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Rujiraprasert P, Suriyasangpetch S, Srijunbarl A, Singthong T, Makornpan C, Nampuksa K, Osathanon T, Nantanapiboon D, Monmaturapoj N. Calcium phosphate ceramic as a model for enamel substitute material in dental applications. BDJ Open 2023; 9:25. [PMID: 37661198 PMCID: PMC10475459 DOI: 10.1038/s41405-023-00152-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/26/2023] [Accepted: 05/29/2023] [Indexed: 09/05/2023] Open
Abstract
OBJECTIVE This study aimed to develop enamel substitute material using a mechanochemical technique. MATERIALS AND METHODS Hydroxyapatite was synthesized with and without tricalcium phosphate under uniaxial pressing of 10 and 17 MPa (HA10, HA17, BCP10, and BCP17), followed by sintering at 1250 °C for 2 h. Human enamel and dentin blocks were used as control groups. The mechanical properties were determined by compressive strength test and Vickers microhardness. The data were analyzed with one-way ANOVA and LSD post-hoc test (α = 0.05). The phase formation and morphology of the specimens were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). RESULTS HA17 and HA10 had compressive strength values comparable to enamel and dentin, respectively (p > 0.05). The microhardness of all synthesized groups was significantly higher than that of tooth structures (p < 0.05). From the XRD graphs, only the hydroxyapatite peak was observed in the control and HA groups. SEM images showed homogeneous hydroxyapatite grains in all groups, while the BCP groups contained higher porosities. CONCLUSIONS Both HA10 and HA17 are suitable for use as the inorganic part of dentin and enamel substitutes.
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Affiliation(s)
- Phakvalunch Rujiraprasert
- Department of Operative Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Sarat Suriyasangpetch
- Department of Advanced General Dentistry, Faculty of Dentistry, Mahidol University, Bangkok, Thailand
| | - Anucharte Srijunbarl
- Dental Materials Research and Development Center, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Thawanrat Singthong
- Dental Materials Research and Development Center, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Chalermkwan Makornpan
- Assistive Technology and Medical Devices Research Center (A-MED), National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Katanchalee Nampuksa
- Assistive Technology and Medical Devices Research Center (A-MED), National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Thanaphum Osathanon
- Dental Stem Cell Biology Research Unit and Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Dusit Nantanapiboon
- Department of Operative Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
- Dental Materials Research and Development Center, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
| | - Naruporn Monmaturapoj
- Assistive Technology and Medical Devices Research Center (A-MED), National Science and Technology Development Agency, Pathum Thani, Thailand
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2
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Besnard C, Marie A, Sasidharan S, Buček P, Walker JM, Parker JE, Spink MC, Harper RA, Marathe S, Wanelik K, Moxham TE, Salvati E, Ignatyev K, Kłosowski MM, Shelton RM, Landini G, Korsunsky AM. Multi-resolution Correlative Ultrastructural and Chemical Analysis of Carious Enamel by Scanning Microscopy and Tomographic Imaging. ACS APPLIED MATERIALS & INTERFACES 2023; 15:37259-37273. [PMID: 37524079 PMCID: PMC10416148 DOI: 10.1021/acsami.3c08031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/17/2023] [Indexed: 08/02/2023]
Abstract
Caries, a major global disease associated with dental enamel demineralization, remains insufficiently understood to devise effective prevention or minimally invasive treatment. Understanding the ultrastructural changes in enamel is hampered by a lack of nanoscale characterization of the chemical spatial distributions within the dental tissue. This leads to the requirement to develop techniques based on various characterization methods. The purpose of the present study is to demonstrate the strength of analytic methods using a correlative technique on a single sample of human dental enamel as a specific case study to test the accuracy of techniques to compare regions in enamel. The science of the different techniques is integrated to genuinely study the enamel. The hierarchical structures within carious tissue were mapped using the combination of focused ion beam scanning electron microscopy with synchrotron X-ray tomography. The chemical changes were studied using scanning X-ray fluorescence (XRF) and X-ray wide-angle and small-angle scattering using a beam size below 80 nm for ångström and nanometer length scales. The analysis of XRF intensity gradients revealed subtle variations of Ca intensity in carious samples in comparison with those of normal mature enamel. In addition, the pathways for enamel rod demineralization were studied using X-ray ptychography. The results show the chemical and structural modification in carious enamel with differing locations. These results reinforce the need for multi-modal approaches to nanoscale analysis in complex hierarchically structured materials to interpret the changes of materials. The approach establishes a meticulous correlative characterization platform for the analysis of biomineralized tissues at the nanoscale, which adds confidence in the interpretation of the results and time-saving imaging techniques. The protocol demonstrated here using the dental tissue sample can be applied to other samples for statistical study and the investigation of nanoscale structural changes. The information gathered from the combination of methods could not be obtained with traditional individual techniques.
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Affiliation(s)
- Cyril Besnard
- MBLEM,
Department of Engineering Science, University
of Oxford, Parks Road, Oxford, Oxfordshire OX1
3PJ, U.K.
| | - Ali Marie
- MBLEM,
Department of Engineering Science, University
of Oxford, Parks Road, Oxford, Oxfordshire OX1
3PJ, U.K.
| | - Sisini Sasidharan
- MBLEM,
Department of Engineering Science, University
of Oxford, Parks Road, Oxford, Oxfordshire OX1
3PJ, U.K.
| | - Petr Buček
- TESCAN-UK
Ltd., Wellbrook Court, Girton, Cambridge CB3 0NA, U.K.
| | | | - Julia E. Parker
- Diamond
Light Source Ltd., Didcot, Oxfordshire OX11 0DE, U.K.
| | | | - Robert A. Harper
- School
of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham, West Midlands B5 7EG, U.K.
| | | | - Kaz Wanelik
- Diamond
Light Source Ltd., Didcot, Oxfordshire OX11 0DE, U.K.
| | - Thomas E.J. Moxham
- MBLEM,
Department of Engineering Science, University
of Oxford, Parks Road, Oxford, Oxfordshire OX1
3PJ, U.K.
- Diamond
Light Source Ltd., Didcot, Oxfordshire OX11 0DE, U.K.
| | - Enrico Salvati
- MBLEM,
Department of Engineering Science, University
of Oxford, Parks Road, Oxford, Oxfordshire OX1
3PJ, U.K.
| | | | | | - Richard M. Shelton
- School
of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham, West Midlands B5 7EG, U.K.
| | - Gabriel Landini
- School
of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham, West Midlands B5 7EG, U.K.
| | - Alexander M. Korsunsky
- MBLEM,
Department of Engineering Science, University
of Oxford, Parks Road, Oxford, Oxfordshire OX1
3PJ, U.K.
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3
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Deshmukh R, Vasquez B, Bhogadi L, Gabe CM, Lukashova L, Verdelis K, Morasso MI, Beniash E. Elucidating the role of keratin 75 in enamel using Krt75 tm1Der knock-in mouse model. Front Physiol 2022; 13:1102553. [PMID: 36620220 PMCID: PMC9816862 DOI: 10.3389/fphys.2022.1102553] [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: 11/19/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
Keratin 75 (K75) was recently discovered in ameloblasts and enamel organic matrix. Carriers of A161T substitution in K75 present with the skin condition Pseudofollicullitis barbae. This mutation is also associated with high prevalence of caries and compromised structural and mechanical properties of enamel. Krt75tm1Der knock-in mouse (KI) with deletion of Asn159, located two amino acids away from KRT75A161T, can be a potential model for studying the role of K75 in enamel and the causes of the higher caries susceptibility associated with KRT75A161T mutation. To test the hypotheses that KI enamel is more susceptible to a simulated acid attack (SAA), and has altered structural and mechanical properties, we conducted in vitro SAA experiments, microCT, and microhardness analyses on 1st molars of one-month-old WT and KI mice. KI and WT hemimandibles were subjected to SAA and contralateral hemimandibles were used as controls. Changes in enamel porosity were assessed by immersion of the hemimandibles in rhodamine, followed by fluorescent microscopy analysis. Fluorescence intensity of KI enamel after SSA was significantly higher than in WT, indicating that KI enamel is more susceptible to acid attack. MicroCT analysis of 1st molars revealed that while enamel volumes were not significantly different, enamel mineral density was significantly lower in KI, suggesting a potential defect of enamel maturation. Microhardness tests revealed that in KI enamel is softer than in WT, and potentially less resilient to damages. These results suggest that the KI enamel can be used as a model to study the role of K75 in enamel.
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Affiliation(s)
- Rutuja Deshmukh
- Center for Craniofacial Regeneration, Pittsburgh, PA, United States
| | - Brent Vasquez
- Center for Craniofacial Regeneration, Pittsburgh, PA, United States,Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine (UPSDM), Pittsburgh, PA, United States
| | - Lasya Bhogadi
- Center for Craniofacial Regeneration, Pittsburgh, PA, United States,Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine (UPSDM), Pittsburgh, PA, United States
| | - Claire M. Gabe
- Center for Craniofacial Regeneration, Pittsburgh, PA, United States,Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine (UPSDM), Pittsburgh, PA, United States
| | | | - Kostas Verdelis
- Center for Craniofacial Regeneration, Pittsburgh, PA, United States,Department of Endodontics, University of Pittsburgh School of Dental Medicine (UPSDM), Pittsburgh, PA, United States
| | - Maria I. Morasso
- Laboratory of Skin Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Bethesda, MD, United States
| | - Elia Beniash
- Center for Craniofacial Regeneration, Pittsburgh, PA, United States,Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine (UPSDM), Pittsburgh, PA, United States,*Correspondence: Elia Beniash,
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4
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Wu Y, Liu J, Yang Y, Tu S, Liu Z, Wang Y, Peng C, Liu G, Jin Y. Special architecture and anti-wear strategies for giant panda tooth enamel: Based on wear simulation findings. Front Vet Sci 2022; 9:985733. [PMID: 36187810 PMCID: PMC9516319 DOI: 10.3389/fvets.2022.985733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/10/2022] [Indexed: 11/13/2022] Open
Abstract
Giant pandas are the flagship species in world conservation. Due to bamboo being the primary food source for giant pandas, dental wear is common owing to the extreme toughness of the bamboo fiber. Even though research on tooth enamel wear in humans and domestic animals is well-established, research on tooth enamel wear in giant pandas is scarce. The purpose of this study is to evaluate tooth enamel wear resistance in giant pandas to provide a basis for a better understanding of their evolutionary process. From microscopic and macroscopic perspectives, the abrasion resistance of dental enamel in giant pandas is compared with that of herbivorous cattle and carnivorous dogs in this study. This involves the use of micro-scratch and frictional wear tests. The results show that the boundary between the enamel prism and the enamel prism stroma is well-defined in panda and canine teeth, while bovine tooth enamel appears denser. Under constant load, the tribological properties of giant panda enamel are similar to those of canines and significantly different from those of bovines. Test results show that the depth of micro scratches in giant panda and canine enamel was greater than in cattle, with greater elastic recovery occurring in dogs. Scratch morphology indicates that the enamel substantive damage critical value is greater in pandas than in both dogs and cattle. The analysis suggests that giant panda enamel consists of a neatly arranged special structure that may disperse extrusion stress and absorb impact energy through a series of inelastic deformation mechanisms to cope with the wear caused by eating bamboo. In this study, the excellent wear resistance of giant panda's tooth enamel is verified by wear tests. A possible theoretical explanation of how the special structure of giant panda tooth enamel may improve its wear resistance is provided. This provides a direction for subsequent theoretical and experimental studies on giant panda tooth enamel and its biomaterials.
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Affiliation(s)
- Yuanheng Wu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jinxing Liu
- Tsinghua Laboratory of Brain and Intelligence, Nonhuman Primate Research Center Tsingua University, Beijing, China
| | - Yongqiang Yang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Shaotong Tu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zichen Liu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yingyun Wang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Chen Peng
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Gang Liu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
- *Correspondence: Gang Liu
| | - Yipeng Jin
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Yipeng Jin
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5
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Surface and Structural Studies of Age-Related Changes in Dental Enamel: An Animal Model. MATERIALS 2022; 15:ma15113993. [PMID: 35683290 PMCID: PMC9182525 DOI: 10.3390/ma15113993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/26/2022] [Accepted: 06/01/2022] [Indexed: 01/28/2023]
Abstract
In the animal kingdom, continuously erupting incisors provided an attractive model for studying the enamel matrix and mineral composition of teeth during development. Enamel, the hardest mineral tissue in the vertebrates, is a tissue sensitive to external conditions, reflecting various disturbances in its structure. The developing dental enamel was monitored in a series of incisor samples extending the first four weeks of postnatal life in the spiny mouse. The age-dependent changes in enamel surface morphology in the micrometre and nanometre-scale and a qualitative assessment of its mechanical features were examined by applying scanning electron microscopy (SEM) and atomic force microscopy (AFM). At the same time, structural studies using XRD and vibrational spectroscopy made it possible to assess crystallinity and carbonate content in enamel mineral composition. Finally, a model for predicting the maturation based on chemical composition and structural factors was constructed using artificial neural networks (ANNs). The research presented here can extend the existing knowledge by proposing a pattern of enamel development that could be used as a comparative material in environmental, nutritional, and pharmaceutical research.
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6
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House KL, Pan L, O'Carroll DM, Xu S. Applications of scanning electron microscopy and focused ion beam milling in dental research. Eur J Oral Sci 2022; 130:e12853. [PMID: 35288994 DOI: 10.1111/eos.12853] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
The abilities of scanning electron microscopy (SEM) and focused ion beam (FIB) milling for obtaining high-resolution images from top surfaces, cross-sectional surfaces, and even in three dimensions, are becoming increasingly important for imaging and analyzing tooth structures such as enamel and dentin. FIB was originally developed for material research in the semiconductor industry. However, use of SEM/FIB has been growing recently in dental research due to the versatility of dual platform instruments that can be used as a milling device to obtain low-artifact cross-sections of samples combined with high-resolution images. The advent of the SEM/FIB system and accessories may offer access to previously inaccessible length scales for characterizing tooth structures for dental research, opening exciting opportunities to address many central questions in dental research. New discoveries and fundamental breakthroughs in understanding are likely to follow. This review covers the applications, key findings, and future direction of SEM/FIB in dental research in morphology imaging, specimen preparation for transmission electron microscopy (TEM) analysis, and three-dimensional volume imaging using SEM/FIB tomography.
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Affiliation(s)
- Krystal L House
- Colgate Palmolive Company, Piscataway, New Jersey, USA.,Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA
| | - Long Pan
- Colgate Palmolive Company, Piscataway, New Jersey, USA
| | - Deirdre M O'Carroll
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA.,Department of Materials Science and Engineering, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA
| | - Shiyou Xu
- Colgate Palmolive Company, Piscataway, New Jersey, USA
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7
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Song L, Huang Z, Guo S, Li Y, Wang Q. Hierarchically Architected Polyvinylidene Fluoride Piezoelectric Foam for Boosted Mechanical Energy Harvesting and Self-Powered Sensor. ACS APPLIED MATERIALS & INTERFACES 2021; 13:37252-37261. [PMID: 34318675 DOI: 10.1021/acsami.1c11158] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
With the rapid development of wearable electronics, piezoelectric materials have received great attention owing to their potential solution to the portable power source. To enhance the output capability and broaden the application, it is highly desired for the design of piezoelectric materials with a three-dimensional and porous structure to facilitate strain accumulation. Herein, enlightened by hierarchical structures in nature, a hierarchically nested network was constructed in polyvinylidene fluoride (PVDF) foam via solid-state shear milling and salt-leaching technology. The as-prepared foam exhibited two hierarchical levels of pores with diameters of 20∼50 μm and 0.3∼4 μm, by which the porosity and flexibility were significantly enhanced, while the highest piezoelectric output reached 11.84 V and 217.78 nA. As a proof-of-concept, the PVDF piezoelectric foam can also be used to monitor human movement toward the different magnitude of strain and frequency, and simultaneously collect energy in a multidimensional stress field for energy harvesting. This work provides a simple and convenient design idea for the preparation of energy harvesters, which have great application potential as a mechanical energy harvester or self-powered sensor in wearable electronic devices.
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Affiliation(s)
- Li Song
- School of Materials Science & Engineering, North Minzu University, Ningxia 750021, China
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Zhaoxia Huang
- National Engineering Research Center of Novel Equipment for Polymer Processing; Key Laboratory of Polymer Processing Engineering, Ministry of Education; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China
| | - Shengwei Guo
- School of Materials Science & Engineering, North Minzu University, Ningxia 750021, China
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Yijun Li
- School of Materials Science & Engineering, North Minzu University, Ningxia 750021, China
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Qi Wang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
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8
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Wang QQ, Wang S, Zhao T, Li Y, Yang J, Liu Y, Zhang H, Miao L, Sun W. Biomimetic oligopeptide formed enamel-like tissue and dentin tubule occlusion via mineralization for dentin hypersensitivity treatment. J Appl Biomater Funct Mater 2021; 19:22808000211005384. [PMID: 33784188 DOI: 10.1177/22808000211005384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Dentin hypersensitivity (DH) is a common oral disease with approximately 41.9% prevalence. Reconstruction of dental hard tissues is the preferred treatment for relieving DH. Here, we applied biomineralization method using oligopeptide simulating cementum protein 1 (CEMP1) to regenerate hard tissues on demineralized dentin. METHODS The self-assembly and biomineralization property of the oligopeptide were detected by scanning electron microscopy (SEM), circular dichroism spectroscopy, and transmission electron microscopy. Oligopeptide's binding capacity to demineralized dentin was evaluated by SEM and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Remineralization was characterized using SEM, ATR-FTIR, X-ray diffraction, and nanoindentation. Oligopeptide's biocompatibility was evaluated using periodontal ligament cells. RESULTS Oligopeptides self-assembled into nano-matrix and templated mineral precursor formation within 24 h. Moreover, oligopeptide nano-matrix bound firmly on demineralized dentin and resisted water rinsing. Then, bound nano-matrix served as a template to initiate nucleation and transformation of hydroxyapatite on demineralized dentin. After 96 h, oligopeptide nano-matrix regenerated an enamel-like tissue layer with a thickness of 15.35 μm, and regenerated crystals occluded dentin tubules with a depth of 31.27 μm. Furthermore, the oligopeptide nano-matrix had good biocompatibility when co-cultured with periodontal ligament cells. CONCLUSIONS This biomimetic oligopeptide simulating CEMP1 effectively induced remineralization and reconstructed hard tissues on demineralized dentin, providing a potential biomaterial for DH treatment.
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Affiliation(s)
- Qing-Qing Wang
- Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China
| | - Siqing Wang
- Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China
| | - Tian Zhao
- Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China
| | - Yan Li
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Jie Yang
- Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China
| | - Yumei Liu
- Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China
| | - He Zhang
- Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China
| | - Leiying Miao
- Department of Cariology and Endodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China
| | - Weibin Sun
- Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China
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9
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Shi S, Li Y, Ngo-Dinh BN, Markmann J, Weissmüller J. Scaling behavior of stiffness and strength of hierarchical network nanomaterials. Science 2021; 371:1026-1033. [DOI: 10.1126/science.abd9391] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 01/25/2021] [Indexed: 01/08/2023]
Affiliation(s)
- Shan Shi
- Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
- Institute of Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany
| | - Yong Li
- Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
- Institute of Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany
| | - Bao-Nam Ngo-Dinh
- Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
- Institute for Materials, Technical University of Braunschweig, 38106 Braunschweig, Germany
| | - Jürgen Markmann
- Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
- Institute of Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany
| | - Jörg Weissmüller
- Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
- Institute of Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany
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10
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Harper RA, Shelton RM, James JD, Salvati E, Besnard C, Korsunsky AM, Landini G. Acid-induced demineralisation of human enamel as a function of time and pH observed using X-ray and polarised light imaging. Acta Biomater 2021; 120:240-248. [PMID: 32438107 DOI: 10.1016/j.actbio.2020.04.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/22/2020] [Accepted: 04/24/2020] [Indexed: 01/19/2023]
Abstract
Acid-induced enamel demineralisation affects many individuals either by exposure to acidic diets, acidic gas pollution (dental erosion) or to dental plaque acids (dental caries). This study aimed to develop in situ X-ray and light imaging methods to determine progression of enamel demineralisation and the dynamic relationship between acid pH and mineral density. Hourly digital microradiograph time-lapse sequences showed the depth of enamel demineralisation in 500 µm thick sections progressed with time from the surface towards the dentine following a power-law function, which was 21% faster than the lateral demineralisation progression after exposure for 85 h to lactic acid (10%, pH 2.2). The minimum greyscale remaining (mineral content) within the induced enamel lesion followed an exponential decay, while the accumulated total greyscale loss with time was linear, which showed a constant anisotropic mineral release within the enamel architecture. This 85 h demineralisation method studied by polarised light microscopy time-lapse sequences showed that once the demineralisation front reached the enamel Hunter-Schreger bands, there was preferential demineralisation along those bands. Mineral density loss was linear with increasing pH acidity between pH 5.2 and pH 4.0 (with 0.4 pH increments) when incubated over a 3-week period exposed to 0.5% lactic acid. At pH 4.0, there was complete mineral loss in the centre of the demineralised area after the 3-week period and the linear function intercepted the x-axis at ~ pH 5.5, near the critical pH for hydroxyapatite (HAp). These observations showed how intrinsic enamel structure and pH affected the progression of demineralisation. STATEMENT OF SIGNIFICANCE: Hydroxyapatite crystallites (HAp) in human enamel dissolve when exposed to an acidic environment but little is known about how the intrinsic structures in enamel and pH influence the demineralisation kinetics. We have developed a time-lapse in situ microradiography method to quantify microscopic anisotropic mineral loss dynamics in response to an acid-only caries model. Correlation with polarised light microscopy time-lapse sequences showed that larger structures in enamel also influence demineralisation progression as demineralisation occurred preferentially along the Hunter-Schreger bands (decussating prismatic enamel). The pH-controlled enamel mineral release in a linear manner quantifying the relationship between HAp orientation and acid solubility. These findings should direct the development of improved anti-demineralisation/ remineralisation treatments to retain/ restore the natural intrinsic enamel structure.
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11
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Hugo J, Koldsland OC, Aass AM, Tiainen H. Development and initial testing of an in vitro model simulating class II furcation defects. Clin Exp Dent Res 2020; 7:179-188. [PMID: 33283478 PMCID: PMC8019757 DOI: 10.1002/cre2.346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 09/10/2020] [Accepted: 09/19/2020] [Indexed: 01/29/2023] Open
Abstract
Objective To compare surface topography of porcine and human root dentin and to develop a new in vitro model for class II furcation defects. The hypothesis for this study was that porcine mandible blocks can function as a model for class II furcation defects. Background Treatment of mandibular class II furcation defects is unpredictable. There is a need for in vitro models to investigate new treatment methods. Methods A model to investigate the surface topography of porcine and human root dentin was developed and the two tissues compared by SEM imaging and profilometer. A novel method for studying class II furcation defects was then tested. Blocks of porcine mandibles with molar 3 were prepared. Buccal class II furcation defects were created. The furcation area was isolated and bioluminescent Staphylococcus epidermidis Xen43 was used to form a biofilm in the furcation area to test the functionality of the novel furcation model. Results Micromechanical damage caused by debridement on porcine and human root dentin showed similar pattern. No significant difference in the surface morphological parameters was observed between the corresponding porcine and human samples. The model allowed for assessment of the root surface inside the furcation area. While the number of viable bacteria in the furcation following debridement could be quantified, no significant difference between the treatment groups was detected, likely due to bacterial colonization within the periodontal ligament space. Conclusion Porcine and human root dentin show similar surface topography following surface debridement. Porcine mandible blocks can function as a model for class II furcation defects. However, further development and refinement of the novel in vitro model is warranted.
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Affiliation(s)
- Jørgen Hugo
- Department of Periodontology, Institute of Clinical Dentistry, University of Oslo, Oslo, Norway.,Department of Biomaterials, Institute of Clinical Dentistry, University of Oslo, Oslo, Norway
| | - Odd Carsten Koldsland
- Department of Periodontology, Institute of Clinical Dentistry, University of Oslo, Oslo, Norway
| | - Anne Merete Aass
- Department of Periodontology, Institute of Clinical Dentistry, University of Oslo, Oslo, Norway
| | - Hanna Tiainen
- Department of Biomaterials, Institute of Clinical Dentistry, University of Oslo, Oslo, Norway
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12
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Smith CE, Hu Y, Strauss M, Hu JCC, Simmer JP. The spatial distribution of focal stacks within the inner enamel layer of mandibular mouse incisors. J Anat 2020; 238:970-985. [PMID: 33145767 PMCID: PMC7930765 DOI: 10.1111/joa.13352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 01/08/2023] Open
Abstract
Focal stacks are an alternative spatial arrangement of enamel rods within the inner enamel of mandibular mouse incisors where short rows comprised of 2–45 enamel rods are nestled at the side of much longer rows, both sharing the same rod tilt directed mesially or laterally. The significance of focal stacks to enamel function is unknown, but their high frequency in transverse sections (30% of all rows) suggests that they serve some purpose beyond representing an oddity of enamel development. In this study, we characterized the spatial distribution of focal stacks in random transverse sections relative to different regions of the inner enamel and to different locations across enamel thickness. The curving dentinoenamel junction (DEJ) in transverse sections complicated spatial distribution analyses, and a technique was developed to “unbend” the curving DEJ allowing for more linear quantitative analyses to be carried out. The data indicated that on average there were 36 ± 7 focal stacks located variably within the inner enamel in any given transverse section. Consistent with area distributions, focal stacks were four times more frequent in the lateral region (53%) and twice as frequent in the mesial region (33%) compared to the central region (14%). Focal stacks were equally split by tilt (52% mesial vs. 48% lateral, not significant), but those having a mesial tilt were more frequently encountered in the lateral and central regions (2:1) and those having a lateral tilt were more numerous in the mesial region (1:3). Focal stacks having a mesial tilt were longer on average compared to those having a lateral tilt (7.5 ± 5.6 vs. 5.9 ± 4.0 rods per row, p < 0.01). There was no relationship between the length of a focal stack and its location within the inner enamel. All results were consistent with the notion that focal stacks travel from the DEJ to the outer enamel the same as the longer and decussating companion rows to which they are paired. The spatial distribution of focal stacks within the inner enamel was not spatially random but best fit a null model based on a heterogenous Poisson point process dependent on regional location within the transverse plane of the enamel layer.
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Affiliation(s)
- Charles E Smith
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Anatomy & Cell Biology, Faculty of Medicine & Health Sciences, McGill University, Montreal, QC, Canada
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Mike Strauss
- Department of Anatomy & Cell Biology, Faculty of Medicine & Health Sciences, McGill University, Montreal, QC, Canada.,Facility for Electron Microscopy Research, McGill University, Montreal, QC, Canada
| | - Jan C-C Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
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13
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Bor B, Heilmann L, Domènech B, Kampferbeck M, Vossmeyer T, Weller H, Schneider GA, Giuntini D. Mapping the Mechanical Properties of Hierarchical Supercrystalline Ceramic-Organic Nanocomposites. Molecules 2020; 25:E4790. [PMID: 33086563 PMCID: PMC7587535 DOI: 10.3390/molecules25204790] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/02/2020] [Accepted: 10/15/2020] [Indexed: 01/30/2023] Open
Abstract
Multiscale ceramic-organic supercrystalline nanocomposites with two levels of hierarchy have been developed via self-assembly with tailored content of the organic phase. These nanocomposites consist of organically functionalized ceramic nanoparticles forming supercrystalline micron-sized grains, which are in turn embedded in an organic-rich matrix. By applying an additional heat treatment step at mild temperatures (250-350 °C), the mechanical properties of the hierarchical nanocomposites are here enhanced. The heat treatment leads to partial removal and crosslinking of the organic phase, minimizing the volume occupied by the nanocomposites' soft phase and triggering the formation of covalent bonds through the organic ligands interfacing the ceramic nanoparticles. Elastic modulus and hardness up to 45 and 2.5 GPa are attained, while the hierarchical microstructure is preserved. The presence of an organic phase between the supercrystalline grains provides a toughening effect, by curbing indentation-induced cracks. A mapping of the nanocomposites' mechanical properties reveals the presence of multiple microstructural features and how they evolve with heat treatment temperature. A comparison with non-hierarchical, homogeneous supercrystalline nanocomposites with lower organic content confirms how the hierarchy-inducing organic excess results in toughening, while maintaining the beneficial effects of crosslinking on the materials' stiffness and hardness.
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Affiliation(s)
- Büsra Bor
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany; (B.B.); (L.H.); (B.D.); (G.A.S.)
| | - Lydia Heilmann
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany; (B.B.); (L.H.); (B.D.); (G.A.S.)
| | - Berta Domènech
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany; (B.B.); (L.H.); (B.D.); (G.A.S.)
| | - Michael Kampferbeck
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (M.K.); (T.V.); (H.W.)
| | - Tobias Vossmeyer
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (M.K.); (T.V.); (H.W.)
| | - Horst Weller
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (M.K.); (T.V.); (H.W.)
| | - Gerold A. Schneider
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany; (B.B.); (L.H.); (B.D.); (G.A.S.)
| | - Diletta Giuntini
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany; (B.B.); (L.H.); (B.D.); (G.A.S.)
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14
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Crofts SB, Smith SM, Anderson PSL. Beyond Description: The Many Facets of Dental Biomechanics. Integr Comp Biol 2020; 60:594-607. [DOI: 10.1093/icb/icaa103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Synopsis
Teeth lie at the interface between an animal and its environment and, with some exceptions, act as a major component of resource procurement through food acquisition and processing. Therefore, the shape of a tooth is closely tied to the type of food being eaten. This tight relationship is of use to biologists describing the natural history of species and given the high instance of tooth preservation in the fossil record, is especially useful for paleontologists. However, correlating gross tooth morphology to diet is only part of the story, and much more can be learned through the study of dental biomechanics. We can explore the mechanics of how teeth work, how different shapes evolved, and the underlying forces that constrain tooth shape. This review aims to provide an overview of the research on dental biomechanics, in both mammalian and non-mammalian teeth, and to synthesize two main approaches to dental biomechanics to develop an integrative framework for classifying and evaluating dental functional morphology. This framework relates food material properties to the dynamics of food processing, in particular how teeth transfer energy to food items, and how these mechanical considerations may have shaped the evolution of tooth morphology. We also review advances in technology and new techniques that have allowed more in-depth studies of tooth form and function.
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Affiliation(s)
- S B Crofts
- Department of Evolution, Ecology, and Behavior, University of Illinois, 515 Morrill Hall, 505 S. Goodwin Avenue, Urbana, IL 61801, USA
| | - S M Smith
- Field Museum of Natural History, Negaunee Integrative Research Center, 1400 South Lake Shore Drive, Chicago, IL 60605-2496, USA
| | - P S L Anderson
- Department of Evolution, Ecology, and Behavior, University of Illinois, 515 Morrill Hall, 505 S. Goodwin Avenue, Urbana, IL 61801, USA
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15
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DeRocher KA, Smeets PJM, Goodge BH, Zachman MJ, Balachandran PV, Stegbauer L, Cohen MJ, Gordon LM, Rondinelli JM, Kourkoutis LF, Joester D. Chemical gradients in human enamel crystallites. Nature 2020; 583:66-71. [PMID: 32612224 PMCID: PMC8290891 DOI: 10.1038/s41586-020-2433-3] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 04/08/2020] [Indexed: 11/16/2022]
Abstract
Dental enamel is a principal component of teeth1, and has evolved to bear large chewing forces, resist mechanical fatigue and withstand wear over decades2. Functional impairment and loss of dental enamel, caused by developmental defects or tooth decay (caries), affect health and quality of life, with associated costs to society3. Although the past decade has seen progress in our understanding of enamel formation (amelogenesis) and the functional properties of mature enamel, attempts to repair lesions in this material or to synthesize it in vitro have had limited success4-6. This is partly due to the highly hierarchical structure of enamel and additional complexities arising from chemical gradients7-9. Here we show, using atomic-scale quantitative imaging and correlative spectroscopies, that the nanoscale crystallites of hydroxylapatite (Ca5(PO4)3(OH)), which are the fundamental building blocks of enamel, comprise two nanometric layers enriched in magnesium flanking a core rich in sodium, fluoride and carbonate ions; this sandwich core is surrounded by a shell with lower concentration of substitutional defects. A mechanical model based on density functional theory calculations and X-ray diffraction data predicts that residual stresses arise because of the chemical gradients, in agreement with preferential dissolution of the crystallite core in acidic media. Furthermore, stresses may affect the mechanical resilience of enamel. The two additional layers of hierarchy suggest a possible new model for biological control over crystal growth during amelogenesis, and hint at implications for the preservation of biomarkers during tooth development.
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Affiliation(s)
- Karen A DeRocher
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Paul J M Smeets
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Michael J Zachman
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Prasanna V Balachandran
- Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA, USA
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA
| | - Linus Stegbauer
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Michael J Cohen
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Lyle M Gordon
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Derk Joester
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
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16
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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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17
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Zhang N, Wang X, Xiang W, Zhong Y, Yan F, Jiang B. Hierarchy structure and fracture mechanisms of the wild wolf tusk's enamel. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 106:110277. [PMID: 31753341 DOI: 10.1016/j.msec.2019.110277] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 09/25/2019] [Accepted: 10/05/2019] [Indexed: 01/05/2023]
Abstract
The self-growth and self-strengthening of natural biomaterials provided us strategies for new materials design. In this paper, the microstructure and fracture mechanisms of the wild wolf tusk's enamel were studied. The enamel included four-order hierarchies, which were the hydroxyapatite (HAP) fiber (first-order, nano-scale, ploy-crystals), enamel rod (second-order, micro-scale, rope-like), enamel type (third-order, meso-scale, mat-like) and the enamel patterns (forth-order, macro-scale), respectively. It was interesting to find that the numerous nano-grains distributed disorderly in a single HAP fiber. The thousands HAP fibers bundled together to form the rope-like enamel rod. The protein ligaments were discovered between adjacent enamel rods. The out enamel, inner enamel and P&D-zones showed a criss-cross type and ran through whole enamel pattern in three-dimensional space. The enamel of the wild wolf tusk exhibited an excellent fracture toughness based on the nanoindentation tests. The fracture morphology in transverse direction indicated that the cracks preferred to propagate along the weak interface (protein or interrod) and cut those enamel rods perpendicular to the propagation direction. However, the cracks extended obviously forward along the step-like paths from the outmost surface of the enamel to the enamel-dentin junction in the longitudinal direction. It was considered that the protein ligament was the main reason for the good fracture toughness of the bulk enamel. Our studies reveal that the design strategies of the natural material can be applied to guide the development of high-performance artificial materials.
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Affiliation(s)
- Nan Zhang
- School of Materials Science and Engineering, Xi'an University of Technology, 5 South Jinhua Road, Xi'an, 710048, China; Key Laboratory of Corrosion and Protection of Shanxi Province, Xi'an University of Technology, No. 5 South Jinhua Road, Xi'an, 710048, China
| | - Xu Wang
- School of Materials Science and Engineering, Xi'an University of Technology, 5 South Jinhua Road, Xi'an, 710048, China; Key Laboratory of Corrosion and Protection of Shanxi Province, Xi'an University of Technology, No. 5 South Jinhua Road, Xi'an, 710048, China.
| | - Wangshuai Xiang
- School of Materials Science and Engineering, Xi'an University of Technology, 5 South Jinhua Road, Xi'an, 710048, China
| | - Yujie Zhong
- School of Materials Science and Engineering, Xi'an Shiyou University, Xi'an, 710065, China; Gaungdong Provincial Key Laboratory of Advance Energy Storage Materials, South China University of Technology, Guangzhou, 510640, China.
| | - Fuxue Yan
- School of Materials Science and Engineering, Xi'an University of Technology, 5 South Jinhua Road, Xi'an, 710048, China
| | - Bailing Jiang
- School of Materials Science and Engineering, Xi'an University of Technology, 5 South Jinhua Road, Xi'an, 710048, China
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18
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Abstract
Enamel is the hardest and most resilient tissue in the human body. Enamel includes morphologically aligned, parallel, ∼50 nm wide, microns-long nanocrystals, bundled either into 5-μm-wide rods or their space-filling interrod. The orientation of enamel crystals, however, is poorly understood. Here we show that the crystalline c-axes are homogenously oriented in interrod crystals across most of the enamel layer thickness. Within each rod crystals are not co-oriented with one another or with the long axis of the rod, as previously assumed: the c-axes of adjacent nanocrystals are most frequently mis-oriented by 1°-30°, and this orientation within each rod gradually changes, with an overall angle spread that is never zero, but varies between 30°-90° within one rod. Molecular dynamics simulations demonstrate that the observed mis-orientations of adjacent crystals induce crack deflection. This toughening mechanism contributes to the unique resilience of enamel, which lasts a lifetime under extreme physical and chemical challenges.
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19
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Smith CE, Hu Y, Hu JCC, Simmer JP. Characteristics of the transverse 2D uniserial arrangement of rows of decussating enamel rods in the inner enamel layer of mouse mandibular incisors. J Anat 2019; 235:912-930. [PMID: 31402450 PMCID: PMC6794213 DOI: 10.1111/joa.13053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2019] [Indexed: 12/16/2022] Open
Abstract
The 2D arrangement of rows of enamel rods with alternating (decussating) tilt angles across the thickness of the inner layer in rat and mouse incisor enamel is well known and assumed to occur in a uniform and repetitive pattern. Some irregularities in the arrangement of rows have been reported, but no detailed investigation of row structure across the entire inner enamel layer currently exists. This investigation was undertaken to determine if the global row pattern in mouse mandibular incisor enamel is predominately regular in nature with only occasional anomalies or if rows of enamel rods have more spatial complexity than previously suspected. The data from this investigation indicate that rows of enamel rods are highly variable in length and have complex transverse arrangements across the width and thickness of the inner enamel layer. The majority of rows are short or medium in length, with 87% having < 100 rods per row. The remaining 13% are long rows (with 100-233 rods per row) that contain 46% of all enamel rods seen in transverse sections. Variable numbers of rows were associated with the lateral, central and mesial regions of the enamel layer. Each region contained different ratios of short, medium and long rows. A variety of relationships was found along the transverse length of rows in each region, including uniform associations of alternating rod tilts between neighboring rows, and instances where two rows having the same rod tilt were paired for variable distances then moved apart to accommodate rows of opposite tilt. Sometimes a row appeared to branch into two rows with the same tilt, or conversely where two rows merged into one row depending upon the mesial-to-lateral direction in which the row was viewed. Some rows showed both pairing and branching/merging along their length. These tended to be among the longest rows identified, and they often crossed the central region with extensions into the lateral and mesial regions. The most frequent row arrangement was a row of petite length nestled at the side of another row having the same rod tilt (30% of all rows). These were termed 'focal stacks' and may relate to the evolution of uniserial rat and mouse incisor enamel from a multilayered ancestor. The mesial and lateral endpoints of rows also showed complex arrangements with the dentinoenamel junction (DEJ), the inner enamel layer itself, and the boundary area to the outer enamel layer. It was concluded that the diversity in row lengths and various spatial arrangements both within and between rows across the transverse plane provides a method to interlock the enamel layer across each region and keep the enamel layer compact relative to the curving DEJ surface. The uniserial pattern for rows in mouse mandibular incisors is not uniform, but diverse and very complex.
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Affiliation(s)
- Charles E Smith
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Anatomy & Cell Biology, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Jan C-C Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
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20
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Green DR, Schulte F, Lee KH, Pugach MK, Hardt M, Bidlack FB. Mapping the Tooth Enamel Proteome and Amelogenin Phosphorylation Onto Mineralizing Porcine Tooth Crowns. Front Physiol 2019; 10:925. [PMID: 31417410 PMCID: PMC6682599 DOI: 10.3389/fphys.2019.00925] [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: 03/27/2019] [Accepted: 07/09/2019] [Indexed: 01/13/2023] Open
Abstract
Tooth enamel forms in an ephemeral protein matrix where changes in protein abundance, composition and posttranslational modifications are critical to achieve healthy enamel properties. Amelogenin (AMELX) with its splice variants is the most abundant enamel matrix protein, with only one known phosphorylation site at serine 16 shown in vitro to be critical for regulating mineralization. The phosphorylated form of AMELX stabilizes amorphous calcium phosphate, while crystalline hydroxyapatite forms in the presence of the unphosphorylated protein. While AMELX regulates mineral transitions over space and time, it is unknown whether and when un-phosphorylated amelogenin occurs during enamel mineralization. This study aims to reveal the spatiotemporal distribution of the cleavage products of the most abundant AMLEX splice variants including the full length P173, the shorter leucine-rich amelogenin protein (LRAP), and the exon 4-containing P190 in forming enamel, all within the context of the changing enamel matrix proteome during mineralization. We microsampled permanent pig molars, capturing known stages of enamel formation from both crown surface and inner enamel. Nano-LC-MS/MS proteomic analyses after tryptic digestion rendered more than 500 unique protein identifications in enamel, dentin, and bone. We mapped collagens, keratins, and proteolytic enzymes (CTSL, MMP2, MMP10) and determined distributions of P173, LRAP, and P190 products, the enamel proteins enamelin (ENAM) and ameloblastin (AMBN), and matrix-metalloprotease-20 (MMP20) and kallikrein-4 (KLK4). All enamel proteins and KLK4 were near-exclusive to enamel and in excellent agreement with published abundance levels. Phosphorylated P173 and LRAP products decreased in abundance from recently deposited matrix toward older enamel, mirrored by increasing abundances of testicular acid phosphatase (ACPT). Our results showed that hierarchical clustering analysis of secretory enamel links closely matching distributions of unphosphorylated P173 and LRAP products with ACPT and non-traditional amelogenesis proteins, many associated with enamel defects. We report higher protein diversity than previously published and Gene Ontology (GO)-defined protein functions related to the regulation of mineral formation in secretory enamel (e.g., casein α-S1, CSN1S1), immune response in erupted enamel (e.g., peptidoglycan recognition protein, PGRP), and phosphorylation. This study presents a novel approach to characterize and study functional relationships through spatiotemporal mapping of the ephemeral extracellular matrix proteome.
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Affiliation(s)
- Daniel R Green
- The Forsyth Institute, Cambridge, MA, United States.,Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | | | - Kyu-Ha Lee
- The Forsyth Institute, Cambridge, MA, United States.,Department of Oral Health Policy and Epidemiology, Harvard School of Dental Medicine, Boston, MA, United States
| | - Megan K Pugach
- The Forsyth Institute, Cambridge, MA, United States.,Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States
| | - Markus Hardt
- The Forsyth Institute, Cambridge, MA, United States.,Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States
| | - Felicitas B Bidlack
- The Forsyth Institute, Cambridge, MA, United States.,Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States
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21
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van Casteren A, Crofts SB. The Materials of Mastication: Material Science of the Humble Tooth. Integr Comp Biol 2019; 59:1681-1689. [DOI: 10.1093/icb/icz129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Dental functional morphology, as a field, represents a confluence of materials science and biology. Modern methods in materials testing have been influential in driving the understanding of dental tissues and tooth functionality. Here we present a review of dental enamel, the outermost tissue of teeth. Enamel is the hardest biological tissue and exhibits remarkable resilience even when faced with a variety of mechanical threats. In the light of recent work, we progress the argument that the risk of mechanical degradation across multiple scales exhibits a strong and continued selection pressure on structural organization of enamel. The hierarchical nature of enamel structure presents a range of scale-dependent toughening mechanisms and provides a means by which natural selection can drive the specialization of this tissue from nanoscale reorganization to whole tooth morphology. There has been much learnt about the biomechanics of enamel recently, yet our understanding of the taxonomic diversity of this tissue is still lacking and may form an interesting avenue for future research.
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Affiliation(s)
- Adam van Casteren
- Department of Anthropology, Washington University in St Louis, Campus Box 1114, One Brookings Drive, St Louis, MO 63130, USA
| | - Stephanie B Crofts
- Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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22
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Wang X, Zhang N, Zhong Y, Yan F, Jiang B. Wild boar's tusk enamel: Structure and mechanical behavior. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 100:354-362. [DOI: 10.1016/j.msec.2019.03.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/22/2019] [Accepted: 03/04/2019] [Indexed: 11/28/2022]
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23
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The potential of three-dimensional printing technologies to unlock the development of new ‘bio-inspired’ dental materials: an overview and research roadmap. J Prosthodont Res 2019; 63:131-139. [DOI: 10.1016/j.jpor.2018.10.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 10/05/2018] [Accepted: 10/26/2018] [Indexed: 11/23/2022]
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24
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Smith CE, Hu Y, Hu JC, Simmer JP. Quantitative analysis of the core 2D arrangement and distribution of enamel rods in cross-sections of mandibular mouse incisors. J Anat 2019; 234:274-290. [PMID: 30426488 PMCID: PMC6326826 DOI: 10.1111/joa.12912] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2018] [Indexed: 02/02/2023] Open
Abstract
Considerable descriptive information about the overall organization of mouse mandibular incisor enamel is available but almost nothing is known about the quantitative characteristics of enamel rod arrangement and distribution in these teeth. This has important implications concerning cell movement during the secretory stage because each ameloblast makes one enamel rod. Knowing how many enamel rods are cut open in a cross-section of the enamel layer could provide insights into understanding the dynamics of how groups of ameloblasts form the enamel layer. In this study, cross-sections of fully mineralized enamel were cut on 24 mandibular mouse incisors, polished and etched, and imaged by scanning electron microscopy in backscatter mode. Montaged maps of the entire enamel layer were made at high magnification and the enamel rod profiles in each map were color-coded based upon rod category. Quantitative analyses of each color layer in the maps were then performed using standard routines available in imagej. The data indicated that that there were on average 7233 ± 575 enamel rod profiles per cross-section in mandibular incisors of 7-week-old mice, with 70% located in the inner enamel layer, 27% located in the outer enamel layer, and 3% positioned near the mesial and lateral cementoenamel junctions. All enamel rod profiles showed progressive increases in tilt angles, some very large in magnitude, from the lateral to mesial sides of the enamel layer, whereas only minor variations in tilt angle were found relative to enamel thickness at given locations across the enamel layer. The decussation angle between alternating rows of rod profiles within the inner enamel layer was fairly constant from the lateral to central labial sides of the enamel layer, but it increased dramatically in the mesial region of the enamel layer. The packing density of all rod profiles decreased from lateral to central labial regions of the enamel layer and then in progressing mesially, decreased slightly (inner enamel, mesial tilt), increased slightly (outer enamel layer) or almost doubled in magnitude (inner enamel, lateral tilt). It was concluded that these variations in rod tilt angle and packing densities are adaptations that allow the tooth to maintain a sharp incisal edge and shovel-shape as renewing segments formed by around 7200 ameloblasts are brought onto the occluding surface of the tooth by continuous renewal.
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Affiliation(s)
- Charles E. Smith
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMIUSA
- Department of Anatomy & Cell BiologyFaculty of MedicineMcGill UniversityMontrealQCCanada
| | - Yuanyuan Hu
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMIUSA
| | - Jan C‐C. Hu
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMIUSA
| | - James P. Simmer
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMIUSA
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Liu Z, Weng Z, Zhai ZF, Huang N, Zhang ZJ, Tan J, Jiang C, Jiao D, Tan G, Zhang J, Jiang X, Zhang Z, Ritchie RO. Hydration-induced nano- to micro-scale self-recovery of the tooth enamel of the giant panda. Acta Biomater 2018; 81:267-277. [PMID: 30273740 DOI: 10.1016/j.actbio.2018.09.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/17/2018] [Accepted: 09/27/2018] [Indexed: 11/19/2022]
Abstract
The tooth enamel of vertebrates comprises a hyper-mineralized bioceramic, but is distinguished by an exceptional durability to resist impact and wear throughout the lifetime of organisms; however, enamels exhibit a low resistance to the initiation of large-scale cracks comparable to that of geological minerals based on fracture mechanics. Here we reveal that the tooth enamel, specifically from the giant panda, is capable of developing durability through counteracting the early stage of damage by partially recovering its innate geometry and structure at nano- to micro- length-scales autonomously. Such an attribute results essentially from the unique architecture of tooth enamel, specifically the vertical alignment of nano-scale mineral fibers and micro-scale prisms within a water-responsive organic-rich matrix, and can lead to a decrease in the dimension of indent damage in enamel introduced by indentation. Hydration plays an effective role in promoting the recovery process and improving the indentation fracture toughness of enamel (by ∼73%), at a minor cost of micro-hardness (by ∼5%), as compared to the dehydrated state. The nano-scale mechanisms that are responsible for the recovery deformation, specifically the reorientation and rearrangement of mineral fragments and the inter- and intra-prismatic sliding between constituents that are closely related to the viscoelasticity of organic matrix, are examined and analyzed with respect to the structure of tooth enamel. Our study sheds new light on the strategies underlying Nature's design of durable ceramics which could be translated into man-made systems in developing high-performance ceramic materials. STATEMENT OF SIGNIFICANCE: Tooth enamel plays a critical role in the function of teeth by providing a hard surface layer to resist wear/impact throughout the lifetime of organisms; however, such enamel exhibits a remarkably low resistance to the initiation of large-scale cracks, of hundreds of micrometers or more, comparable to that of geological minerals. Here we reveal that tooth enamel, specifically that of the giant panda, is capable of partially recovering its geometry and structure to counteract the early stages of damage at nano- to micro-scale dimensions autonomously. Such an attribute results essentially from the architecture of enamel but is markedly enhanced by hydration. Our work discerns a series of mechanisms that lead to the deformation and recovery of enamel and identifies a unique source of durability in the enamel to accomplish this function. The ingenious design of tooth enamel may inspire the development of new durable ceramic materials in man-made systems.
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Affiliation(s)
- Zengqian Liu
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China; Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA
| | - Zhaoyong Weng
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Zhao-Feng Zhai
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Nan Huang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Zhen-Jun Zhang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Jun Tan
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Chuanbin Jiang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Da Jiao
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Guoqi Tan
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China; School of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Jian Zhang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China; State Key Laboratory of Advanced Non-ferrous Materials, Lanzhou University of Technology, Lanzhou 730050, China
| | - Xin Jiang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Zhefeng Zhang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
| | - Robert O Ritchie
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA.
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Al-Jawad M, Addison O, Sirovica S, Siddiqui S, Martin RA, Wood DJ, Watts DC. Intracoronal stress transfer through enamel following RBC photopolymerisation: A synchrotron X-ray study. Dent Mater 2018; 34:1426-1439. [PMID: 30119841 DOI: 10.1016/j.dental.2018.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/29/2018] [Accepted: 07/29/2018] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To measure the spatial distribution of crystallographic strain in tooth enamel induced by the photo-polymerisation of a dimethacrylate resin based composite cavity restoration. METHODS Six sound first premolar teeth, allocated into two groups (n=3), were prepared with mesio-occlusal distal cavities. The enamel was machined at the point of maximum convexity on the outer tooth to create a vertical fin of thickness 100μm and 0.5mm depth to allow for synchrotron X-ray diffraction measurements. 2D diffraction patterns were used to determine crystallite orientation and quantify changes in the hydroxyapatite crystal lattice parameters, before and after photo-polymerisation of a composite material placed in the cavity, to calculate strain in the respective axis. The composite was photo-polymerised with either relatively high (1200mWcm-2, group 1) or low (480mWcm-2, group 2) irradiances using LED or quartz halogen light sources, respectively. A paired t-test was used to determine significant differences in strain between irradiance protocols at ɑ=0.001. RESULTS Photo-polymerisation of the composite in the adjacent cavity induced significant changes in both the crystallographic c and a axes of the enamel measurement area. However the magnitude of strain was low with ∼0.1% difference before and after composite photo-polymerisation. Strain in enamel was not uniformly distributed and varied spatially as a function of crystallite orientation. Increased alignment of crystallites perpendicular to the cavity wall was associated with higher c axis strain. Additionally, strain was significantly greater in the c (p<0.001) and a axis (p<0.001) when using a high irradiance photo-polymerisation protocol. SIGNIFICANCE Although cuspal deflection is routinely measured to indirectly assess the 'global' effect of composite shrinkage on the tooth-restoration complex, here we show that absolute strains generated in enamel are low, indicating strain relief mechanisms may be operative. The use of low irradiance protocols for photo-polymerisation resulted in reduced strain.
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Affiliation(s)
- Maisoon Al-Jawad
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Owen Addison
- Biomaterials Unit, University of Birmingham School of Dentistry, Birmingham, UK; University of Alberta, School of Dentistry, Edmonton, AB, Canada.
| | - Slobodan Sirovica
- University of Alberta, School of Dentistry, Edmonton, AB, Canada; Aston Institute of Materials Research, Aston University, Birmingham, UK
| | - Samera Siddiqui
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Richard A Martin
- Aston Institute of Materials Research, Aston University, Birmingham, UK
| | - David J Wood
- Biomaterials and Tissue Engineering Research Group, School of Dentistry, University of Leeds, Leeds, UK
| | - David C Watts
- School of Medical Sciences and Photon Science Institute, University of Manchester, UK
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Hua L, Zheng J, Zhou Z, Tian ZR. Water-Switchable Interfacial Bonding on Tooth Enamel Surface. ACS Biomater Sci Eng 2018; 4:2364-2369. [PMID: 33435101 DOI: 10.1021/acsbiomaterials.8b00403] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Tooth enamel is a distinctive nanocomposite with a highly organized hierarchical structure made of nanometer- and micrometer-scale building blocks. This structure has an excellent mechanical function that can last for decades thanks to an effective but underexploited interfacial chemical bonding between the building blocks. In this study, the nanomechanical system test (NST), scanning electron microscope (SEM), X-ray diffraction (XRD, including powder XRD or PXRD, small angle XRD or SAXRD, and grazing incidence small angle XRD or GISAXRD), and atomic force microscope (AFM) have been employed to analyze the water-mediated bonding on the enamel surface. Via the cycling between hydration, dehydration, and rehydration treatments, a reversible change in the interfacial distance (i.e., d-space in the XRD pattern) between hydroxyapatite (HAP) nanocrystallites have been found switchable between the embrittling and toughening on the enamel surface. From the hydrated to the dehydrated conditions, an energy dissipation to deform a unit volume (1 μm3) of biocomposite on the enamel surface and subsurface has decreased by 20%. This finding can help quantify and predict biomineral-surface properties in all humidity and develop new methods to protect tooth enamel of "dry-mouth" patients.
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Affiliation(s)
- Licheng Hua
- Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China.,Faculty of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, Zhejiang, China
| | - Jing Zheng
- Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
| | - Zhongrong Zhou
- Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China
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Abstract
This article provides a brief review of recent investigations concerning the structure and properties of the tooth. The last decade has brought a greater emphasis on the durability of the tooth, an improved understanding of the fatigue and fracture behavior of the principal tissues, and their importance to tooth failures. The primary contributions to tooth durability are discussed, including the process of placing a restoration, the impact of aging, and challenges posed by the oral environment. The significance of these findings to the dental community and their importance to the pursuit of lifelong oral health are highlighted.
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Affiliation(s)
- Dwayne D Arola
- Department of Materials Science and Engineering, University of Washington School of Dentistry, Roberts Hall, 333, Box 352120, Seattle, WA 98195-2120, USA; Department of Oral Health Sciences, University of Washington School of Dentistry, Seattle, WA 98195-2120, USA; Department of Restorative Dentistry, Box 357456, University of Washington School of Dentistry, Seattle, WA 98195-7456, USA.
| | - Shanshan Gao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Renmin South Road, Chengdu, 610041, China
| | - Hai Zhang
- Department of Restorative Dentistry, Box 357456, University of Washington School of Dentistry, Seattle, WA 98195-7456, USA
| | - Radi Masri
- Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland School of Dentistry, 650 West Baltimore Street, 4th Floor, Suite 4228, Baltimore, MD 21201, USA
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van Casteren A, Lucas PW, Strait DS, Michael S, Bierwisch N, Schwarzer N, Al-Fadhalah KJ, Almusallam AS, Thai LA, Saji S, Shekeban A, Swain MV. Evidence that metallic proxies are unsuitable for assessing the mechanics of microwear formation and a new theory of the meaning of microwear. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171699. [PMID: 29892367 PMCID: PMC5990759 DOI: 10.1098/rsos.171699] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 04/20/2018] [Indexed: 05/14/2023]
Abstract
Mammalian tooth wear research reveals contrasting patterns seemingly linked to diet: irregularly pitted enamel surfaces, possibly from consuming hard seeds, versus roughly aligned linearly grooved surfaces, associated with eating tough leaves. These patterns are important for assigning diet to fossils, including hominins. However, experiments establishing conditions necessary for such damage challenge this paradigm. Lucas et al. (Lucas et al. 2013 J. R. Soc. Interface10, 20120923. (doi:10.1098/rsif.2012.0923)) slid natural objects against enamel, concluding anything less hard than enamel would rub, not abrade, its surface (producing no immediate wear). This category includes all organic plant matter. Particles harder than enamel, with sufficiently angular surfaces, could abrade it immediately, prerequisites that silica/silicate particles alone possess. Xia et al. (Xia, Zheng, Huang, Tian, Chen, Zhou, Ungar, Qian. 2015 Proc. Natl Acad. Sci. USA112, 10 669-10 672. (doi:10.1073/pnas.1509491112)) countered with experiments using brass and aluminium balls. Their bulk hardness was lower than enamel, but the latter was abraded. We examined the ball exteriors to address this discrepancy. The aluminium was surfaced by a thin rough oxide layer harder than enamel. Brass surfaces were smoother, but work hardening during manufacture gave them comparable or higher hardness than enamel. We conclude that Xia et al.'s results are actually predicted by the mechanical model of Lucas et al. To explain wear patterns, we present a new model of textural formation, based on particle properties and presence/absence of silica(tes).
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Affiliation(s)
- Adam van Casteren
- Max Planck Weizmann Center for Integrative Archeology and Anthropology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103, Leipzig, Germany
| | - Peter W. Lucas
- Smithsonian Tropical Research Institute, Luis Clement Ave., Bldg. 401 Tupper Balboa Ancon, Panama, Republic of Panama
| | - David S. Strait
- Department of Anthropology, Washington University in St Louis, Campus Box 1114, One Brookings Drive, St Louis, MO 63130, USA
| | - Shaji Michael
- Department of Bioclinical Sciences, Faculty of Dentistry, Kuwait University, PO Box 24923, Safat 11310, Kuwait
| | - Nick Bierwisch
- Saxonian Institute of Surface Mechanics SIO, Tankow 2, 18569 Ummanz, Rügen, Germany
| | - Norbert Schwarzer
- Saxonian Institute of Surface Mechanics SIO, Tankow 2, 18569 Ummanz, Rügen, Germany
| | - Khaled J. Al-Fadhalah
- Department of Mechanical Engineering, College of Engineering and Petroleum, Kuwait University, PO Box 5969, Safat 13060, Kuwait
| | - Abdulwahab S. Almusallam
- Department of Chemical Engineering, College of Engineering and Petroleum, Kuwait University, PO Box 5969, Safat 13060, Kuwait
| | - Lidia A. Thai
- Nanotechnology Research Facility, College of Engineering and Petroleum, Kuwait University, PO Box 5969, Safat 13060, Kuwait
| | - Sreeja Saji
- Department of Bioclinical Sciences, Faculty of Dentistry, Kuwait University, PO Box 24923, Safat 11310, Kuwait
| | - Ali Shekeban
- Nanotechnology Research Facility, College of Engineering and Petroleum, Kuwait University, PO Box 5969, Safat 13060, Kuwait
| | - Michael V. Swain
- Department of Bioclinical Sciences, Faculty of Dentistry, Kuwait University, PO Box 24923, Safat 11310, Kuwait
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van Casteren A, Lucas PW, Strait DS, Michael S, Bierwisch N, Schwarzer N, Al-Fadhalah KJ, Almusallam AS, Thai LA, Saji S, Shekeban A, Swain MV. Evidence that metallic proxies are unsuitable for assessing the mechanics of microwear formation and a new theory of the meaning of microwear. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171699. [PMID: 29892367 DOI: 10.5061/dryad.72431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 04/20/2018] [Indexed: 05/27/2023]
Abstract
Mammalian tooth wear research reveals contrasting patterns seemingly linked to diet: irregularly pitted enamel surfaces, possibly from consuming hard seeds, versus roughly aligned linearly grooved surfaces, associated with eating tough leaves. These patterns are important for assigning diet to fossils, including hominins. However, experiments establishing conditions necessary for such damage challenge this paradigm. Lucas et al. (Lucas et al. 2013 J. R. Soc. Interface10, 20120923. (doi:10.1098/rsif.2012.0923)) slid natural objects against enamel, concluding anything less hard than enamel would rub, not abrade, its surface (producing no immediate wear). This category includes all organic plant matter. Particles harder than enamel, with sufficiently angular surfaces, could abrade it immediately, prerequisites that silica/silicate particles alone possess. Xia et al. (Xia, Zheng, Huang, Tian, Chen, Zhou, Ungar, Qian. 2015 Proc. Natl Acad. Sci. USA112, 10 669-10 672. (doi:10.1073/pnas.1509491112)) countered with experiments using brass and aluminium balls. Their bulk hardness was lower than enamel, but the latter was abraded. We examined the ball exteriors to address this discrepancy. The aluminium was surfaced by a thin rough oxide layer harder than enamel. Brass surfaces were smoother, but work hardening during manufacture gave them comparable or higher hardness than enamel. We conclude that Xia et al.'s results are actually predicted by the mechanical model of Lucas et al. To explain wear patterns, we present a new model of textural formation, based on particle properties and presence/absence of silica(tes).
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Affiliation(s)
- Adam van Casteren
- Max Planck Weizmann Center for Integrative Archeology and Anthropology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103, Leipzig, Germany
| | - Peter W Lucas
- Smithsonian Tropical Research Institute, Luis Clement Ave., Bldg. 401 Tupper Balboa Ancon, Panama, Republic of Panama
| | - David S Strait
- Department of Anthropology, Washington University in St Louis, Campus Box 1114, One Brookings Drive, St Louis, MO 63130, USA
| | - Shaji Michael
- Department of Bioclinical Sciences, Faculty of Dentistry, Kuwait University, PO Box 24923, Safat 11310, Kuwait
| | - Nick Bierwisch
- Saxonian Institute of Surface Mechanics SIO, Tankow 2, 18569 Ummanz, Rügen, Germany
| | - Norbert Schwarzer
- Saxonian Institute of Surface Mechanics SIO, Tankow 2, 18569 Ummanz, Rügen, Germany
| | - Khaled J Al-Fadhalah
- Department of Mechanical Engineering, College of Engineering and Petroleum, Kuwait University, PO Box 5969, Safat 13060, Kuwait
| | - Abdulwahab S Almusallam
- Department of Chemical Engineering, College of Engineering and Petroleum, Kuwait University, PO Box 5969, Safat 13060, Kuwait
| | - Lidia A Thai
- Nanotechnology Research Facility, College of Engineering and Petroleum, Kuwait University, PO Box 5969, Safat 13060, Kuwait
| | - Sreeja Saji
- Department of Bioclinical Sciences, Faculty of Dentistry, Kuwait University, PO Box 24923, Safat 11310, Kuwait
| | - Ali Shekeban
- Nanotechnology Research Facility, College of Engineering and Petroleum, Kuwait University, PO Box 5969, Safat 13060, Kuwait
| | - Michael V Swain
- Department of Bioclinical Sciences, Faculty of Dentistry, Kuwait University, PO Box 24923, Safat 11310, Kuwait
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Fractographic Analysis of a Split Tooth Presenting Radiographically as a Horizontal Root Fracture in an Unrestored Mandibular Second Molar. J Endod 2017; 44:304-311. [PMID: 29275853 DOI: 10.1016/j.joen.2017.10.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/10/2017] [Accepted: 10/17/2017] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Spontaneously catastrophic fracture of intact unrestored molar teeth is not common. Nevertheless, cracks do occur that progress apically, resulting in the complete splitting of the tooth and root. This report describes a catastrophic fracture that occurred in an unrestored mandibular second molar resulting in a previously unreported combination of a longitudinal and horizontal root fracture, appearing radiographically as a single horizontal root fracture. METHODS Tooth fragments were examined clinically, stereoscopically, and by scanning electron microscopy. Fractographic analysis was used to investigate the dynamics involved in fracture initiation, structural resistances encountered during progression of the fracture, and reasons for direction changes culminating in the unusual radiographic appearance. RESULT The uniqueness of this report is that it describes fractographic evidence of factors contributing to the initiation and progression of an in vivo crack. It shows fracture markings that are evidence of the energy dissipation mechanisms. The topographic location of these markings confirmed that cracks occur in vivo in stages with different rates of progression. CONCLUSION This analysis helps to explain why split teeth are uncommon and highlights some of the multitude of factors that have to coincide for a tooth to catastrophically fracture. The report describes the mechanism of fracture and should stimulate clinicians and researchers to investigate cracking of teeth by undertaking fractographic analysis of extracted cracked teeth.
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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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Yilmaz ED, Schneider GA. Mechanical behavior of enamel rods under micro-compression. J Mech Behav Biomed Mater 2016; 63:183-194. [PMID: 27415405 DOI: 10.1016/j.jmbbm.2016.06.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/09/2016] [Accepted: 06/17/2016] [Indexed: 11/24/2022]
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Ma S, Scheider I, Bargmann S. Anisotropic constitutive model incorporating multiple damage mechanisms for multiscale simulation of dental enamel. J Mech Behav Biomed Mater 2016; 62:515-533. [DOI: 10.1016/j.jmbbm.2016.05.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/23/2016] [Accepted: 05/24/2016] [Indexed: 01/04/2023]
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Lucas PW, Wagner M, Al-Fadhalah K, Almusallam AS, Michael S, Thai LA, Strait DS, Swain MV, van Casteren A, Renno WM, Shekeban A, Philip SM, Saji S, Atkins AG. Dental abrasion as a cutting process. Interface Focus 2016; 6:20160008. [PMID: 27274807 DOI: 10.1098/rsfs.2016.0008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A mammalian tooth is abraded when a sliding contact between a particle and the tooth surface leads to an immediate loss of tooth tissue. Over time, these contacts can lead to wear serious enough to impair the oral processing of food. Both anatomical and physiological mechanisms have evolved in mammals to try to prevent wear, indicating its evolutionary importance, but it is still an established survival threat. Here we consider that many wear marks result from a cutting action whereby the contacting tip(s) of such wear particles acts akin to a tool tip. Recent theoretical developments show that it is possible to estimate the toughness of abraded materials via cutting tests. Here, we report experiments intended to establish the wear resistance of enamel in terms of its toughness and how friction varies. Imaging via atomic force microscopy (AFM) was used to assess the damage involved. Damage ranged from pure plastic deformation to fracture with and without lateral microcracks. Grooves cut with a Berkovich diamond were the most consistent, suggesting that the toughness of enamel in cutting is 244 J m(-2), which is very high. Friction was higher in the presence of a polyphenolic compound, indicating that this could increase wear potential.
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Affiliation(s)
- Peter W Lucas
- Department of Bioclinical Sciences, Faculty of Dentistry , Kuwait University , PO Box 24923, Safat 11310 , Kuwait
| | - Mark Wagner
- Department of Mechanical Engineering, School of Engineering and Applied Science, Science and Engineering Hall, 800 22nd St NW, Washington, DC 20052 , USA
| | - Khaled Al-Fadhalah
- Department of Mechanical Engineering , Kuwait University , PO Box 5969, Safat 13060 , Kuwait
| | | | - Shaji Michael
- Department of Bioclinical Sciences, Faculty of Dentistry , Kuwait University , PO Box 24923, Safat 11310 , Kuwait
| | - Lidia A Thai
- Nanotechnology Research Facility, College of Engineering and Petroleum , Kuwait University , PO Box 5969, Safat 13060 , Kuwait
| | - David S Strait
- Department of Anthropology , Washington University in St Louis , Campus Box 1114, One Brookings Drive, St Louis, MO 63130-4899 , USA
| | - Michael V Swain
- Department of Bioclinical Sciences, Faculty of Dentistry , Kuwait University , PO Box 24923, Safat 11310 , Kuwait
| | - Adam van Casteren
- Max Planck Weizmann Center for Integrated Archaeology and Anthropology , Max Planck Institute for Evolutionary Anthropology , Deutscher Platz 6, 04103 Leipzig , Germany
| | - Waleed M Renno
- Department of Anatomy, Faculty of Medicine , Kuwait University , PO Box 24923, Safat 11310 , Kuwait
| | - Ali Shekeban
- Nanotechnology Research Facility, College of Engineering and Petroleum , Kuwait University , PO Box 5969, Safat 13060 , Kuwait
| | - Swapna M Philip
- Department of Bioclinical Sciences, Faculty of Dentistry , Kuwait University , PO Box 24923, Safat 11310 , Kuwait
| | - Sreeja Saji
- Department of Bioclinical Sciences, Faculty of Dentistry , Kuwait University , PO Box 24923, Safat 11310 , Kuwait
| | - Anthony G Atkins
- School of Construction Management and Engineering , University of Reading , Whiteknights, PO Box 219, Reading RG6 6AW , UK
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Lucas PW, Philip SM, Al-Qeoud D, Al-Draihim N, Saji S, van Casteren A. Structure and scale of the mechanics of mammalian dental enamel viewed from an evolutionary perspective. Evol Dev 2015; 18:54-61. [DOI: 10.1111/ede.12169] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Peter W. Lucas
- Department of Bioclinical Sciences; Faculty of Dentistry; Kuwait University; Jabriya, Kuwait, P.O. Box 24923 Safat 13110 Kuwait
| | - Swapna M. Philip
- Department of Bioclinical Sciences; Faculty of Dentistry; Kuwait University; Jabriya, Kuwait, P.O. Box 24923 Safat 13110 Kuwait
| | - Dareen Al-Qeoud
- Department of Bioclinical Sciences; Faculty of Dentistry; Kuwait University; Jabriya, Kuwait, P.O. Box 24923 Safat 13110 Kuwait
| | - Nuha Al-Draihim
- Department of Bioclinical Sciences; Faculty of Dentistry; Kuwait University; Jabriya, Kuwait, P.O. Box 24923 Safat 13110 Kuwait
| | - Sreeja Saji
- Department of Bioclinical Sciences; Faculty of Dentistry; Kuwait University; Jabriya, Kuwait, P.O. Box 24923 Safat 13110 Kuwait
| | - Adam van Casteren
- Max Planck Weizmann Center for Integrative Archaeology and Anthropology; Max Planck Institute for Evolutionary Anthropology; Deutscher Platz 6 D-04103 Leipzig Germany
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Armstrong RW, Antolovich SD, Griffiths JR, Knott JF. Fracturing across the multi-scales of diverse materials. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2014.0474. [PMID: 25713460 PMCID: PMC4342982 DOI: 10.1098/rsta.2014.0474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Everyone has to deal with fracturing of materials at one level or another, beginning from normal household chores and extending to the largest scale of observations reported for catastrophic events occurring on a geological level or even expanded to events in outer space. Such wide perspective is introduced in the current introduction of this theme issue. The follow-on organization of technical articles provides a flavour of the range in size scales at which fracturing occurs in a wide diversity of materials-from 'fracking' oil extraction and earth moving to laboratory testing of rock material and extending to the cracking of tooth enamel. Of important scientific interest are observations made and analysed at the smallest dimensions corresponding to the mechanisms by which fracture is either enhanced or hindered by permanent deformation or other processes. Such events are irrevocably linked to the atomic structure in all engineering materials, a sampling of which is presented, including results for crystalline and amorphous materials. Hooray for the broad subject description that is hoped to be appealing to the interested reader.
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Affiliation(s)
- R W Armstrong
- Department of Mechanical Engineering, University of Maryland, College Park, MD, USA
| | | | | | - J F Knott
- School of Metallurgy and Materials, University of Birmingham, , UK
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