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Wilmers J, Wurmshuber M, Gescher C, Graupp CM, Kiener D, Bargmann S. Unraveling the orientation-dependent mechanics of dental enamel in the red-necked wallaby. Acta Biomater 2024:S1742-7061(24)00373-8. [PMID: 38992410 DOI: 10.1016/j.actbio.2024.07.004] [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: 04/04/2024] [Revised: 07/02/2024] [Accepted: 07/03/2024] [Indexed: 07/13/2024]
Abstract
Dental enamels of different species exhibit a wide variety of microstructural patterns that are attractive to mimic in bioinspired composites to simultaneously achieve high stiffness and superior toughness. Non-human enamel types, however, have not yet received the deserved attention and their mechanical behaviour is largely unknown. Using nanoindentation tests and finite element modelling, we investigate the mechanical behaviour of Macropus rufogriseus enamel, revealing a dominating influence of the microstructure on the effective mechanical behaviour and allowing insight into structural dependencies. We find a shallow gradient in stiffness and low degree of anisotropy over the enamel thickness that is attributed to the orientation and size of microstructural features. Most notably, M. rufogriseus's modified radial enamel has a far simpler structural pattern than other species', but achieves great property amplification. It is therefore a very promising template for biomimetic design. STATEMENT OF SIGNIFICANCE: The diversity of dental enamel structures in different species is well documented, but the mechanical behaviour of non-human enamel types is largely unknown. In this work, we investigate the microstructure and structure-dependent mechanical properties of marsupial enamel by nanoindentation and finite element simulations. Combining these methods gives valuable insights into the performance of modified radial enamel structures. Their stiffness and toughness stems from a unique structural design that is far less complex than well-studied human enamel types, which makes it a uniquely suitable template for biomimetic design.
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Affiliation(s)
- Jana Wilmers
- Chair of Solid Mechanics, University of Wuppertal, Germany; Wuppertal Center for Smart Materials, University of Wuppertal, Germany
| | - Michael Wurmshuber
- Department of Materials Science & Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany; Department Materials Science, Montanuniversität Leoben, Austria
| | | | | | - Daniel Kiener
- Department Materials Science, Montanuniversität Leoben, Austria.
| | - Swantje Bargmann
- Chair of Solid Mechanics, University of Wuppertal, Germany; Wuppertal Center for Smart Materials, University of Wuppertal, Germany
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Saxena K, Ann CM, Azwar MABM, Banavar SR, Matinlinna J, Peters OA, Daood U. Effect of strontium fluoride on mechanical and remineralization properties of enamel: An in-vitro study on a modified orthodontic adhesive. Dent Mater 2024; 40:811-823. [PMID: 38490919 DOI: 10.1016/j.dental.2024.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 01/05/2024] [Accepted: 02/12/2024] [Indexed: 03/17/2024]
Abstract
OBJECTIVES Evaluate the ability of strontium fluoride on bond strength and enamel integrity after incorporation within orthodontic adhesive system as a delivery vehicle. METHODS Experimental orthodontic adhesive system Transbond™ XT were modified with 1% Sr2+, 0.5% SrF2, 1% strontium, 0.5% Sr2+, 1% F-, 0.5% F-, and no additions were control. Mixing of formulation was monitored using Fourier transform infrared spectroscopy. Small-molecule drug-discovery suite was used to gain insights into Sr2+, F-, and SrF2 binding. Shear bond testing was performed after 6-months of ageing. Enamel blocks were cut, and STEM pictures were recorded. Specimens were indented to evaluate elastic modulus. Raman microscope was used to collect Raman spectra and inspected using a scanning electron microscope. Crystal structural analysis was performed using X-ray diffraction. Effect of material on cellular proliferation was determined. Confocal was performed to evaluate the effect of formulation on biofilms. RESULTS FTIR of modified adhesives depicted peak changes within range due to various functional groups existing within samples. TEM represented structurally optimized hexagonal unit-cell of hydroxyapatite. Mean shear bond strength is recorded highest for Transbond XT with 1% SrF2. Dead bacterial percentage appeared higher in 0.5% SrF2 and 1% F- specimens. Crystal lengths showed an increase in 0.5% and 1% SrF2 specimens. Phase contrast within TEM images showed a union of 0.5% SrF2 crystal with enamel crystal with higher elastic modulus and highly mineralized crystalline hydroxyapatite. Intensity of ν1 PO43- and ν1 CO32- along with carbonate - / ν1PO43- ratio displayed good association with strontium fluoride. The formulation showed acceptable cell biocompatibility (p < 0.353). All specimens displayed characteristic diffraction maxima of different apatite angles within XRD. SIGNIFICANCE Experimental results suggested good biocompatibility, adequate mechanical strength, and far-ranging crystallization ability. This would provide a new strategy to overcome the two major challenges of fixed orthodontics, biofilm growth, and demineralization of enamel.
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Affiliation(s)
- Kirti Saxena
- Children and Community Oral Health, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia
| | - Chew Ming Ann
- Restorative Dentistry Division, School of Dentistry, International Medical University Kuala Lumpur, 126, Jalan Jalil Perkasa 19, Bukit Jalil, Wilayah Persekutuan, Kuala Lumpur 57000, Malaysia
| | - Masturina Anati Binti Mohd Azwar
- Restorative Dentistry Division, School of Dentistry, International Medical University Kuala Lumpur, 126, Jalan Jalil Perkasa 19, Bukit Jalil, Wilayah Persekutuan, Kuala Lumpur 57000, Malaysia
| | - Spoorthi Ravi Banavar
- Children and Community Oral Health, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia
| | - Jukka Matinlinna
- Dental Materials Science, Applied Oral Sciences & Community Dental Care, Faculty of Dentistry, The University of Hong Kong, 34 Hospital Road, Sai Ying Pun, Special Administrative Regions of China; Biomaterials Science, Division of Dentistry, School of Medical Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Ove A Peters
- Department of Endodontics, Arthur A Dugoni School of Dentistry, University of the Pacific, San Francisco, CA, USA; School of Dentistry, The University of Queensland, Herston, Qld 4006, Australia
| | - Umer Daood
- Restorative Dentistry Division, School of Dentistry, International Medical University Kuala Lumpur, 126, Jalan Jalil Perkasa 19, Bukit Jalil, Wilayah Persekutuan, Kuala Lumpur 57000, Malaysia; Dental Materials Science, Applied Oral Sciences & Community Dental Care, Faculty of Dentistry, The University of Hong Kong, 34 Hospital Road, Sai Ying Pun, Special Administrative Regions of China.
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3
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Hegedűs M, Kis VK, Rózsa N, Kovács Z. A novel image processing procedure for the quantitative evaluation of dental enamel prism arrangement. Microsc Res Tech 2024; 87:808-817. [PMID: 38093599 DOI: 10.1002/jemt.24473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 11/27/2023] [Indexed: 03/02/2024]
Abstract
Enamel prism is the main microstructural unit of mammalian enamel which composed of hundreds of bioapatite nanocrystals. Prism structure plays a key role in the excellent mechanical performance of dental enamel during millions of chewing cycles without significant remodeling. Thus, quantitative understanding of prism architecture is of utmost importance for biomechanical materials design. To characterize enamel prism orientation quantitatively, a novel image processing method has been developed. Our method is based on scanning electron microscopy images of etched enamel surface and consists of an ellipse fitting procedure, which provides a numerical approximation of prism shape and orientation in the studied cross section. The obtained analytical data allow to construct color coded orientation maps, which provide quick and useful insight into the microstructure of enamel. Besides striking visualization, orientation maps allow to extract and plot the rich information on the azimuthal and inclination angles of the prisms as function of location. Numerical data on prism arrangement can be analyzed using statistical tools over large areas, which paves the way towards quantifying comparative investigation of prism arrangement either in dentistry research or evolution biology. The application of the method is demonstrated for a distal-mesial cross-section of sound human tooth enamel. HIGHLIGHTS: Scanning electron microscopy images of etched enamel surface are analyzed using ellipse fitting. Geometrical parameters of the fitted ellipses provide numerical data of thousands of prisms. Prism arrangement is visualized on color coded orientation maps and analyzed using statistical tools.
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Affiliation(s)
- Máté Hegedűs
- Department of Materials Physics, Eötvös Loránd University, Budapest, Hungary
| | - Viktória K Kis
- HUN-REN Centre for Energy Research, Budapest, Hungary
- Department of Mineralogy, Eötvös Loránd University, Budapest, Hungary
| | - Noémi Rózsa
- Faculty of Dentistry, Department of Pedodontics and Orthodontics, Semmelweis University, Budapest, Hungary
| | - Zsolt Kovács
- Department of Materials Physics, Eötvös Loránd University, Budapest, Hungary
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4
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Hu D, Ren Q, Li Z, Han S, Ding L, Lu Z, Zhang L. Unveiling the mechanism of an amelogenin-derived peptide in promoting enamel biomimetic remineralization. Int J Biol Macromol 2023; 253:127322. [PMID: 37848117 DOI: 10.1016/j.ijbiomac.2023.127322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/06/2023] [Accepted: 10/06/2023] [Indexed: 10/19/2023]
Abstract
Amelogenin and its derived peptides have exhibited excellent efficacy in promoting enamel biomimetic remineralization. However, little is known about their specific action mechanisms. Herein, by combining experiments and computer simulation, the mechanism of an amelogenin-derived peptide QP5 in regulating enamel biomimetic remineralization is unveiled for the first time. In experiments, peptide QP5 was separated into (QPX)5 and C-tail domains, the interactions of peptide-minerals in nucleation solution and the regulation of peptide on enamel biomimetic remineralization were explored. QP5 exhibited an unordered conformation when mineral ions existed, and it could adsorb on minerals through its two domains, thereby inhibiting spontaneous nucleation. The remineralized enamel regulated by C-tail showed better mechanical properties and formed more biomimetic crystals than that of (QPX)5, indicating the C-tail domain of QP5 played an important role in forming enamel-like crystals. The simulation results showed that the conformation of QP5 changed greatly, mainly exhibiting β-bend, β-turn, and coil structures, and it eventually adsorbed on enamel through negatively charged residues of the C-tail domain, then captured Ca2+ from solution to promote enamel remineralization. This study improved the evaluation methods of the mechanism of biomimetic peptides, and laid a theoretical basis for the amelioration and clinical transformation of peptide QP5.
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Affiliation(s)
- Die Hu
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, No.14, Section 3, Renmin Road South, Chengdu 610041, China
| | - Qian Ren
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, No.14, Section 3, Renmin Road South, Chengdu 610041, China
| | - Zhongcheng Li
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, No.14, Section 3, Renmin Road South, Chengdu 610041, China
| | - Sili Han
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, No.14, Section 3, Renmin Road South, Chengdu 610041, China
| | - Longjiang Ding
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, No.14, Section 3, Renmin Road South, Chengdu 610041, China
| | - Ziqian Lu
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, No.14, Section 3, Renmin Road South, Chengdu 610041, China
| | - Linglin Zhang
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, No.14, Section 3, Renmin Road South, Chengdu 610041, China.
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Sheng X, Yu J, Liu H, Wang Z, Deng S, Shen Y. Dual effectiveness of a novel all-in-one endodontic irrigating solution in antibiofilm activity and smear layer removal. Front Bioeng Biotechnol 2023; 11:1254927. [PMID: 37593327 PMCID: PMC10427723 DOI: 10.3389/fbioe.2023.1254927] [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: 07/07/2023] [Accepted: 07/24/2023] [Indexed: 08/19/2023] Open
Abstract
The continuous destruction of dental hard tissues increases the risk of bacterial invasion, which leads to pulp infections. Irrigation is critical for successful root canal treatment in terms of infection control. However, no single irrigant covers all of the functions demanded, including antibiofilm and tissue-dissolving activities. The aim of this study was to investigate the antimicrobial properties of Triton, an all-in-one irrigant, on Enterococcus faecalis and multispecies oral biofilms in dentin canals, as well as its ability to remove the smear layer. Dentin blocks (192 specimens) were prepared from single-root human teeth and then assigned to 48 groups (24 groups for each biofilm type). Serial centrifugation was used for bacterial introduction into dentinal tubules. After 3 weeks, half of the specimens were created a uniform smear layer. The following treatments were applied: short time (separate): Triton, 6% NaOCl, 2% NaOCl, and water (all for 3 min); short time (combined): Triton (3 + 1 min), 6% NaOCl +17% EDTA (3 + 1 or 2 + 1 min), and 2% NaOCl +17% EDTA (3 + 1 min); and long time: Triton (3 + 3 min), 6% NaOCl (5 min), 6% NaOCl +17% EDTA (5 + 1 min), and water (3 + 3 min). Confocal laser scanning microscopy and scanning electron microscopy were employed to examine the antimicrobial activity and smear layer removal, respectively. The results revealed that despite the absence or presence of the smear layer, Triton (3 + 3 min) showed the highest killing for both tested biofilms (61.53%-72.22%) among all groups (p < 0.05). Furthermore, the smear layer was removed by Triton after 3 + 3 min, exposing open dentin canals. These findings demonstrated that Triton can provide dual benefits of antibiofilm and smear layer removal capabilities simultaneously, indicating a simplified and effective strategy for application in root canal treatment.
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Affiliation(s)
- Xuyan Sheng
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
- Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada
| | - Jian Yu
- Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada
- State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - He Liu
- Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada
| | - Zhejun Wang
- Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada
| | - Shuli Deng
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Ya Shen
- Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada
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Li P, Zeng B, Xie W, Xiao X, Lin L, Yu D, Zhao W. Enamel Structure Defects in Kdf1 Missense Mutation Knock-in Mice. Biomedicines 2023; 11:biomedicines11020482. [PMID: 36831017 PMCID: PMC9953722 DOI: 10.3390/biomedicines11020482] [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: 01/17/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023] Open
Abstract
The Keratinocyte differentiation factor 1 (KDF1) is reported to take part in tooth formation in humans, but the dental phenotype of Kdf1 mutant mice has not been understood. Additionally, the role of the KDF1 gene in dental hard tissue development is rarely known. In this study, we constructed a Kdf1 missense mutation knock-in mouse model through CRISPR/Cas9 gene-editing technology. Enamel samples from wildtypes (WT) and Kdf1 homozygous mutants (HO) were examined using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), an atomic force microscope (AFM) and Raman microspectroscopy. The results showed that a novel Kdf1 missense mutation (c. 908G>C, p.R303P) knock-in mice model was constructed successfully. The enamel of HO mice incisors appeared chalky and defective, exposing the rough interior of the inner enamel and dentin. Micro-CT showed that HO mice had lower volume and mineral density in their tooth enamel. In addition, declined thickness was found in the unerupted enamel layer of incisors in the HO mice. Using SEM and AFM, it was found that enamel prisms in HO mice enamel were abnormally and variously shaped with loose decussating crystal arrangement, meanwhile the enamel rods were partially fused and collapsed, accompanied by large gaps. Furthermore, misshapen nanofibrous apatites were disorderly combined with each other. Raman microspectroscopy revealed a compromised degree of order within the crystals in the enamel after the Kdf1 mutation. To conclude, we identified enamel structure defects in the Kdf1 missense mutation knock-in mice, which displayed fragmentary appearance, abnormally shaped prism structure, decreased mineral density, altered crystal ordering degree and chemical composition of the enamel layer. This may support the potential role of the KDF1 gene in the natural development of enamel.
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Hunter-Schreger Band configuration in human molars reveals more decussation in the lateral enamel of 'functional' cusps than 'guiding' cusps. Arch Oral Biol 2022; 142:105524. [PMID: 36029738 DOI: 10.1016/j.archoralbio.2022.105524] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 08/11/2022] [Accepted: 08/15/2022] [Indexed: 11/21/2022]
Abstract
OBJECTIVES Enamel prism decussation, which manifests as Hunter-Schreger Bands (HSB), is considered a mechanism to mitigate crack propagation. During the chewing cycle, the 'functional' cusps that are involved in Phase II crushing and grinding experience more complex patterns of stress than do those that 'guide' the molars into occlusion (Phase I). This study examines HSB configuration in the lateral enamel of human molars to identify potential differences between these cusps as predicted from their functional distinctions. DESIGN Measurements were recorded from scanning electron micrographs of sections through the mesial cusps of unworn permanent molars. For each section, HSB packing density and the relative thickness of decussated enamel were quantified in the cuspal and middle segments of lateral enamel over the guiding and functional cusps. RESULTS No clear trend from first to third molars in HSB configuration was found in either jaw. In maxillary molars, the functional cusp displays higher HSB packing density in the cuspal and middle segments, and relatively thicker decussated enamel in the cuspal segment than does the guiding cusp. In mandibular molars, the functional cusp displays higher HSB packing density in the middle segment than does the guiding cusp, but no difference in relative thickness was found between them. Enamel of mandibular molars shows weaker decussation than maxillary molars. CONCLUSIONS The results suggest that guiding cusps are intrinsically more susceptible to crack propagation than functional cusps in human permanent molars. Structural factors such as enamel decussation should be considered when interpreting enamel chipping patterns in dietary contexts.
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Baldi A, Carossa M, Comba A, Alovisi M, Femiano F, Pasqualini D, Berutti E, Scotti N. Wear Behaviour of Polymer-Infiltrated Network Ceramics, Lithium Disilicate and Cubic Zirconia against Enamel in a Bruxism-Simulated Scenario. Biomedicines 2022; 10:biomedicines10071682. [PMID: 35884986 PMCID: PMC9313215 DOI: 10.3390/biomedicines10071682] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 11/16/2022] Open
Abstract
The present study aimed to evaluate the wear rate of polymer-infiltrated network composites and ceramics against enamel in a bruxism-simulated scenario. Ninety-six (n = 96) molars were divided into six groups (n = 16) according to their occlusal material: group 1—a polymer-infiltrated network ceramic (PINC); group 2—a second polymer-infiltrated network ceramic (PINC2); group 3—nanohybrid resin-based composite (CO); group 4—cubic zirconia (ZR); group 5—lithium disilicate (LS); and group 6—sound enamel (EN). A laser scanner was used to digitalize all of the occlusal surfaces before and after a fatigue test, which was conducted with a chewing simulator set at 80 N and semicircular movement in order to simulate bruxist movement and loads. Statistical analysis of volume loss was performed with a one-way ANOVA and post hoc Bonferroni test. ZR had significantly inferior wear to PINC (p ≤ 0.01) and CO (p = 0.04). LS wore the antagonist enamel significantly more than PINC, CO, PINC2 and EN (p ≤ 0.01). On the other hand, ZR wore the antagonist enamel significantly more than CO (p ≤ 0.01) and PINC2 (p = 0.05). In conclusion, PINCs better preserved antagonist enamel at the expense of a higher wear of their own. LS causes significantly higher enamel wear compared with PINCs. ZR caused significantly higher enamel wear compared with CO and PINC2, but it was wear-resistant.
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Affiliation(s)
- Andrea Baldi
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Massimo Carossa
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
- Correspondence:
| | - Allegra Comba
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Mario Alovisi
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Felice Femiano
- Restorative Dentistry, Multidisciplinary Department of Medical-Surgical and Dental Specialties, University of Study of Campania, “Luigi Vanvitelli”, Via De Crecchio 6, 83138 Naples, Italy;
| | - Damiano Pasqualini
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Elio Berutti
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Nicola Scotti
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
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Liu S, Xu Y, An B, Zhang D. Interaction of rod decussation and crack growth in enamel. Comput Methods Biomech Biomed Engin 2022; 26:700-709. [PMID: 35815376 DOI: 10.1080/10255842.2022.2084333] [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: 11/03/2022]
Abstract
Enamel possesses ingenious hierarchical structure that gives rise to superior fracture resistance. Despite considerable efforts devoted to characterization of fracture behavior of enamel, the role of rod decussation in fracture of enamel is largely unknown. In this study, the features of rod decussation in the inner enamel are experimentally identified, and analyses of crack growth in enamel are carried out using a micromechanical model of enamel, in which the structural features of the outer enamel and rod decussation of the inner enamel are incorporated. We carry out calculations within a framework based on the extended finite element method, and the crack growth and crack path selection are natural outcomes of imposed loading. We show that crack deflection in enamel is controlled by rod decussation. For crack growth in the parazone, the crack path is oriented along the axis of enamel rods, leading to gross crack deflection. The microstructure of inner enamel with intermediate inclination angle enables multiple crack deflections, giving rise to enhanced toughness. For crack growth in the diazone, the transition in orientation of crack deflection occurs as inclination angle increases. The relatively straight crack path emerges in the case of the microstructure of enamel with intermediate inclination angle, leading to weak fracture resistance. It is further found that compared with the diazone, the gross crack deflection in the parazone provides greater contribution to fracture resistance of enamel. The findings of this study provide a good mechanistic understanding of the role of rod decussation in enamel.
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Affiliation(s)
- Siyong Liu
- School of Mechanics and Engineering Science, Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai, China.,Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai, China
| | - Yuanzhi Xu
- Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200072, P R China
| | - Bingbing An
- School of Mechanics and Engineering Science, Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai, China.,Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai, China
| | - Dongsheng Zhang
- School of Mechanics and Engineering Science, Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai, China.,Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai, China
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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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Peng J, Xiao H, Lei L, Yang D, Zheng J, Zhou Z. Heterogeneous hardening of enamel surface by occlusal loading: Effect of nanofiber orientation. J Mech Behav Biomed Mater 2022; 130:105221. [DOI: 10.1016/j.jmbbm.2022.105221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 03/27/2022] [Accepted: 04/02/2022] [Indexed: 11/30/2022]
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12
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A Chitosan-Agarose Polysaccharide-Based Hydrogel for Biomimetic Remineralization of Dental Enamel. Biomolecules 2021; 11:biom11081137. [PMID: 34439803 PMCID: PMC8392529 DOI: 10.3390/biom11081137] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/30/2022] Open
Abstract
Developing multifunctional systems for the biomimetic remineralization of human enamel is a challenging task, since hydroxyapatite (HAP) rod structures of tooth enamel are difficult to replicate artificially. The paper presents the first report on the simultaneous use of chitosan (CS) and agarose (A) in a biopolymer-based hydrogel for the biomimetic remineralization of an acid-etched native enamel surface during 4–10-day immersion in artificial saliva with or without (control group) fluoride. Scanning electron microscopy coupled with energy-dispersive X-ray spectrometry, Fourier transform infrared and Raman spectroscopies, X-ray diffraction, and microhardness tests were applied to investigate the properties of the acid-etched and remineralized dental enamel layers under A and CS-A hydrogels. The results show that all biomimetic epitaxial reconstructed layers consist mostly of a similar hierarchical HAP structure to the native enamel from nano- to microscale. An analogous Ca/P ratio (1.64) to natural tooth enamel and microhardness recovery of 77.4% of the enamel-like layer are obtained by a 7-day remineralization process in artificial saliva under CS-A hydrogels. The CS component reduced carbonation and moderated the formation of HAP nanorods in addition to providing an extracellular matrix to support growing enamel-like structures. Such activity lacked in samples exposed to A-hydrogel only. These data suggest the potential of the CS-A hydrogel in guiding the formation of hard tissues as dental enamel.
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13
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Ramadoss R, Padmanaban R, Subramanian B. Role of bioglass in enamel remineralization: Existing strategies and future prospects-A narrative review. J Biomed Mater Res B Appl Biomater 2021; 110:45-66. [PMID: 34245107 DOI: 10.1002/jbm.b.34904] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 06/22/2021] [Accepted: 06/27/2021] [Indexed: 12/24/2022]
Abstract
Enamel, once formed, loses the ability to regenerate due to the loss of the formative ameloblasts. It is subjected to constant damaging events due to exposure to external agents and oral microbiomes. An enamel remineralization process targets to replenish the lost ionic component of the enamel through a multitude of methods. Enamel remineralization is highly challenging as it has a complex organized hierarchical microstructure. Hydroxyapatite nanocrystals of the enamel vary in size and orientation along alignment planes inside the enamel rod. The inability of the enamel to remodel unlike other mineralized tissues is another substantial deterrent. One of the well-known biomaterials, bioglass (BG) induces apatite formation on the external surface of the enamel in the presence of saliva or other physiological fluids. Calcium, sodium, phosphate, and silicate ions in BG become responsive in the presence of body fluids, leading to the precipitation of calcium phosphate. Studies have also demonstrated the bactericidal potential of BG against Streptococcus mutans biofilms. The anticariogenicity and antibacterial activity were found to be enhanced when BG was doped with inorganic ions such as F, Ag, Mg, Sr, and Zn. Due to the versatility of BG, it has been combined with a variety of agents such as chitosan, triclosan, and amelogenin to biomimic remineralization process. Key strategies that can aid in the development of contemporary enamel remineralization agents are also included in this review.
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Affiliation(s)
- Ramya Ramadoss
- Department of Oral & Maxillofacial Pathology, Saveetha Dental College, Chennai, Tamil Nadu, India
| | - Rajashree Padmanaban
- CAS Biophysics & Crystallography, University of Madras, Guindy Campus, Chennai, Tamil Nadu, India
| | - Balakumar Subramanian
- Center for Nanoscience and Nanotechnology, University of Madras, Guindy Campus, Chennai, Tamil Nadu, India
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14
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Ma Y, Ran D, Shi X, Zhao H, Liu Z. Cadmium toxicity: A role in bone cell function and teeth development. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 769:144646. [PMID: 33485206 DOI: 10.1016/j.scitotenv.2020.144646] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 12/16/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
Cadmium (Cd) is a widespread environmental contaminant that causes severe bone metabolism disease, such as osteoporosis, osteoarthritis, and osteomalacia. The present review aimed to explore the molecular mechanisms of Cd-induced bone injury starting from bone cell function and teeth development. Cd inhibits the differentiation of bone marrow mesenchymal stem cells (BMSCs) into osteoblasts, and directly causes BMSC apoptosis. In the case of osteoporosis, Cd mainly affects the activation of osteoclasts and promotes bone resorption. Cd-induces osteoblast injury and oxidative stress, which causes DNA damage, mitochondrial dysfunction, and endoplasmic reticulum stress, resulting in apoptosis. In addition, the development of osteoarthritis (OA) might be related to Cd-induced chondrocyte damage. The high expression of metallothionein (MT) might reduce Cd toxicity toward osteocytes. The toxicity of Cd toward teeth mainly focuses on enamel development and dental caries. Understanding the effect of Cd on bone cell function and teeth development could contribute to revealing the mechanisms of Cd-induced bone damage. This review explores Cd-induced bone disease from cellular and molecular levels, and provides new directions for removing this heavy metal from the environment.
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Affiliation(s)
- Yonggang Ma
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, PR China
| | - Di Ran
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, PR China
| | - Xueni Shi
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, PR China
| | - Hongyan Zhao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, PR China
| | - Zongping Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, PR China.
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15
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Yu J, Yi L, Guo R, Guo J, Yang H, Huang C. The Stability of Dentin Surface Biobarrier Consisting of Mesoporous Delivery System on Dentinal Tubule Occlusion and Streptococcus Mutans Biofilm Inhibition. Int J Nanomedicine 2021; 16:3041-3057. [PMID: 33948084 PMCID: PMC8088303 DOI: 10.2147/ijn.s290254] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 03/31/2021] [Indexed: 01/21/2023] Open
Abstract
Background The dentin exposure always leads to dentin hypersensitivity and/or caries. Given the dentin’s tubular structure and low mineralization degree, reestablishing an effective biobarrier to stably protect dentin remains significantly challenging. This study reports a versatile dentin surface biobarrier consisting of a mesoporous silica-based epigallocatechin-3-gallate (EGCG)/nanohydroxyapatite delivery system and evaluates its stability on the dentinal tubule occlusion and the Streptococcus mutans (S. mutans) biofilm inhibition. Materials and Methods The mesoporous delivery system was fabricated and characterized. Sensitive dentin discs were prepared and randomly allocated to three groups: 1, control group; 2, casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) group; and 3, the mesoporous delivery system group. The dentin permeability, dentinal tubule occlusion, acid and abrasion resistance, and S. mutans biofilm inhibition were determined for 1 week and 1 month. The in vitro release profiles of EGCG, Ca, and P were also monitored. Results The mesoporous delivery system held the ability to sustainably release EGCG, Ca, and P and could persistently occlude dentinal tubules with acid and abrasion resistance, reduce the dentin permeability, and inhibit the S. mutans biofilm formation for up to 1 month compared with the two other groups. The system provided prolonged stability to combat oral adverse challenges and served as an effective surface biobarrier to protect the exposed dentin. Conclusion The establishment of the dentin surface biobarrier consisting of a mesoporous delivery system indicates a promising strategy for the prevention and the management of dentin hypersensitivity and caries after enamel loss.
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Affiliation(s)
- Jian Yu
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, People's Republic of China
| | - Luyao Yi
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, People's Republic of China
| | - Rui Guo
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, People's Republic of China
| | - Jingmei Guo
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, People's Republic of China
| | - Hongye Yang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, People's Republic of China
| | - Cui Huang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, People's Republic of China
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16
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Stifler CA, Jakes JE, North JD, Green DR, Weaver JC, Gilbert PUPA. Crystal misorientation correlates with hardness in tooth enamels. Acta Biomater 2021; 120:124-134. [PMID: 32711081 DOI: 10.1016/j.actbio.2020.07.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 07/14/2020] [Accepted: 07/17/2020] [Indexed: 01/31/2023]
Abstract
The multi-scale hierarchical structure of tooth enamel enables it to withstand a lifetime of damage without catastrophic failure. While many previous studies have investigated structure-function relationships in enamel, the effects of crystal misorientation on mechanical performance have not been assessed. To address this issue, in the present study, we review previously published polarization-dependent imaging contrast (PIC) maps of mouse and human enamel, and parrotfish enameloid, in which crystal orientations were measured and displayed in every 60-nm-pixel. By combining those previous results with the PIC maps of sheep enamel presented here we discovered that, in all enamel(oid)s, adjacent crystals are slightly misoriented, with misorientation angles in the 0°-30° range, and mean 2°-8°. Within this limited range, misorientation is positively correlated with literature hardness values, demonstrating an important structure-property relation, not previously identified. At greater misorientation angles 8°30°, this correlation is expected to reverse direction, but data from different non-enamel systems, with more diverse crystal misorientations, are required to determine if and where this occurs. STATEMENT OF SIGNIFICANCE: We identify a structure-function relationship in tooth enamels from different species: crystal misorientation correlates with hardness, contributing to the remarkable mechanical properties of enamel in diverse animals.
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Affiliation(s)
- Cayla A Stifler
- Department of Physics, University of Wisconsin, Madison, WI 53706, United States
| | - Joseph E Jakes
- Forest Biopolymers Science and Engineering, USDA Forest Service, Forest Products Laboratory, Madison, WI 53726, United States
| | - Jamie D North
- Department of Chemistry, Carleton College, Northfield, MN 55057, United States
| | - Daniel R Green
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, United States
| | - James C Weaver
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, United States
| | - Pupa U P A Gilbert
- Department of Physics, University of Wisconsin, Madison, WI 53706, United States; Departments of Chemistry, Geoscience, Materials Science, University of Wisconsin, Madison, WI 53706, United States.
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17
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Exploiting teeth as a model to study basic features of signaling pathways. Biochem Soc Trans 2020; 48:2729-2742. [DOI: 10.1042/bst20200514] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/06/2020] [Accepted: 10/08/2020] [Indexed: 12/21/2022]
Abstract
Teeth constitute a classical model for the study of signaling pathways and their roles in mediating interactions between cells and tissues in organ development, homeostasis and regeneration. Rodent teeth are mostly used as experimental models. Rodent molars have proved fundamental in the study of epithelial–mesenchymal interactions and embryonic organ morphogenesis, as well as to faithfully model human diseases affecting dental tissues. The continuously growing rodent incisor is an excellent tool for the investigation of the mechanisms regulating stem cells dynamics in homeostasis and regeneration. In this review, we discuss the use of teeth as a model to investigate signaling pathways, providing an overview of the many unique experimental approaches offered by this organ. We discuss how complex networks of signaling pathways modulate the various aspects of tooth biology, and the models used to obtain this knowledge. Finally, we introduce new experimental approaches that allow the study of more complex interactions, such as the crosstalk between dental tissues, innervation and vascularization.
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18
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Peng J, Xiao H, Yang D, Lei L, Zheng J, Zhou Z. Surface Hardening Behavior of Enamel by Masticatory Loading: Occurrence Mechanism and Antiwear Effect. ACS Biomater Sci Eng 2020; 6:4454-4461. [PMID: 33455168 DOI: 10.1021/acsbiomaterials.0c00740] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies have suggested that surface hardening occurs in human tooth enamel under certain loading conditions. However, the occurrence mechanism and significance remain unclear. In this study, the surface hardening behavior of enamel under masticatory loading was studied in vitro using impact treatment and the nanoindentation/scratch technique to identify the mechanism and antiwear effect. The fundamental block of enamel is made of hydroxyapatite (HAP) nanofibers, which consist of fine nanoparticles held together by protein. These fibers respond to masticatory loading in two ways: bending deflection at low loads and fragmentation at high loads. When the contact pressure exceeds the bonding strength between the nanoparticles, the HAP fibers split into fine nanoparticles and then form a surface layer consisting of tightly packed nanoparticles. This results in surface hardening dominated by an increased hardness and elastic modulus. The maximum degree and depth of surface hardening were determined as approximately 60% and 100 nm, respectively. With the occurrence of surface hardening, the wear resistance of the enamel is enhanced, which is manifested by a reduced friction coefficient and wear volume. In summary, the surface hardening of enamel induced by masticatory loading is a result of HAP nanoparticle rearrangement as a response of the enamel hierarchical structure to high chewing loads. It is adaptive overload protection derived from the enamel hierarchical structure and plays a critical role in resisting excessive wear induced by high chewing loads.
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Affiliation(s)
- Jiapin Peng
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Heng Xiao
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Dan Yang
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Lei Lei
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Jing Zheng
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - Zhongrong Zhou
- Tribology Research Institute, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
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Wilmers J, Bargmann S. Nature's design solutions in dental enamel: Uniting high strength and extreme damage resistance. Acta Biomater 2020; 107:1-24. [PMID: 32087326 DOI: 10.1016/j.actbio.2020.02.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/07/2020] [Accepted: 02/12/2020] [Indexed: 02/06/2023]
Abstract
The most important demand of today's high-performance materials is to unite high strength with extreme fracture toughness. The combination of withstanding large forces (strength) and resistance to fracture (toughness), especially preventing catastrophic material failure by cracking, is of utmost importance when it comes to structural applications of these materials. However, these two properties are commonly found to be mutually exclusive: strong materials are brittle and tough materials are soft. In dental enamel, nature has combined both properties with outstanding success - despite a limited number of available constituents. Made up of brittle mineral crystals arranged in a sophisticated hierarchical microstructure, enamel exhibits high stiffness and excellent toughness. Different species exhibit a variety of structural adaptations on varying scales in their dental enamel which optimise not only fracture toughness, but also hardness and abrasion behaviour. Nature's materials still outperform their synthetic counterparts due to these complex structure-property relationships that are not yet fully understood. By analysing structure variations and the underlying mechanical mechanisms systematically, design principles which are the key for the development of advanced synthetic materials uniting high strength and toughness can be formulated. STATEMENT OF SIGNIFICANCE: Dental enamel is a hard protective tissue that combines high strength with an exceptional resistance to catastrophic fracture, properties that in classical materials are commonly found to be mutually exclusive. The biological material is able to outperform its synthetic counterparts due to a sophisticated hierarchical microstructure. Between different species, microstructural adaptations can vary significantly. In this contribution, the different types of dental enamel present in different species are reviewed and connections between microstructure and (mechanical) properties are drawn. By consolidating available information for various species and reviewing it from a materials science point of view, design principles for the development of advanced biomimetic materials uniting high strength and toughness can be formulated.
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20
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Koldehoff J, Swain MV, Schneider GA. The geometrical structure of interfaces in dental enamel: A FIB-STEM investigation. Acta Biomater 2020; 104:17-27. [PMID: 31917293 DOI: 10.1016/j.actbio.2019.12.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 12/20/2019] [Accepted: 12/31/2019] [Indexed: 11/26/2022]
Abstract
In this study a high resolution structural analysis revealed that enamel prisms are surrounded by an interface that is discontinuous with frequent mineral to mineral contact separated by gaps. This contact manifests either by crystallites bridging the boundary between prismatic and interprismatic enamel or continuous crystallites curving and bridging the interprismatic enamel to the prisms. The geometrical resolution of this TEM investigation of the interfaces is ≤2 nm as a basis for micromechanical models. Within this resolution, contrary to existing structural descriptions of dental enamel structure in materials science literature, here the crystallites themselves are shown to be either in direct contact with each other, sometimes even fusing together, or are separated by gaps. Image analysis revealed that on average only 57 ± 15% of the interface consists of points of no contact between crystallites. This work reveals structural features of dental enamel that contribute important understanding to both the architecture and mechanical properties of this biological material. A new structural model is proposed and the implications for the mechanical properties of dental enamel are discussed. STATEMENT OF SIGNIFICANCE: In this study a high resolution structural analysis, employing focused ion beam and transmission electron microscopy revealed that enamel prisms are surrounded by interfaces that are discontinuous with frequent mineral to mineral contact separated by gaps. Although the interfaces in enamel have been investigated previously, existing studies are lacking in detail considering the geometry and morphology of the interfaces. We think that this result is of great importance when it comes to the understanding of the mechanical properties. In our opinion the concept of soft sheaths is no longer feasible. The resulting observations are included in a new structural model which provides new qualitative insights into the mechanical behavior. Existing analytical models were applied to simulate the new geometrical structure.
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21
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Zhang S, Liu Y, Shang J, Ujjaman Chudry MK, Zheng Y, Cai J, An B, Zhang D, Zheng R. Enamel-inspired materials design achieving balance of high stiffness and large energy dissipation. J Mech Behav Biomed Mater 2020; 103:103587. [PMID: 32090916 DOI: 10.1016/j.jmbbm.2019.103587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 11/25/2019] [Accepted: 12/06/2019] [Indexed: 11/19/2022]
Abstract
Owing to the unique non-self-similar hierarchical microstructure, enamel achieves the balance of high stiffness and toughness, and in turn provides important ideas for the bio-inspired materials design. In this study, a multiscale numerical study has been conducted to investigate whether the property of high stiffness and large energy dissipation could be duplicated in engineering materials through certain material design principles. Motivated by the structure of enamel, the bio-inspired materials consisting of hard and soft phases were considered, and the designing parameters including the cross-sectional shape, volume fraction, and inclination angle of the reinforcement, and other three parameters related to the waviness of the reinforcement were taken into account. It was found that by employing the non-self-similar hierarchical structure, the designed composites exhibited the balance between stiffness and toughness, which has not been achieved in many engineering materials yet. Furthermore, the influences of the aforementioned designing parameters on the mechanical performance of the composites have been elucidated. The findings of this study have provided a guideline for designing bio-inspired composites achieving the balance between stiffness and toughness.
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Affiliation(s)
- Shuiqiang Zhang
- School of Engineering, Huzhou University, Huzhou, 313000, China.
| | - Yuying Liu
- School of Engineering, Huzhou University, Huzhou, 313000, China
| | - Jiangyinzi Shang
- Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai, China
| | | | - Yuqing Zheng
- School of Engineering, Huzhou University, Huzhou, 313000, China
| | - Jiabin Cai
- School of Engineering, Huzhou University, Huzhou, 313000, China
| | - Bingbing An
- Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai, 200072, China; School of Mechanics and Engineering Science, Shanghai University, Shanghai, 200444, China
| | - Dongsheng Zhang
- Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai, 200072, China; School of Mechanics and Engineering Science, Shanghai University, Shanghai, 200444, China
| | - Ruizhe Zheng
- Shanghai Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200050, China
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22
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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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23
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Shao C, Jin B, Mu Z, Lu H, Zhao Y, Wu Z, Yan L, Zhang Z, Zhou Y, Pan H, Liu Z, Tang R. Repair of tooth enamel by a biomimetic mineralization frontier ensuring epitaxial growth. SCIENCE ADVANCES 2019; 5:eaaw9569. [PMID: 31497647 PMCID: PMC6716959 DOI: 10.1126/sciadv.aaw9569] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 07/16/2019] [Indexed: 05/18/2023]
Abstract
The regeneration of tooth enamel, the hardest biological tissue, remains a considerable challenge because its complicated and well-aligned apatite structure has not been duplicated artificially. We herein reveal that a rationally designed material composed of calcium phosphate ion clusters can be used to produce a precursor layer to induce the epitaxial crystal growth of enamel apatite, which mimics the biomineralization crystalline-amorphous frontier of hard tissue development in nature. After repair, the damaged enamel can be recovered completely because its hierarchical structure and mechanical properties are identical to those of natural enamel. The suggested phase transformation-based epitaxial growth follows a promising strategy for enamel regeneration and, more generally, for biomimetic reproduction of materials with complicated structure.
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Affiliation(s)
- Changyu Shao
- Department of Chemistry and Center for Biomaterials and Biopathways, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Biao Jin
- Department of Chemistry and Center for Biomaterials and Biopathways, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Zhao Mu
- Department of Chemistry and Center for Biomaterials and Biopathways, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Hao Lu
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute, Xiamen University, Xiamen, Fujian 361005, China
| | - Yueqi Zhao
- Department of Chemistry and Center for Biomaterials and Biopathways, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Zhifang Wu
- Department of Prosthodontics, Hospital of Stomatology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, China
| | - Lumiao Yan
- Department of Chemistry and Center for Biomaterials and Biopathways, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Zhisen Zhang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute, Xiamen University, Xiamen, Fujian 361005, China
| | - Yanchun Zhou
- Zhejiang University Hospital, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Haihua Pan
- Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Zhaoming Liu
- Department of Chemistry and Center for Biomaterials and Biopathways, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Ruikang Tang
- Department of Chemistry and Center for Biomaterials and Biopathways, Zhejiang University, Hangzhou, Zhejiang 310027, China
- State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027, China
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24
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Świetlicka I, Tomaszewska E, Muszyński S, Valverde Piedra JL, Świetlicki M, Prószyński A, Cieślak K, Wiącek D, Szymańczyk S, Kamiński D. The effect of cadmium exposition on the structure and mechanical properties of rat incisors. PLoS One 2019; 14:e0215370. [PMID: 30978248 PMCID: PMC6461291 DOI: 10.1371/journal.pone.0215370] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 04/01/2019] [Indexed: 01/25/2023] Open
Abstract
Alterations in the structure and mechanical properties of teeth in adult Wistar rats exposed to cadmium were investigated. Analyses were conducted on two sets of incisors from female and male specimens, that were intoxicated with cadmium (n = 12) or belonged to the control (n = 12). The cadmium group was administered with CdCl2 dissolved in drinking water with a dose of 4mg/kgbw for 10 weeks. The oral intake of cadmium by adult rats led to the range of structural changes in enamel morphology and its mechanical features. A significant increase of cadmium levels in the teeth in comparison to the control, a slight shift in the colour and reduction of pigmented enamel length, higher surface irregularity, a decrease of hydroxyapatite crystals size in the c-axis and simultaneous increase in pigmented enamel hardness were observed. The extent of these changes was sex-dependent and was more pronounced in males.
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Affiliation(s)
- Izabela Świetlicka
- Department of Biophysics, Faculty of Production Engineering, University of Life Sciences in Lublin, Lublin, Poland
| | - Ewa Tomaszewska
- Department of Animal Physiology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Lublin, Poland
| | - Siemowit Muszyński
- Department of Biophysics, Faculty of Production Engineering, University of Life Sciences in Lublin, Lublin, Poland
| | - Jose Luis Valverde Piedra
- Department of Preclinical Veterinary Sciences, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Lublin, Poland
| | - Michał Świetlicki
- Department of Applied Physics, Faculty of Mechanical Engineering, Lublin University of Technology, Lublin, Poland
| | - Adam Prószyński
- Department of Applied Physics, Faculty of Mechanical Engineering, Lublin University of Technology, Lublin, Poland
| | - Krystian Cieślak
- Institute of Renewable Energy Engineering, Faculty of Environmental Engineering, Lublin University of Technology, Lublin, Poland
| | - Dariusz Wiącek
- Department of Physical Properties of Plant Materials, Institute of Agrophysics, Polish Academy of Sciences, Lublin, Poland
| | - Sylwia Szymańczyk
- Department of Animal Physiology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Lublin, Poland
| | - Daniel Kamiński
- Department of Crystallography, Faculty of Chemistry, Maria Curie-Skłodowska University, Lublin, Poland
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Yilmaz ED, Koldehoff J, Schneider GA. On the systematic documentation of the structural characteristics of bovine enamel: A critic to the protein sheath concept. Dent Mater 2018; 34:1518-1530. [DOI: 10.1016/j.dental.2018.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 05/24/2018] [Accepted: 06/07/2018] [Indexed: 11/28/2022]
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26
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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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DENG QIANG, ZONG ZHIFANG, NING ZHENWU, ZHENG JING, LIU JIANTAO, ZHOU ZHONGRONG. A COMPUTATIONAL STRATEGY TO EXAMINE THE PROFILE EFFECTS OF MICROPRISM REGIONS ON THE OVERALL ANISOTROPY OF HUMAN ENAMELS. J MECH MED BIOL 2018. [DOI: 10.1142/s0219519418500276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this study, our attention is mainly on elaborating a computational strategy to effectively predict the influence of prism profiles on the overall anisotropic property of human enamels (HEs). At first, two distinct schemes are developed separately with the aid of the polynomial fitting technique and the general power functions to mathematically describe the practical irregular and simplified regular profiles of enamel prisms. Hereafter, two parametric piecewise formulas, which facilitate the definition of anisotropic material properties of finite elements at different locations and make the numerical simulation of HE microstructures consisting of irregularly shaped prisms feasible, are presented to describe the orientation of hydroxyapatite (HAP) crystallites embedded in microprisms. The effective anisotropic moduli over a representative unit cell (RUC) under the periodic displacement constraint is concisely introduced according to the micromechanics, and a computational strategy is established to calculate these moduli numerically. Finally, the evaluations in the open literature are employed to demonstrate the validity of the elaborated computational strategy, and more investigations are conducted and yield the conclusions such that the material property of the inter-prism regions as well as the prism shapes plays a crucial role in determining the overall anisotropy of HEs.
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Affiliation(s)
- QIANG DENG
- School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, P. R. China
| | - ZHIFANG ZONG
- School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, P. R. China
| | - ZHENWU NING
- School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, P. R. China
| | - JING ZHENG
- School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, P. R. China
| | - JIANTAO LIU
- School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, P. R. China
- Laboratoire de Mécanique d’Evry, Université d’Evry, 40 rue du Pelvoux, Évry 91020, France
| | - ZHONGRONG ZHOU
- School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, P. R. China
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28
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Prajapati S, Ruan Q, Mukherjee K, Nutt S, Moradian-Oldak J. The Presence of MMP-20 Reinforces Biomimetic Enamel Regrowth. J Dent Res 2017; 97:84-90. [PMID: 28846464 DOI: 10.1177/0022034517728504] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Biomimetic synthesis of artificial enamel is a promising strategy for the prevention and restoration of defective enamel. We have recently reported that a hydrogel system composed of chitosan-amelogenin (CS-AMEL) and calcium phosphate is effective in forming an enamel-like layer that has a seamless interface with natural tooth surfaces. Here, to improve the mechanical system function and to facilitate the biomimetic enamel regrowth, matrix metalloproteinase-20 (MMP-20) was introduced into the CS-AMEL hydrogel. Inspired by our recent finding that MMP-20 prevents protein occlusion inside enamel crystals, we hypothesized that addition of MMP-20 to CS-AMEL hydrogel could reinforce the newly grown layer. Recombinant human MMP-20 was added to the CS-AMEL hydrogel to cleave full-length amelogenin during the growth of enamel-like crystals on an etched enamel surface. The MMP-20 proteolysis of amelogenin was studied, and the morphology, composition, and mechanical properties of the newly grown layer were characterized. We found that amelogenin was gradually degraded by MMP-20 in the presence of chitosan. The newly grown crystals in the sample treated with MMP-20-CS-AMEL hydrogel showed more uniform orientation and greater crystallinity than the samples treated with CS-AMEL hydrogel without MMP-20. Stepwise processing of amelogenin by MMP-20 in the CS-AMEL hydrogel prevented undesirable protein occlusion within the newly formed crystals. As a result, both the modulus and hardness of the repaired enamel were significantly increased (1.8- and 2.4-fold, respectively) by the MMP-20-CS-AMEL hydrogel. Although future work is needed to further incorporate other enamel matrix proteins into the system, this study brings us one step closer to biomimetic enamel regrowth.
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Affiliation(s)
- S Prajapati
- 1 Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
| | - Q Ruan
- 1 Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
| | - K Mukherjee
- 1 Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
| | - S Nutt
- 2 Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA
| | - J Moradian-Oldak
- 1 Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
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Ding C, Chen Z, Li J. From molecules to macrostructures: recent development of bioinspired hard tissue repair. Biomater Sci 2017; 5:1435-1449. [DOI: 10.1039/c7bm00247e] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This review summarizes the bioinspired strategies for hard tissue repair, ranging from molecule-induced mineralization, to microscale assembly to macroscaffold fabrication.
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Affiliation(s)
- Chunmei Ding
- College of Polymer Science and Engineering
- Sichuan University
- Chengdu 610065
- P. R. China
| | - Zhuoxin Chen
- College of Polymer Science and Engineering
- Sichuan University
- Chengdu 610065
- P. R. China
| | - Jianshu Li
- College of Polymer Science and Engineering
- Sichuan University
- Chengdu 610065
- P. R. China
- State Key Laboratory of Polymer Materials Engineering
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30
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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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31
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Gao S, An B, Yahyazadehfar M, Zhang D, Arola D. Contact fatigue of human enamel: Experiments, mechanisms and modeling. J Mech Behav Biomed Mater 2016; 60:438-450. [DOI: 10.1016/j.jmbbm.2016.02.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/04/2016] [Accepted: 02/23/2016] [Indexed: 10/22/2022]
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32
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Abstract
Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization in vitro, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recent findings on amelogenin secondary and tertiary structural properties with a focus on its interactions with different targets including other enamel proteins, apatite mineral, and phospholipids. Following a brief overview of enamel hierarchical structure and its mechanical properties we will present the state-of-the-art strategies in the biomimetic reconstruction of human enamel.
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Affiliation(s)
- Qichao Ruan
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
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33
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Effect of gamma irradiation on the wear behaviour of human tooth enamel. Sci Rep 2015; 5:11568. [PMID: 26099692 PMCID: PMC4477323 DOI: 10.1038/srep11568] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 05/28/2015] [Indexed: 02/05/2023] Open
Abstract
Radiotherapy is a frequently used treatment for oral cancer. Extensive research has been conducted to detect the mechanical properties of dental hard tissues after irradiation at the macroscale. However, little is known about the influence of irradiation on the tribological properties of enamel at the micro- or nanoscale. Therefore, this study aimed to investigate the effect of gamma irradiation on the wear behaviour of human tooth enamel in relation to prism orientation. Nanoscratch tests, surface profilometer and scanning electron microscope (SEM) analysis were used to evaluate the friction behaviour of enamel slabs before and after treatment with identical irradiation procedures. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were performed to analyse the changes in crystallography and chemical composition induced by irradiation. Surface microhardness (SMH) alteration was also evaluated. The results showed that irradiation resulted in different scratch morphologies, friction coefficients and remnant depth and width at different loads. An inferior nanoscratch resistance was observed independent of prism orientation. Moreover, the variation of wear behaviours was closely related to changes in the crystallography, chemical composition and SMH of the enamel. Together, these measures indicated that irradiation had a direct deleterious effect on the wear behaviour of human tooth enamel.
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34
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Yahyazadehfar M, Arola D. The role of organic proteins on the crack growth resistance of human enamel. Acta Biomater 2015; 19:33-45. [PMID: 25805107 PMCID: PMC4499056 DOI: 10.1016/j.actbio.2015.03.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 02/06/2015] [Accepted: 03/05/2015] [Indexed: 11/18/2022]
Abstract
With only 1% protein by weight, tooth enamel is the most highly mineralized tissue in mammals. The focus of this study was to evaluate contributions of the proteins on the fracture resistance of this unique structural material. Sections of enamel were obtained from the cusps of human molars and the crack growth resistance was quantified using a conventional fracture mechanics approach with complementary finite element analysis. In selected specimens the proteins were extracted using a potassium hydroxide treatment. Removal of the proteins resulted in approximately 40% decrease in the fracture toughness with respect to the fully proteinized control. The loss of organic content was most detrimental to the extrinsic toughening mechanisms, causing over 80% reduction in their contribution to the total energy to fracture. This degradation occurred by embrittlement of the unbroken bridging ligaments and consequent reduction in the crack closure stress. Although the organic content of tooth enamel is very small, it is essential to crack growth toughening by facilitating the formation of unbroken ligaments and in fortifying their potency. Replicating functions of the organic content will be critical to the successful development of bio-inspired materials that are designed for fracture resistance.
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Affiliation(s)
- Mobin Yahyazadehfar
- Department of Material Science and Engineering, University of Washington, Seattle, WA, USA; Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD, USA
| | - Dwayne Arola
- Department of Material Science and Engineering, University of Washington, Seattle, WA, USA; Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA, USA.
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35
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Scheider I, Xiao T, Yilmaz E, Schneider G, Huber N, Bargmann S. Damage modeling of small-scale experiments on dental enamel with hierarchical microstructure. Acta Biomater 2015; 15:244-53. [PMID: 25484332 DOI: 10.1016/j.actbio.2014.11.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 10/27/2014] [Accepted: 11/18/2014] [Indexed: 11/27/2022]
Abstract
Dental enamel is a highly anisotropic and heterogeneous material, which exhibits an optimal reliability with respect to the various loads occurring over years. In this work, enamel's microstructure of parallel aligned rods of mineral fibers is modeled and mechanical properties are evaluated in terms of strength and toughness with the help of a multiscale modeling method. The established model is validated by comparing it with the stress-strain curves identified by microcantilever beam experiments extracted from these rods. Moreover, in order to gain further insight in the damage-tolerant behavior of enamel, the size of crystallites below which the structure becomes insensitive to flaws is studied by a microstructural finite element model. The assumption regarding the fiber strength is verified by a numerical study leading to accordance of fiber size and flaw tolerance size, and the debonding strength is estimated by optimizing the failure behavior of the microstructure on the hierarchical level above the individual fibers. Based on these well-grounded properties, the material behavior is predicted well by homogenization of a representative unit cell including damage, taking imperfections (like microcracks in the present case) into account.
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36
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An B, Wang R, Arola D, Zhang D. Damage mechanisms in uniaxial compression of single enamel rods. J Mech Behav Biomed Mater 2015; 42:1-9. [DOI: 10.1016/j.jmbbm.2014.10.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 10/18/2014] [Accepted: 10/21/2014] [Indexed: 10/24/2022]
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37
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Ruan Q, Moradian-Oldak J. Amelogenin and enamel biomimetics. J Mater Chem B 2015. [DOI: 10.1039/c5tb00163c and 21=21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mature tooth enamel is acellular and does not regenerate itself.
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Affiliation(s)
- Qichao Ruan
- Center for Craniofacial Molecular Biology
- Herman Ostrow School of Dentistry
- University of Southern California
- Los Angeles
- USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology
- Herman Ostrow School of Dentistry
- University of Southern California
- Los Angeles
- USA
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38
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Ghadimi E, Eimar H, Song J, Marelli B, Ciobanu O, Abdallah MN, Stähli C, Nazhat SN, Vali H, Tamimi F. Regulated fracture in tooth enamel: A nanotechnological strategy from nature. J Biomech 2014; 47:2444-51. [DOI: 10.1016/j.jbiomech.2014.04.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 04/07/2014] [Accepted: 04/07/2014] [Indexed: 10/25/2022]
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39
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Size dependent elastic modulus and mechanical resilience of dental enamel. J Biomech 2014; 47:1060-6. [DOI: 10.1016/j.jbiomech.2013.12.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 12/12/2013] [Accepted: 12/22/2013] [Indexed: 11/22/2022]
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40
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An B, Zhao X, Zhang D. On the mechanical behavior of bio-inspired materials with non-self-similar hierarchy. J Mech Behav Biomed Mater 2014; 34:8-17. [PMID: 24548949 DOI: 10.1016/j.jmbbm.2013.12.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Revised: 12/27/2013] [Accepted: 12/28/2013] [Indexed: 10/25/2022]
Abstract
Biological materials exhibiting non-self-similar hierarchical structures possess desirable mechanical properties. Motivated by their penetration resistance and fracture toughness, the mechanical performance of model materials with non-self-similar hierarchical structures was explored and the distinct advantages were identified. A numerical model was developed, based on microscopic observation of enamel prisms. Computational simulations showed that the systems with non-self-similar hierarchy displayed lateral expansion when subjected to longitudinal tensile loading, which reflected negative Poisson׳s ratio and potential for greater volume strain energies when compared with conventional materials with positive Poisson׳s ratio. Employing the non-self-similar hierarchical design, the capability of resilience can be improved. Additionally, the non-self-similar hierarchical structure exhibited larger toughness, resulting from the large pull-out work of the reinforcements. The findings of this study not only elucidate the deformation mechanisms of biological materials with non-self-similar hierarchical structure, but also provide a new path for bio-inspired materials design.
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Affiliation(s)
- Bingbing An
- Department of Mechanics, Shanghai University, 99 Shangda Road, Shanghai 200444, PR China; Department of Physics, Shanghai University, Shanghai 200444, PR China
| | - Xinluo Zhao
- Department of Physics, Shanghai University, Shanghai 200444, PR China
| | - Dongsheng Zhang
- Department of Mechanics, Shanghai University, 99 Shangda Road, Shanghai 200444, PR China; Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai 200072, PR China.
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