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Ronan EA, Nagel M, Emrick JJ. The anatomy, neurophysiology, and cellular mechanisms of intradental sensation. FRONTIERS IN PAIN RESEARCH 2024; 5:1376564. [PMID: 38590718 PMCID: PMC11000636 DOI: 10.3389/fpain.2024.1376564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 03/11/2024] [Indexed: 04/10/2024] Open
Abstract
Somatosensory innervation of the oral cavity enables the detection of a range of environmental stimuli including minute and noxious mechanical forces. The trigeminal sensory neurons underlie sensation originating from the tooth. Prior work has provided important physiological and molecular characterization of dental pulp sensory innervation. Clinical dental experiences have informed our conception of the consequence of activating these neurons. However, the biological role of sensory innervation within the tooth is yet to be defined. Recent transcriptomic data, combined with mouse genetic tools, have the capacity to provide important cell-type resolution for the physiological and behavioral function of pulp-innervating sensory neurons. Importantly, these tools can be applied to determine the neuronal origin of acute dental pain that coincides with tooth damage as well as pain stemming from tissue inflammation (i.e., pulpitis) toward developing treatment strategies aimed at relieving these distinct forms of pain.
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Affiliation(s)
- Elizabeth A. Ronan
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI, United States
| | - Maximilian Nagel
- Sensory Cells and Circuits Section, National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Joshua J. Emrick
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI, United States
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Taghvaei N, Ghavami-Lahiji M, Evazalipour M, Tayefeh Davalloo R, Zamani E. Ion release, biocompatibility, and bioactivity of resin-modified calcium hydroxide cavity liners. BMC Oral Health 2023; 23:1034. [PMID: 38129851 PMCID: PMC10740215 DOI: 10.1186/s12903-023-03723-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023] Open
Abstract
BACKGROUND The placement of liners near the pulp area is essential for therapeutic effects and maintaining pulp health while stimulating the formation of tertiary dentin. This in vitro study aimed to evaluate the calcium release, pH, biocompatibility, solubility, and bioactivity of three resin-modified calcium hydroxide cavity liners. METHODS The disc specimens of each cavity liner were prepared using polyethylene molds of 7 mm in diameter and 2 mm in height (n = 10). Three light-cure liners evaluated include Ultra-Blend Plus (UB), Base-it (BI), and Master Dent (MD). The samples were then immersed in flasks containing 10 mL of distilled water. Calcium ion release, pH, and solubility were evaluated in two weeks of incubation. The cytotoxicity of extracts adjacent to the specimens was evaluated by MTT assay using NIH/3T3 cells after 1, 3, and 7 days of incubation. The ability to induce the nucleation of calcium phosphates (CaPs) after 28-day immersion in a simulated body fluid was investigated by SEM-EDX analysis. Statistical analysis was performed using ANOVA, Kruskal-Wallis, and repeated measures tests at the significant level of 0.05. RESULTS There was a significant difference in the release of calcium ions among the three liners investigated on days 1, 7, and 14 (p < 0.05). UB liners exhibited a significantly higher amount of calcium release than the other two liners, followed by BI, and MD. On day 1, there was no significant difference in the average pH among the three liners. However, after day 7, the MD liner showed a significant decrease in pH compared to the other two liners. BI liner demonstrated the highest level of biocompatibility, followed by the MD and UB liners. UB showed a high calcium release, solubility with no alkalizing activity, and the formation of more mature Ca-rich apatite deposits than the other two liners. CONCLUSION Based on the results of this study, the cavity liner material's performance is material dependent. It can impact ion release, biocompatibility, and bioactivity which are important factors to consider in clinical practice. Further studies are needed to investigate the long-term effects of different liner materials on oral tissues.
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Affiliation(s)
- Nastaran Taghvaei
- Dental Sciences Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran
| | - Mehrsima Ghavami-Lahiji
- Department of Restorative Dentistry, Dental Sciences Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
| | - Mehdi Evazalipour
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Guilan University of Medical Sciences, Rasht, Iran
| | - Reza Tayefeh Davalloo
- Department of Restorative Dentistry, Dental Sciences Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran
| | - Ehsan Zamani
- Department of Pharmacology and Toxicology, School of Pharmacy, Guilan University of Medical Sciences, Rasht, Iran
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Ohyama S, Ouchi T, Kimura M, Kurashima R, Yasumatsu K, Nishida D, Hitomi S, Ubaidus S, Kuroda H, Ito S, Takano M, Ono K, Mizoguchi T, Katakura A, Shibukawa Y. Piezo1-pannexin-1-P2X 3 axis in odontoblasts and neurons mediates sensory transduction in dentinal sensitivity. Front Physiol 2022; 13:891759. [PMID: 36589456 PMCID: PMC9795215 DOI: 10.3389/fphys.2022.891759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 11/22/2022] [Indexed: 12/15/2022] Open
Abstract
According to the "hydrodynamic theory," dentinal pain or sensitivity is caused by dentinal fluid movement following the application of various stimuli to the dentin surface. Recent convergent evidence in Vitro has shown that plasma membrane deformation, mimicking dentinal fluid movement, activates mechanosensitive transient receptor potential (TRP)/Piezo channels in odontoblasts, with the Ca2+ signal eliciting the release of ATP from pannexin-1 (PANX-1). The released ATP activates the P2X3 receptor, which generates and propagates action potentials in the intradental Aδ afferent neurons. Thus, odontoblasts act as sensory receptor cells, and odontoblast-neuron signal communication established by the TRP/Piezo channel-PANX-1-P2X3 receptor complex may describe the mechanism of the sensory transduction sequence for dentinal sensitivity. To determine whether odontoblast-neuron communication and odontoblasts acting as sensory receptors are essential for generating dentinal pain, we evaluated nociceptive scores by analyzing behaviors evoked by dentinal sensitivity in conscious Wistar rats and Cre-mediated transgenic mouse models. In the dentin-exposed group, treatment with a bonding agent on the dentin surface, as well as systemic administration of A-317491 (P2X3 receptor antagonist), mefloquine and 10PANX (non-selective and selective PANX-1 antagonists), GsMTx-4 (selective Piezo1 channel antagonist), and HC-030031 (selective TRPA1 channel antagonist), but not HC-070 (selective TRPC5 channel antagonist), significantly reduced nociceptive scores following cold water (0.1 ml) stimulation of the exposed dentin surface of the incisors compared to the scores of rats without local or systemic treatment. When we applied cold water stimulation to the exposed dentin surface of the lower first molar, nociceptive scores in the rats with systemic administration of A-317491, 10PANX, and GsMTx-4 were significantly reduced compared to those in the rats without systemic treatment. Dentin-exposed mice, with somatic odontoblast-specific depletion, also showed significant reduction in the nociceptive scores compared to those of Cre-mediated transgenic mice, which did not show any type of cell deletion, including odontoblasts. In the odontoblast-eliminated mice, P2X3 receptor-positive A-neurons were morphologically intact. These results indicate that neurotransmission between odontoblasts and neurons mediated by the Piezo1/TRPA1-pannexin-1-P2X3 receptor axis is necessary for the development of dentinal pain. In addition, odontoblasts are necessary for sensory transduction to generate dentinal sensitivity as mechanosensory receptor cells.
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Affiliation(s)
- Sadao Ohyama
- Department of Physiology, Tokyo Dental College, Tokyo, Japan,Oral Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, Japan
| | - Takehito Ouchi
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Ryuya Kurashima
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | | | - Daisuke Nishida
- Oral Health Science Center, Tokyo Dental College, Tokyo, Japan
| | - Suzuro Hitomi
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan,Division of Physiology, Kyushu Dental University, Fukuoka, Japan
| | - Sobhan Ubaidus
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Hidetaka Kuroda
- Department of Physiology, Tokyo Dental College, Tokyo, Japan,Department of Dental Anesthesiology, Kanagawa Dental University, Yokosuka, Japan
| | - Shinichirou Ito
- Department of Oral and Maxillofacial Surgery, Tokyo Dental College, Tokyo, Japan
| | - Masayuki Takano
- Department of Oral and Maxillofacial Surgery, Tokyo Dental College, Tokyo, Japan
| | - Kentaro Ono
- Division of Physiology, Kyushu Dental University, Fukuoka, Japan
| | | | - Akira Katakura
- Department of Oral Pathological Science and Surgery, Tokyo Dental College, Tokyo, Japan
| | - Yoshiyuki Shibukawa
- Department of Physiology, Tokyo Dental College, Tokyo, Japan,*Correspondence: Yoshiyuki Shibukawa,
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Wang Q, Luan J, Zhao Z, Kong W, Zhang C, Ding J. Dentin-desensitizing biomaterials. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.108060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Lewis CM, Griffith TN. The mechanisms of cold encoding. Curr Opin Neurobiol 2022; 75:102571. [DOI: 10.1016/j.conb.2022.102571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 03/31/2022] [Accepted: 05/06/2022] [Indexed: 11/15/2022]
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Grover V, Kumar A, Jain A, Chatterjee A, Grover HS, Pandit N, Satpathy A, Madhavan Pillai BR, Melath A, Dhruvakumar D, Thakur R, Joshi NV, Deshpande N, Dadlani H, Meenakshi AA, Ashok KP, Reddy KV, Bhasin MT, Salaria SK, Verma A, Gaikwad RP, Darekar H, Amirisetty R, Phadnaik M, Karemore V, Dhulipalla R, Mody D, Rao TS, Chakarpani S, Ranganath V. ISP Good Clinical Practice Recommendations for the management of Dentin Hypersensitivity. J Indian Soc Periodontol 2022; 26:307-333. [PMID: 35959314 PMCID: PMC9362809 DOI: 10.4103/jisp.jisp_233_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 05/11/2022] [Accepted: 05/11/2022] [Indexed: 11/24/2022] Open
Abstract
Dentin hypersensitivity (DH) is a rising concern in clinical dentistry that causes pain and discomfort and negatively affects the quality of life of patients. Indian Society of Periodontology conducted a nationwide survey, involving 3000 dentists in December 2020, which revealed significant knowledge gaps regarding DH, viz., under-diagnosis, incorrect differential diagnosis, and treatment strategies/recommendations for the management of DH patients in daily clinical practice. The current paper has been envisioned and conceptualized to update the practicing Indian dentists regarding the so-called enigma of dentistry “Dentin Hypersensitivity,” based on the best available contemporary evidence. An expert panel was constituted comprising 30 subject experts from across the country, which after extensive literature review and group discussions formulated these recommendations. The panel advocated routine screening of all dentate patients for exposed dentin areas and DH to avoid under-diagnosis of the condition and suggested an early preventive management. Consensus guidelines/recommendations for the use of desensitizing agents (DAs) at home, including the use of herbal agents, are also provided within the backdrop of the Indian context. The guidelines recommend that active management of DH shall be accomplished by a combination of at home and in-office therapies, starting with the simplest and cost-effective home use of desensitizing toothpastes. A diagnostic decision tree and a flowchart for application in daily practice are designed to manage the patients suffering from DH or presenting with exposed dentin areas in dentition. Various treatment methods to manage DH have been discussed in the paper, including the insights from previously published treatment guidelines. Further, a novel system of classification of DH patients based on specific case definitions has been developed for the first time. Explicit charts regarding the available treatment options and the chronology of institution of the agent, for the management in different case categories of DH, have been provided for quick reference. The management strategy takes into account a decision algorithm based on hierarchy of complexity of treatment options and intends to improve the quality of life of the patient by long-term maintenance with an innovatively defined triple C's or 3Cs approach.
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Affiliation(s)
- Vishakha Grover
- Department of Periodontology, Dr. H. S. J. Institute of Dental Sciences, Panjab University, Chandigarh, India
| | - Ashish Kumar
- Department of Periodontology, Dental College, Regional Institute of Medical Sciences, Imphal, Manipur, India
| | - Ashish Jain
- Department of Periodontology, Dental Institute, Regional Institute of Medical Sciences, Ranchi, Jharkhand, India
| | - Anirban Chatterjee
- Department of Periodontology, Renupriya Dental Health Care, Bengaluru, Karnataka, India
| | | | - Nymphea Pandit
- Department of Periodontology, D. A. V Dental College and Hospital, Yamunanagar, Haryana, India
| | - Anurag Satpathy
- Department of Periodontics and Oral Implantology, Institute of Dental Sciences, Siksha "O" Anusandhan (Deemed to be University), Bhubaneswar, Odisha, India
| | | | - Anil Melath
- Department of Periodontics, Mahe Institute of Dental Sciences and Hospital, Mahe, Puducherry, India
| | - Deepa Dhruvakumar
- Department of Periodontology, Teerthanker Mahaveer Dental College and Research Centre, Teerthanker Mahaveer University, Moradabad, Uttar Pradesh, India
| | - Roshani Thakur
- Department of Periodontics, Saraswati Dhanvantari Dental College and Hospital, Parbhani, India
| | - Nilesh V Joshi
- Department of Periodontology, Dental College and Hospital, Bharati Vidyapeeth (Deemed to be) University, Navi Mumbai, India
| | - Neeraj Deshpande
- Department of Periodontology, K. M. Shah Dental College, Sumandeep Vidyapeeth Deemed to be University, Vadodara, Gujarat, India
| | - Himanshu Dadlani
- Department of Periodontology, Kalka Dental College, Meerut, Uttar Pradesh, India
| | - A Archana Meenakshi
- Department of Periodontology, Ragas Dental College and Hospitals, Chennai, Tamil Nadu, India
| | - K P Ashok
- Department of Periodontics, GSL Dental College, Rajahmundry, India
| | - K Vinathi Reddy
- Department of Periodontics, Sri Sai College of Dental Surgery, Kaloji Narayana Rao University of Health Sciences, Vikarabad, Telangana, India
| | - Meenu Taneja Bhasin
- Department of Periodontics, Sudha Rustagi Dental College, Faridabad, Haryana, India
| | | | - Abhishek Verma
- Department of Periodontics, Sri Sai College of Dental Surgery, Kaloji Narayana Rao University of Health Sciences, Vikarabad, Telangana, India
| | | | | | - Ramesh Amirisetty
- Department of Periodontology, G. Pulla Reddy Dental College and Hospital, Dr. NTR University of Health Sciences, Kurnool, Andhra Pradesh, India
| | - Mangesh Phadnaik
- Department of Periodontology, Government Dental College and Hospital, Guntur, Andhra Pradesh, India
| | - Vaibhav Karemore
- Department of Periodontology, Government Dental College and Hospital, Guntur, Andhra Pradesh, India
| | - Ravindranath Dhulipalla
- Department of Periodontology, Sibar Institute of Dental Sciences, Dr. NTR University of Health Sciences, Guntur, Andhra Pradesh, India
| | - Dhawal Mody
- VSPM Dental College and Research Centre, Nagpur, Maharashtra, India
| | - Tushar Shri Rao
- Department of Periodontics and Implantology, VSPM Dental College and Research Centre, Nagpur, Maharashtra, India
| | - Swarna Chakarpani
- Department of Periodontics, Sibar Institute of Dental Sciences, Dr. NTR University of Health Sciences, Guntur, Andhra Pradesh, India
| | - V Ranganath
- Department of Periodontics, AECS Maaruti Dental College and Research Center, Bengaluru, Karnataka, India
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Time-course of the effect of potassium oxalate in the treatment of hypersensitive dentine in man. Arch Oral Biol 2021; 126:105109. [PMID: 33813358 DOI: 10.1016/j.archoralbio.2021.105109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 03/18/2021] [Accepted: 03/18/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Investigate the cause of hypersensitive dentine (HD) by recording the time course of changes in dentine sensitivity, sensory threshold to electrical stimulation (ET) and pulpal blood flow (PBF) following tubular occlusion using in vitro and clinical experiments. DESIGN Nineteen teeth with HD and 13 with normal dentine from 8 participants were evaluated, and the intensity of any pain produced by various stimuli was recorded at different times after oxalate treatment. The participants used a visual-analogue scale (VAS) to indicate the intensity of any pain. The ET and PBF were recorded at the same times. RESULTS Preliminary in vitro experiments showed that oxalate treatment had no effect on the method used to record PBF, and blocked the treated tubules immediately after application. Considering teeth with HD, a decrease in the median VAS evoked by all forms of stimulation was observed at all post-treatment times, except immediately after treatment (p < 0.05), while the treatment produced no significant effect in teeth with normal dentine. No significant changes in ET or PBF was observed in any of the groups. CONCLUSIONS The effect of oxalate in relieving the symptoms of HD is not only due to a reduction in the intensity of stimulation of sensory receptors sensitive to fluid flow in the dentinal tubules, but also to a reduce in the sensitivity of the receptors that respond to dentine stimulation. There was no evidence that acute pulpitis or central sensitization to pain, which would be associated with changes in PBF or ET, contributes to HD.
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Schuh CMAP, Benso B, Aguayo S. Potential Novel Strategies for the Treatment of Dental Pulp-Derived Pain: Pharmacological Approaches and Beyond. Front Pharmacol 2019; 10:1068. [PMID: 31620000 PMCID: PMC6759635 DOI: 10.3389/fphar.2019.01068] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 08/22/2019] [Indexed: 12/18/2022] Open
Abstract
The diagnosis and management of pain is an everyday occurrence in dentistry, and its effective control is essential to ensure the wellbeing of patients. Most tooth-associated pain originates from the dental pulp, a highly vascularized and innervated tissue, which is encased within mineralized dentin. It plays a crucial role in the sensing of stimuli from the local environment, such as infections (i.e. dental caries) and traumatic injury, leading to a local inflammatory response and subsequently to an increase in intra-pulp pressure, activating nerve endings. However, thermal, chemical, and mechanical stimuli also have the ability to generate dental pulp pain, which presents mechanisms highly specific to this tissue and which have to be considered in pain management. Traditionally, the management of dental pulp pain has mostly been pharmacological, using non-steroidal anti-inflammatory drugs (NSAIDs) and opioids, or restorative (i.e. removal of dental caries), or a combination of both. Both research areas continuously present novel and creative approaches. This includes the modulation of thermo-sensitive transient receptor potential cation channels (TRP) by newly designed drugs in pharmacological research, as well as the use of novel biomaterials, stem cells, exosomes and physical stimulation to obtain pulp regeneration in regenerative medicine. Therefore, the aim of this review is to present an up-to-date account of causes underlying dental pain, novel treatments involving the control of pain and inflammation and the induction of pulp regeneration, as well as insights in pain in dentistry from the physiological, pharmacological, regenerative and clinical perspectives.
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Affiliation(s)
- Christina M. A. P. Schuh
- Centro de Medicina Regenerativa, Facultad de Medicina Clínica Alemana-Universidad del Desarrollo, Santiago, Chile
| | - Bruna Benso
- School of Dentistry, Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
- Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Millennium Nucleus of Ion Channels Associated Diseases (MiNICAD), Valdivia, Chile
| | - Sebastian Aguayo
- School of Dentistry, Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
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Choi AN, Jang IS, Son SA, Jung KH, Park JK. Effect of erosive and abrasive stress on sealing ability of different desensitizers: In-vitro study. PLoS One 2019; 14:e0220823. [PMID: 31369650 PMCID: PMC6675100 DOI: 10.1371/journal.pone.0220823] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 07/23/2019] [Indexed: 11/30/2022] Open
Abstract
This in vitro study examined the sealing ability of different desensitizing agents under a chemo-mechanical stress condition. For the study, a total of 144 extracted, caries-free human third molars were used to produce 1 mm-thick dentin discs. The specimens were divided randomly into four groups: Superseal (SS), Gluma (GL), Gluma Self-etch (GS), and Tooth Coat (TC). For each group, the permeability was measured before and after applying the desensitizer, after being exposed to Coca Cola for 5 minutes, and after 3150 strokes of a brushing abrasion. The decrease in permeability after the erosive and abrasive stress was analyzed by ANOVA and Tukey post hoc test. As a result, the dentin permeability decreased significantly for all desensitizers immediately after application (p < 0.05). SS and GS showed a significant difference in permeability reduction observed immediately after application and after acid action with Coca Cola (p < 0.05). After brushing abrasion, the permeability reduction decreased significantly for all desensitizers tested in this study (p < 0.05). TC showed the largest decrease in dentinal permeability compared to that of the other desensitizers and the differences were significant after brushing abrasion (p < 0.05). All tested desensitizers were effective in reducing dentin permeability. The behavioral characteristics under erosive and abrasive stress varied according to the products used. TC exhibited excellent sealing ability among the other desensitizers.
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Affiliation(s)
- An-Na Choi
- Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea
| | - Il-Seok Jang
- Department of Microbiology, School of Natural Sciences, Pusan National University, Busan, Korea
| | - Sung-Ae Son
- Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea
| | - Kyoung-Hwa Jung
- Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea
| | - Jeong-Kil Park
- Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea
- * E-mail:
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Byers MR. Chewing causes rapid changes in immunoreactive nerve patterns in rat molar teeth: Implications for dental proprioception and pain. Arch Oral Biol 2019; 107:104511. [PMID: 31445382 DOI: 10.1016/j.archoralbio.2019.104511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/19/2019] [Accepted: 07/28/2019] [Indexed: 01/06/2023]
Abstract
OBJECTIVE This study tests the hypothesis that normal use of teeth (chewing) causes changes in immunoreactive-(IR) patterns for endings of large Aβ and CGRP axons in rat molar cusps. DESIGN First, a new paradigm to test chewing in adult male rats was developed. Then IR patterns for large dental axons were analysed for a calcium-binding protein, parvalbumin (PV), heavy neurofilament protein-200 (NFP), and vesicle-release molecule synaptophysin (SYN) that all typify large dental axons and proprioceptors for comparison with endings of CGRP-IR neuropeptide axons. The behavior groups were: (1) daytime sleeping/fasting (Group:SF); (2) brief feeding after 8-11 h of daytime sleeping/fasting (Group:SF-C); (3) normal nocturnal feeding (Group:N); (4) nocturnal fasting (Group:NF); (5) brief feeding/chewing after nocturnal fasting (Group:NF-C). RESULTS Nerve endings with NFP-, PV-, or SYN-IR were lost or altered in pulp and dentin in all chewing groups. Other endings with CGRP-IR were near those with PV-, NFP- and SYN-IR at the pulp-dentin border and in dentin, and they also lost immunoreactivity in all chewing groups. The special beaded regions along the crown pulp/dentin borders lost neural labeling in all chewing groups. Nerves of molar roots and periodontal ligament were not changed. CONCLUSIONS Rapid neural reactions to chewing show extensive, reversible, non-nociceptive depletions of crown innervation. Those changes were rapid enough to occur during normal feeding followed by recovery during rest. The new dental paradigm related to chewing and fasting allows dissection of intradental proprioceptive-like mechanisms during normal tooth functions for comparison with nociceptive and mechanosensitive reactions after injury or inflammation.
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Affiliation(s)
- Margaret R Byers
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, 98195-6540 USA.
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Michot B, Lee CS, Gibbs JL. TRPM8 and TRPA1 do not contribute to dental pulp sensitivity to cold. Sci Rep 2018; 8:13198. [PMID: 30181551 PMCID: PMC6123413 DOI: 10.1038/s41598-018-31487-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 08/15/2018] [Indexed: 01/17/2023] Open
Abstract
Sensory neurons innervating the dental pulp have unique morphological and functional characteristics compared to neurons innervating other tissues. Stimulation of dental pulp afferents whatever the modality or intensity of the stimulus, even light mechanical stimulation that would not activate nociceptors in other tissues, produces an intense pain. These specific sensory characteristics could involve receptors of the Transient Receptor Potential channels (TRP) family. In this study, we compared the expression of the cold sensitive receptors TRPM8 and TRPA1 in trigeminal ganglion neurons innervating the dental pulp, the skin of the cheek or the buccal mucosa and we evaluated the involvement of these receptors in dental pulp sensitivity to cold. We showed a similar expression of TRPM8, TRPA1 and CGRP in sensory neurons innervating the dental pulp, the skin or the mucosa. Moreover, we demonstrated that noxious cold stimulation of the tooth induced an overexpression of cFos in the trigeminal nucleus that was not prevented by the genetic deletion of TRPM8 or the administration of the TRPA1 antagonist HC030031. These data suggest that the unique sensory characteristics of the dental pulp are independent to TRPM8 and TRPA1 receptors expression and functionality.
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Affiliation(s)
- Benoit Michot
- Department of Endodontics, New York University College of Dentistry, New York, USA.
| | - Caroline S Lee
- Department of Endodontics, New York University College of Dentistry, New York, USA
| | - Jennifer L Gibbs
- Department of Endodontics, New York University College of Dentistry, New York, USA
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Thermal analysis of the dentine tubule under hot and cold stimuli using fluid-structure interaction simulation. Biomech Model Mechanobiol 2018; 17:1599-1610. [PMID: 29956062 DOI: 10.1007/s10237-018-1046-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 06/24/2018] [Indexed: 12/14/2022]
Abstract
The objective of this study is to compare the thermal stress changes in the tooth microstructures and the hydrodynamic changes of the dental fluid under hot and cold stimuli. The dimension of the microstructures of eleven cats' teeth was measured by scanning electron microscopy, and the changes in thermal stress during cold and hot stimulation were calculated by 3D fluid-structure interaction modeling. Evaluation of results, following data validation, indicated that the maximum velocities in cold and hot stimuli were - 410.2 ± 17.6 and + 205.1 ± 8.7 µm/s, respectively. The corresponding data for maximum thermal stress were - 20.27 ± 0.79 and + 10.13 ± 0.24 cmHg, respectively. The thermal stress caused by cold stimulus could influence almost 2.9 times faster than that caused by hot stimulus, and the durability of the thermal stress caused by hot stimulus was 71% greater than that by cold stimulus under similar conditions. The maximum stress was on the tip of the odontoblast, while the stress in lateral walls of the odontoblast and terminal fibril was very weak. There is hence a higher possibility of pain transmission with activation of stress-sensitive ion channels at the tip of the odontoblast. The maximum thermal stress resulted from the cold stimulus is double that produced by the hot stimulus. There is a higher possibility of pain transmission in the lateral walls of the odontoblast and terminal fibril by releasing mediators during the cold stimulation than the hot stimulation. These two reasons can be associated with a greater pain sensation due to intake of cold liquids.
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Sato M, Ogura K, Kimura M, Nishi K, Ando M, Tazaki M, Shibukawa Y. Activation of Mechanosensitive Transient Receptor Potential/Piezo Channels in Odontoblasts Generates Action Potentials in Cocultured Isolectin B 4-negative Medium-sized Trigeminal Ganglion Neurons. J Endod 2018; 44:984-991.e2. [PMID: 29709295 DOI: 10.1016/j.joen.2018.02.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 02/15/2018] [Accepted: 02/20/2018] [Indexed: 01/22/2023]
Abstract
INTRODUCTION Various stimuli to the dentin surface elicit dentinal pain by inducing dentinal fluid movement causing cellular deformation in odontoblasts. Although odontoblasts detect deformation by the activation of mechanosensitive ionic channels, it is still unclear whether odontoblasts are capable of establishing neurotransmission with myelinated A delta (Aδ) neurons. Additionally, it is still unclear whether these neurons evoke action potentials by neurotransmitters from odontoblasts to mediate sensory transduction in dentin. Thus, we investigated evoked inward currents and evoked action potentials form trigeminal ganglion (TG) neurons after odontoblast mechanical stimulation. METHODS We used patch clamp recordings to identify electrophysiological properties and record evoked responses in TG neurons. RESULTS We classified TG cells into small-sized and medium-sized neurons. In both types of neurons, we observed voltage-dependent inward currents. The currents from medium-sized neurons showed fast inactivation kinetics. When mechanical stimuli were applied to odontoblasts, evoked inward currents were recorded from medium-sized neurons. Antagonists for the ionotropic adenosine triphosphate receptor (P2X3), transient receptor potential channel subfamilies, and Piezo1 channel significantly inhibited these inward currents. Mechanical stimulation to odontoblasts also generated action potentials in the isolectin B4-negative medium-sized neurons. Action potentials in these isolectin B4-negative medium-sized neurons showed a short duration. Overall, electrophysiological properties of neurons indicate that the TG neurons with recorded evoked responses after odontoblast mechanical stimulation were myelinated Aδ neurons. CONCLUSIONS Odontoblasts established neurotransmission with myelinated Aδ neurons via P2X3 receptor activation. The results also indicated that mechanosensitive TRP/Piezo1 channels were functionally expressed in odontoblasts. The activation of P2X3 receptors induced an action potential in the Aδ neurons, underlying a sensory generation mechanism of dentinal pain.
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Affiliation(s)
- Masaki Sato
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Kazuhiro Ogura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Koichi Nishi
- Removable Prosthodontics and Gerodontology, Tokyo Dental College, Tokyo, Japan
| | - Masayuki Ando
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Masakazu Tazaki
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
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14
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Lin M, Liu SB, Genin GM, Zhu Y, Shi M, Ji C, Li A, Lu TJ, Xu F. Melting Away Pain: Decay of Thermal Nociceptor Transduction during Heat-Induced Irreversible Desensitization of Ion Channels. ACS Biomater Sci Eng 2017; 3:3029-3035. [DOI: 10.1021/acsbiomaterials.6b00789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
| | | | - Guy M. Genin
- Department
of Neurological Surgery, Washington University School of Medicine,
NSF Science and Technology Center for Engineering Mechanobiology,
and School of Engineering, Washington University, St. Louis, Missouri 63110, United States
| | | | | | - Changchun Ji
- Department
of Acupuncture, Shaanxi Hospital of Traditional Chinese Medicine, Xi’an 710003, PR China
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15
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Passos AD, Tziafas D, Mouza AA, Paras SV. Study of the transdentinal diffusion of bioactive molecules. Med Eng Phys 2016; 38:1408-1415. [PMID: 27727119 DOI: 10.1016/j.medengphy.2016.09.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 09/04/2016] [Accepted: 09/21/2016] [Indexed: 11/28/2022]
Abstract
In this work the mass transfer characteristics in a µ-tube that simulates a simplified dentinal tubule geometry are numerically investigated. The aim is to assess the key features that affect transdentinal diffusion of substances and consequently to define the necessary quantitative and qualitative issues related to a specific bioactive agent before its potential application in clinical practice. CFD simulations were performed in an S-shaped tapered micro-tube, while the code was validated using the non-intrusive optical measuring technique Laser Induced Fluorescence (LIF). As the phenomenon is one-dimensional, diffusion dominated and strongly dependent on the molecular size, the time needed for the concentration of released molecules to attain a required value can be controlled by their initial concentration. Thus, we propose a model, which is successfully verified by experimental data using a dentinal disc and which given the type of applied molecules and their critical pulpal concentration is able to estimate the initial concentration to be imposed.
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Affiliation(s)
- A D Passos
- Department of Chemical Engineering, Aristotle University of Thessaloniki, University Box 455, GR 54124 Thessaloniki, Greece
| | - D Tziafas
- Hamdan Bin Mohamed College of Dental Medicine, DHCC, Dubai, United Arab Emirates
| | - A A Mouza
- Department of Chemical Engineering, Aristotle University of Thessaloniki, University Box 455, GR 54124 Thessaloniki, Greece
| | - S V Paras
- Department of Chemical Engineering, Aristotle University of Thessaloniki, University Box 455, GR 54124 Thessaloniki, Greece.
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16
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17
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Nishiyama A, Sato M, Kimura M, Katakura A, Tazaki M, Shibukawa Y. Intercellular signal communication among odontoblasts and trigeminal ganglion neurons via glutamate. Cell Calcium 2016; 60:341-355. [PMID: 27452727 DOI: 10.1016/j.ceca.2016.07.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 07/08/2016] [Accepted: 07/12/2016] [Indexed: 01/01/2023]
Abstract
Various stimuli to the exposed surface of dentin induce changes in the hydrodynamic force inside the dentinal tubules resulting in dentinal pain. Recent evidences indicate that mechano-sensor channels, such as the transient receptor potential channels, in odontoblasts receive these hydrodynamic forces and trigger the release of ATP to the pulpal neurons, to generate dentinal pain. A recent study, however, has shown that odontoblasts also express glutamate receptors (GluRs). This implies that cells in the dental pulp tissue have the ability to release glutamate, which acts as a functional intercellular mediator to establish inter-odontoblast and odontoblast-trigeminal ganglion (TG) neuron signal communication. To investigate the intercellular signal communication, we applied mechanical stimulation to odontoblasts and measured the intracellular free Ca2+ concentration ([Ca2+]i). During mechanical stimulation in the presence of extracellular Ca2+, we observed a transient [Ca2+]i increase not only in single stimulated odontoblasts, but also in adjacent odontoblasts. We could not observe these responses in the absence of extracellular Ca2+. [Ca2+]i increases in the neighboring odontoblasts during mechanical stimulation of single odontoblasts were inhibited by antagonists of metabotropic glutamate receptors (mGluRs) as well as glutamate-permeable anion channels. In the odontoblast-TG neuron coculture, we observed an increase in [Ca2+]i in the stimulated odontoblasts and TG neurons, in response to direct mechanical stimulation of single odontoblasts. These [Ca2+]i increases in the neighboring TG neurons were inhibited by antagonists for mGluRs. The [Ca2+]i increases in the stimulated odontoblasts were also inhibited by mGluRs antagonists. We further confirmed that the odontoblasts express group I, II, and III mGluRs. However, we could not record any currents evoked from odontoblasts near the mechanically stimulated odontoblast, with or without extracellular Mg2+, indicating that N-methyl-d-aspartic acid receptor does not contribute to inter-odontoblast signal communication. The results suggest that a mechanically stimulated odontoblast is capable of releasing glutamate into the extracellular space via glutamate-permeable anion channels. The released glutamate activates mGluRs on the odontoblasts in an autocrine/paracrine manner, forming an inter-odontoblasts communication, which drives dentin formation via odontoblast-odontoblast signal communication. Glutamate and mGluRs also mediate neurotransmission between the odontoblasts and neurons in the dental pulp to modulate sensory signal transmission for dentinal sensitivity.
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Affiliation(s)
- A Nishiyama
- Department of Oral Pathobiological Science and Surgery, Tokyo Dental College, Tokyo 101-0061, Japan
| | - M Sato
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan
| | - M Kimura
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan
| | - A Katakura
- Department of Oral Pathobiological Science and Surgery, Tokyo Dental College, Tokyo 101-0061, Japan
| | - M Tazaki
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan
| | - Y Shibukawa
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan.
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18
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Sato M, Furuya T, Kimura M, Kojima Y, Tazaki M, Sato T, Shibukawa Y. Intercellular Odontoblast Communication via ATP Mediated by Pannexin-1 Channel and Phospholipase C-coupled Receptor Activation. Front Physiol 2015; 6:326. [PMID: 26617529 PMCID: PMC4639624 DOI: 10.3389/fphys.2015.00326] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/27/2015] [Indexed: 11/13/2022] Open
Abstract
Extracellular ATP released via pannexin-1 channels, in response to the activation of mechanosensitive-TRP channels during odontoblast mechanical stimulation, mediates intercellular communication among odontoblasts in dental pulp slice preparation dissected from rat incisor. Recently, odontoblast cell lines, such as mouse odontoblast lineage cells, have been widely used to investigate physiological/pathological cellular functions. To clarify whether the odontoblast cell lines also communicate with each other by diffusible chemical substance(s), we investigated the chemical intercellular communication among cells from mouse odontoblast cell lines following mechanical stimulation. A single cell was stimulated using a glass pipette filled with standard extracellular solution. We measured intracellular free Ca(2+) concentration ([Ca(2+)]i) by fura-2 in stimulated cells, as well as in cells located nearby. Direct mechanical stimulation to a single odontoblast increased [Ca(2+)]i, which showed sensitivity to capsazepine. In addition, we observed increases in [Ca(2+)]i not only in the mechanically stimulated odontoblast, but also in nearby odontoblasts. We could observe mechanical stimulation-induced increase in [Ca(2+)]i in a stimulated human embryo kidney (HEK) 293 cell, but not in nearby HEK293 cells. The increase in [Ca(2+)]i in nearby odontoblasts, but not in the stimulated odontoblast, was inhibited by adenosine triphosphate (ATP) release channel (pannexin-1) inhibitor in a concentration- and spatial-dependent manner. Moreover, in the presence of phospholipase C (PLC) inhibitor, the increase in [Ca(2+)]i in nearby odontoblasts, following mechanical stimulation of a single odontoblast, was abolished. We could record some inward currents evoked from odontoblasts near the stimulated odontoblast, but the currents were observed in only 4.8% of the recorded odontoblasts. The results of this study showed that ATP is released via pannexin-1, from a mechanically stimulated odontoblast, which transmits a signal to nearby odontoblasts by predominant activation of PLC-coupled nucleotide receptors.
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Affiliation(s)
- Masaki Sato
- Department of Physiology, Tokyo Dental College Tokyo, Japan
| | - Tadashi Furuya
- Department of Physiology, Tokyo Dental College Tokyo, Japan ; Department of Crown and Bridge Prosthodontics, Tokyo Dental College Tokyo, Japan
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College Tokyo, Japan
| | - Yuki Kojima
- Department of Physiology, Tokyo Dental College Tokyo, Japan
| | | | - Toru Sato
- Department of Crown and Bridge Prosthodontics, Tokyo Dental College Tokyo, Japan
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Wang K, He T, Luo YI, Bentsen B, Arendt-Nielsen L. Quantitative sensory testing of dentinal sensitivity in healthy humans. Acta Odontol Scand 2015; 74:259-64. [PMID: 26542888 DOI: 10.3109/00016357.2015.1110248] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The study was to provide information on quantitative sensory testing (QST) of normal teeth to establish a sensory profile and investigate the possible gender and regional differences. MATERIALS AND METHODS A modified QST protocol was applied on both left and right upper-jaw incisors and pre-molar sof 14 healthy men and 14 age-matched healthy women (18-25 years). Mechanical stimulus sensitivity (MSS), cold detection threshold (CDT), cold pain threshold (CPT), warm detection threshold (WDT), heat pain threshold (HPT), electrical detection threshold (EDT) and electrical pain threshold (EPT) were determined from the four teeth (labial side of incisor and buccal side of the first premolar). The QST parameters were analysed by ANOVA. RESULTS The applied mechanical or thermal stimuli did not evoke any pain sensation. A normal tooth did not seem to be able to distinguish between the warm or cold stimuli applied. No significant differences were found between genders (p > 0.099) or teeth (p > 0.053) regarding mechanical and thermal stimuli. The EDT and EPT were significantly higher in the pre-molar compared with incisor (p < 0.002) without gender differences (p > 0.573). CONCLUSION The established methods and results provided important information on diagnosis and treatment evaluation of dentinal hypersensitivity.
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Affiliation(s)
- Kelun Wang
- a Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
| | - Tao He
- b The Procter & Gamble Company , Global Oral Care Clinical , Mason , Ohio USA
| | - Y I Luo
- a Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
| | - Bo Bentsen
- a Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
| | - Lars Arendt-Nielsen
- a Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
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20
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A photochemical method for in vitro evaluation of fluid flow in human dentine. Arch Oral Biol 2015; 60:193-8. [DOI: 10.1016/j.archoralbio.2014.09.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/12/2014] [Accepted: 09/22/2014] [Indexed: 11/22/2022]
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21
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Nweeia MT, Eichmiller FC, Hauschka PV, Donahue GA, Orr JR, Ferguson SH, Watt CA, Mead JG, Potter CW, Dietz R, Giuseppetti AA, Black SR, Trachtenberg AJ, Kuo WP. Sensory ability in the narwhal tooth organ system. Anat Rec (Hoboken) 2014; 297:599-617. [PMID: 24639076 DOI: 10.1002/ar.22886] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/15/2014] [Indexed: 01/20/2023]
Abstract
The erupted tusk of the narwhal exhibits sensory ability. The hypothesized sensory pathway begins with ocean water entering through cementum channels to a network of patent dentinal tubules extending from the dentinocementum junction to the inner pulpal wall. Circumpulpal sensory structures then signal pulpal nerves terminating near the base of the tusk. The maxillary division of the fifth cranial nerve then transmits this sensory information to the brain. This sensory pathway was first described in published results of patent dentinal tubules, and evidence from dissection of tusk nerve connection via the maxillary division of the fifth cranial nerve to the brain. New evidence presented here indicates that the patent dentinal tubules communicate with open channels through a porous cementum from the ocean environment. The ability of pulpal tissue to react to external stimuli is supported by immunohistochemical detection of neuronal markers in the pulp and gene expression of pulpal sensory nerve tissue. Final confirmation of sensory ability is demonstrated by significant changes in heart rate when alternating solutions of high-salt and fresh water are exposed to the external tusk surface. Additional supporting information for function includes new observations of dentinal tubule networks evident in unerupted tusks, female erupted tusks, and vestigial teeth. New findings of sexual foraging divergence documented by stable isotope and fatty acid results add to the discussion of the functional significance of the narwhal tusk. The combined evidence suggests multiple tusk functions may have driven the tooth organ system's evolutionary development and persistence.
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Affiliation(s)
- Martin T Nweeia
- Department of Restorative Dentistry and Biomaterial Sciences, Harvard School of Dental Medicine, 188 Longwood Ave., Boston, MA, 02115; Department of Vertebrate Zoology, Smithsonian Institution, 1000 Jefferson Drive SW, Washington, DC, 20004; Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138
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Oskui IZ, Ashtiani MN, Hashemi A, Jafarzadeh H. Effect of thermal stresses on the mechanism of tooth pain. J Endod 2014; 40:1835-9. [PMID: 25172227 DOI: 10.1016/j.joen.2014.06.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 06/20/2014] [Accepted: 06/20/2014] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Daily hot and cold thermal loadings on teeth may result in structural deformation, mechanical stress, and pain signaling. The aim of this study was to compare the adverse effects of hot and cold beverages on an intact tooth and, then, to provide physical evidence to support the hydrodynamic theory of tooth pain sensation mechanism. METHODS Three-dimensional finite element analysis was performed on a premolar model subjected to hot and cold thermal loadings. Elapsed times for heat diffusion and stress detection at the pulp-dentin junction were calculated as measures of the pain sensation. RESULTS Extreme tensile stress within the enamel resulted in damage in cold loadings. Also, extreme values of stress at the pulpal wall occurred 21.6 seconds earlier than extreme temperatures in hot and cold loadings. CONCLUSIONS The intact tooth was remarkably vulnerable to cold loading. Earlier changes in mechanical stress rather than temperature at the pulp-dentin junction indicate that the dental pain caused by hot or cold beverages may be based on the hydrodynamic theory.
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Affiliation(s)
- Iman Z Oskui
- Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran
| | - Mohammed N Ashtiani
- Faculty of Biomedical Engineering, Hamedan University of Technology, Hamedan
| | - Ata Hashemi
- Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran.
| | - Hamid Jafarzadeh
- Dental Research Center, Department of Endodontics, Faculty of Dentistry Mashhad University of Medical Sciences, Mashhad, Iran
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Shibukawa Y, Sato M, Kimura M, Sobhan U, Shimada M, Nishiyama A, Kawaguchi A, Soya M, Kuroda H, Katakura A, Ichinohe T, Tazaki M. Odontoblasts as sensory receptors: transient receptor potential channels, pannexin-1, and ionotropic ATP receptors mediate intercellular odontoblast-neuron signal transduction. Pflugers Arch 2014; 467:843-63. [PMID: 24939701 DOI: 10.1007/s00424-014-1551-x] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 05/16/2014] [Accepted: 06/05/2014] [Indexed: 01/09/2023]
Abstract
Various stimuli induce pain when applied to the surface of exposed dentin. However, the mechanisms underlying dentinal pain remain unclear. We investigated intercellular signal transduction between odontoblasts and trigeminal ganglion (TG) neurons following direct mechanical stimulation of odontoblasts. Mechanical stimulation of single odontoblasts increased the intracellular free calcium concentration ([Ca(2+)]i) by activating the mechanosensitive-transient receptor potential (TRP) channels TRPV1, TRPV2, TRPV4, and TRPA1, but not TRPM8 channels. In cocultures of odontoblasts and TG neurons, increases in [Ca(2+)]i were observed not only in mechanically stimulated odontoblasts, but also in neighboring odontoblasts and TG neurons. These increases in [Ca(2+)]i were abolished in the absence of extracellular Ca(2+) and in the presence of mechanosensitive TRP channel antagonists. A pannexin-1 (ATP-permeable channel) inhibitor and ATP-degrading enzyme abolished the increases in [Ca(2+)]i in neighboring odontoblasts and TG neurons, but not in the stimulated odontoblasts. G-protein-coupled P2Y nucleotide receptor antagonists also inhibited the increases in [Ca(2+)]i. An ionotropic ATP (P2X3) receptor antagonist inhibited the increase in [Ca(2+)]i in neighboring TG neurons, but not in stimulated or neighboring odontoblasts. During mechanical stimulation of single odontoblasts, a connexin-43 blocker did not have any effects on the [Ca(2+)]i responses observed in any of the cells. These results indicate that ATP, released from mechanically stimulated odontoblasts via pannexin-1 in response to TRP channel activation, transmits a signal to P2X3 receptors on TG neurons. We suggest that odontoblasts are sensory receptor cells and that ATP released from odontoblasts functions as a neurotransmitter in the sensory transduction sequence for dentinal pain.
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Lin M, Genin GM, Xu F, Lu T. Thermal Pain in Teeth: Electrophysiology Governed by Thermomechanics. APPLIED MECHANICS REVIEWS 2014; 66:0308011-3080114. [PMID: 25516631 PMCID: PMC4240033 DOI: 10.1115/1.4026912] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 02/01/2014] [Indexed: 05/12/2023]
Abstract
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.
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Affiliation(s)
- 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
| | - Guy M Genin
- Department of Neurological Surgery, and School of Engineering, Washington University , St. Louis, MO 63110
| | - 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
| | - TianJian Lu
- Bioinspired Engineering and Biomechanics Center, Xi'an Jiaotong University , Xi'an 710049 , China e-mail:
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25
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Tsumura M, Sobhan U, Sato M, Shimada M, Nishiyama A, Kawaguchi A, Soya M, Kuroda H, Tazaki M, Shibukawa Y. Functional expression of TRPM8 and TRPA1 channels in rat odontoblasts. PLoS One 2013; 8:e82233. [PMID: 24358160 PMCID: PMC3864925 DOI: 10.1371/journal.pone.0082233] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/22/2013] [Indexed: 11/18/2022] Open
Abstract
Odontoblasts produce dentin during development, throughout life, and in response to pathological conditions by sensing stimulation of exposed dentin. The functional properties and localization patterns of transient receptor potential (TRP) melastatin subfamily member 8 (TRPM8) and ankyrin subfamily member 1 (TRPA1) channels in odontoblasts remain to be clarified. We investigated the localization and the pharmacological, biophysical, and mechano-sensitive properties of TRPM8 and TRPA1 channels in rat odontoblasts. Menthol and icilin increased the intracellular free Ca(2+) concentration ([Ca(2+)]i). Icilin-, WS3-, or WS12-induced [Ca(2+)]i increases were inhibited by capsazepine or 5-benzyloxytriptamine. The increase in [Ca(2+)]i elicited by allyl isothiocyanate (AITC) was inhibited by HC030031. WS12 and AITC exerted a desensitizing effect on [Ca(2+)]i increase. Low-temperature stimuli elicited [Ca(2+)]i increases that are sensitive to both 5-benzyloxytriptamine and HC030031. Hypotonic stimulation-induced membrane stretch increased [Ca(2+)]i; HC030031 but not 5-benzyloxytriptamine inhibited the effect. The results suggest that TRPM8 channels in rat odontoblasts play a role in detecting low-temperature stimulation of the dentin surface and that TRPA1 channels are involved in sensing membrane stretching and low-temperature stimulation. The results also indicate that odontoblasts act as mechanical and thermal receptor cells, detecting the stimulation of exposed dentin to drive multiple cellular functions, such as sensory transduction.
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Affiliation(s)
- Maki Tsumura
- Department of Physiology, Tokyo Dental College, Chiba, Japan
| | - Ubaidus Sobhan
- Department of Physiology, Tokyo Dental College, Chiba, Japan
- Clinical Research Center, National Center for Child Health and Development, Tokyo, Japan
| | - Masaki Sato
- Department of Physiology, Tokyo Dental College, Chiba, Japan
| | - Miyuki Shimada
- Department of Clinical Oral Health Science, Tokyo Dental College, Tokyo, Japan
| | - Akihiro Nishiyama
- Department of Oral Medicine, Oral and Maxillofacial Surgery, Tokyo Dental College, Chiba, Japan
| | - Aya Kawaguchi
- Department of Dental Anesthesiology, Tokyo Dental College, Chiba, Japan
| | - Manabu Soya
- Department of Dental Anesthesiology, Tokyo Dental College, Chiba, Japan
| | - Hidetaka Kuroda
- Department of Anesthesiology and Pain Relief Center, University of Tokyo Hospital, Tokyo, Japan
| | - Masakazu Tazaki
- Department of Physiology, Tokyo Dental College, Chiba, Japan
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Su KC, Chuang SF, Ng EYK, Chang CH. An investigation of dentinal fluid flow in dental pulp during food mastication: simulation of fluid-structure interaction. Biomech Model Mechanobiol 2013; 13:527-35. [PMID: 23913183 DOI: 10.1007/s10237-013-0514-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 07/10/2013] [Indexed: 11/28/2022]
Abstract
This study uses fluid-structure interaction (FSI) simulation to investigate the relationship between the dentinal fluid flow in the dental pulp of a tooth and the elastic modulus of masticated food particles and to investigate the effects of chewing rate on fluid flow in the dental pulp. Three-dimensional simulation models of a premolar tooth (enamel, dentine, pulp, periodontal ligament, cortical bone, and cancellous bone) and food particle were created. Food particles with elastic modulus of 2,000 and 10,000 MPa were used, respectively. The external displacement loading (5 μm) was gradually directed to the food particle surface for 1 and 0.1 s, respectively, to simulate the chewing of food particles. The displacement and stress on tooth structure and fluid flow in the dental pulp were selected as evaluation indices. The results show that masticating food with a high elastic modulus results in high stress and deformation in the tooth structure, causing faster dentinal fluid flow in the pulp in comparison with that obtained with soft food. In addition, fast chewing of hard food particles can induce faster fluid flow in the pulp, which may result in dental pain. FSI analysis is shown to be a useful tool for investigating dental biomechanics during food mastication. FSI simulation can be used to predict intrapulpal fluid flow in dental pulp; this information may provide the clinician with important concept in dental biomechanics during food mastication.
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Affiliation(s)
- Kuo-Chih Su
- Department of Biomedical Engineering College of Engineering, National Cheng Kung University, 1 University Road, Tainan City, 701, Taiwan
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Hypotonic-induced Stretching of Plasma Membrane Activates Transient Receptor Potential Vanilloid Channels and Sodium–Calcium Exchangers in Mouse Odontoblasts. J Endod 2013; 39:779-87. [DOI: 10.1016/j.joen.2013.01.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 01/29/2013] [Accepted: 01/30/2013] [Indexed: 11/22/2022]
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28
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Markowitz K. A new treatment alternative for sensitive teeth: A desensitizing oral rinse. J Dent 2013; 41 Suppl 1:S1-11. [DOI: 10.1016/j.jdent.2012.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 08/21/2012] [Accepted: 09/12/2012] [Indexed: 11/30/2022] Open
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Fujisawa M, Tokuda M, Morimoto-Yamashita Y, Tatsuyama S, Arany S, Sugiyama T, Kitamura C, Shibukawa Y, Torii M. Hyperosmotic Stress Induces Cell Death in an Odontoblast-lineage Cell Line. J Endod 2012; 38:931-5. [DOI: 10.1016/j.joen.2012.03.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 03/23/2012] [Accepted: 03/27/2012] [Indexed: 10/28/2022]
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ZHU YJ, XU F, SU JH, ZHOU H, LU TJ. MATHEMATICAL MODELING FOR THE PREDICTION AND IMPROVEMENT OF TOOTH THERMAL PAIN: A REVIEW. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519411004095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Tooth pain, especially tooth thermal pain, is one of the most important symptoms and signs in dental clinic and daily life. As a special sensation, pain has been studied extensively in both clinic and experimental research aimed at reducing or eliminating the possible negative effects of pain. Unfortunately, the full underlying mechanism of pain is still unclear, because the pain could be influenced by many factors, including physiological, psychological, physical, chemical, and biological factors and so on. Besides, most studies on pain mechanisms in the literature are based on skin pain sensation and only few are based on tooth pain. In this paper, we present a comprehensive review on both neurophysiology of tooth pain mechanism, and corresponding thermal, mechanical, and thermomechanical behaviors of teeth. We also describe a multiscale modeling approach for quantifying tooth thermal pain by integrating the mathematic methods of engineering into the neuroscience. The mathematical model of tooth thermal pain will enable better understanding of thermal pain mechanism and optimization of existing diagnosis and treatment in dental clinic.
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Affiliation(s)
- Y. J. ZHU
- Stomatological Hospital, College of Medicine, Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - F. XU
- Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
- School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - J. H. SU
- Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - H. ZHOU
- Stomatological Hospital, College of Medicine, Xi'an Jiaotong University, Xi'an 710004, P. R. China
| | - T. J. LU
- Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
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31
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LIN M, LUO ZY, BAI BF, XU F, LU TJ. FLUID DYNAMICS ANALYSIS OF SHEAR STRESS ON NERVE ENDINGS IN DENTINAL MICROTUBULE: A QUANTITATIVE INTERPRETATION OF HYDRODYNAMIC THEORY FOR DENTAL PAIN. J MECH MED BIOL 2011. [DOI: 10.1142/s0219519411003983] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Noxious thermal and/or mechanical stimuli applied to dentine can cause fluid flow in dentinal microtubules (DMTs). The fluid flow induces shear stress (SS) on intradental nerve endings and may excite pulpal mechanoreceptors to generate dental pain sensation. There exist numerous studies on dental thermal pain, but few are mathematical. For this, we developed a computational fluid dynamics (CFD) model of dentinal fluid flow (DFF) in innervated DMTs. Based on this model, we systematically investigated the effects of various parameters (e.g., biological structure, DFF velocity, and fluid properties) on the SS experienced by intradental nerve endings and thus provide a quantitative interpretation to the hydrodynamic theory. The dimensions of biological structures, odontoblastic process (OP) movement, dentinal fluid velocity, and viscosity were found to have significant influences on the SS while dentinal fluid density showed negligible influence under conditions studied. The results indicate that: (i) dental pain study of animal models may not be directly applied to human being and the results may even vary from one person to another and (ii) OP movement caused by DFF changes the dimension of the space for the fluid flow, affecting thus the SS on nerve endings. The present work enables better understanding of the mechanisms underlying dental pain sensation and quantification of dental pain intensity resulted from clinical procedures such as dentine sensitivity testing and dental restorative processes.
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Affiliation(s)
- M. LIN
- Biomedical Engineering and Biomechanics Center, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - Z. Y. LUO
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University Xi'an 710049, P. R. China
| | - B. F. BAI
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University Xi'an 710049, P. R. China
| | - F. XU
- Biomedical Engineering and Biomechanics Center, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, P. R. China
- HST-Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - T. J. LU
- Biomedical Engineering and Biomechanics Center, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, P. R. China
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Effects of dentin tubule occlusion by dentifrice containing a PVM/MA bioadhesive copolymer in a silica base. J Dent 2011; 39:293-301. [DOI: 10.1016/j.jdent.2010.10.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 10/26/2010] [Accepted: 10/26/2010] [Indexed: 11/19/2022] Open
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Fluid mechanics in dentinal microtubules provides mechanistic insights into the difference between hot and cold dental pain. PLoS One 2011; 6:e18068. [PMID: 21448459 PMCID: PMC3063177 DOI: 10.1371/journal.pone.0018068] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 02/19/2011] [Indexed: 11/19/2022] Open
Abstract
Dental thermal pain is a significant health problem in daily life and dentistry. There is a long-standing question regarding the phenomenon that cold stimulation evokes sharper and more shooting pain sensations than hot stimulation. This phenomenon, however, outlives the well-known hydrodynamic theory used to explain dental thermal pain mechanism. Here, we present a mathematical model based on the hypothesis that hot or cold stimulation-induced different directions of dentinal fluid flow and the corresponding odontoblast movements in dentinal microtubules contribute to different dental pain responses. We coupled a computational fluid dynamics model, describing the fluid mechanics in dentinal microtubules, with a modified Hodgkin-Huxley model, describing the discharge behavior of intradental neuron. The simulated results agreed well with existing experimental measurements. We thence demonstrated theoretically that intradental mechano-sensitive nociceptors are not “equally sensitive” to inward (into the pulp) and outward (away from the pulp) fluid flows, providing mechanistic insights into the difference between hot and cold dental pain. The model developed here could enable better diagnosis in endodontics which requires an understanding of pulpal histology, neurology and physiology, as well as their dynamic response to the thermal stimulation used in dental practices.
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Analysis of thermal-induced dentinal fluid flow and its implications in dental thermal pain. Arch Oral Biol 2011; 56:846-54. [PMID: 21411060 DOI: 10.1016/j.archoralbio.2011.02.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 01/27/2011] [Accepted: 02/11/2011] [Indexed: 11/21/2022]
Abstract
OBJECTIVES The initiation of the pain sensation experienced following the thermal stimulation of dentine has been correlated with fluid flow in the dentinal tubules. There may be other mechanisms. METHODS This study examines this possibility using a mathematical model to simulate the temperature and thermal stress distribution in a tooth undergoing thermal stimulation. The results obtained were then used to predict the fluid flow in a single dentinal tubule by considering the deformation of the dentinal tubules and dentinal fluid. RESULTS Deformation of the pulp chamber was observed before a noticeable temperature change was recorded at the dentine-enamel junction. Tubule deformation leads to changes in fluid flow more rapidly than fluid expansion or contraction. This finding agreed with previously reported experimental observations. An initially high rate of outward fluid flow under cooling was found to correspond to short latency neural responses whilst heating was associated with long latency neural responses. CONCLUSION Rapid fluid flow caused by thermal deformation of dentinal tubules may account for the short latency (<1s) activation of mechano-sensitive receptors after of cooling. Long latency (>10s) neural responses could be associated with the activation of thermo-sensitive receptors.
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Wanachantararak S, Vongsavan N, Matthews B. Electrophysiological observations on the effects of potassium ions on the response of intradental nerves to dentinal tubular flow in the cat. Arch Oral Biol 2011; 56:294-305. [DOI: 10.1016/j.archoralbio.2010.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 09/29/2010] [Accepted: 10/05/2010] [Indexed: 10/18/2022]
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Ajcharanukul O, Chidchuangchai W, Charoenlarp P, Vongsavan N, Matthews B. Sensory Transduction in Human Teeth with Inflamed Pulps. J Dent Res 2011; 90:678-82. [DOI: 10.1177/0022034510395022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- O. Ajcharanukul
- Department of Stomatology, Faculty of Dentistry, Srinakharinwirot University, Bangkok 10500, Thailand
| | | | - P. Charoenlarp
- Department of Physiology and Biochemistry, Faculty of Dentistry, Mahidol University, Yothi Street, Rajthavee, Bangkok 10400, Thailand
| | - N. Vongsavan
- Department of Physiology and Biochemistry, Faculty of Dentistry, Mahidol University, Yothi Street, Rajthavee, Bangkok 10400, Thailand
| | - B. Matthews
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
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Solé-Magdalena A, Revuelta EG, Menénez-Díaz I, Calavia MG, Cobo T, García-Suárez O, Pérez-Piñera P, De Carlos F, Cobo J, Vega JA. Human odontoblasts express transient receptor protein and acid-sensing ion channel mechanosensor proteins. Microsc Res Tech 2010; 74:457-63. [DOI: 10.1002/jemt.20931] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2010] [Accepted: 07/31/2010] [Indexed: 02/03/2023]
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Hernández SZ, Negro VB, Paulero RH, Toriggia PG, Saccomanno DM. Scanning electron microscopy of pulp cavity dentin in dogs. J Vet Dent 2010; 27:7-11. [PMID: 20469789 DOI: 10.1177/089875641002700101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Dentin morphology and tubule diameter and density of peripulpal dentin were evaluated in 36 teeth from 12 adult dogs, aged between 2.5 and 13-years. The right maxillary canine and third premolar and right mandibular first molar teeth were extracted from euthanized dogs. The teeth were prepared and photomicrographs (n=108) were taken of the radicular and coronal dentin. Dentinal tubule density (tubules/mm2) was determined and tubular diameter and luminal area were measured in 3240 randomly chosen tubules using measurement software. Results from group 1 dogs (< 7-years-old) were compared with group 2 dogs (> 7-years-old). The majority of dentinal tubules were round or oval in shape and had uniform distribution at the radicular coronal third, and coronal levels. Dentin surfaces showed morphological differences at different levels of the tooth. Group 1 dentinal tubule diameter (1.87 +/- 0.44 microm) and area (1.91 +/- 0.83 microm2) were significantly different compared with Group 2 dentinal tubule diameter (1.53 +/- 0.39 microm) and area (1.22 +/- 0.50 microm2). There was no significant difference in tubular density between groups 1 (74,692 +/- 25,991 tubules/mm2) and 2 (72,938 +/- 24,646 tubules/mm2). Site-specific differences were observed in the pulp cavity dentin in the same tooth. These results provide a reference for future research in dogs or where dogs are used as a model for investigations in human dentistry.
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Affiliation(s)
- Sabás Z Hernández
- Department of Surgery, Faculty of Veterinary Sciences, University of Buenos Aires, Argentina.
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39
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Markowitz K. Pretty painful: Why does tooth bleaching hurt? Med Hypotheses 2010; 74:835-40. [DOI: 10.1016/j.mehy.2009.11.044] [Citation(s) in RCA: 143] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 11/27/2009] [Indexed: 11/16/2022]
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40
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Yeon K, Chung G, Shin M, Jung S, Kim J, Oh S. Adult Rat Odontoblasts Lack Noxious Thermal Sensitivity. J Dent Res 2009; 88:328-32. [DOI: 10.1177/0022034509334100] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Dentin hypersensitivity is a common symptom treated in the dental clinic, yet the underlying cellular and molecular mechanisms are not clear. We hypothesized that odontoblasts detect noxious thermal stimuli by expressing temperature-sensing molecules, and investigated whether temperature-activated TRP channels (thermo-TRP channels), which are known to initiate temperature signaling, mediate temperature sensing in odontoblasts. mRNA expression of dentin sialophosphoprotein and collagenase type 1, odontoblast-specific proteins, was shown in acutely isolated adult rat odontoblasts by single-cell RT-PCR, while TRPV1, TRPV2, TRPM8, and TRPA1 were not detected. Application of noxious temperatures of 42°C and 12°C, as well as capsaicin, menthol, and icilin, agonists of thermo-TRP channels, failed to increase intracellular calcium concentration. Immunohistochemical study also revealed no expression of TRPV1. Thus, it is unlikely that odontoblasts serve as thermal sensors in teeth via thermo-TRP channels.
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Affiliation(s)
- K.Y. Yeon
- National Research Laboratory for Pain, Dental Research Institute and Department of Physiology, School of Dentistry, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749, Korea; and
- Department of Physiology, College of Medicine, Kangwon National Universtiy, Chunchon 200-710, Korea
| | - G. Chung
- National Research Laboratory for Pain, Dental Research Institute and Department of Physiology, School of Dentistry, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749, Korea; and
- Department of Physiology, College of Medicine, Kangwon National Universtiy, Chunchon 200-710, Korea
| | - M.S. Shin
- National Research Laboratory for Pain, Dental Research Institute and Department of Physiology, School of Dentistry, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749, Korea; and
- Department of Physiology, College of Medicine, Kangwon National Universtiy, Chunchon 200-710, Korea
| | - S.J. Jung
- National Research Laboratory for Pain, Dental Research Institute and Department of Physiology, School of Dentistry, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749, Korea; and
- Department of Physiology, College of Medicine, Kangwon National Universtiy, Chunchon 200-710, Korea
| | - J.S. Kim
- National Research Laboratory for Pain, Dental Research Institute and Department of Physiology, School of Dentistry, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749, Korea; and
- Department of Physiology, College of Medicine, Kangwon National Universtiy, Chunchon 200-710, Korea
| | - S.B. Oh
- National Research Laboratory for Pain, Dental Research Institute and Department of Physiology, School of Dentistry, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749, Korea; and
- Department of Physiology, College of Medicine, Kangwon National Universtiy, Chunchon 200-710, Korea
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Noparatkailas S, Wanachantararak S, Vongsavan N, Matthews B. The effect of applying potassium chloride solutions at atmospheric pressure on the sensitivity of dentine in man. Arch Oral Biol 2009; 54:50-4. [DOI: 10.1016/j.archoralbio.2008.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 07/29/2008] [Accepted: 08/07/2008] [Indexed: 11/17/2022]
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Hermanstyne TO, Markowitz K, Fan L, Gold MS. Mechanotransducers in rat pulpal afferents. J Dent Res 2008; 87:834-8. [PMID: 18719209 DOI: 10.1177/154405910808700910] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The hydrodynamic theory suggests that pain associated with stimulation of a sensitive tooth ultimately involves mechanotransduction as a consequence of fluid movement within exposed dentinal tubules. To determine whether putative mechanotransducers could underlie mechanotransduction in pulpal afferents, we used a single-cell PCR approach to screen retrogradely labeled pulpal afferents. The presence of mRNA encoding BNC-1, ASIC3, TRPV4, TRPA1, the alpha, beta, and gamma subunits of ENaC, and the two pore K+ channels (TREK1, TREK2) and TRAAK were screened in pulpal neurons from rats with and without pulpal inflammation. ASIC3, TRPA1, TREK1, and TREK2 were present in approximately 67%, 64%, 14%, and 10% of pulpal neurons, respectively. There was no detectable influence of inflammation on the proportion of neurons expressing these mechanotransducers. Given that the majority of pulpal afferents express ASIC3 and TRPA1, our results raise the possibility that these channels may be novel targets for the treatment of dentin sensitivity.
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Affiliation(s)
- T O Hermanstyne
- Program in Neuroscience, University of Maryland, Baltimore, MD 21201, USA
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MARKOWITZ K, PASHLEY DH. Discovering new treatments for sensitive teeth: the long path from biology to therapy. J Oral Rehabil 2008; 35:300-15. [DOI: 10.1111/j.1365-2842.2007.01798.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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44
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Linsuwanont P, Palamara JE, Messer HH. Thermal transfer in extracted incisors during thermal pulp sensitivity testing. Int Endod J 2008; 41:204-10. [DOI: 10.1111/j.1365-2591.2007.01341.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Linsuwanont P, Versluis A, Palamara JE, Messer HH. Thermal stimulation causes tooth deformation: a possible alternative to the hydrodynamic theory? Arch Oral Biol 2007; 53:261-72. [PMID: 18037388 DOI: 10.1016/j.archoralbio.2007.10.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 08/13/2007] [Accepted: 10/06/2007] [Indexed: 10/22/2022]
Abstract
OBJECTIVES To investigate the relationship between temperature distribution and tooth structure deformation during and after localised application of thermal stimuli used during pulp vitality testing. METHODS Strains and temperature changes within tooth structures were recorded when three different thermal stimuli, namely heated gutta percha (120-140 degrees C), carbon dioxide dry ice (-72 degrees C) and refrigerant spray (-50 degrees C), were applied to extracted bovine incisors. Each stimulus was applied for 5s on the labial enamel surface in a random order, with a 30-min interval between tests. Finite element analysis was performed on basic geometrical shapes to investigate structural deformation in relation to temperature change. RESULTS Application of thermal stimuli to the labial enamel surface resulted in rapid development of strain at the pulpal dentine surface before any temperature change was detected at the dentino-enamel junction. The strain pattern was biphasic; heat produced an initial contraction of the pulpal surface, followed by an expansion, and the reverse pattern was found with cold stimulation. Finite element analysis confirmed that the initially pronounced thermal gradient across the enamel and dentine caused rapid flexural deformation before temperature changes reached the dentino-enamel junction. When the temperature changes reached the pulpal dentine and thus reduced the thermal gradient, the direction of the strain was reversed. CONCLUSION These results indicate possible alternatives to the hydrodynamic theory for thermal stimuli applied to intact teeth. Mechanically induced dentine deformation may trigger nerve impulses directly, or may exert mechanically induced dentinal fluid flow that triggers nerve activity.
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Affiliation(s)
- Pairoj Linsuwanont
- School of Dental Science, University of Melbourne, Melbourne, Victoria, Australia
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46
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Vongsavan N, Matthews B. The relationship between the discharge of intradental nerves and the rate of fluid flow through dentine in the cat. Arch Oral Biol 2007; 52:640-7. [PMID: 17303068 DOI: 10.1016/j.archoralbio.2006.12.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 12/08/2006] [Accepted: 12/13/2006] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To investigate further the relationship between dentinal tubular flow and the discharge evoked in intradental nerves. DESIGN In anaesthetised cats, recordings were made of fluid flow through dentine during the application of hydrostatic pressure stimuli of 5 s duration in the range +500 to -500 mm Hg to exposed dentine and of the nerve impulses evoked by these stimuli. Single unit recordings were obtained from filaments dissected from the inferior alveolar nerve and multi-unit recordings, from the exposed dentine. RESULTS Of 20 single units tested, 10 (conduction velocities: 2.4-36.2 m s(-1)) responded to negative pressures and four of these, also to positive pressures. None responded to only positive pressures. The pressure thresholds of the units (single and multi-unit preparations) ranged from -100 to -500 and +100 to +500. In terms of flow (measured 1 s after the start of a stimulus) the thresholds ranged from 0.4 to 2.2 nl s(-1) mm(-2) exposed dentine with outward flow, and 0.4-2.1 nl s(-1) mm(-2) with inward flow. The outward flow per tubule at the threshold of the most sensitive units was estimated to be 21 fl s(-1) and the corresponding mean velocity of the contents of the dentinal tubules at their pulpal ends, 27 microm s(-1). Although the thresholds to outward and inward flow were similar, with outward flow the mean discharge rate increased with stimulus intensity; whereas with inward flow few impulses were evoked and the number was little affected by the stimulus intensity. CONCLUSION The transduction mechanism that generates impulses in hydrodynamic intradental afferents is much more responsive to outward than inward flow through the dentinal tubules, although the thresholds in both directions are similar.
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Affiliation(s)
- Noppakun Vongsavan
- Department of Physiology, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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47
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Charoenlarp P, Wanachantararak S, Vongsavan N, Matthews B. Pain and the rate of dentinal fluid flow produced by hydrostatic pressure stimulation of exposed dentine in man. Arch Oral Biol 2007; 52:625-31. [PMID: 17288989 DOI: 10.1016/j.archoralbio.2006.12.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 10/30/2006] [Accepted: 12/06/2006] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine the relationship between pain intensity and the rate of fluid flow through dentine in human subjects. DESIGN The experiments were carried out on 16 premolars in 13 human subjects (aged 15-25 years). Dentine was exposed at the tip of the buccal cusp, etched with acid and covered with saline. A series of 5 s hydrostatic pressure stimuli between 400 mmHg above and 400 mmHg below atmospheric were applied to the dentine, in steps of 50 mmHg. The subject indicated the intensity of any pain produced on a visual analogue scale (VAS). The fluid flow through dentine during application of the same stimuli was measured in vitro within 3 h after tooth extraction. RESULTS The median pain threshold with negative (subatmospheric) stimuli was -125 mmHg and, with positive pressure stimuli, 200 mmHg, which corresponded to dentinal fluid flow rates of 3.29 nL/(s mm(2)) exposed dentine and 5.75 nL/(s mm(2)), respectively. Both the median pressure and the mean rate of flow at threshold with negative pressures were significantly lower than with positive pressures. The curves relating VAS score to stimulus intensity were similar with both negative and positive pressures. CONCLUSION The sensory transduction mechanism for pain in human teeth is more sensitive to outward than inward flow through dentinal tubules. The difference in sensitivity was however much less than that of the hydrodynamic receptors in the cat, which respond very much more strongly to negative than positive pressure stimuli.
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Affiliation(s)
- Panta Charoenlarp
- Department of Hospital Dentistry, Mahidol University, Bangkok 10400, Thailand
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Chidchuangchai W, Vongsavan N, Matthews B. Sensory transduction mechanisms responsible for pain caused by cold stimulation of dentine in man. Arch Oral Biol 2006; 52:154-60. [PMID: 17109813 DOI: 10.1016/j.archoralbio.2006.09.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 09/04/2006] [Accepted: 09/11/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To determine the effects on the sensitivity of exposed dentine to cold that are produced when dentine is etched to remove the smear layer and when the tubules are blocked again with calcium oxalate. Separate in vitro observations were made on the effects of these procedures on fluid flow through the dentine. DESIGN The experiments were carried out on 24 premolars in 17 subjects. Dentine was exposed at the tip of the buccal cusp and cold stimuli were applied by placing the tip of an ice stick on the cavity floor for 5s under the following conditions: before etching the dentine, after etching, and after oxalate treatment. The subject indicated the intensity of any pain produced on a visual analogue scale (VAS). Fluid flow through the dentine was recorded under similar conditions in eight of the teeth in vitro. RESULTS The mean VAS score produced by the ice before etching was 21.3+/-19.5mm (S.D.). This increased significantly to 85.4+/-15.6mm after etching (P<0.01). After oxalate treatment, it decreased significantly to 8.5+/-13.3mm. The corresponding mean rates of fluid flow through dentine were 2.15+/-1.02, 1.55+/-0.84, and 2.29+/-1.28nL/smm(2) exposed dentine, respectively. The mean after etching was significantly less than the other two values (P<0.05). CONCLUSION If the pain was due to hydrodynamic receptors, their sensitivity to dentinal fluid flow changed when the tubules were opened or closed. Alternatively the pain was produced by receptors sensitive to some other change produced by the cold stimuli, such as specific cold receptors.
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Affiliation(s)
- Warungkana Chidchuangchai
- Department of Pharmacology, Faculty of Dentistry, Mahidol University, Yothi Street, Rajathavee, Bangkok 10400, Thailand
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Linsuwanont P, Palamara JEA, Messer HH. An investigation of thermal stimulation in intact teeth. Arch Oral Biol 2006; 52:218-27. [PMID: 17109811 DOI: 10.1016/j.archoralbio.2006.10.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 09/12/2006] [Accepted: 10/07/2006] [Indexed: 11/24/2022]
Abstract
OBJECTIVES To investigate the response of extracted intact teeth to thermal stimulation in terms of fluid movement, in relation to temperature change within tooth structure. METHODS Dentinal fluid movement was measured in response to thermal stimuli applied to enamel. Freshly extracted teeth with intact crowns were investigated for the effects of thermal stimulation; namely, hot water (80 degrees C), iced water (2 degrees C) and carbon dioxide dry ice (-72 degrees C) for 5s application. Two capillary-based methods were used to measure fluid flow. To measure temperature changes at the dentino-enamel junction (DEJ) and pulpal wall in response to the same stimuli, fine J type thermocouples were used. RESULTS Thermal stimuli caused fluid movement, which occurred before the temperature changed at the pulp wall. Sealing the dentinal tubules resulted in a delayed response time. In general, fluid movement occurred coincident with the temperature change detected at the DEJ. However, many teeth showed a "bidirectional" response to thermal stimulation. The initial fluid movement in the bidirectional response was detected before the earliest temperature change observed at the DEJ, and was in the opposite direction to the main fluid movement. CONCLUSION Our results imply that thermal contraction and expansion of dentinal fluid may not be the complete explanation for dentinal fluid movement in intact teeth. Enamel may serve not only as a temperature transfer medium but may also expand or contract when subjected to thermal stimulation.
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Affiliation(s)
- P Linsuwanont
- School of Dental Science, The University of Melbourne, Melbourne, Victoria, Australia
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Park CK, Kim MS, Fang Z, Li HY, Jung SJ, Choi SY, Lee SJ, Park K, Kim JS, Oh SB. Functional expression of thermo-transient receptor potential channels in dental primary afferent neurons: implication for tooth pain. J Biol Chem 2006; 281:17304-17311. [PMID: 16595689 DOI: 10.1074/jbc.m511072200] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Temperature signaling can be initiated by members of transient receptor potential family (thermo-TRP) channels. Hot and cold substances applied to teeth usually elicit pain sensation. This study investigated the expression of thermo-TRP channels in dental primary afferent neurons of the rat identified by retrograde labeling with a fluorescent dye in maxillary molars. Single cell reverse transcription-PCR and immunohistochemistry revealed expression of TRPV1, TRPM8, and TRPA1 in subsets of such neurons. Capsaicin (a TRPV1 agonist), menthol (a TRPM8 agonist), and icilin (a TRPM8 and TRPA1 agonist) increased intracellular calcium and evoked cationic currents in subsets of neurons, as did the appropriate temperature changes (>43 degrees , <25 degrees , and <17 degrees C, respectively). Some neurons expressed more than one TRP channel and responded to two or three corresponding stimuli (ligands or thermal stimuli). Immunohistochemistry and single cell reverse transcription-PCR following whole cell recordings provided direct evidence for the association between the responsiveness to thermo-TRP ligands and expression of thermo-TRP channels. The results suggest that activation of thermo-TRP channels expressed by dental afferent neurons contributes to tooth pain evoked by temperature stimuli. Accordingly, blockade of thermo-TRP channels will provide a novel therapeutic intervention for the treatment of tooth pain.
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Affiliation(s)
- Chul-Kyu Park
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749
| | - Mi Sun Kim
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749
| | - Zhi Fang
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749
| | - Hai Ying Li
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749
| | - Sung Jun Jung
- Department of Physiology, College of Medicine, Kangwon National University, Chunchon 200-710, Korea
| | - Se-Young Choi
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749
| | - Sung Joong Lee
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749
| | - Kyungpyo Park
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749
| | - Joong Soo Kim
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749
| | - Seog Bae Oh
- Department of Physiology and Molecular and Cellular Neuroscience Program, College of Dentistry and Dental Research Institute, Seoul National University, 28-2 Yeongeon-Dong Chongno-Ku, Seoul 110-749.
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