Review Article

Thermal Pain in Teeth: Electrophysiology Governed by Thermomechanics

[+] Author and Article Information
Min Lin

The Key Laboratory of Biomedical Information
Engineering of Ministry of Education,
School of Life Science and Technology,
Xi'an Jiaotong University,
Xi'an 710049, China;
Bioinspired Engineering
and Biomechanics Center,
Xi'an Jiaotong University,
Xi'an 710049, China

Guy M. Genin

Department of Neurological Surgery,
and School of Engineering,
Washington University,
St. Louis, MO 63110;
Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63130

Feng Xu

The Key Laboratory of Biomedical Information
Engineering of Ministry of Education,
School of Life Science and Technology,
Xi'an Jiaotong University,
Xi'an 710049, China;
Bioinspired Engineering
and Biomechanics Center,
Xi'an Jiaotong University,
Xi'an 710049, China
e-mail: fengxu@mail.xjtu.edu.cn

TianJian Lu

Bioinspired Engineering
and Biomechanics Center,
Xi'an Jiaotong University,
Xi'an 710049, China
e-mail: tjlu@mail.xjtu.edu.cn

1Corresponding author.

Manuscript received July 26, 2013; final manuscript received February 1, 2014; published online April 18, 2014. Assoc. Editor: Francois Barthelat.

Appl. Mech. Rev 66(3), 030801 (Apr 18, 2014) (14 pages) Paper No: AMR-13-1054; doi: 10.1115/1.4026912 History: Received July 26, 2013; Revised February 01, 2014

Thermal pain arising from the teeth is unlike that arising from anywhere else in the body. The source of this peculiarity is a long-standing mystery that has begun to unravel with recent experimental measurements and, somewhat surprisingly, new thermomechanical models. Pain from excessive heating and cooling is typically sensed throughout the body through the action of specific, heat sensitive ion channels that reside on sensory neurons known as nociceptors. These ion channels are found on tooth nociceptors, but only in teeth does the pain of heating differ starkly from the pain of cooling, with cold stimuli producing more rapid and sharper pain. Here, we review the range of hypotheses and models for these phenomena, and focus on what is emerging as the most promising hypothesis: pain transduced by fluid flowing through the hierarchical structure of teeth. We summarize experimental evidence, and critically review the range of heat transfer, solid mechanics, fluid dynamics, and electrophysiological models that have been combined to support this hypothesis. While the results reviewed here are specific to teeth, this class of coupled thermomechanical and neurophysiological models has potential for informing design of a broad range of thermal therapies and understanding of a range of biophysical phenomena.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.


Brännström, M., 1986, “The Hydrodynamic Theory of Dentinal Pain: Sensation in Preparations, Caries, and the Dentinal Crack Syndrome,” J. Endod., 12(10), pp. 453–457. [CrossRef] [PubMed]
Lin, M., Liu, S. B., Niu, L., Xu, F., and Lu, T. J., 2011, “Analysis of Thermal-Induced Dentinal Fluid Flow and Its Implications in Dental Thermal Pain,” Arch. Oral. Biol., 56(9), pp. 846–854. [CrossRef] [PubMed]
Lin, M., Luo, Z. Y., Bai, B. F., Xu, F., and Lu, T. J., 2011, “Fluid Mechanics in Dentinal Microtubules Provides Mechanistic Insights Into the Difference Between Hot and Cold Dental Pain,” PLoS One, 6(3), p. e18068. [CrossRef] [PubMed]
Ahn, D. K., Doutova, E. A., Mcnaughton, K., Light, A. R., Närhi, M., and Maixner, W., 2012, “Functional Properties of Tooth Pulp Neurons Responding to Thermal Stimulation,” J. Dent. Res., 91(4), pp. 401–406. [CrossRef] [PubMed]
Brännström, M., and Johnson, G., 1970, “Movements of the Dentine and Pulp Liquids on Application of Thermal Stimuli. An in Vitro Study,” Acta Odontol. Scand., 28(1), pp. 59–70. [CrossRef] [PubMed]
Matthews, B., 1977, “Responses of Intradental Nerves to Electrical and Thermal Stimulation of Teeth in Dogs,” J. Physiol. (London), 264, pp. 641–664.
Matthews, B., 1968, “Cold-Sensitive and Heat-Sensitive Nerves in Teeth,” J. Dent. Res., 47, pp. 974–975.
Jyvasjarvi, E., and Kniffki, K. D., 1987, “Cold Stimulation of Teeth: A Comparison Between the Responses of Cat Intradental a Delta and C Fibres and Human Sensation,” J. Physiol. (London), 391, pp. 193–207.
Andrew, D., and Matthews, B., 2000, “Displacement of the Contents of Dentinal Tubules and Sensory Transduction in Intradental Nerves of the Cat,” J. Physiol. (London), 529(3), pp. 791–802. [CrossRef]
Sessle, B. J., 1987, “Invited Review: The Neurobiology of Facial and Dental Pain: Present Knowledge, Future Directions,” J. Dent. Res., 66(5), pp. 962–981. [CrossRef] [PubMed]
Brännström, M., and Aström, A., 1972, “The Hydrodynamics of the Dentine; Its Possible Relationship to Dentinal Pain,” Int. Dent. J., 22(2), pp. 219–227. [PubMed]
Brännström, M., and Johnson, G., 1978, “The Sensory Mechanism in Human Dentin as Revealed by Evaporation and Mechanical Removal of Dentin,” J. Dent. Res., 57(1), pp. 49–53. [CrossRef] [PubMed]
Brännström, M., Linden, L. A., and Astrom, A., 1967, “The Hydrodynamics of the Dental Tubule and of Pulp Fluid. A Discussion of Its Significance in Relation to Dentinal Sensitivity,” Caries Res., 1(4), pp. 310–317. [CrossRef] [PubMed]
Ratih, D. N., Palamara, J. E. A., and Messer, H. H., 2007, “Dentinal Fluid Flow and Cuspal Displacement in Response to Resin Composite Restorative Procedures,” Dent. Mater., 23(11), pp. 1405–1411. [CrossRef] [PubMed]
Kim, S. Y., Ferracane, J., Kim, H. Y., and Lee, I. B., 2010, “Real-Time Measurement of Dentinal Fluid Flow During Amalgam and Composite Restoration,” J. Dent., 38(4), pp. 343–351. [CrossRef] [PubMed]
Paphangkorakit, J., and Osborn, J. W., 2000, “The Effect of Normal Occlusal Forces on Fluid Movement Through Human Dentine in Vitro,” Arch. Oral. Biol., 45(12), pp. 1033–1041. [CrossRef] [PubMed]
Linsuwanont, P., Palamara, J. E. A., and Messer, H. H., 2007, “An Investigation of Thermal Stimulation in Intact Teeth,” Arch. Oral. Biol., 52(3), pp. 218–227. [CrossRef] [PubMed]
Vongsavan, N., and Matthews, B., 2007, “The Relationship Between the Discharge of Intradental Nerves and the Rate of Fluid Flow Through Dentine in the Cat,” Arch. Oral. Biol., 52(7), pp. 640–647. [CrossRef] [PubMed]
Su, K. C., Chuang, S. F., Ng, E. K., and Chang, C. H., 2013, “An Investigation of Dentinal Fluid Flow in Dental Pulp During Food Mastication: Simulation of Fluid–Structure Interaction,” Biomech. Model. Mechanobiol., 12(4), pp. 1–9. [CrossRef]
Linsuwanont, P., Versluis, A., Palamara, J. E., and Messer, H. H., 2008, “Thermal Stimulation Causes Tooth Deformation: A Possible Alternative to the Hydrodynamic Theory?,” Arch. Oral. Biol., 53(3), pp. 261–272. [CrossRef] [PubMed]
Julius, D., and Basbaum, A. I., 2001, “Molecular Mechanisms of Nociception,” Nature, 43(13), pp. 203–210. [CrossRef]
Närhi, M., Jyväsjärvi, E., Virtanen, A., Huopaniemi, T., Ngassapa, D., and Hirvonen, T., 1992, “Role of Intradental A- and C-Type Nerve Fibres in Dental Pain Mechanisms,” Proc. Finn. Dent. Soc., 88 (Suppl. 1), pp. 507–516. [PubMed]
Grayson, W., and Marshall, J., 1993, “Dentin: Microstructure and Characterization,” Ouint. lnt.24(9), pp. 606–617.
Byers, M. R., 1994, “Dynamic Plasticity of Dental Sensory Nerve Structure and Cytochemistry,” Arch. Oral. Biol., 39(Suppl. 1), pp. S13–S21. [CrossRef]
Byers, M. R., 1984, “Dental Sensory Receptors,” Int. Rev. Neurobiol., 25, pp. 39–94. [CrossRef] [PubMed]
Carda, C., and Peydro, A., 2006, “Ultrastructural Patterns of Human Dentinal Tubules, Odontoblasts Processes and Nerve Fibres,” Tissue & Cell, 38(2), pp. 141–150. [CrossRef]
Närhi, M. V. O., 1985, “The Characteristics of Intradental Sensory Units and Their Response to Stimulation,” J. Dent. Res., 64, pp. 564–571.
Mengel, M. K., Stiefenhofer, A. E., Jyväsjärvi, E., and Kniffki, K. D., 1993, “Pain Sensation During Cold Stimulation of the Teeth: Differential Reflection of A [δ] and C Fibre Activity?,” Pain, 55(2), pp. 159–169. [CrossRef]
Chidchuangchai, W., Vongsavan, N., and Matthews, B., 2007, “Sensory Transduction Mechanisms Responsible for Pain Caused by Cold Stimulation of Dentine in Man,” Arch. Oral. Biol., 52(2), pp. 154–160. [CrossRef]
Gillam, D. G., Mordan, N. J., and Newman, H. N., 1997, “The Dentin Disc Surface: A Plausible Model for Dentin Physiology and Dentin Sensitivity Evaluation,” Adv. Dent. Res., 11(4), pp. 487–501. [CrossRef]
Woolf, C. J., and Ma, Q., 2007, “Nociceptors—Noxious Stimulus Detectors,” Neuron, 55(3), pp. 353–364. [CrossRef]
Mummery, J. H., 1924, “The Nerve Supply of the Dentine,” Proc. R. Soc. Med., 17, pp. 35–47.
Trowbridge, H. O., Franks, M., Korostoff, E., and Emling, R., 1980, “Sensory Response to Thermal Stimulation in Human Teeth,” J. Endod., 6(1), pp. 405–412. [CrossRef]
Naylor, M. N., 1963, “Sensory Mechanisms in Dentine,” Studies on the Mechanism of Sensation to Cold Stimulation of Human Dentine, D. J.Anderson, ed., Pergamon Press, Oxford, p. 73.
Kollmann, W., and Matthews, B., 1982, “Anatomical, Physiological and Pharmacological Aspects of Trigeminal Pain,” Anatomical, Physiological and Pharmacological Aspects of Trigeminal Pain, B.Matthews and R. G.Hill, eds,., Excerpta Medica, Amsterdam, pp. 51–65.
Marquez, J. P., Elson, E. L., and Genin, G. M., 2010, “Whole Cell Mechanics of Contractile Fibroblasts: Relations Between Effective Cellular and Extracellular Matrix Moduli,” Philos. Trans. R. Soc. A, 368, pp. 635–654. [CrossRef]
Marquez, J. P., Genin, G. M., Zahalak, G. I., and Elson, E. L., 2005, “Thin Bio-Artificial Tissues in Plane Stress: The Relationship Between Cell and Tissue Strain, and an Improved Constitutive Model,” Biophys. J., 88(2), pp. 765–777. [CrossRef]
Marquez, J. P., Genin, G. M., Zahalak, G. I., and Elson, E. L., 2005, “The Relationship between Cell and Tissue Strain in Three-Dimensional Bio-Artificial Tissues,” Biophys. J., 88(2), pp. 778–789. [CrossRef]
Maurin, J. C., Couble, M. L., Didier-Bazes, M., Brisson, C., Magloire, H., and Bleicher, F., 2004, “Expression and Localization of Reelin in Human Odontoblasts,” Matrix Biol., 23(5), pp. 277–285. [CrossRef]
Allard, B., Magloire, H., Couble, M. L., Maurin, J. C., and Bleicher, F., 2006, “Voltage-Gated Sodium Channels Confer Excitability to Human Odontoblasts: Possible Role in Tooth Pain Transmission,” J. Biol. Chem., 281(39), pp. 29002–29010. [CrossRef]
Magloire, H., Allard, B., Couble, M. L., Maurin, J. C., and Bleicher, F., 2008, “Mechanosensitivity in Cells and Tissues,” Mechanosensitive Ion Channels in Odontoblasts, A. Kamkin and I. Kiseleva, eds., Springer, New York.
El Karim, I. A., Linden, G. J., Curtis, T. M., About, I., Mcgahon, M. K., Irwin, C. R., Killough, S. A., and Lundy, F. T., 2011, “Human Dental Pulp Fibroblasts Express the “Cold-Sensing” Transient Receptor Potential Channels Trpa1 and Trpm8,” J. Endod., 37(4), pp. 473–478. [CrossRef]
El Karim, I. A., Linden, G. J., Curtis, T. M., About, I., Mcgahon, M. K., Irwin, C. R., and Lundy, F. T., 2011, “Human Odontoblasts Express Functional Thermo-Sensitive TRP Channels: Implications for Dentin Sensitivity,” Pain, 152(10), pp. 2211–2223. [CrossRef]
Holland, G. R., 1985, “The Odontoblast Process: Form and Function,” J. Dent. Res., 64, pp. 499–514.
Hirvonen, T. J., and Narhi, M. V., 1986, “The Effect of Dentinal Stimulation on Pulp Nerve Function and Pulp Morphology in the Dog,” J. Dent. Res., 65(11), pp. 1290–1293. [CrossRef]
Magloire, H., Couble, M. L., Thivichon-Prince, B., Maurin, J. C., and Bleicher, F., 2009, “Odontoblast: A Mechano-Sensory Cell,” J. Exp. Zool., Part B, 312(5), pp. 416–424. [CrossRef]
Magloire, H., Lesage, F., Couble, M. L., Lazdunski, M., and Bleicher, F., 2003, “Expression and Localization of Trek-1 K+ Channels in Human Odontoblasts,” J. Dent. Res., 82(7), pp. 542–545. [CrossRef]
Allard, B., Couble, M. L., Magloire, H., and Bleicher, F., 2000, “Characterization and Gene Expression of High Conductance Calcium-Activated Potassium Channels Displaying Mechanosensitivity in Human Odontoblasts,” J. Biol. Chem., 275(33), pp. 25556–25561. [CrossRef]
Son, A. R., Yang, Y. M., Hong, J. H., Lee, S. I., Shibukawa, Y., and Shin, D. M., 2009, “Odontoblast Trp Channels and Thermo/Mechanical Transmission,” J. Dent. Res., 88(11), pp. 1014–1019. [CrossRef]
Charoenlarp, P., Wanachantararak, S., Vongsavan, N., and Matthews, B., 2007, “Pain and the Rate of Dentinal Fluid Flow Produced by Hydrostatic Pressure Stimulation of Exposed Dentine in Man,” Arch. Oral. Biol., 52(7), pp. 625–631. [CrossRef]
Wang, R., and Weiner, S., 1998, “Human Root Dentin: Structural Anisotropy and Vickers Microhardness Isotropy,” Connect Tissue Res., 39(4), pp. 269–279. [CrossRef]
Kinney, J. H., Marshall, S. J., and Marshall, G. W., 2003, “The Mechanical Properties of Human Dentin: A Critical Review and Re-Evaluation of the Dental Literature,” Crit. Rev. Oral Biol. Med., 14(1), pp. 13–29. [CrossRef]
Spears, I. R., Van Noort, R., Crompton, R. H., Cardew, G. E., and Howard, I. C., 1993, “The Effects of Enamel Anisotropy on the Distribution of Stress in a Tooth,” J. Dent. Res., 72(11), pp. 1526–1531. [CrossRef]
Lin, M., Liu, Q. D., Kim, T., Xu, F., Bai, B. F., and Lu, T. J., 2010, “A New Method for Characterization of Thermal Properties of Human Enamel and Dentine: Influence of Microstructure,” Infrared Phys. Technol., 53(6), pp. 457–463. [CrossRef]
De Vree, J. H., Spierings, T. A., and Plasschaert, A. J., 1983, “A Simulation Model for Transient Thermal Analysis of Restored Teeth,” J. Dent. Res., 62(6), pp. 756–759. [CrossRef] [PubMed]
Brown, W. S., Dewey, W. A., and Jacobs, H. R., 1970, “Thermal Properties of Teeth,” J. Dent. Res., 49(4), pp. 752–755. [CrossRef] [PubMed]
Xu, H. H., Smith, D. T., Jahanmir, S., Romberg, E., Kelly, J. R., Thompson, V. P., and Rekow, E. D., 1998, “Indentation Damage and Mechanical Properties of Human Enamel and Dentin,” J. Dent. Res., 77(3), pp. 472–480. [CrossRef] [PubMed]
Fenner, D. N., Robinson, P. B., and Cheung, P. M. Y., 1998, “Three-Dimensional Finite Element Analysis of Thermal Shock in a Premolar With a Composite Resin Mod Restoration,” Med. Eng. Phys., 20(4), pp. 269–275. [CrossRef] [PubMed]
Xu, H. C., Liu, W. Y., and Wang, T., 1989, “Measurement of Thermal Expansion Coefficient of Human Teeth,” Aust. Dent. J., 34(6), pp. 530–535. [CrossRef] [PubMed]
Jakubinek, M. B., O'Neill, C., Felix, C., Price, R. B., and White, M. A., 2008, “Temperature Excursions at the Pulp-Dentin Junction During the Curing of Light-Activated Dental Restorations,” Dent. Mater., 24(11), pp. 1468–1476. [CrossRef] [PubMed]
Xu, F., Wen, T., Seffen, K. A., and Lu, T. J., 2008, “Biothermomechanics of Skin Tissue,” J. Mech. Phys. Solids, 56(5), pp. 1852–1884. [CrossRef]
Lin, M., Luo, Z. Y., Bai, B. F., Xu, F., and Lu, T. J., 2011, “Fluid Dynamics Analysis of Shear Stress on Nerve Endings in Dentinal Microtubule: A Quantitative Interpretation of Hydrodynamic Theory for Tooth Pain,” J. Mech. Med. Biol., 11(1), pp. 205–219. [CrossRef]
Pashley, D. H., 1996, “Dynamics of the Pulpo-Dentin Complex,” Crit. Rev. Oral Biol. Med., 7(2), pp. 104–133. [CrossRef] [PubMed]
Berggren, G., and Brännström, M., 1965, “The Rate of Flow in Dentinal Tubules Due to Capillary Attraction,” J. Dent. Res., 44(2), pp. 408–415. [CrossRef] [PubMed]
Holland, G. R., Matthews, B., and Robinson, P. P., 1987, “An Electrophysiological and Morphological Study of the Innervation and Reinnervation of Cat Dentine,” J. Physiol., 386, pp. 31–43. [PubMed]
Pashley, D. H., Livingston, M. I., Reeder, O. W., and Horner, J. A., 1978, “Effects of the Degree of Tubule Occlusion on the Permeability of Human Dentine, in Vitro,” Arch. Oral. Biol., 23, pp. 1127–1133. [CrossRef] [PubMed]
McCleskey, E. W., and Gold, M. S., 1999, “Ion Channels of Nociception,” Annu. Rev. Physiol., 61, pp. 835–856. [CrossRef] [PubMed]
Hodgkin, A. L., and Huxley, A. F., 1952, “A Quantitative Description of Membrane Current and Its Application to Conduction and Excitation in Nerve,” J. Physiol., 117, pp. 500–544. [PubMed]
Francois, R., Liam, J. D., and John, N. W., 2010, “Kinetic Properties of Mechanically Activated Currents in Spinal Sensory Neurons,” J. Physiol., 588(2), pp. 301–314. [CrossRef] [PubMed]
Xu, F., Wen, T., Lu, T. J., and Seffen, K. A., 2008, “Modeling of Nociceptor Transduction in Skin Thermal Pain Sensation,” ASME J. Biomech. Eng., 130(4), p. 041013. [CrossRef]
Xu, F., Lu, T. J., and Seffen, K. A., 2008, “Skin Thermal Pain Modeling—A Holistic Method,” J. Therm. Biol., 33(4), pp. 223–237. [CrossRef]
Connor, J. A., Walkter, D., and McKown, R., 1977, “Neural Repetitive Firing Modifications of the Hodgkin–Huxley Axon Suggested by Experimental Results From Crustacean Axons,” Biophys. J., 18, pp. 81–102. [CrossRef] [PubMed]
Hodgkin, A. L., 1964, The Conduction of the Nervous Impulses, Liverpool University Press, Livepool.
Llyod, B. A., McGinley, M. B., and Brown, W. S., 1978, “Thermal Stress in Teeth,” J. Dent. Res., 57(4), pp. 571–582. [CrossRef] [PubMed]
Su, K. C., Chang, C. H., Chuang, S. F., and Ng, E. Y. K., 2013, “The Effect of Dentinal Fluid Flow During Loading in Various Directions—Simulation of Fluid–Structure Interaction,” Arch. Oral. Biol., 58(6), pp. 575–582. [CrossRef] [PubMed]
Brännström, M., and Astroem, A., 1964, “A Study on the Mechanism of Pain Elicited From the Dentin,” J. Dent. Res., 43, pp. 619–625. [CrossRef] [PubMed]
Chul-Kyu, P., Mi Sun, K., Zhi, F., Hai, Y. L., Sung, J. J., Se-Young, C., Sung, J. L., KyungpyoP., Kim, J. S., and Oh, S. B., 2006, “Functional Expression of Thermo-Transient Receptor Potential Channels in Dental Primary Afferent Neurons: Implication for Tooth Pain,” J. Biol. Chem., 281(25), pp. 17304–17311. [CrossRef] [PubMed]
Polak, S., Rustom, L., Genin, G., Talcott, M., and Wagoner Johnson, A., 2013, “A Mechanism for Effective Cell-Seeding in Rigid, Microporous Substrates,” Acta Biomater., 9(8), pp. 7977–7986. [CrossRef] [PubMed]
Liu, Y., Birman, V., Chen, C., Thomopoulos, S., and Genin, G. M., 2011, “Mechanisms of Bimaterial Attachment at the Interface of Tendon to Bone,” J. Eng. Mater. Technol., 133(1), pp. 76–85. [CrossRef]
Liu, Y., Thomopoulos, S., Birman, V., Li, J.-S., and Genin, G., 2012, “Bi-Material Attachment Through a Compliant Interfacial System at the Tendon-to-Bone Insertion Site,” Mech. Mater., 44, pp. 83–92. [CrossRef]
Thomopoulos, S., Birman, V., and Genin, G. M., 2013, Structural Interfaces and Attachments in Biology, Springer, New York.
Xiang, J., Natarajan, S. K., Tremmel, M., Ma, D., Mocco, J., Hopkins, L. N., Siddiqui, A. H., Levy, E. I., and Meng, H., 2011, “Hemodynamic–Morphologic Discriminants for Intracranial Aneurysm Rupture,” Stroke, 42(1), pp. 144–152. [CrossRef] [PubMed]
Meng, H., Metaxa, E., Gao, L., Liaw, N., Natarajan, S. K., Swartz, D. D., Siddiqui, A. H., Kolega, J., and Mocco, J., 2011, “Progressive Aneurysm Development Following Hemodynamic Insult,” J. Neurosurg., 114(4), pp. 1095–1103. [CrossRef] [PubMed]
Fritton, S. P., and Weinbaum, S., 2009, “Fluid and Solute Transport in Bone: Flow-Induced Mechanotransduction,” Annu. Rev. Fluid. Mech., 41, pp. 347–374. [CrossRef] [PubMed]
Wang, Y., Mcnamara, L. M., Schaffler, M. B., and Weinbaum, S., 2007, “A Model for the Role of Integrins in Flow Induced Mechanotransduction in Osteocytes,” Proc. Natl. Acad. Sci., U. S. A.,104(40), pp. 15941–15946. [CrossRef]
Cowin, S. C., and Weinbaum, S., 1998, “Strain Amplification in the Bone Mechanosensory System,” Am. J. Med. Sci., 316(3), pp. 184–188. [CrossRef] [PubMed]
Robert, R., Perrouin-Verbe, B., Albert, T., Bussel, B., and Hamel, O., 2009, “Chronic Neuropathic Pain in Spinal Cord Injured Patients: What is the Effectiveness of Surgical Treatments Excluding Central Neurostimulations?,” Annal. Phys. Rehabil. Med., 52(2), pp. 194–202. [CrossRef]
Chou, R., Qaseem, A., Snow, V., Casey, D., Cross, J. T. J., Shekelle, P., and Owens, D. K., 2007, “Diagnosis and Treatment of Low Back Pain: A Joint Clinical Practice Guideline from the American College of Physicians and the American Pain Society,” Ann. Intern. Med., 147(7), pp. 478–491. [CrossRef] [PubMed]
Ulett, G. A., Han, S., and Han, J.-S., 1998, “Electroacupuncture: Mechanisms and Clinical Application,” Biol. Psychiatry, 44(2), pp. 129–138. [CrossRef] [PubMed]


Grahic Jump Location
Fig. 1

Tooth structure and neuron innervation. (Reprinted Quintessence International with permission from Europe PubMed Center.) (a) Cut-away image of a human tooth illustrating several key composite layers; (b) SEM image of dentine showing solid dentine material and dentinal microtubules running perpendicularly from the pulpal wall toward dentine-enamel junction; (c) schematic of the innervation of a dentinal microtubule. The pulpal terminus of a dentinal microtubule usually contains the terminus of a nociceptor and a process extended by an odontoblast. The terminal fibril of the nociceptor ends with a terminal bead that is rich in ion channels that are sensitive to noxious stimuli including heat and shear stress.

Grahic Jump Location
Fig. 2

Experimentally recorded neural discharge patterns under hot or cold stimulations. (Reprinted from Archives of Oral Biology with permission from Elsevier.) (a) Neural discharge pattern (voltage trace, top) following heating from 37 °C to 55 °C for 12 s (temperature trace, middle) and a cooling back to 37 °C; (b) neural discharge pattern following cooling from 37 °C to 5 °C for 15 s and a re-warming to 37 °C.

Grahic Jump Location
Fig. 3

The three dominant hypotheses explaining differences between pain associated with heating and cooling. (a) The neural theory, in which differences arise from hot- and cold-sensitive ion channels on the terminal fibril of a nociceptor; (b) the odontoblastic transduction theory, in which signals transduced by odontoblasts are conveyed to the terminal fiber of a nociceptor; (c) the hydrodynamic theory, in which thermally induced dentinal fluid flow over the terminal bead of a nociceptor plays an important role in thermal pain transduction.

Grahic Jump Location
Fig. 4

Idealized models for the thermomechanics of tooth heating. (Reprinted from Archives of Oral Biology with permission from Elsevier.) (a) One-dimensional, three-layer tooth model; (b) one-dimensional, two-layer tooth model; (c) individual dentinal microtubule; (4) representative area sectioned from (c) illustrating deformation of the dentinal microtubule wall. DM: dentine matrix; TW: microtubule wall before deformation; TWC: microtubule wall following compressive thermal stress induced deformation; TWT: microtubule wall following tensile thermal stress induced deformation.

Grahic Jump Location
Fig. 5

Microscale model of tooth physiology. (Reprinted from PLoS ONE with permission from PLoS.) (a) A slightly outward displacement of an OP and its CB in response to “outward” flow from the dentinal microtubule into the pulpal space; (b) a slightly inward displacement of an odontoblastic process and its cell body in response to “inward” flow from the pulpal space into the dentinal microtubule; (c) an idealization used to estimate fluid shear stresses on the TB of a nociceptor TF associated with DFF. NF: nerve firing.

Grahic Jump Location
Fig. 6

Simulated temperature and thermal stress change as a function of time at the enamel surface, the DEJ and the pulpal wall following 5 °C cold saline ((a) and (b)) and 80 °C hot saline ((c) and (d)) stimulation on an enamel surface. (Reprinted from Archives of Oral Biology with permission from Elsevier.) Thermal stimulation for 5 s was followed by natural convection for35 s in a 25 °C room temperature. The heat transfer coefficient in the simulations was 10 W/(m2K). Initial condition: entire tooth at body temperature (37 °C). Boundary condition: bottom of pulp layer kept at body temperature (37 °C).

Grahic Jump Location
Fig. 7

Estimates of how dentinal fluid flow velocity changes following thermal stimulation. Experimentally measured time course of dentinal fluid flow velocity (a) and corresponding temperature variation (b), (reprinted from Archives of Oral Biology with permission from Elsevier); simulated dentinal fluid flow velocity as a function of time for thermal stimulation on exposed dentine surface (c) and enamel surface (d). Heating: 55 °C, 3 s duration; cooling: 5 °C, 3 s duration, rewarming: 37 °C, (reprinted from Ref. [2] with permission from Elsevier).

Grahic Jump Location
Fig. 8

Simulated dentinal fluid flow velocity as a function of time during thermal stimulation. (Reprinted from Archives of Oral Biology with permission from Elsevier.) Solid line: cooling at 5 °C, 15 s duration, followed by rewarming at 37 °C. Dashed line: heating at 55 °C, 12 s duration, followed by rewarming at 37 °C.

Grahic Jump Location
Fig. 9

Estimated shear stress on a terminal bead compared to experimentally measured neural discharge rates. (Reprinted from PLoS ONE with permission from PLoS.) Dentinal fluid flow induces shear stress over the terminal bead of a nociceptor. The maximum estimated shear stress experienced by the terminal bead (line with, filled symbols) correlates with neural discharge rate (line with, open symbols) over a range of dentinal fluid flow velocities (negative for inward flow from the dentinal microtubules into the pulp; positive for outward flow from the pulp into the dentinal microtubules).

Grahic Jump Location
Fig. 10

Variations in nociceptor membrane potential induced by an outward flow velocity (from the pulp into the dentinal microtubules) of 611.6 m/s. (Reprinted from PLoS ONE, Archives of Oral Biology, and The Journal of Physiology with permission from PLoS, Elsevier, and John Wiley and Sons respectively). (a) Simulated action potential; ((b) and (c)) experimental measurements by Vongsavan and Matthews [18] and Andrew and Matthews [9], respectively. N is the number of neural firing impulses in 5 s.

Grahic Jump Location
Fig. 11

Comparison of simulated and measured nociceptor frequency responses. (Reprinted from PLoS ONE and The Journal of Physiology with permission from PLoS and John Wiley and Sons respectively). The data of Andrew and Matthews [9] can be well predicted by a the series of models reviewed in this article that embody the hydrodynamic theory.




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In