurately diagnoses revascularization of avulsed maxillary incisors after replantation and splinting.



LDF may become useful in detecting revascularization much earlier than standard sensitivity tests.

title: Diagnostic characteristics of pulpal blood flow levels associated with adverse outcomes of luxated permanent maxillary incisors.
abstract: Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood flow (PBF). Dental injury has been associated with significant PBF reduction. The purpose of this study was (i) to describe PBF characteristics of teeth with specific clinical outcomes, and (ii) to demonstrate diagnostic characteristics for different threshold PBF values for detection of specific multiple adverse outcomes. In 80 trauma patients, a single maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous control tooth were investigated by LDF to assess local PBF values. Perfusion units (PU) were taken in two sessions, on the day of splint removal (session I), and 12 weeks after splint removal (session II). The ability of session II-related PBF measurements at 2.9, 6.4 and 9.9 PU levels to identify adverse outcomes occurring 36 weeks after splint removal was investigated. Adverse outcomes were classified as type I (loss of sensitivity), type II (periapical radiolucency), type III (grey discolouration), type IV (loss of sensitivity and periapical radiolucency), and type V (loss of sensitivity, periapical radiolucency and grey discolouration of crown). Receiver-operator characteristic (ROC) curves were used to evaluate the sensitivity and specificity of PBF assessments. There was a significant increase in PBF values from session I to session II (P=0.0001) for teeth without an adverse outcome, while teeth affected by a type II-V outcome showed a significant decrease in PBF values (P <0.05). PBF measurements did not change over time for the contralateral incisors (P >0.05). A type IV and V outcome occurred in 21 and 24% of the instances, respectively. The PBF of 2.9 PU demonstrated a sensitivity of 70% and a specificity of 93% for type V outcomes. The best likelihood ratio was found for the PBF 2.9 PU level and incisors associated with a type V outcome. The data suggest that the LDF test to be a valuable diagnostic adjunct for luxated teeth showing signs of adverse outcomes including grey discolouration or a combination of other signs. However, it may also become necessary to apply clinical decision-making methods in order to correctly evaluate the value of information gathered. The clinical implication is that LDF may become useful in the prediction of adverse outcomes at a much earlier time period than may be accomplished by standard sensitivity tests.

title: Evaluation of pulpal blood flow after tooth splinting of luxated permanent maxillary incisors.
abstract: Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood flow (PBF). Dental injury has been associated with losses of pulpal sensibility. The purpose of this study was to assess whether LDF could be used to detect short- and long-term changes of PBF values of luxated permanent maxillary central incisors after repositioning and splinting. In 18 trauma patients, a single maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous tooth were investigated by LDF to assess local PBF values. Perfusion units (PU) were taken in four sessions: on the day of splint removal, and 12, 24, and 36 weeks after splint removal. Analysis of the luxation type-related PBF measurements revealed intrusion type-related PBF values to be associated with a significant decrease in PBF values (P < 0.05), while lateral luxation and extrusion type-related PBF values showed no significant difference between the session-related values (P > 0.05). PBF measurements did not change over time for the contralateral incisors (P > 0.05). Teeth affected by an intrusion-type luxation injury remained unresponsive to sensitivity testing at follow up, while 3 (60%) developed grey discoloration of the crown. LDF may become useful in the detection of ischemic episodes of luxated maxillary central incisors after repositioning and splinting. Further studies are warranted to assess the validity of post-traumatic 'ischemic episodes' by comparing it to histological tooth pulp changes.

title: Evaluation of a laser Doppler flowmeter to assess blood flow in human primary incisor teeth.
abstract: This study determined whether the portable Advance Laser Flowmeter Model 21, a clinical instrument, would indicate significant values when pulpal blood flow was present or absent; whether the analog output of the flowmeter was time-linked to the heart rate; and whether labial and lingual crown surfaces produced different flow values.



Teeth were tested under two conditions: with the teeth in situ and extracted, or with the pulp present and removed.



Values before and after the teeth were extracted, and those before and after pulpectomy with the tooth in situ were significantly different. These findings verified that the flowmeter measured the presence of bloodflow. Peaks of the electrocardiogram waves and the regular signal fluctuations of the flowmeter were time-linked and verified the measurement of the heart rate from the dental pulp. Differences in the values for the lingual and labial surfaces of individual teeth were not significant.



This instrument proved a valid means of determining the presence of pulpal blood flow in primary incisors.

title: Laser Doppler flowmetry: an aid in differential diagnosis of apical radiolucencies.
abstract: The case of a patient having 2 teeth with associated apical radiolucencies that responded to conventional pulp tests is presented. A decision was made to reexamine the patient at intervals rather than perform root canal treatment. During a recall visit, use of an available laser Doppler flowmeter allowed detection of blood flow within the affected teeth. A diagnosis of periapical cemental dysplasia (cementoma) was made.

title: Laser Doppler flowmetry: a clinical test of pulpal vitality.
abstract: A rapid, accurate, noninvasive method of determining pulpal blood flow would be helpful in determining pulpal vitality.



The purpose of this study was to determine if laser Doppler flowmetry can measure induced changes in pulpal blood flow.



Two percent lidocaine with epinephrine 1:100,000 was infiltrated into the labial vestibule to anesthetize five anterior teeth in healthy human volunteers. Stents were placed on the teeth to stabilize the laser Doppler probes. Measurements of pulpal blood flow were made along with electrocardiograms to record the cardiac cycle.



Laser Doppler flowmetry demonstrated pulpal blood flow and pulse amplitude decreases under test conditions. These decreases were most significant at 10 minutes after the injection of anesthetic with vasoconstrictor.



Laser Doppler flowmetry was able to measure pulpal blood flow and record changes in blood flow that occurred when epinephrine was used with infiltration anesthesia. The pulse width and the mean flow were dramatically affected as was synchronization with the cardiac cycle.

title: Microcirculation of the dental pulp and its autonomic control.
abstract: Pulpal vessels are innervated with sympathetic adrenergic vasoconstrictor fibers. Electrical stimulation of the cervical sympathetic nerve causes pulpal arteriolar constriction and a reduction of arteriolar and venular flow rate (in mm3/s) in rat incisor pulps and a decrease in pulpal blood flow (in ml/min/100 g) in canine pulps of cats and dogs. The alpha-antagonist phenoxybenzamine and the alpha-1 antagonist prazosin attenuated the decrease in pulpal blood flow (PBF) caused by sympathetic stimulation. Reflex excitation of the sympathetic nerve system by hemorrhage caused pulpal vasoconstriction and a reduction of PBF. Induction of hemorrhagic hypotension in dogs subjected to cervical sympathectomy and adrenalectomy caused less pronounced pulpal vasoconstriction and flow reduction than in normal dogs. Pulpal vessels are also equipped with alpha-1, alpha-2 and beta-adrenergic receptors. Activation of alpha-1 and alpha-2 receptors by intraarterial injection of phenylephrine and clonidine caused a reduction in PBF in dogs and decreases in arteriolar and venular diameters and volumetric flow in rats. These responses were blocked by the alpha-1 and alpha-2 antagonists. Activation of beta-2 receptors by i.a. injection of isoproterenol caused a paradoxical reduction of PBF in dogs. In rats isoproterenol caused a transient increase in the flow rate followed by a reduction, and arteriolar dilation was accompanied by venular constriction. These flow responses to isoproterenol were blocked by the beta-2 antagonist propranolol. Results of microcirculatory studies in dogs and rats indicate that pulpal hemodynamics are regulated significantly by the sympathetic adrenergic system.

title: Experiments in pigs on the sources of laser Doppler blood-flow signals recorded from teeth.
abstract: A laser Doppler blood-flow meter (Moor Type MBF3D) was used to record from the crowns of eight deciduous mandibular incisors in three anaesthetized pigs. The flow-meter probe was attached to the crown either 2 or 6 mm from the gingival margin. Recordings were made from each tooth with the supporting tissues intact, after exposing the root pulp, after cutting the pulp, and after death of the animal. At each stage the effect of wrapping the crown in aluminium foil was determined. There was no significant change in the signals when the root pulp was exposed (p > 0.05, paired t-test). Without foil, cutting the pulp reduced the signal recorded 2 mm from the gingival margin by an average of 85.1 percent (n = 8, p < 0.001) and at 6 mm by 87.9 percent (n = 4, p < 0.001). There were further significant reductions (p < 0.01) equivalent to 12.9 percent and 9.0 percent, respectively, of the control values when the animal was killed. The foil increased the average blood-flow signals recorded from intact teeth at both 2 and 6 mm from the gingival margin by 77.8 percent and 98.3 percent (p < 0.05), respectively. It also had a similar effect after pulp exposure. With foil, cutting the pulp reduced the signal by 86.2 percent and 92.8 percent at the two sites, respectively, and post mortem there was a further reduction of 12.4 percent and 6.1 percent. Thus, under all conditions the major part of the signal recorded from an intact tooth was from the pulp but a significant component (an average of between 14.9 percent and 7.2 percent depending on the conditions) was from tissues outside the tooth. The best performance was obtained with foil and with the probe 6 mm from the gingival margin.

title: Laser Doppler flow measurements of pulpal blood flow and severity of dental injury.
abstract: To evaluate laser Doppler flowmetry (LDF) measurements of pulpal blood flow (PBF) and severity of dental injury.



The relationship between adverse outcomes and PBF measurements was analysed in 94 permanent maxillary incisors of 71 consecutive dental trauma patients. The diagnostic adverse outcome group was comprised of 72 incisors in 52 patients with a type I (loss of sensitivity), type II (loss of sensitivity and periapical radiolucency), or type III (loss of sensitivity, periapical radiolucency and grey discoloration of crown) diagnosis. The nonadverse outcome group consisted of 22 incisors in 19 patients with the finding of an absence of an adverse outcome. At each session, when an injured permanent maxillary incisor was recorded, a contralateral homologous tooth was used as a control. An ordinal stepwise regression was completed to assess the degree of association between PBF measurements and adverse outcomes



Using chi-square analysis for pairwise comparison, a significant relationship between PBF measurements and types of adverse outcomes (chi(2) =119.635, d.f. = 12, P = 0.000) was observed. PBF measurements that were significantly associated with more severe outcome were PBF levels of </=3 perfusion units (PU) (119.1 odds ratio) (P = 0.000), and those of >3 PU and </=6 PU (12.7 odds ratio) (P = 0.000).



PBF measurements were related to the severity of adverse outcomes. Further studies are required to evaluate whether PBF measurements can predict dental injuries that progress to adverse treatment outcomes.

title: Lasers in endodontics.
abstract: The first application of lasers in dentistry was the surgical treatment of tumors in the oral cavity, and various lasers, including semiconductor diode, carbon dioxide, helium-neon, neodymium:yttrium-aluminum-garnet, argon, erbium, and erbium chromium, have been developed since and applied in dentistry. This article describes the current and possible future clinical indications, laser devices, techniques, assessment methods, and mechanics.

title: Effect of wavelength and bandwidth on the clinical reliability of laser Doppler recordings.
abstract: The aim of this study was to investigate the effect of wavelength and bandwidth on laser Doppler flowmeter signals from vital and root-filled teeth, and to establish their sensitivity and specificity. Twenty human subjects were recruited, each with a vital tooth and the contralateral tooth root filled but not restored apart from the palatal access cavity. Readings were taken from these teeth for 3 min at 20 Hz for each of 3.1 kHz, 14.9 kHz and 22.1 kHz bandwidths using a modified laser Doppler blood flow monitor which permitted simultaneous recording using 810 nm and 633 nm light sources with a probe of four optical fibres with 0.25 mm separation. Ten traces from each combination of variables was examined by 10 trained observers who indicated if the traces came from vital or root-filled teeth judged by the amplitude and regularity of pulsatility of the trace. From the accuracy of their replies, sensitivity and specificity were calculated. Median flux values were higher for vital teeth than for root-filled teeth and for the 810 nm wavelength than for the 633 nm wavelength. Flux values increased with wider bandwidth using the 810 nm light source. With the 633 nm light source, the highest flux values were recorded using the 3.1 kHz bandwidth. Using the Mann-Whitney U test, there was a highly significant difference between readings from vital and root-filled teeth for the 3.1 kHz/810 nm wave length combination (p<0.003) and a significant difference for the 3.1 kHz/633 nm wavelength group (p<0.02). Comparison of other groups showed no significant difference (p>0.05). The 810 nm wavelength showed good sensitivity but poor specificity at 14.9 and 22.1 kHz bandwidths. The 633 nm wavelength showed good specificity, but poor sensitivity, at 14.9 and 22.1 kHz bandwidths. The 3.1 kHz bandwidth showed the best sensitivity and specificity for both wavelengths. Sensitivity and specificity were increased if the results of fast Fourier analysis were considered in addition to observations of flux values and pulsatility of traces. The 810 nm/3.1 kHz combination offered the greatest sensitivity and specificity as a test to distinguish between root-filled and vital teeth. This combination was best when the results of Fourier analysis were considered in addition to visual observations.

title: The effect of wavelength, bandwidth, and probe design and position on assessing the vitality of anterior teeth with laser Doppler flowmetry.
abstract: To investigate the effect of four variables: wavelength (633 nm and 780 nm), bandwidth filter (3 kHz, 15 kHz, 22 kHz), probe fibre separation (250 microns) and 500 microns) and distance of the probe from the gingival margin (2-3 mm and 4-5 mm) when assessing the vitality of anterior teeth with a laser Doppler flowmetry system.



Split-mouth cohort clinical trial.



Childrens dental clinic, Glasgow Dental Hospital and School.



Sample included 11 non-vital maxillary incisors with necrotic pulps in 10 patients (mean age 12.25 years old). Recordings were taken from the non-vital tooth and from a vital maxillary incisor from the same patient, using all 24 combinations of the recording variables listed above. The vital/non-vital ratios of the signals from the 11 pairs of teeth were calculated and discriminant analysis applied to the data.



Of the variables investigated, the combination of a 633 nm laser source with a 3 kHz bandwidth filter using a probe with a 500 microns fibre separation placed 2-3 mm from the gingival margin was the most reliable, with 10 out of a possible 11 true positives for pulpal necrosis, no false positives, and one equivocal diagnosis, and was the only combination that recorded a smaller blood flow from the non-vital tooth compared with the vital control tooth for all 11 pairs of teeth investigated.



It was concluded, therefore, that laser Doppler flowmetry can be of use in assessing the vitality of anterior teeth and that this is the preferred combination of recording variables for further investigations.

title: Penetration depth of laser Doppler flowmetry beam in teeth.
abstract: The aim of this study was to determine the penetration depth of laser light in teeth for contact and noncontact probe tip.



Fifty-one freshly extracted human mature maxillary and mandibular single rooted teeth were selected for the study. A laser Doppler flowmeter was used as a laser source. A digital camera was used to take pictures (with "night shot" mode in total darkness). When probe tip was in contact and when it was 1 mm away from the tooth, the depths of the areas illuminated in high and low density were measured.



In contact probe, root was illuminated to 4.28 +/- 0.14 mm depth with high density and 13.27 +/- 0.27 mm depth with low density. In noncontact probe, 4.36 +/- 0.16 mm with high density and 13.28 +/- 0.30 mm with low density of illumination were seen on the root. Between contact and noncontact probe situations the difference was not statistically significant in the depth of illumination. On the other hand, in both groups the difference between areas illuminated in high and low density was statistically significant (P < .05).



Contact or noncontact of the probe on tooth surface did not show any significant difference in light penetration. Besides, we think that, for the present, it is impossible to eliminate the contamination from periodontal tissues completely even if the necessary precautions (periodontal paste etc.) are taken.

title: The lamp effect of laser Doppler flowmetry on teeth.
abstract: The aim of this study is to analyse the intra and extracoronal scattering of laser light. Twelve vital teeth from 12 volunteer individuals (aged 22-29 years) were used. The camera removing the charge coupled device's infrared cut filter was used for imaging the laser Doppler flowmetry light during pulpal blood flow measurement. When the obtained photos were analysed, it was seen that the laser beam caused the tooth to shine like a lamp and it also illuminated the tissues inside the mouth (tongue, lips, adjacent teeth, etc.). As a result, it was shown that when the necessary cautions were not taken, the laser could scatter all around the tissues surrounding the tooth. Because of the conductive characteristic of the fibre and the optical characteristics of the tooth, we think that the beam is inevitably scattered onto the tissues outside the pulp and together with the isolation of the gingiva, crown should be isolated, as well.

title: Comparative study of two laser Doppler blood flowmeters.
abstract: A new infrared laser Doppler blood flow instrument (Moor MBF3D) was evaluated using an in vitro model allowing measurements over a range of flow velocities and concentrations. The responses correlated well (r = 0.96, p less than 0.01) with those obtained simultaneously using a Perimed PF3 laser Doppler instrument. The different processing bandwidths of the instruments were investigated and the wideband mode of operation is recommended for flow measurements where there may be fast moving red blood cells (rbcs). The infrared instrument is capable of dual-channel operation, and the two channels are shown to respond almost identically for similar changes in blood flow through the in vitro model (r = 0.999, p less than 0.01). The main advantage of the dual-channel instrument is that continuous measurements may be made simultaneously at two different skin sites allowing dynamic flow responses to be compared.

title: Reliability of laser Doppler flowmetry in a 2-probe assessment of pulpal blood flow.
abstract: The reliability of using 2 probes with laser Doppler signals when adjacent teeth are being measured simultaneously to determine pulpal blood flow is unknown. The purpose of this study was to determine whether 2 probes are more reliable than 1 in a single-tool assessment.



Tooth pulp vitality was studied in 19 adults through use of laser Doppler flowmetry tests. In each subject, testing was carried out on 2 successive occasions with 2 probes positioned on the maxillary central incisors.



Significant mean differences of 31% for blood flux and 96% for concentration were found between the 2 probes, although they shared equal coefficients of variation. The reproducibility for each probe was found to be consistent, and the probes were highly correlated with each other. Flux and concentration, however, were not systematically correlated.



Simultaneous measurements with 2 probes were clearly more reliable. The necessity for a calibration control was evident.

title: Effect of probe design on the suitability of laser Doppler flowmetry in vitality testing of human teeth.
abstract: The aim of this investigation was to study the influence of probe design on the signal output from the dental pulp in experiments with laser Doppler flowmetry (LDF). Eighteen patients 14 to 39 years of age were examined. Recordings were made from a maxillary and a mandibular central incisor and a maxillary canine with an infrared laser Doppler flowmeter. The radiographic appearance of the tested teeth was within normal limits and all teeth responded normally to electric pulp testing (EPT). Five configurations of probes were used. Each probe had 3 fibers arranged in a triangle. One fiber carried the laser light to the pulp tissue and 2 fibers carried the backscattered light to the detector giving the signal output. The diameter of each of the 3 fibers in the probe was 200 microns except in 1 probe where the diameter of the fibers was 125 microns. The distance between the 3 fibers in the triangular arrangement in each probe was 250, 500, 800, 1000, and 1500 microns. A special rubber base splint was used to hold the probe in place on the buccal surface of the tested teeth. The output signals from the LDF were fed into an analog printer and a lap top computer where all calculations were done. The probe with the largest separation of the fibers produced significantly higher output signals from the maxillary and mandibular incisors than the other probes. The same probe also produced significantly higher output signals than the smaller probes from the maxillary canine with the exception of the 200/800 probe.(ABSTRACT TRUNCATED AT 250 WORDS)

title: Age-related changes in the human pulpal blood flow measured by laser Doppler flowmetry.
abstract: The purpose of this study was to examine the age-related changes in human pulpal blood flow (PBF). Recordings were taken from 22 clinically healthy upper central incisors in 22 healthy participants (age: 8-75 years). A Moor blood flow monitor (type MBF3D) was used to measure PBF; and subjects' electrocardiogram (ECG), mean blood pressure (BP) and heart rate (HR) were also recorded. The resting PBF was significantly decreased with the increased age of the participants (Pearson's correlation coefficient, P < 0.001). The examined tooth crown was briefly(1 s) cooled using a dental coolant, and significant reductions in PBF were induced (one-way repeated measures anova, P < 0.05). The magnitude of the reduction (%) was significantly decreased with the increased age of the participants (Pearson's correlation coefficient, P < 0.05). The findings indicate that the hemodynamics in the human pulp is reduced with age.

title: Reliability of Pulpal Blood-flow Measurements Utilizing Laser Doppler Flowmetry
abstract: Pulpal blood flow can now be measured non-invasively in the clinic utilizing laser Doppler flowmetry. The purpose of our study was to test (1) whether the position of the measurement probe on the tooth affects blood-flow measurements and (2) whether measurements from identical locations vary over time. Blood flow of one maxillary central incisor was measured in each of 13 volunteers. Measurements were recorded at five different locations on the labial surface of each tooth. Four measurement sessions were performed, and two sets of measurements were recorded at each session. Custom-made splints ensured accurate and reproducible positioning of the measurement probe at each session. Spatial position of the probe had a clear effect on the pulpal blood-flow measurements (p < 0.0001). Measurements made at incisal and gingival locations were less and greater (p < 0.05), respectively, than those made at central locations. Measurements from various mesio-distal locations did not differ (p > 0.05) when made at the same height on the tooth. Pulpal blood-flow measurements recorded at a given site were not consistent across all of the testing sessions (p < 0.0001). Our data suggest that reliable interpretation of longitudinal measurements of pulpal blood flow obtained with laser Doppler flowmetry requires accurate repositioning of the measurement probe. In addition, an adequate control condition should be included to account for bias due to temporal variation.

title: The sources of laser Doppler blood-flow signals recorded from human teeth.
abstract: Records of pulpal blood flow obtained from human teeth with a laser Doppler flowmeter include a very large component derived from periodontal and other tissues outside the pulp, but this contamination can be reduced by covering the surrounding tissues with opaque rubber dam. The present experiments were carried out to determine what proportion of the signal obtained with this dam in place is derived from non-pulpal tissues. Recordings were made from 22 healthy, intact upper incisors in 14 individuals (aged 22-40 years) with and without dam under the following conditions: from the intact teeth, after local anaesthesia (LA) and the preparation of a deep cavity in the incisal third of the labial surface of the tooth, and after removal of the pulp and arrest of bleeding. In some cases, a reading was also made after replacing the pulp in the pulp cavity. The rubber dam reduced significantly (P<0.05) the mean blood flow reading from the intact teeth by 73%, from 6.98 arbitrary perfusion units (PU) (+/-1.30 S.D., n=22) to 1.92+/-1.50 PU. After LA and cavity preparation, the mean signal with dam was 1.45+/-0.61 PU (n=16). This fell significantly by 76% to 0.35+/-0.19 PU (n=16) when the pulp was removed but not replaced, and by 43% to 0.98+/-0.36 PU (n=14) when the pulp was removed and replaced in the pulp cavity. The latter condition is thought to reproduce most closely the scattering of light in an intact tooth. The results confirm previous findings that up to 80% of the laser Doppler blood-flow signal recorded from an intact human tooth without rubber dam is of non-pulpal origin. They also show that only approximately 43% of the signal recorded with an opaque rubber dam is from pulp.

title: The sources of laser Doppler blood-flow signals recorded from vital and root canal treated teeth.
abstract: The aim was to determine the strength of signals derived from the dental pulp and those from the surrounding tissues in human teeth using the laser Doppler flowmetry (LDF).



Twenty-six vital teeth (13 experimental and 13 controls) from 12 patients were used. Experimental teeth had root canal treatment in a single visit and their healthy antimeres were controls. Blood flow measurements were made before and after local anaesthesia, after root canal preparation, following root canal filling and coronal restoration.



Perfusion unit (PU) values recorded from empty pulp chamber were determined to be only 30% lower than the values recorded before anaesthesia from the experimental intact teeth. When the measurements in the group were compared with each other the values of variation in the both groups were not statistically significant. The variation between the groups when the measurement values before anaesthesia, 10min after anaesthesia and after coronal restoration were compared, it was not statistically significant (P>0.05). The variation between the groups after preparation and root canal filling in their values of measurements was important statistically (P<0.05). The measurement values of the study group were lower than that of the control group.



In pulpal, LDF a major portion of the signal comes from tissues other than pulp. Without taking precautions (such as rubber-dam application) in pulp blood flow measurements, the results may be inconsistent.

title: Tooth discoloration and resolution following a luxation injury: significance of blood pigment in dentin to laser Doppler flowmetry readings.
abstract: Discoloration of teeth is common sequel of dental trauma and is often taken as a sign of irreversible pulpal degeneration, particularly if the crown becomes gray or blue-gray in appearance. If a viable blood supply remains or revascularization occurs following trauma to teeth, removal of blood pigments by normal biologic processes can occur. The assessment of blood flow with laser Doppler flowmetry is an additional diagnostic aid following dental injuries. This technology has been used to monitor the clinical progress of two central incisors that had been palatally luxated in a sporting accident. Color changes were observed and were correlated with symptomatic and radiographic evaluation, sensibility tests, and laser Doppler readings. The results of these examinations indicated that the blood pigment within a discolored tooth crown interfered with laser light transmission. The limitation of this new technology in the assessment of teeth discolored following trauma is significant. Visual radiographic and symptomatic assessment remain as the principal diagnostic criteria at the present time.

title: Non-invasive recording of blood flow in human dental pulp.
abstract: Laser Doppler flowmetry was applied to human teeth to study whether blood How in the pulp can be recorded. In sensitive, intact incisors the level of the output signal Ironi the flowmeter was clearly distinguishable from that obtained in adjacent nonsensitive or pulpeetomized teeth. Heart beat synchronous oscillations, which were present in the recording signal from normal teeth, were absent in nonvital teeth. Local injection of lidocaine (20 mg/ml) with adrenaline (12.5 μg/ml) caused a pronounced and long-lasting reduction of the flowmetric values in healthy teeth. The oscillations were also reduced in amplitude. Repeated recordings showed good reproducibility. Thus, changes in blood (low may be assessed in a tooth by tin's non-invasive method. The instrument is a promising tool in the clinical evaluation of pulp vitality following traumatic injuries.

title: Pulpal blood-flow characteristics of maxillary tooth morphotypes as assessed with laser Doppler flowmetry.
abstract: The purpose of this study was to determine the effect of tooth morphotype on intraindividual and interindividual variations of baseline data as well as on temporal variations between testing intervals in the assessment of pulpal blood-flow by means of laser Doppler flowmetry.



In 14 volunteers, maxillary incisors, canines, premolars, and first molars were investigated bilaterally by laser Doppler flowmetry to assess local pulpal blood-flow values. Measurements in perfusion units were taken during 3 sessions, with a time interval of 7 days between sessions.



Intraindividual comparisons of tooth morphotype-related pulpal blood-flow values revealed significant differences only for the first molar, whereas significant interindividual differences were found for the lateral incisor, canine, premolars, and first molar. Pulpal blood-flow values for the second premolar (11.1 perfusion units) were significantly higher and those for the central incisor (7.6 perfusion units) significantly lower than those for the lateral incisor (9.2 perfusion units) and first molar (9.4 perfusion units). In contrast, measurements at the lateral incisor, first premolar, and first molar did not differ significantly (P > .05). Multiple testing showed no statistically significant effect on tooth morphotype-related pulpal blood-flow measurements.



The findings indicate that contralateral incisors, canines, and premolars are appropriate intraindividual controls for local pulpal blood-flow recordings. Other studies may identify the effect of environmental and technique-related factors on the assessment of local pulpal blood-flow values.

title: A comparison of laser Doppler flowmetry with other methods of assessing the vitality of traumatised anterior teeth.
abstract: Laser Doppler flowmetry is a non-invasive electrooptical technique which allows the semi-quantitative recording of pulpal blood flow. This study aimed to determine the reliability (measured as the sensitivity and specificity) of laser Doppler flowmetry as a method of assessing the vitality of traumatised anterior teeth, and to compare it with standard pulpal diagnostic tests. Recordings of pulpal blood flow were taken from 67 non-vital anterior teeth (55 patients), where the pulpal status was confirmed by pulpectomy. For comparison, recordings were also taken from 84 vital anterior teeth (84 patients). Analysis of the recordings allowed diagnostic criteria to be developed which gave the technique a sensitivity and specificity of 1.0 for this sample. None of the other standard pulpal diagnostic methods tested was as reliable. This was usually due to low sensitivities, which ranged between 0.92 for sensibility testing with ethyl chloride down to 0.36 for periapical radiolucency and 0.16 for a history of pain. Laser Doppler flowmetry was found to be a reliable method of assessing the pulpal status of traumatised anterior teeth, although it is technique-sensitive and time-consuming to use.

title: Evaluation of a pulse oximeter and customized probe for pulp vitality testing.
abstract: Current routine methods for assessment of pulp vitality rely on stimulation of A-delta nerve fibers and give no direct indication of blood flow within the pulp. Recent papers have suggested that pulse oximeters may be used to diagnose pulp vitality by detection of blood flow. In this study, an optimized pulse oximeter probe for teeth was designed, built and tested using the Biox 3740 Oximeter (Ohmeda, Louisville, CO). Following preliminary in vitro tests, the probe was tested clinically. Pulse waveforms from maxillary and mandibular anterior teeth were noted. Simultaneous readings from the subjects' finger were used as controls. Pulse wave readings from the teeth were found to be synchronous with the finger probe, but not consistently. It was easier to maintain continuous readings from mandibular incisors than from maxillary incisors. The average percentage synchronization with the pulse was 28.95% for maxillary incisors and 50.28% for mandibular incisors. This difference was significant (p = 0.05). The overall accuracy of the commercial instrument was disappointing, and in its present form it was not considered to have clinical value.

title: Detection of pulpal circulation in vitro by pulse oximetry.
abstract: Evaluation of pulse oximetry as a potential method of determining pulp vitality was the subject of this research. An in vitro model of pulpal circulation was fabricated to test the design for a dental pulse oximetry sensor. Blood samples equilibrated with hypoxic gas mixtures were circulated through the model by a peristaltic pump. A pulse was simulated by introduction of gas bubbles into the blood circulation. Pulse oximeter readings for saturation were recorded and compared with blood gas analysis results. Statistical analysis revealed no difference between pulse oximetry and blood gas analysis with a highly significant correlation coefficient. Clinical evaluation of this application is currently in progress.

title: Pulse oximetry: a diagnostic instrument in pulpal vitality testing.
abstract: One hundred children with normal maxillary central and lateral incisors were subjected to vitality tests each by electrical and pulse oximetry. As a control population to confirm the readings, 10 known nonvital anterior teeth with complete endodontic fillings were tested. The systemic oxygen saturation values measured on the index finger of the patient served as the control for the comparison of the oxygen saturation values measure on the teeth. The SaO2 values obtained on the teeth were correlated with the electrical test readings. The correlation between the SaO2 readings and electrical testing readings were found to be negative i.e. as the values of the electrical pulp testing reading increased, the SaO2 values decreased. Since a reproducible SaO2 level is obtainable on the vital teeth, pulse oximetry has immediate clinical value in providing base line vitality data for the traumatised teeth.

title: Pulse oximetry evaluation of vitality in primary and immature permanent teeth.
abstract: Present methods of assessing pulp vitality (electric and thermal testing) are of limited use with children, often resulting in false positive or false negative results. Pulse oximetry is a proven, atraumatic method of measuring vascular health by evaluating oxygen saturation (SaO2). This pilot study explores the use of a modified pulse oximetry ear probe to assess pulpal vascular oxygen saturation in primary and immature permanent teeth. Pulse oximetry readily differentiated between known vital and nonvital teeth. Vital teeth consistently provided SaO2 values that were lower than the values recorded on the patients' fingers. Further study of the SaO2 changes in traumatized teeth, with a probe designed specifically for teeth, is warranted by these initial results. Although additional research is indicated, pulse oximetry is already an objective, atraumatic clinical alternative to the present electrical and thermal methods of assessing pulp vitality in children's teeth.

title: Optical determination of dental pulp vitality
abstract: 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/sub 2/) of blood in the pulp was examined using an in vitro test setup. Results suggest that the measurement of relative SO/sub 2/ changes is feasible, but standard dual-wavelength pulse oximetry does not allow determination of SO/sub 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.<<ETX>>

title: Evaluation of optical methods of detecting dental pulp vitality.
abstract: An attempt to develop an optical probe to assess dental pulp vitality led to the conclusion that it would be difficult to construct an effective optical probe for the middle-aged and older patient who is a common candidate for pulpal assessment. In such patients, vascularity of the gingiva is so much greater than that of the pulp that signals originating in the gingiva overwhelm pulpal effects. This conclusion applies to photoplethysmography, 
pulse oximetry, and laser Doppler flowmetry, and probably to spectrophotometry as well. The effect of the gingiva was first demonstrated by placing opaque plastic film in the gingival sulcus, which caused attenuation of light passing through molar and bicuspid teeth. More dramatically, the remaining 
pulsatile signal could be much further attenuated by vasoconstricting the gingiva. An unusually sensitive 
photoplethysmograph was developed (noise floor, with signal averaging, was near 10 fA), as were a variety 
of optical probes (including two that approached the tooth below the gingival margin). The tools, methods, 
and conceptual models that were developed are intended also to be of use to investigators who are developing optical probes for use in younger subjects, in whom such probes appear to be useful.

title: Dental pulp photoplethysmography in human beings.
abstract: Circulatory changes in human dental pulp have been investigated with the photoplethysmographic technique. The effect of respiratory maneuvers, local cooling and axial pressure has been studied before and after local application of anesthesia on the examined tooth. Local anesthesia has not altered the observed changes. It is suggested that the changes recorded by photoplethysmography of the dental pulp represent variations in blood distribution.

title: Dual wavelength spectrophotometry as a diagnostic test of the pulp chamber contents.
abstract: The purpose of this in vitro study was to determine the feasibility of using dual wavelength spectrophotometry to identify teeth with pulp chambers that are either empty, filled with fixed pulp tissue, or filled with oxygenated blood. In phase I of the experiment, a human third molar was prepared so that its pulp space could be filled with oxygenated blood and later emptied. In phase II, the lower jaw of a beagle dog was removed and placed in formalin, thereby fixing the pulps of the teeth. The pulp of the right canine was removed via an apical approach, and attachments were placed in a similar position to those on the human tooth, to allow filling and emptying of the pulp space. Cavit was placed over the exposed fixed pulp in the left canine. Ten readings, which were separated by light source and detector removal and replacement, were taken of the right canine pulp space when it was empty or filled with oxygenated blood, or the left canine pulp space when it was filled with fixed tissue. Distinct and reproducible changes were measured for pulp spaces filled with air, tissue, or oxygenated blood. In phase III, simulated pulp testing on a dog tooth model was performed. Blood was introduced into the root canal space, the chamber was rinsed with water and replaced with air, according to a predetermined code. Spectrophotometer readings were recorded. The identification of pulpal contents was correctly determined in all 20 of the predetermined conditions. The findings indicate that continuous wave spectrophotometry may become a useful pulp testing method.

title: Possible application of transmitted laser light for the assessment of human pulpal vitality.
abstract: The purpose of this study was to determine whether use of transmitted laser light would enable a better assessment of human pulpal vitality than back-scattered light does (LDF: laser Doppler flowmetry). The experiments were carried out on ten upper central incisors in six subjects aged 23-28 years; five of the teeth were vital with no restoration, and five were non-vital. For use with transmitted laser light, the fibers within the probe of a conventional LDF apparatus were used, one for transmitting light onto the buccal surface, the other for receiving it at the palatal surface of the same tooth. For LDF, the probe was fixed at the buccal surface. Blood flow was measured at three different locations on each experimental tooth: the incisal third, the center and the cervical third of the tooth crown. In non-vital teeth, 1) output signals with transmitted laser light all registered zero, and no oscillation could be seen in recordings from any location on the tooth, but 2) LDF signals were above zero, there were regular oscillations related to heart rate, and passive increases in blood flow (corresponding to blood pressure increases) were recorded from both the center and the cervical third of the tooth, indicating that LDF registered blood flow of non-pulpal origin. In vital teeth, LDF signals were significantly higher than in non-vital teeth at each location on the tooth. At the central site on vital teeth, the output signals for transmitted laser light were about twice those seen with LDF, and passive blood flow changes corresponding to blood pressure increases were more clearly observed. These results indicated that transmitted laser light would be useful for the assessment of tooth pulp vitality both because the blood flow signals did not include flow of non-pulpal origin, and because its output signals and response to blood flow changes were clear and could easily be monitored.

title: Possible application of transmitted laser light for the assessment of human pulp vitality. Part 2. Increased laser power for enhanced detection of pulpal blood flow.
abstract: The purpose of this study was to investigate the effect of an increase in laser power on the transmitted laser signals from vital and non-vital teeth, in the hope of achieving a better assessment of human pulp vitality with the transmitted laser-light flowmeter. The experiments were carried out on total of 61 vital teeth with no restoration (19 upper central incisors, 16 upper lateral incisors, 16 upper canines, and 10 first premolars) and five non-vital upper central incisors (the root canals of which were filled with gutta-percha) in 15 subjects aged 22-28 years. For use with transmitted laser light, the fibers within the probe of a conventional laser Doppler flowmeter (LDF) apparatus were used, one for transmitting light onto the labial surface, the other for receiving it at the palatal surface of the same tooth, as reported previously. Laser output power was set at the original 2 mW and also at 5, 7, and 10 mW. The number of vital teeth displaying a blood flow (BF) signal at each laser power setting was: 1) 12/19 central incisors at 2 mW, 19/19 at 5, 7, and 10 mW, 2) 19/19 lateral incisors at 2, 5, 7, and 10 mW, 3) 0/16 canines at 2 mW, but eight, 12, and 14 at 5, 7, and 10 mW, 4) 0/10 first premolars at 2, 5, 7, and 10 mW. Thus, an increase in laser power increased BF detection from the thicker teeth (but not from premolars). In addition, clearer BF signals synchronized with heart rate, and greater passive BF changes secondary to blood pressure (BP) changes were observed at higher laser settings. In non-vital teeth, no signals synchronized with heart rate or BP changes were observed, indicating that no BF signal of non-pulpal origin was ever monitored with this ballistic light even when the laser power was increased. These results indicate that high-powered transmitted laser light could be a useful tool both for monitoring pulpal BF and for the assessment of tooth-pulp vitality.