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.     

Efficacy of laser Doppler flowmetry for the diagnosis of revascularization of reimplanted immature dog teeth

Abstract – This study was performed to assess if laser Doppler flowmetry (LDF) is an improved method for the detection of revascularization of replanted teeth. Teeth were extracted and reimplanted under different experimental conditions. LDF readings were taken before extraction and weekly for 3 months. In control teeth, LDF baseline readings were taken and then repeated after the apical blood vessels were cut surgically. At the end of 3 months it was determined radiographically and histologically whether revascularization had occurred, i.e. vitality had returned. Results: LDF readings correctly predicted the pulp status (vital vs. non-vital) in 83.7% of the readings. 73.9% (17 of 23) were correct for the vital teeth and 95% (19 of 20) were correct for the non-vital teeth. Fisher's exact test (2-tail) indicated that there was no significant association between the efficacy of LDF and tooth type ( P= 0.166), although P2 was the least accurate tooth tested. Wilcoxon's matched-pair signed rank test demonstrated that in the revascularized (vital) teeth, the flux value between the baseline and week 2 dropped significantly ( P= 0.0001), increased significantly from week 2 to week 4 ( P= 0.0001) and then decreased steadily until week 12. However, at week 12 the flux was still significantly higher than at week 2 ( P= 0.010). In the teeth that failed to revascularize, the flux value dropped significantly by weeks 1 and 2 ( P= 0.004 and P= 0.0001, respectively). Flux values did not increase from week 2. A Fast Fourier Transform (FFT) analysis confirmed a pulse of dominant frequency of 2 Hz in the teeth that returned to vitality and the lack thereof in those that stayed non-vital. One tooth in which the flux value evaluation indicated a non-vital tooth but the radiographic/histologic findings showed vital (false negative) possessed a pulse of dominant frequency and proved by this method to have successfully revascularized.     

Laser light passage through restored and carious posterior teeth

Laser Doppler flowmetry (LDF) has been used to investigate pulpal blood flow as a means of pulp vitality testing. Transmission of laser light from the tooth surface to the pulp space may be influenced by caries and restorations. One hundred and twenty‐two first and second molars that had caries into dentine, restorations or significant loss of coronal tissue were sectioned in half axio‐bucco‐lingually. The two sections were illuminated with a laser from their buccal and lingual aspects 2 mm coronal to the amelocemental junction. Light reaching the pulp space was recorded. Buccal and lingual illumination sites were equally effective for 67 teeth (55%). Buccal sites alone were effective for 35 teeth (29%), despite over one‐third of these surfaces being restored or featuring enamel or dentine caries. A lingual position alone was effective for 20 teeth (16%). Caries affected light transmission, but for over half the teeth, the pulp could be illuminated from all four probe positions. No effect was found when the influence of mesial and distal restorations on transmission into the corresponding tooth section was examined. The pulp spaces of most (84%) restored, and carious posterior teeth could be illuminated by laser light from their buccal aspect and these teeth could potentially be vitality tested using LDF.     

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 jam. 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.     

The effect of wavelength, bandwidth, and probe design and position on assessing the vitality of anterior teeth with laser Doppler flowmetry

Objectives . 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 μm and 500 μm) 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.
Design . Split-mouth cohort clinical trial.
Setting . Childrens dental clinic, Glasgow Dental Hospital and School.
Sample and methods . 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.
Results . Of the variables investigated, the combination of a 633 nm laser source with a 3 kHz bandwidth filter using a probe with a 500 μm 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.
Conclusions . 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.     

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 flowmetry. The radiographic appearance of the tested teeth was within normal limits and all teeth responded normally to electric pulp testing (EFT). 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 μm except in 1 probe where the diameter of the fibers was 125 μm. The distance between the 3 fibers in the triangular arrangement in each probe was 250, 500, 800, 1000, and 1500 μm. 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. The output signals were significantly higher from the mandibular incisor than from the maxillary incisor and canine. Consecutive recordings with the LDF from the maxillary incisor in 5 patients within 1 hour gave coefficient of variation from 7.9% to 10.3% in output signals. The results of this study showed that all 5 experimental probes gave output signals indicative of blood flow in the dental pulp and the probe with the largest separation of fibers seemed to be the most suitable one under the experimental conditions used. It appeared to be possible to make reproducible recordings from the pulp of the teeth under the experimental conditions used.     

Reliability of laser Doppler flowmetry in testing vitality of human teeth

Abstract The aim of this investigation was to study the reliability of the laser Doppler flowmetry (LDF) output signals when testing from 4 different positions on the buccal surface of human teeth. Recordings were made from 10 intact anterior teeth in 10 patients, mean age 27.4 years. Five types of probes were used. Each probe had 3 fibers arranged in a triangle, one lighted fiber and 2 receiving ones. The separation of the fibers was 1500, 1000. 800, 500 and 250 μm. The diameter of the fibers was 200 μm in all probes except the one with the smallest separation of fibers where it was 125 μm, A rubber base splint was used to position the probe on the buccal surface of the teeth tested. The first recording was made with the ingoing light in a gingival position. Then 3 additional recordings were made turning the probe 90° each time consequently changing the position of the ingoing light accordingly. Thus, gingival, mesial, incisal and distal recordings were obtained. The output signals were fed into a lap-top computer upon which all calculations were done. The output signals from the incisalmost position of the teeth were significantly lower than the output signals from the other 3 positions with all probes except one. The turning of the probes into the 4 different positions affected the output signals from the probe with the smallest separation of fibers significantly more than the output signals from the other probes.     

Laser Doppler flowmetry in endodontics: a review

Vascular supply is the most accurate marker of pulp vitality. Tests for assessing vascular supply that rely on the passage of light through a tooth have been considered as possible methods for detecting pulp vitality. Laser Doppler flowmetry (LDF), which is a noninvasive, objective, painless, semi-quantitative method, has been shown to be reliable for measuring pulpal blood flow. The relevant literature on LDF in the context of endodontics up to March 2008 was reviewed using PubMed and MEDLINE database searches. This search identified papers published between June 1983 and March 2008. Laser light is transmitted to the pulp by means of a fibre optic probe. Scattered light from moving red blood cells will be frequency-shifted whilst that from the static tissue remains unshifted. The reflected light, composed of Doppler-shifted and unshifted light, is returned by afferent fibres and a signal is produced. This technique has been successfully employed for estimating pulpal vitality in adults and children, differential diagnosis of apical radiolucencies (on the basis of pulp vitality), examining the reactions to pharmacological agents or electrical and thermal stimulation, and monitoring of pulpal responses to orthodontic procedures and traumatic injuries. Assessments may be highly susceptible to environmental and technique-related factors. Nonpulpal signals, principally from periodontal blood flow, may contaminate the signal. Because this test produces no noxious stimuli, apprehensive or distressed patients accept it more readily than current methods of pulp vitality assessment. A review of the literature and a discussion of the application of this system in endodontics are presented.     

A comparison of laser Doppler flowmetry with other methods of assessing the vitality of traumatised anterior teeth

Evans D, ReidJ, Strang R, Stirrups D. A comparison of laser Doppler flowmetry with other methods of assessing the vitality of traumatised anterior teeth. Endod Dent Traumatol 1999; 15: 284–290. © Munksgaard, 1999.
Abstract — Laser Doppler flowmetry is a non-invasive electro-optical 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 radio-lucency 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.     

Pulpal blood flow recorded from human premolar teeth with a laser Doppler flow meter using either red or infrared light

Objective

To compare red (635 nm) and infrared (780 nm) light for recording pulpal blood flow from human premolar teeth.

Design

Recordings were made from 11 healthy teeth in 9 subjects (aged 16–30 years) using a laser Doppler flow meter (Periflux 4001) equipped with both red and infrared lasers. Average blood flow signals were obtained with both light sources alternately from each tooth under five conditions: intact tooth without opaque rubber dam, intact tooth with dam, after injecting local anaesthetic (3% Mepivacaine) (LA) over the apex of the tooth and cavity preparation to almost expose the pulp, after removal and replacement of the pulp, and with the root canal empty.

Results

With infrared light, the dam significantly decreased the mean blood flow by 80%. Injecting LA and cavity preparation had no significant effect. Removal and replacement of the pulp reduced the mean blood flow by 58%. There was no further change when the pulp was removed. With red light, the dam reduced the signal from intact teeth by 60%. Injecting LA and cavity preparation had no significant effect. The signal fell by 67% after pulp removal and replacement and did not change significantly when the pulp was removed.

Conclusions

Opaque rubber dam minimises the contribution of non-pulpal tissues to the laser Doppler signal recorded from premolars. Using dam, the pulp contributed about 60% to the blood flow signal with both red and infrared light. The difference between them in this respect was not significant.     

Evaluation of the effect of tooth vitality on regenerative outcomes in infrabony defects

BACKGROUND, AIMS: This investigation was designed to evaluate the null hypothesis of no differences in GTR outcomes in intrabony defects at vital and successfully root-canal-treated teeth. METHOD: 208 consecutive patients with one intrabony defect each were enrolled. Based on tooth vitality, the treated population was divided at baseline into 2 groups: one with 41 non-vital teeth and the other with 167 vital teeth. The 2 groups were similar in terms of patient and defect characteristics. RESULTS: A slight unbalance in terms of depth of the intrabony component was observed in the non-vital group compared to the vital group (6.9+/-2.1 mm versus 6.2+/-2.3 mm, p=0.08). All defects were treated with GTR therapy. At 1 year, the non-vital and the vital groups showed a clinical attachment level (CAL) gain of 4.9+/-2.2 mm and of 4.2+/-2 mm, respectively. The difference was statistically significant (p=0.03). To correct for the baseline unbalance in defect depth, data were expressed as a % of clinical attachment level gains with respect to the original intrabony depth of the defect. % CAL gains were 72.8+/-42.2% and 73+/-26.4% for vital and non-vital teeth, respectively: the difference was not statistically significant (p=0.48). Average residual pocket depths were 2.8+/-1 mm in the vital and 2.8+/-0.9 mm in the non-vital group. Tooth vitality was assessed at baseline, at 1-year and at follow-up (5.4+/-2.8 years after surgery): all teeth vital at baseline were still vital at follow-up with the exception of 2 teeth that received endodontic treatment for reconstructive reasons and for caries. At follow-up visit, the difference in CAL with respect to 1-year measurements was -0.9+/-0.8 mm in the vital group and -0.7+/-0.8 mm in the non-vital group, indicating stability of the regenerated attachment at the majority of sites. CONCLUSIONS: Data from this study demonstrate that root canal treatment does not negatively affect the healing response of deep intrabony defects treated with GTR therapy; furthermore GTR therapy in deep intrabony defects does not negatively influence tooth vitality.     

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.     

The sources of laser Doppler blood-flow signals recorded from human teeth

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.     

The lamp effect of laser Doppler flowmetry on teeth

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.     

Laser light transmission in teeth: a study of the patterns in different species

AIM: The aim of this study was to investigate the pattern of light transmission through teeth of different species and to examine laser light propagation within enamel from various animal sources. METHODOLOGY: Sectioned teeth from five species--pig, horse, sheep, cat and rat--were evaluated. Samples were illuminated individually by a helium-neon laser light from the buccal surface using a probe 0.5 mm in diameter placed at varying angles between 60 and 120 degrees C. The pattern of light transmission was observed macroscopically. Further evaluation of laser light transmission in enamel was achieved using confocal microscopy. RESULTS: In each species, light was transmitted through the tooth to the pulp, but in the cat and the rat, light was also transmitted to the far side of the tooth. Despite the different patterns of enamel in the species, light was transmitted through enamel to dentine. CONCLUSION: Light from a laser Doppler probe appeared to reach the dental pulp in all the species: however, in the mammals with smaller teeth, light may also have been able to reach the periodontium and thus the reflected signal may not be entirely of pulpal origin.     

Pulp size in molars: underestimation on radiographs

The aim was to determine whether radiographs provide a clinically useful indication of pulp size in diseased/restored human first molar teeth, and to investigate accessibility of pulp tissue for diagnostic testing using laser Doppler flowmetry (LDF). Extracted teeth of known age were collected. Restorative materials were removed and teeth with evidence of pulp exposures excluded. Fifty-six teeth were radiographed from buccal and mesial aspects, and then their crowns were sectioned axiobuccolingually and photographed. Images were digitally scanned and measurements made of the total pulp area (above a line across the most superior part of the pulpal floor) and the pulp area in the clinical crown (superior to a line between the amelocemental junctions). The pulp width at the cervix and the highest point of the pulp were also recorded. Data were analysed using Pearson correlations. Pulp areas within the clinical crowns were significantly larger than indicated by radiographs, by 23% in the case of the clinically attainable buccal view (P < 0.05). Pulps may be more accessible to flowmeter testing than they appear. Absence of pulp tissues in the crown was recorded in equal numbers of teeth on radiographs and sections, but with agreement for only one tooth. Sixteen per cent of the teeth had no pulp area in the clinical crown when sectioned, but might still be suitable for testing using LDF.     

Improvement of the detection of human pulpal blood flow using a laser Doppler flowmeter modified for low flow velocity

ObjectiveHuman pulpal blood flow (PBF) signals as measured by laser Doppler flowmeter (LDF) decrease with age. Although this decrease is considered to be due in part to slow blood flow, information regarding this velocity in humans has been lacking. The aims of the present study were to estimate the blood flow velocity in human dental pulp and to evaluate the validity of LDF modified for the measurement of slow blood flow.DesignMean blood flow velocities at the upper central incisor, gingiva, fingertip and forearm of 28 volunteers (mean age: 38.6 years old) were estimated using LDF with a frequency analyser. Blood flow signals at these measurement areas were recorded using two different LDFs: (a) one with a standard blood flow range; and (b) one modified for low blood flow velocity.ResultsThe frequency range of the Doppler shift measured at the teeth with an opaque rubber dam was the narrowest (median: 4.3 kHz) among all of the measurement areas. The estimated mean blood flow velocity was the slowest at the teeth with a dam (median: 0.18 mm/s). LDF for low blood flow velocity detected larger and clearer pulsatile blood flow signals from the teeth with dams than did standard LDF.ConclusionsThe present results indicate that the velocity of PBF in humans is very low and that LDF modified for the measurement of slow blood flow is appropriate for PBF measurement in humans.     

A comparison of laser Doppler flowmetry with other methods of assessing the vitality of traumatised anterior teeth

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.     

Blood flow changes in the dental pulp during limited exercise measured by laser Doppler flowmetry

The effect of limited exercise on pulpal blood flow was assessed by laser Doppler flowmetry (LDF). The primary aim of the investigation was to determine whether clinically significant changes could be induced by mild exercise when LDF was used to monitor pulpal blood flow. Blood flow readings were obtained from the coronal pulps of 17 upper central incisor teeth of 10 human volunteers before, during and after limited exercise. Readings were also obtained from the adjacent attached gingivae. Pulse rate was recorded concurrently. Pulpal blood flow was found to vary during exercise, with a mean percentage change of 38% from the level at rest; the range was from a 100% decrease to a 200% increase. The mean percentage increase in gingival blood flow was 65%, with a range of 6-300%. The main indication that blood flow was being assessed was the pulsatile nature of the output. Results were compared only within individual teeth. The pulse rate increased during exercise (mean percentage increase 54%, range 11-98%). There was no direct relationship between increased pulse rate and pulpal blood flow. It was evident that the mechanisms controlling pulpal and gingival blood flows differed. Laser Doppler flowmetry readings were only reproducible in individual teeth provided that the patient was at rest, and this should be taken into account in clinical or research measurements.     

Laser Doppler flowmetry for assessment of anterior mandibular teeth in conjunction with bone harvesting in the symphysis: a clinical pilot study

PURPOSE: To evaluate the pulp sensitivity and vitality of mandibular incisors and canines before and after bone harvesting in the symphysis. MATERIALS AND METHODS: In 20 patients requiring bone grafts from the symphysis, pulp sensitivity (carbon dioxide [CO2]) and pulpal blood flow (laser Doppler flowmetry [LDF]) of mandibular incisors and canines were evaluated preoperatively, postoperatively, and 6 months after surgery. Teeth were allocated to 1 of 3 groups according to their initial and final reaction to CO2 (group A = teeth with a positive reaction throughout the study, group B = teeth that exhibited a sensitivity change from positive to negative, and group C = teeth with a negative reaction throughout the study). RESULTS: Preoperative flux measurements (LDF) did not differ between groups A, B, and C. Teeth with sensitivity changes (group B) showed the greatest decrease (a statistically significant decrease) of pulpal blood flow over time, whereas teeth in groups A and C demonstrated an insignificant reduction of flux over time. DISCUSSION AND CONCLUSIONS: LDF was purely used as an experimental tool in the present study. Pulpal blood flow measurements using LDF demonstrated a decrease of flux over time in anterior mandibular teeth following bone harvesting in the symphysis. A significant change of flux, however, was only observed for teeth that also demonstrated a loss of pulp sensitivity during the same study period. Loss of pulp sensitivity appeared to be correlated to a significant decrease of blood flow assessed by LDF.