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Detection of the pulpal blood flow in primary teeth by laser Doppler flowmeter
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PEDIATRIC DENTAL JOURNAL 14(1): 103–107, 2004
Detection of the pulpal blood flow in primary teeth by laser Doppler flowmeter Hideji Komatsu, Motohide Ikawa* and Hideaki Mayanagi Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, * Division of Periodontology and Endodontology, Department of Oral Biology, Tohoku University Graduate School of Dentistry 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, JAPAN
Abstract In this study, pulpal blood flow (PBF) of human primary teeth was measured using laser Doppler flowmeter (LDF) and efficacy of opaque rubber dam application was examined. Twenty-two healthy and 3 non-vital upper primary central incisors in 13 children (age: 3 years 11 months–7 years 3 months) were examined. Recordings were made with and without opaque rubber dam application. Electrocardiogram (ECG) of the subjects was simultaneously recorded. Results obtained were as follows: 1) With dam application, pulsatile signals synchronous with ECG were recorded from all the healthy teeth, whereas no pulsatile signals were recognized in non-vital teeth. 2) Without dam application, pulsatile signals synchronous with ECG were recorded from all the healthy teeth and non-vital teeth. 3) The amplitude of blood flow signal was significantly reduced by the opaque dam application. Results indicated that PBF measurement using LDF with dam application in human primary central incisors was applicable for pulp vitality assessment.
Introduction The determination of the tooth pulp vitality in adult humans is made by clinical examinations such as visual examination, radiographs, electric pulp tests and thermal tests1,2). Among these methods, electric and thermal tests rely on patients’ pain sensation, which is untrustworthy in primary teeth in children. Furthermore, the pain sensation produced by these test may disturb further dental treatment. Pulpal blood flow (PBF) measurement using laser Doppler flowmeter (LDF) has been applied to pulp vitality testing in traumatized permanent teeth3–8) and primary teeth9,10) because of the advantages of being objective and painless. It has been reported that LDF signals contain an artifact component derived from periodontal blood flow and did not accurately reflect PBF11–14). The laser light on Received on October 1, 2003 Accepted on January 20, 2004
Key words Diagnosis, Laser Doppler, Primary teeth, Pulp, Vitality
the tooth surface scatters widely outside the tooth15), partly reaching the periodontal tissue, and then returns to the detector, resulting in contamination from periodontal blood flow. One of the methods used to eliminate such signal contamination is an opaque black rubber dam11–13). Information regarding the signal contamination due to periodontal blood flow during PBF measurement using LDF in primary teeth is limited. Fratkin et al.9) reported that the blood flow values before and after pulpectomy of the primary incisors with obturation were significantly different. In their report, the fiber optic probe was placed on the lingual surface of the teeth at least 2 mm from the gingiva to avoid soft tissue interference. However, no numerical data were given with respect to the signal contamination. Funatsu et al.10) measured PBF with primary incisors and permanent incisors using a transmitted laser flowmeter with a slide caliper type probe. They reported that PBF in the primary teeth were larger than those in the 103
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Komatsu, H., Ikawa, M. and Mayanagi, H.
permanent teeth. No details were given of the possible contamination of the signal artifact due to periodontal blood flow and its elimination. Therefore, the aims of this study were: 1) to examine the contamination of the signal artifact due to periodontal blood in PBF measurement using LDF in human primary teeth; and 2) the efficacy of opaque rubber dam application on eliminating such noise, if any.
Materials and methods 1. Subjects and examined teeth This study was approved by the Tohoku University School of Dentistry Research Ethical Committee. Twenty-two healthy maxillary primary central incisors in 13 children (3 years 11 months–7 years 3 months, mean: 5 years 6 months) and 3 non-vital teeth; 2 root canal filled (3 years 11 months–5 years 0 months) and the other confirmed as pulp necrosis by endodontic treatment (5 years 11 months), were examined. The experimental purpose and methodology were explained to the subjects and informed consent was obtained. The examined teeth were diagnosed as healthy if they were free of caries, restoration, defects, attrition, recession and discoloration. Teeth with a degree of mobility greater than 2 were excluded. Prior to the recording, an individual resin cap was prepared for each tooth from a plaster model of the upper tooth arch of each subject so as to cover the labial and the palatal surface of the tooth examined16,17). A hole, 2.0 mm in diameter and with its center approximately. 2 mm from the gingival margin, was drilled in the labial side of the cap at right angles to the mesio-distal center of the tooth surface, and a stainless steel tube (outer diameter 2.0 mm, inner diameter 1.6 mm, length 3 mm) for the insertion of an LDF probe was fixed into the hole. 2. Laser Doppler flowmetry A Moor blood flow monitor (type MBF3D, Moor Instruments, Axminster, U.K.; wavelength, 780– 820 nm) was used with a dental probe (ext. diam. 1.1 mm, fibre diam. 0.2 mm, centres 0.5 mm apart). The probe tip was inserted into a polythene tube (o.d. 1.5 mm, i.d. 1.0 mm) to obtain a satisfactory fit into the stainless steel tube. The laser Doppler flow meter was set up in the same way as described by Vongsavan and Matthews18), with a 0.1 second time constant and an upper band-pass limit of 14.9 kHz.
Fig. 1 A schematic drawing of pulpal blood flow (PBF) measurement in human maxillary primary central incisors using laser Doppler flowmeter (LDF)
The laser Doppler signal was also recorded from a stationary reflector with the same level of illumination as was present during recording from the tooth. This was used to determine the output equivalent to zero blood flow in the recording. The sensitivity of the blood flow monitor was adjusted using a standard suspension of polystyrene beads, and measurements were made in arbitrary perfusion units (P.U.). 3. Recording procedure and rubber dam application Each subject was placed in a supine position and the lips were retracted. An opaque black rubber dam (Four D Rubber Co. Ltd., Heanor, Derbyshire, U.K.; thickness 0.25 mm) was applied to the tooth being examined and to the adjacent teeth in order to examine its effects on eliminating signals derived from periodontal blood flow. The individual resin cap was fitted to the test tooth and was retained using a small amount of dental cement (Dycal, The L.D. Calk Division, Dentsply International Inc., Milford, U.S.A.) along the incisal edge, if necessary. The LDF probe tip was inserted tightly into the buccal hole of the cap until the tips touched the tooth surface (Fig. 1). LDF was recorded for about one minute with the dam in place. Simultaneously the subject’s electrocardiogram (ECG) was recorded. The dam was then removed using scissors without disturbing the optical fibre and recording was resumed. The mean blood flow signals with and without dam application were measured afterwards using a personal computer (Power Macintosh G3, Apple Computer Inc., Cupertino, CA) and a laboratory interface (Power Lab, ADInstruments Pty Ltd., Australia).
PULPAL BLOOD FLOW IN HUMAN PRIMARY TEETH
Fig. 2 An example of the recording from vital primary tooth (upper right maxillary primary central incisors, subject age; 5 years 6 months, female) Upper traces: PBF (left: with opaque rubber dam, right: without opaque rubber dam) Lower traces:ECG (left: with opaque rubber dam, right: without opaque rubber dam)
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Fig. 3 An example of the recording from non-vital primary tooth (upper right maxillary primary central incisors, subject age; 5 years 11 months, male) Upper traces: PBF (left: with opaque rubber dam, right: without opaque rubber dam) Lower traces:ECG (left: with opaque rubber dam, right: without opaque rubber dam)
Table 1 Summary of the blood flow signals Teeth type
n
Rubber dam
blood flow signals (P.U.)
vital teeth
22 22 3 3
with dam without dam with dam without dam
6.242Ⳳ5.375 22.364Ⳳ10.698 0.432 (0.162–0.502) 17.112 (12.14–25.968)
non-vital teeth
*
*: P⬍0.01 (Mann-Whitney U-test) In the vital teeth, blood flow signals are expressed as mean with standard division. In the non-vital teeth, blood flow signals are expressed as median with 25–75 percentiles. The dam reduced PBF signal amplitudes and this change was statistically significant (n⳱25, meanⳲSD, 73.1Ⳳ13.7%, P⬍0.01, Wilcoxon matched pairs test).
4. Statistics The effect of dam application was examined by the Wilcoxon matched pairs test. PBF signal amplitudes were compared between the vital teeth and the non-vital teeth using the Mann-Whitney U-test. A P-value less than 0.05 was taken as indicating statistical significance.
Results The pulse waves synchronous with ECG were
recognized in all the healthy teeth both with and without dam application. Fig. 2 shows a recording of PBF and ECG with and without dam application from a vital tooth (upper right maxillary primary central incisors, subject age, 5 years 6 months, female). Fig. 3 shows a recording of PBF and ECG with and without dam application from a non-vital tooth (upper right maxillary primary central incisors, subject age, 5 years 11 months, male). No pulse waves synchronous with ECG was observed with dam application, whereas pulse waves synchronous with ECG were observed without dam application.
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This was also the case with a root canal filled tooth (data not shown). The dam reduced PBF signal amplitudes ranging between 59.3% and 86.8% (n⳱25, meanⳲSD, 73.1Ⳳ13.7%) and this change was statistically significant (P⬍0.01, Wilcoxon matched pairs test) (Table 1). With dam application a significant difference of mean flux signal between the vital teeth and the non-vital teeth was obtained (P⬍0.01, Mann-Whitney U-test). Without dam application the difference of the mean flux between the vitals and the non-vitals was not significant (P⬎0.05, Mann-Whitney U-test).
Discussion With dam application pulsatile signals synchronous with subject’s ECG were recognized in all the healthy teeth but none of the non-vital teeth. There was a significant difference in signal amplitudes between vital and non-vital teeth with the dam in place. These results indicate that PBF measurement using LDF with an opaque dam is applicable to distinguish vital from non-vital primary teeth in humans. Without dam application, however, the pulsatile signal was observed also from non-vital teeth. This is interpreted as a signal component of non-pulpal origin in the blood flow signals. The reduction of the signal amplitudes by means of opaque rubber dam application is comparable with previous reports; 65%16), 75%11), 80%12) in permanent central incisors. The large amount of signal component, which reflects periodontal blood flow, is derived from the light scattering widely outside the tooth15), partly reaching the periodontal tissue, and then returning to the detector. The present finding that pulsatile signals were observed from all of the non-vital teeth without the dam in place was in contrast to Fratkin et al.’s report9) in which they identified 100% of vital teeth and 100% of non-vital (pulp extirpation or extraction) teeth. This discrepancy in the results may be explained by the different optical characteristics of the teeth and periodontal tissues as follows: 1) In Fratkin et al.’s study9), the measurement probe was placed in contact with the lingual surface of the root canal filled non-vital teeth where the opaque cement was filled after the root canal fillings. This prevented the scattering of laser light to surrounding tissue; and 2) in the extracted teeth, blood coagulated in the root canal and pulp chamber and on the surface of the extracted teeth and tooth socket, which prevented
the scattering of laser light to the periodontal tissue. Funatsu et al.10) performed laser Doppler blood flow measurement using transmitted laser light and compared adult vital and non-vital upper central incisors. They observed pulsatile signals from vital teeth and no obvious blood flow signals from non-vital teeth. Transmitted laser light blood flow measurement is considered to have possible advantages due to less signal contamination compared with conventional LDF using reflection light. This may be in part due to the difference in the pathway of the light, i.e. collection of the transmitted light through the tooth contains less light that scatters outside of the tooth and then comes into the tooth than collection of the reflected light. Roebuck et al.14) suggested that the use of transmitted laser light19) may be of use when using LDF as a diagnostic tool. Application of transmitted light photoplethysmography to adult permanent20) and young permanent21) teeth has also been reported. Acknowledgments We are grateful to D. Mrozek for English proofing of this manuscript. This study was supported by Scientific Research Grant from Ministry of Education in Japan (No. 13771253) to Hideji Komatsu.
References 1) Cohen, S.: Diagnostic procedures. In: Pathways of the Pulp. 6th ed., (Cohen, S. and Burns, R.C. eds.) Copenhagen, Munksgaard, 1994, pp. 2–24. 2) Cooley, R.L., Stilley, J. and Lubow, R.M.: Evaluation of a digital pulp tester. Oral Surg Oral Med Oral Pathol 58: 437–442, 1984. 3) Gazelius, B., Olgart, L., Edwall, B. and Edwall, L.: Non-invasive recording of blood flow in human dental pulp. Endod Dent Traumatol 2: 219–221, 1986. 4) Gazelius, B., Olgart, L. and Edwall, B.: Restored vitality in luxated teeth assessed by laser Doppler flowmeter. Endod Dent Traumatol 4: 265–268, 1988. 5) Olgart, L., Gazelius, B. and Lindh-Strömberg, U.: Laser Doppler flowmetry in assessing vitality in luxated permanent teeth. Int Endod J 21: 300–306, 1988. 6) Shinoguchi, K., Shirakawa, T., Miura, M. and Oguchi, H.: Laser Doppler flowmetry for noninvasive measurement of pulpal blood flow in immatured permanent teeth. Jpn J Ped Dent 29: 688– 697, 1991. (in Japanese) 7) Andreasen, F.M. and Andreasen, J.O.: Examination and diagnosis of dental injuries. In: Textbook and
PULPAL BLOOD FLOW IN HUMAN PRIMARY TEETH
8)
9)
10)
11) 12)
13)
14)
Color Atlas of Traumatic Injuries to the Teeth. 3rd ed., (Andreasen, J.O. and Andreasen, F.M. eds.) Copenhagen, Munksgaard, 1994, pp. 195–217. Kikuiri, T., Shirakawa, T., Wada, S., Mitome, M., Nozaki, M. and Oguchi, H.: Pulpal blood flow in immatured permanent teeth after luxation injuries. Jpn J Ped Dent 34: 753–761, 1996. (in Japanese) Fratkin, R.D., Kenny, D.J. and Johnoston, D.H.: Evaluation of a laser Doppler flowmeter to assess blood flow in human primary incisor teeth. Ped Dent 21: 53–56, 1999. Funatsu, K., Matsuda, E., Nishi, Y., Asari, Z., Amino, S., Mukoyama, K., Inoue, M. and Sasa, R.: The observation of pulpal blood flow using the transmitted laser flowmeter—Application of slide caliper type probe for children—. Jpn J Ped Dent 39: 1121–1127, 2001. (in Japanese) Matthews, B., Ikawa, M. and Horiuchi, H.: Techniques for recording pulpal blood flow in man. J Dent Res 75: 1150, (Abst #166), 1996. Matthews, B., Amess, T.R., Andrew, D. and Son, H.: Non-pulpal component of laser-Doppler blood flow signal from human teeth. J Dent Res 73: 287, (Abst #1484), 1994. Hartmann, A., Azérad, J. and Boucher, Y.: Environmental effects on laser Doppler pulpal blood-flow measurements in man. Arch Oral Biol 41: 333–339, 1996. Roebuck, E.M., Evans, D.J.P., Stirrups, D. and Strang, R.: The effect of wavelength, bandwidth, and probe design and position on assessing the vitality of anterior teeth with laser Doppler flowmetry. Int J
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Paed Dent 10: 213–220, 2000. 15) Ikawa, M., Vongsavan, N. and Horiuchi, H.: Scattering of Laser light directed onto the labial surface of extracted human upper central incisor. J Endod 25: 483–485, 1999. 16) Ikawa, M., Fujiwara, M., Horiuchi, H. and Shimauchi, H.: The effect of short-term tooth intrusion on human pulpal blood flow measured by laser Doppler flowmetry. Arch Oral Biol 46: 781–787, 2001. 17) Ikawa, M., Komatsu, H., Ikawa, K., Mayanagi, H. and Shimauchi, H.: Age-related changes in the human pulpal blood flow measured by laser Doppler flowmetry. Dent Traumatol 19: 36–40, 2003. 18) Vongsavan, N. and Matthews, B.: Experiments on extracted teeth into the validity of using laser Doppler techniques for recording pulpal blood flow. Arch Oral Biol 38: 431–439, 1993. 19) Sasano, T., Nakajima, I., Shoji, N., Kuriwada, S., Sanjo, D., Ogino, H. and Miyahara, T.: Possible application of transmitted laser light for the assessment of human pulpal vitality. Endod Dent Traumatol 13: 88–91, 1997. 20) Ikawa, M., Horiuchi, H. and Ikawa, K.: Optical characteristics of human extracted teeth and the possible application of photoplethysmography to the human pulp. Arch Oral Biol 39: 821–827, 1994. 21) Miwa, Z., Ikawa, M., Iijima, H., Saito, M. and Takagi, Y.: Pulpal blood flow in vital and nonvital young permanent teeth measured by transmittedlight photoplethysmography: a pilot study. Pediatr Dent 24: 594–598, 2002.
PEDIATRIC DENTAL JOURNAL 14(1): 103–107, 2004
Detection of the pulpal blood flow in primary teeth by laser Doppler flowmeter Hideji Komatsu, Motohide Ikawa* and Hideaki Mayanagi Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, * Division of Periodontology and Endodontology, Department of Oral Biology, Tohoku University Graduate School of Dentistry 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, JAPAN
Abstract In this study, pulpal blood flow (PBF) of human primary teeth was measured using laser Doppler flowmeter (LDF) and efficacy of opaque rubber dam application was examined. Twenty-two healthy and 3 non-vital upper primary central incisors in 13 children (age: 3 years 11 months–7 years 3 months) were examined. Recordings were made with and without opaque rubber dam application. Electrocardiogram (ECG) of the subjects was simultaneously recorded. Results obtained were as follows: 1) With dam application, pulsatile signals synchronous with ECG were recorded from all the healthy teeth, whereas no pulsatile signals were recognized in non-vital teeth. 2) Without dam application, pulsatile signals synchronous with ECG were recorded from all the healthy teeth and non-vital teeth. 3) The amplitude of blood flow signal was significantly reduced by the opaque dam application. Results indicated that PBF measurement using LDF with dam application in human primary central incisors was applicable for pulp vitality assessment.
Introduction The determination of the tooth pulp vitality in adult humans is made by clinical examinations such as visual examination, radiographs, electric pulp tests and thermal tests1,2). Among these methods, electric and thermal tests rely on patients’ pain sensation, which is untrustworthy in primary teeth in children. Furthermore, the pain sensation produced by these test may disturb further dental treatment. Pulpal blood flow (PBF) measurement using laser Doppler flowmeter (LDF) has been applied to pulp vitality testing in traumatized permanent teeth3–8) and primary teeth9,10) because of the advantages of being objective and painless. It has been reported that LDF signals contain an artifact component derived from periodontal blood flow and did not accurately reflect PBF11–14). The laser light on Received on October 1, 2003 Accepted on January 20, 2004
Key words Diagnosis, Laser Doppler, Primary teeth, Pulp, Vitality
the tooth surface scatters widely outside the tooth15), partly reaching the periodontal tissue, and then returns to the detector, resulting in contamination from periodontal blood flow. One of the methods used to eliminate such signal contamination is an opaque black rubber dam11–13). Information regarding the signal contamination due to periodontal blood flow during PBF measurement using LDF in primary teeth is limited. Fratkin et al.9) reported that the blood flow values before and after pulpectomy of the primary incisors with obturation were significantly different. In their report, the fiber optic probe was placed on the lingual surface of the teeth at least 2 mm from the gingiva to avoid soft tissue interference. However, no numerical data were given with respect to the signal contamination. Funatsu et al.10) measured PBF with primary incisors and permanent incisors using a transmitted laser flowmeter with a slide caliper type probe. They reported that PBF in the primary teeth were larger than those in the 103
104
Komatsu, H., Ikawa, M. and Mayanagi, H.
permanent teeth. No details were given of the possible contamination of the signal artifact due to periodontal blood flow and its elimination. Therefore, the aims of this study were: 1) to examine the contamination of the signal artifact due to periodontal blood in PBF measurement using LDF in human primary teeth; and 2) the efficacy of opaque rubber dam application on eliminating such noise, if any.
Materials and methods 1. Subjects and examined teeth This study was approved by the Tohoku University School of Dentistry Research Ethical Committee. Twenty-two healthy maxillary primary central incisors in 13 children (3 years 11 months–7 years 3 months, mean: 5 years 6 months) and 3 non-vital teeth; 2 root canal filled (3 years 11 months–5 years 0 months) and the other confirmed as pulp necrosis by endodontic treatment (5 years 11 months), were examined. The experimental purpose and methodology were explained to the subjects and informed consent was obtained. The examined teeth were diagnosed as healthy if they were free of caries, restoration, defects, attrition, recession and discoloration. Teeth with a degree of mobility greater than 2 were excluded. Prior to the recording, an individual resin cap was prepared for each tooth from a plaster model of the upper tooth arch of each subject so as to cover the labial and the palatal surface of the tooth examined16,17). A hole, 2.0 mm in diameter and with its center approximately. 2 mm from the gingival margin, was drilled in the labial side of the cap at right angles to the mesio-distal center of the tooth surface, and a stainless steel tube (outer diameter 2.0 mm, inner diameter 1.6 mm, length 3 mm) for the insertion of an LDF probe was fixed into the hole. 2. Laser Doppler flowmetry A Moor blood flow monitor (type MBF3D, Moor Instruments, Axminster, U.K.; wavelength, 780– 820 nm) was used with a dental probe (ext. diam. 1.1 mm, fibre diam. 0.2 mm, centres 0.5 mm apart). The probe tip was inserted into a polythene tube (o.d. 1.5 mm, i.d. 1.0 mm) to obtain a satisfactory fit into the stainless steel tube. The laser Doppler flow meter was set up in the same way as described by Vongsavan and Matthews18), with a 0.1 second time constant and an upper band-pass limit of 14.9 kHz.
Fig. 1 A schematic drawing of pulpal blood flow (PBF) measurement in human maxillary primary central incisors using laser Doppler flowmeter (LDF)
The laser Doppler signal was also recorded from a stationary reflector with the same level of illumination as was present during recording from the tooth. This was used to determine the output equivalent to zero blood flow in the recording. The sensitivity of the blood flow monitor was adjusted using a standard suspension of polystyrene beads, and measurements were made in arbitrary perfusion units (P.U.). 3. Recording procedure and rubber dam application Each subject was placed in a supine position and the lips were retracted. An opaque black rubber dam (Four D Rubber Co. Ltd., Heanor, Derbyshire, U.K.; thickness 0.25 mm) was applied to the tooth being examined and to the adjacent teeth in order to examine its effects on eliminating signals derived from periodontal blood flow. The individual resin cap was fitted to the test tooth and was retained using a small amount of dental cement (Dycal, The L.D. Calk Division, Dentsply International Inc., Milford, U.S.A.) along the incisal edge, if necessary. The LDF probe tip was inserted tightly into the buccal hole of the cap until the tips touched the tooth surface (Fig. 1). LDF was recorded for about one minute with the dam in place. Simultaneously the subject’s electrocardiogram (ECG) was recorded. The dam was then removed using scissors without disturbing the optical fibre and recording was resumed. The mean blood flow signals with and without dam application were measured afterwards using a personal computer (Power Macintosh G3, Apple Computer Inc., Cupertino, CA) and a laboratory interface (Power Lab, ADInstruments Pty Ltd., Australia).
PULPAL BLOOD FLOW IN HUMAN PRIMARY TEETH
Fig. 2 An example of the recording from vital primary tooth (upper right maxillary primary central incisors, subject age; 5 years 6 months, female) Upper traces: PBF (left: with opaque rubber dam, right: without opaque rubber dam) Lower traces:ECG (left: with opaque rubber dam, right: without opaque rubber dam)
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Fig. 3 An example of the recording from non-vital primary tooth (upper right maxillary primary central incisors, subject age; 5 years 11 months, male) Upper traces: PBF (left: with opaque rubber dam, right: without opaque rubber dam) Lower traces:ECG (left: with opaque rubber dam, right: without opaque rubber dam)
Table 1 Summary of the blood flow signals Teeth type
n
Rubber dam
blood flow signals (P.U.)
vital teeth
22 22 3 3
with dam without dam with dam without dam
6.242Ⳳ5.375 22.364Ⳳ10.698 0.432 (0.162–0.502) 17.112 (12.14–25.968)
non-vital teeth
*
*: P⬍0.01 (Mann-Whitney U-test) In the vital teeth, blood flow signals are expressed as mean with standard division. In the non-vital teeth, blood flow signals are expressed as median with 25–75 percentiles. The dam reduced PBF signal amplitudes and this change was statistically significant (n⳱25, meanⳲSD, 73.1Ⳳ13.7%, P⬍0.01, Wilcoxon matched pairs test).
4. Statistics The effect of dam application was examined by the Wilcoxon matched pairs test. PBF signal amplitudes were compared between the vital teeth and the non-vital teeth using the Mann-Whitney U-test. A P-value less than 0.05 was taken as indicating statistical significance.
Results The pulse waves synchronous with ECG were
recognized in all the healthy teeth both with and without dam application. Fig. 2 shows a recording of PBF and ECG with and without dam application from a vital tooth (upper right maxillary primary central incisors, subject age, 5 years 6 months, female). Fig. 3 shows a recording of PBF and ECG with and without dam application from a non-vital tooth (upper right maxillary primary central incisors, subject age, 5 years 11 months, male). No pulse waves synchronous with ECG was observed with dam application, whereas pulse waves synchronous with ECG were observed without dam application.
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Komatsu, H., Ikawa, M. and Mayanagi, H.
This was also the case with a root canal filled tooth (data not shown). The dam reduced PBF signal amplitudes ranging between 59.3% and 86.8% (n⳱25, meanⳲSD, 73.1Ⳳ13.7%) and this change was statistically significant (P⬍0.01, Wilcoxon matched pairs test) (Table 1). With dam application a significant difference of mean flux signal between the vital teeth and the non-vital teeth was obtained (P⬍0.01, Mann-Whitney U-test). Without dam application the difference of the mean flux between the vitals and the non-vitals was not significant (P⬎0.05, Mann-Whitney U-test).
Discussion With dam application pulsatile signals synchronous with subject’s ECG were recognized in all the healthy teeth but none of the non-vital teeth. There was a significant difference in signal amplitudes between vital and non-vital teeth with the dam in place. These results indicate that PBF measurement using LDF with an opaque dam is applicable to distinguish vital from non-vital primary teeth in humans. Without dam application, however, the pulsatile signal was observed also from non-vital teeth. This is interpreted as a signal component of non-pulpal origin in the blood flow signals. The reduction of the signal amplitudes by means of opaque rubber dam application is comparable with previous reports; 65%16), 75%11), 80%12) in permanent central incisors. The large amount of signal component, which reflects periodontal blood flow, is derived from the light scattering widely outside the tooth15), partly reaching the periodontal tissue, and then returning to the detector. The present finding that pulsatile signals were observed from all of the non-vital teeth without the dam in place was in contrast to Fratkin et al.’s report9) in which they identified 100% of vital teeth and 100% of non-vital (pulp extirpation or extraction) teeth. This discrepancy in the results may be explained by the different optical characteristics of the teeth and periodontal tissues as follows: 1) In Fratkin et al.’s study9), the measurement probe was placed in contact with the lingual surface of the root canal filled non-vital teeth where the opaque cement was filled after the root canal fillings. This prevented the scattering of laser light to surrounding tissue; and 2) in the extracted teeth, blood coagulated in the root canal and pulp chamber and on the surface of the extracted teeth and tooth socket, which prevented
the scattering of laser light to the periodontal tissue. Funatsu et al.10) performed laser Doppler blood flow measurement using transmitted laser light and compared adult vital and non-vital upper central incisors. They observed pulsatile signals from vital teeth and no obvious blood flow signals from non-vital teeth. Transmitted laser light blood flow measurement is considered to have possible advantages due to less signal contamination compared with conventional LDF using reflection light. This may be in part due to the difference in the pathway of the light, i.e. collection of the transmitted light through the tooth contains less light that scatters outside of the tooth and then comes into the tooth than collection of the reflected light. Roebuck et al.14) suggested that the use of transmitted laser light19) may be of use when using LDF as a diagnostic tool. Application of transmitted light photoplethysmography to adult permanent20) and young permanent21) teeth has also been reported. Acknowledgments We are grateful to D. Mrozek for English proofing of this manuscript. This study was supported by Scientific Research Grant from Ministry of Education in Japan (No. 13771253) to Hideji Komatsu.
References 1) Cohen, S.: Diagnostic procedures. In: Pathways of the Pulp. 6th ed., (Cohen, S. and Burns, R.C. eds.) Copenhagen, Munksgaard, 1994, pp. 2–24. 2) Cooley, R.L., Stilley, J. and Lubow, R.M.: Evaluation of a digital pulp tester. Oral Surg Oral Med Oral Pathol 58: 437–442, 1984. 3) Gazelius, B., Olgart, L., Edwall, B. and Edwall, L.: Non-invasive recording of blood flow in human dental pulp. Endod Dent Traumatol 2: 219–221, 1986. 4) Gazelius, B., Olgart, L. and Edwall, B.: Restored vitality in luxated teeth assessed by laser Doppler flowmeter. Endod Dent Traumatol 4: 265–268, 1988. 5) Olgart, L., Gazelius, B. and Lindh-Strömberg, U.: Laser Doppler flowmetry in assessing vitality in luxated permanent teeth. Int Endod J 21: 300–306, 1988. 6) Shinoguchi, K., Shirakawa, T., Miura, M. and Oguchi, H.: Laser Doppler flowmetry for noninvasive measurement of pulpal blood flow in immatured permanent teeth. Jpn J Ped Dent 29: 688– 697, 1991. (in Japanese) 7) Andreasen, F.M. and Andreasen, J.O.: Examination and diagnosis of dental injuries. In: Textbook and
PULPAL BLOOD FLOW IN HUMAN PRIMARY TEETH
8)
9)
10)
11) 12)
13)
14)
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