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Wan B, Man Z, Li KC, Swain MV, Li Q. On elastoplastic behavior of porous enamel-An indentation and numerical study. Acta Biomater 2024; 183:210-220. [PMID: 38801871 DOI: 10.1016/j.actbio.2024.05.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 05/16/2024] [Accepted: 05/22/2024] [Indexed: 05/29/2024]
Abstract
The micro/nano pores in natural mineralized tissues can, to a certain extent, affect their responses to mechanical loading but are generally ignored in existing indentation analysis. In this study, we first examined the void volume fraction of sound and caries lesion enamels through micro-computed tomography (micro-CT). A Berkovich indentation study was then carried out to characterize the effect of porous microstructure on the mechanical behavior of the human enamels. The indentation tests were also modeled using the nonlinear finite element analysis technique to simulate indentation load-displacement curves, which showed reasonable agreement with the experimental measurements. From the simulation results, the extent of densification in the plastic zone was identified and the corresponding stress and contact pressure evolutions were quantified. Further, a conventional elastic-perfectly plastic material model without considering micropores was also developed to investigate the compaction effect of the porous structure. The simulation results reveal that conventional elastic perfect-plastic constitutive models become less reliable to model the mechanical behavior of carious lesion enamel with increasing loss of mineral content as it underestimates the yield stress and plastic energy dissipation. This study divulges the importance of compaction of porous enamel structure beneath the indented area. Note that understanding the effect of porous microstructures on plastic behavior is vital as the involved inelastic deformation mechanism associated with irreversible processes, such as wear and localized microcracking, has a significant bearing on wear and fatigue behavior of enamel. STATEMENT OF SIGNIFICANCE: Based on micro-CT and nano-indentation characterization, a numerical model was developed aiming to precisely describe the deformation behavior of naturally porous enamel. Inelastic properties and energy dissipation characteristics of porous enamel were investigated in detail. This work demonstrated that the existence of micro-pores in White Spot Lesions (WSLs) contributes to mechanical stability, which can mitigate the reduction in Young's modulus and fracture toughness resulting from loss of mineral components. The knowledge gained from this study can be used to explain the mechanisms related to irreversible processes, such as contact induced cracking and wear, and strengthen understanding of the mechanical behavior of porous mineralized tissues.
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Affiliation(s)
- Boyang Wan
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
| | - Ziyan Man
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
| | - Kai Chun Li
- Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand
| | - Michael V Swain
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
| | - Qing Li
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia.
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2
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Kruzic JJ, Hoffman M, Arsecularatne JA. Fatigue and wear of human tooth enamel: A review. J Mech Behav Biomed Mater 2023; 138:105574. [PMID: 36473402 DOI: 10.1016/j.jmbbm.2022.105574] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/14/2022] [Accepted: 11/15/2022] [Indexed: 11/21/2022]
Abstract
Human tooth enamel must withstand the cyclic contact forces, wear, and corrosion processes involved with typical oral functions. Furthermore, unlike other human tissues, dental enamel does not have a significant capacity for healing or self-repair and thus the longevity of natural teeth in the oral environment depends to a large degree on the fatigue and wear properties of enamel. The purpose of this review is to provide an overview of our understanding of the fatigue and wear mechanisms of human enamel and how they relate to in vivo observations of tooth damage in the complex oral environment. A key finding of this review is that fatigue and wear processes are closely related. For example, the presence of abrasive wear particles significantly lowers the forces needed to initiate contact fatigue cracking while subsurface fatigue crack propagation drives key delamination wear mechanisms during attrition or attrition-corrosion of enamel. Furthermore, this review seeks to bring a materials science and mechanical engineering perspective to fatigue and wear phenomena. In this regard, we see developing a mechanistic description of fatigue and wear, and understanding the interconnectivity of the processes, as essential for successfully modelling enamel fatigue and wear damage and developing strategies and treatments to improve the longevity of our natural teeth. Furthermore, we anticipate that this review will stimulate ideas for extending the lifetime of the natural tooth structure and will help highlight where our understanding is too limited and where additional research into fatigue and wear of human tooth enamel is warranted.
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Affiliation(s)
- Jamie J Kruzic
- School of Mechanical and Manufacturing Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia.
| | - Mark Hoffman
- School of Engineering, University of Newcastle, Callaghan NSW 2308, Australia; School of Materials Science and Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia
| | - Joseph A Arsecularatne
- School of Mechanical and Manufacturing Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia
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3
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Wang D, Han S, Yang M. Tooth Diversity Underpins Future Biomimetic Replications. Biomimetics (Basel) 2023; 8:biomimetics8010042. [PMID: 36810373 PMCID: PMC9944091 DOI: 10.3390/biomimetics8010042] [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: 12/26/2022] [Revised: 01/14/2023] [Accepted: 01/15/2023] [Indexed: 01/20/2023] Open
Abstract
Although the evolution of tooth structure seems highly conserved, remarkable diversity exists among species due to different living environments and survival requirements. Along with the conservation, this diversity of evolution allows for the optimized structures and functions of teeth under various service conditions, providing valuable resources for the rational design of biomimetic materials. In this review, we survey the current knowledge about teeth from representative mammals and aquatic animals, including human teeth, herbivore and carnivore teeth, shark teeth, calcite teeth in sea urchins, magnetite teeth in chitons, and transparent teeth in dragonfish, to name a few. The highlight of tooth diversity in terms of compositions, structures, properties, and functions may stimulate further efforts in the synthesis of tooth-inspired materials with enhanced mechanical performance and broader property sets. The state-of-the-art syntheses of enamel mimetics and their properties are briefly covered. We envision that future development in this field will need to take the advantage of both conservation and diversity of teeth. Our own view on the opportunities and key challenges in this pathway is presented with a focus on the hierarchical and gradient structures, multifunctional design, and precise and scalable synthesis.
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Peng J, Xiao H, Lei L, Yang D, Zheng J, Zhou Z. Heterogeneous hardening of enamel surface by occlusal loading: Effect of nanofiber orientation. J Mech Behav Biomed Mater 2022; 130:105221. [DOI: 10.1016/j.jmbbm.2022.105221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 03/27/2022] [Accepted: 04/02/2022] [Indexed: 11/30/2022]
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Peng J, Xiao H, Yang D, Lei L, Zheng J, Zhou Z. Surface Hardening Behavior of Enamel by Masticatory Loading: Occurrence Mechanism and Antiwear Effect. ACS Biomater Sci Eng 2020; 6:4454-4461. [PMID: 33455168 DOI: 10.1021/acsbiomaterials.0c00740] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies have suggested that surface hardening occurs in human tooth enamel under certain loading conditions. However, the occurrence mechanism and significance remain unclear. In this study, the surface hardening behavior of enamel under masticatory loading was studied in vitro using impact treatment and the nanoindentation/scratch technique to identify the mechanism and antiwear effect. The fundamental block of enamel is made of hydroxyapatite (HAP) nanofibers, which consist of fine nanoparticles held together by protein. These fibers respond to masticatory loading in two ways: bending deflection at low loads and fragmentation at high loads. When the contact pressure exceeds the bonding strength between the nanoparticles, the HAP fibers split into fine nanoparticles and then form a surface layer consisting of tightly packed nanoparticles. This results in surface hardening dominated by an increased hardness and elastic modulus. The maximum degree and depth of surface hardening were determined as approximately 60% and 100 nm, respectively. With the occurrence of surface hardening, the wear resistance of the enamel is enhanced, which is manifested by a reduced friction coefficient and wear volume. In summary, the surface hardening of enamel induced by masticatory loading is a result of HAP nanoparticle rearrangement as a response of the enamel hierarchical structure to high chewing loads. It is adaptive overload protection derived from the enamel hierarchical structure and plays a critical role in resisting excessive wear induced by high chewing loads.
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Affiliation(s)
- Jiapin Peng
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Heng Xiao
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Dan Yang
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Lei Lei
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Jing Zheng
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Zhongrong Zhou
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
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6
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Thompson VP. The tooth: An analogue for biomimetic materials design and processing. Dent Mater 2020; 36:25-42. [DOI: 10.1016/j.dental.2019.08.106] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 08/21/2019] [Accepted: 08/28/2019] [Indexed: 01/05/2023]
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7
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Xiao H, Lei L, Peng J, Yang D, Zeng Q, Zheng J, Zhou Z. Research of the role of microstructure in the wear mechanism of canine and bovine enamel. J Mech Behav Biomed Mater 2019; 92:33-39. [PMID: 30654218 DOI: 10.1016/j.jmbbm.2018.12.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 12/26/2018] [Accepted: 12/27/2018] [Indexed: 10/27/2022]
Abstract
The relationship between the microstructure and tribological behavior of mammalian tooth enamel has not been fully understood. In this paper, the microstructure, mechanical properties, and tribological behavior of canine (carnivore) and bovine (herbivore) enamel are studied using scanning electronic microscopy and nano-indentation/scratch technique, aiming to reveal the contribution of enamel microstructure to its mechanical and tribological properties. Canine enamel has a microstructure of hard keyhole-like rods embedded in soft inter-rod enamel, and its surface exhibits high resistance against both micro-crack initiation and crack-induced delamination during friction and wear process. Bovine enamel with the microstructure consisting of the hydroxyapatite (HAP) nano-fibers in decussation has higher surface hardness and better capabilities of resisting wear and encumbering crack propagation, as compared to canine enamel. In sum, the soft inter-rod enamel in the canine enamel contributes to high load tolerance and then protects enamel surface from brittle damage, while the staggered arrangement of HAP nano-fibers benefits hard bovine enamel in crack propagation resistance and then help resist wear and fatigue. The findings suggest that there exists a self-adaptation in enamel microstructure and tribological performance of mammals with their feeding habits, which will promote and assist the bionic design of high-performance materials.
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Affiliation(s)
- Heng Xiao
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Lei Lei
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Jiapin Peng
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Dan Yang
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Qihang Zeng
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Jing Zheng
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China.
| | - Zhongrong Zhou
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
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8
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Sorozini M, Dos Reis Perez C, Rocha GM. Enamel sample preparation for AFM: Influence on roughness and morphology. Microsc Res Tech 2018; 81:1071-1076. [PMID: 30295354 DOI: 10.1002/jemt.23073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 05/08/2018] [Accepted: 05/25/2018] [Indexed: 11/07/2022]
Abstract
Human dental enamel is organized by prisms that are structured between 3 and 6 µm in diameter. Determining the relationships between different treatments on the surface of enamel using ultrastructural analysis is the purpose of many in vitro experiments. Different sample pretreatments have been reported in the literature. Grinding and polishing are common procedures for enamel preparation. They provide a flat and standardized surface, which is imperative for the use of some techniques such as ATR-FTIR. However, for morphological analysis, SEM and AFM represent easier methods to measure and reduce the biological sample variation. Therefore, the objective of this study was to establish how different forms of enamel preparation can influence the advent of artifacts during ultrastructural observation, especially by AFM analysis. Four groups (n = 10) were tested: (a) without preparation; (b) polishing with a diamond paste; (c) grinding with decreasing granulations of silicon carbide papers; (d) grinding with polishing. Images were obtained using the Peak-Force Tapping mode. After the first images were obtained, all fragments were acid etched with 37% phosphoric acid for 30 seconds, rinsed for 60 seconds, and dried intensively. Upon grinding and polishing, the exposure of the inner enamel surfaces provided a less mineralized layer that was marked by scratches and a higher susceptibility to treatments. Moreover, using native enamel provided more valuable information on the surface and the roughness changes for clinical applications. In addition, phosphoric acid is an option for observing the prismatic arrangement after grinding and/or polishing changes the morphology. RESEARCH HIGHLIGHTS: The use of native enamel samples to investigate the effects of different treatments on surface should be preferred in research, when the technique allows it.
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Affiliation(s)
- Marianna Sorozini
- Department of Restorative Dentistry, Faculty of Dentistry of University of Rio de Janeiro State, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Cesar Dos Reis Perez
- Department of Restorative Dentistry, Faculty of Dentistry of University of Rio de Janeiro State, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gustavo Miranda Rocha
- Department of Biophysics, Biological Physics Laboratory, Biophysics Institute Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
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9
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Influence of indenter geometry on the frictional sliding resistance of tooth enamel. BIOSURFACE AND BIOTRIBOLOGY 2017. [DOI: 10.1016/j.bsbt.2017.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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10
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Zheng J, Zeng Y, Wen J, Zheng L, Zhou Z. Impact wear behavior of human tooth enamel under simulated chewing conditions. J Mech Behav Biomed Mater 2016; 62:119-127. [DOI: 10.1016/j.jmbbm.2016.04.039] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 03/28/2016] [Accepted: 04/28/2016] [Indexed: 11/27/2022]
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11
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Constantino PJ, Borrero‐Lopez O, Pajares A, Lawn BR. Simulation of enamel wear for reconstruction of diet and feeding behavior in fossil animals: A micromechanics approach. Bioessays 2015; 38:89-99. [DOI: 10.1002/bies.201500094] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
| | - Oscar Borrero‐Lopez
- Departamento de Ingeniería MecánicaEnergética y de los MaterialesUniversidad de ExtremaduraBadajozSpain
| | - Antonia Pajares
- Departamento de Ingeniería MecánicaEnergética y de los MaterialesUniversidad de ExtremaduraBadajozSpain
| | - Brian R. Lawn
- Materials Measurement LaboratoryNational Institute of Standards and TechnologyGaithersburgMDUSA
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12
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Peng Z, Izzat Abdul Rahman M, Zhang Y, Yin L. Wear behavior of pressable lithium disilicate glass ceramic. J Biomed Mater Res B Appl Biomater 2015; 104:968-78. [PMID: 25980530 DOI: 10.1002/jbm.b.33447] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 04/10/2015] [Accepted: 04/24/2015] [Indexed: 11/05/2022]
Abstract
This article reports effects of surface preparation and contact loads on abrasive wear properties of highly aesthetic and high-strength pressable lithium disilicate glass-ceramics (LDGC). Abrasive wear testing was performed using a pin-on-disk device in which LDGC disks prepared with different surface finishes were against alumina pins at different contact loads. Coefficients of friction and wear volumes were measured as functions of initial surface finishes and contact loads. Wear-induced surface morphology changes in both LDGC disks and alumina pins were characterized using three-dimensional laser scanning microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results show that initial surface finishes of LDGC specimens and contact loads significantly affected the friction coefficients, wear volumes and wear-induced surface roughness changes of the material. Both wear volumes and friction coefficients of LDGC increased as the load increased while surface roughness effects were complicated. For rough LDGC surfaces, three-body wear was dominant while for fine LDGC surfaces, two-body abrasive wear played a key role. Delamination, plastic deformation, and brittle fracture were observed on worn LDGC surfaces. The adhesion of LDGC matrix materials to alumina pins was also discovered. This research has advanced our understanding of the abrasive wear behavior of LDGC and will provide guidelines for better utilization and preparation of the material for long-term success in dental restorations. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 968-978, 2016.
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Affiliation(s)
- Zhongxiao Peng
- School of Mechanical & Manufacturing Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Muhammad Izzat Abdul Rahman
- School of Mechanical & Manufacturing Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, New York, 10010, USA
| | - Ling Yin
- Matter and Materials, College of Science, Technology & Engineering, James Cook University, Townsville, QLD, 4811, Australia
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14
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Reduced wear of enamel with novel fine and nano-scale leucite glass-ceramics. J Dent 2013; 41:561-8. [DOI: 10.1016/j.jdent.2013.02.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/29/2013] [Accepted: 02/08/2013] [Indexed: 11/22/2022] Open
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15
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Bastos FDS, Las Casas EBD, Oller SM. Analytical and numerical analysis of human dental occlusal contact. Comput Methods Biomech Biomed Engin 2013; 16:495-503. [DOI: 10.1080/10255842.2011.627328] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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16
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Abstract
Some of the efforts that have been made to document tooth wear are reviewed here with an emphasis on nonhuman mammals, literature with which dentists may not be very familiar. We project a change in research strategy from the description of wear at various scales of measurement towards investigation of the mechanical mechanisms that actually create the texture of a worn surface. These studies should reveal exactly how tooth tissue is lost and what aspects of the structure of dental tissues affect this. The most important aspects of the interaction between the tooth surface and wear particles would appear to be particle size, particle shape, their mechanical properties with respect to those of tooth tissues, and the influence of saliva.
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Arsecularatne JA, Hoffman M. Ceramic-like wear behaviour of human dental enamel. J Mech Behav Biomed Mater 2011; 8:47-57. [PMID: 22402153 DOI: 10.1016/j.jmbbm.2011.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 12/05/2011] [Accepted: 12/07/2011] [Indexed: 11/29/2022]
Abstract
This paper reports a transmission electron microscopy (TEM) analysis of subsurfaces of enamel specimens following in vitro reciprocating wear tests with an enamel cusp sliding on a flat enamel specimen under hydrated conditions. The obtained results show that crack formation occurred in the wear scar subsurface. The path followed by these cracks seems to be dictated either by the histological structure of enamel or by the contact stress field. Moreover, the analysis of a set of enamel wear results obtained from the literature and application of fracture-based models, originally developed for ceramics, correlate well, confirming the similar wear processes taking place in these materials. This analysis also reveals a marked influence of coefficient of friction on the enamel wear rate: for a higher coefficient of friction value, enamel wear can be severe even under forces generated during normal operation of teeth.
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Affiliation(s)
- J A Arsecularatne
- School of Materials Science and Engineering, The University of New South Wales, Sydney 2052, Australia.
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18
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Jeng YR, Lin TT, Hsu HM, Chang HJ, Shieh DB. Human enamel rod presents anisotropic nanotribological properties. J Mech Behav Biomed Mater 2010; 4:515-22. [PMID: 21396600 DOI: 10.1016/j.jmbbm.2010.12.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 11/27/2010] [Accepted: 12/05/2010] [Indexed: 10/18/2022]
Abstract
The AFM combined nanoindentation was performed to observe the ultrastructure of enamel rod from various section plans and positions while probing their mechanical and tribological properties of the area. The nanohardness and the elastic modulus of the head region of the enamel rods are significantly higher than that of the tail region and the axial-sectional plane. Both nanohardness and elastic modulus gradually decrease from enamel surface toward dentino-enamel junction. Such a variation correlates well with the decreasing trend of calcium composition from our element analysis. The friction coefficient and nanowear of the enamel showed an inversed trend to the hardness with respect to their relative topological position in the long axis of enamel rod toward DEJ. The relationship between the nanowear depth and the distance from the outer enamel surface to DEJ presented exponential function. The results presented clarify the basic nanomechanical and nanotribological properties of human enamel rods and provide a useful reference for the future development of dental restorative materials.
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Affiliation(s)
- Yeau-Ren Jeng
- Department of Mechanical Engineering of National Chung Cheng University, Chia-Yi, 62100, Taiwan.
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Ranjitkar S, Kaidonis JA, Richards LC, Townsend GC. The effect of CPP–ACP on enamel wear under severe erosive conditions. Arch Oral Biol 2009; 54:527-32. [DOI: 10.1016/j.archoralbio.2009.03.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 03/23/2009] [Accepted: 03/26/2009] [Indexed: 10/20/2022]
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