1
|
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.
Collapse
|
2
|
Abdallah MN, Abughanam G, Tran SD, Sheikh Z, Mezour MA, Basiri T, Xiao Y, Cerruti M, Siqueira WL, Tamimi F. Comparative adsorption profiles of basal lamina proteome and gingival cells onto dental and titanium surfaces. Acta Biomater 2018; 73:547-558. [PMID: 29660511 DOI: 10.1016/j.actbio.2018.04.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 03/06/2018] [Accepted: 04/09/2018] [Indexed: 01/24/2023]
Abstract
Titanium (Ti) dental implants are susceptible to bacterial infections and failure due to lack of proper epithelial seal. Epithelial cells establish a strong epithelial seal around natural teeth by the deposition of basal lamina (BL) proteins that adsorb on the tooth surface. This seal can even be re-established onto cementum or dentin following injury or periodontal therapy. However, it is unclear how tooth surfaces promote this cell attachment and protein adsorption. Understanding the interactions between BL proteins and epithelial cells with dentin and Ti will facilitate the development of implant surfaces that promote the formation of an epithelial seal and improve the success of periodontal therapy and wound healing on natural teeth. To study these interactions, we used a surface proteomic approach to decipher the adsorption profile of BL proteins onto Ti and dentin, and correlated these adsorption profiles with in vitro interactions of human gingival fibroblasts and epithelial cells. Results showed that dentin adsorbed higher amounts of key BL proteins, particularly laminin and nidogen-1, and promoted more favorable interactions with epithelial cells than Ti. Next, dentin specimens were deproteinized or partially demineralized to determine if its mineral or protein component was responsible for BL adsorption and cell attachment. Deproteinized (mineral-rich) and partially demineralized (protein-rich) dentin specimens revealed BL proteins (i.e. laminin and nidogen-1) and epithelial cells interact preferentially with dentinal proteins rather than dentin mineral. These findings suggest that, unlike Ti, dentin and, in particular, dentinal proteins have a selective affinity to BL proteins that enhance epithelial cell attachment. STATEMENT OF SIGNIFICANCE It is remains unclear why natural teeth, unlike titanium dental implants, promote the formation of an epithelial seal that protects them against the external environment. This study used a surface screening approach to analyze the adsorption of proteins produced by epithelial tissues onto tooth-dentin and titanium surfaces, and correlate it with the behaviour of cells. This study shows that tooth-dentin, in particular its proteins, has a higher selective affinity to certain adhesion proteins, and subsequently allows more favourable interactions with epithelial cells than titanium. This knowledge could help in developing new approaches for re-establishing and maintaining the epithelial seal around teeth, and could pave the way for developing implants with surfaces that allow the formation of a true epithelial seal.
Collapse
|
3
|
Alageel O, Abdallah M, Alsheghri A, Song J, Caron E, Tamimi F. Removable partial denture alloys processed by laser‐sintering technique. J Biomed Mater Res B Appl Biomater 2017; 106:1174-1185. [DOI: 10.1002/jbm.b.33929] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 05/03/2017] [Accepted: 05/12/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Omar Alageel
- Faculty of DentistryMcGill UniversityMontreal Quebec Canada
- College of Applied Medical SciencesKing Saud UniversityRiyadh Saudi Arabia
| | | | - Ammar Alsheghri
- Department of Mining and Materials EngineeringMcGill UniversityMontreal Quebec Canada
| | - Jun Song
- Department of Mining and Materials EngineeringMcGill UniversityMontreal Quebec Canada
| | | | - Faleh Tamimi
- Faculty of DentistryMcGill UniversityMontreal Quebec Canada
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Abdallah MN, Eimar H, Bassett DC, Schnabel M, Ciobanu O, Nelea V, McKee MD, Cerruti M, Tamimi F. Diagenesis-inspired reaction of magnesium ions with surface enamel mineral modifies properties of human teeth. Acta Biomater 2016; 37:174-83. [PMID: 27060619 DOI: 10.1016/j.actbio.2016.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/09/2016] [Accepted: 04/06/2016] [Indexed: 11/18/2022]
Abstract
UNLABELLED Mineralized tissues such as teeth and bones consist primarily of highly organized apatitic calcium-phosphate crystallites within a complex organic matrix. The dimensions and organization of these apatite crystallites at the nanoscale level determine in part the physical properties of mineralized tissues. After death, geological processes such as diagenesis and dolomitization can alter the crystallographic properties of mineralized tissues through cycles of dissolution and re-precipitation occurring in highly saline environments. Inspired by these natural exchange phenomena, we investigated the effect of hypersalinity on tooth enamel. We discovered that magnesium ions reacted with human tooth enamel through a process of dissolution and re-precipitation, reducing enamel crystal size at the surface of the tooth. This change in crystallographic structure made the teeth harder and whiter. Salt-water rinses have been used for centuries to ameliorate oral infections; however, our discovery suggests that this ancient practice could have additional unexpected benefits. STATEMENT OF SIGNIFICANCE Here we describe an approach inspired by natural geological processes to modify the properties of a biomineral - human tooth enamel. In this study we showed that treatment of human tooth enamel with solutions saturated with magnesium induced changes in the nanocrystals at the outer surface of the protective enamel layer. As a consequence, the physical properties of the tooth were modified; tooth microhardness increased and the color shade became whiter, thus suggesting that this method could be used as a clinical treatment to improve dental mechanical properties and esthetics. Such an approach is simple and straightforward, and could also be used to develop new strategies to synthesize and modify biominerals for biomedical and industrial applications.
Collapse
Affiliation(s)
| | - Hazem Eimar
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - David C Bassett
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Martin Schnabel
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Ovidiu Ciobanu
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Valentin Nelea
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Marc D McKee
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada; Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Marta Cerruti
- Department of Mining and Materials Engineering, McGill University, H3A 0E8 Montreal, QC, Canada
| | - Faleh Tamimi
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada.
| |
Collapse
|
6
|
Yahyazadehfar M, Zhang D, Arola D. On the importance of aging to the crack growth resistance of human enamel. Acta Biomater 2016; 32:264-274. [PMID: 26747980 DOI: 10.1016/j.actbio.2015.12.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 12/03/2015] [Accepted: 12/30/2015] [Indexed: 11/28/2022]
Abstract
With improvements in oral health and an overall increase in quality of life, the percentage of fully or largely dentate seniors is increasing. Understanding the effects of aging on the mechanical properties of teeth is essential to the maintenance of lifelong oral health. In this investigation the effects of aging on the fracture toughness of human enamel were evaluated from incremental crack growth experiments performed on tissue of donor teeth representing "young" (17 ⩽ age ⩽ 25) and "old" (age ⩾ 55) age groups. Results showed that the old enamel exhibited significantly lower resistance to fracture than that of the young tissue in two orthogonal directions of crack growth. For crack growth transverse to the enamel rods, the fracture toughness of the old enamel (0.37 ± 0.15 MPa m(0.5)) was nearly 70% lower than that of tissue from the young teeth (1.23 ± 0.20 MPa m(0.5)). Based on results from a mechanistic analysis of crack growth, the reduction in fracture resistance is attributed to a decrease in the degree of extrinsic toughening. The practice of restorative dentistry should account for these changes in tooth tissues in the treatment of senior patients. STATEMENT OF SIGNIFICANCE The mechanical behavior of enamel has been studied for over 3 decades. Due to the limited volume of tissue available for evaluation, past work has been largely based on indentation methods. In this investigation we have evaluated the resistance to fracture of human enamel using a conventional fracture mechanics approach and incremental crack growth. We compared the fracture resistance of cuspal enamel obtained from the teeth of representative "young" and "old" donor groups. Our results show that there is a substantial reduction in the resistance to fracture with age, that it is anisotropic, and that the degradation is more severe than that which occurs to dentin. As such, we feel this work is a significant contribution to the field.
Collapse
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
| | - Dongsheng Zhang
- Department of Mechanics, Shanghai University, Shanghai 200444, PR China
| | - 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; Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, USA.
| |
Collapse
|
7
|
Advances in Dental Materials through Nanotechnology: Facts, Perspectives and Toxicological Aspects. Trends Biotechnol 2015; 33:621-636. [PMID: 26493710 DOI: 10.1016/j.tibtech.2015.09.005] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 08/16/2015] [Accepted: 09/08/2015] [Indexed: 01/25/2023]
Abstract
Nanotechnology is currently driving the dental materials industry to substantial growth, thus reflecting on improvements in materials available for oral prevention and treatment. The present review discusses new developments in nanotechnology applied to dentistry, focusing on the use of nanomaterials for improving the quality of oral care, the perspectives of research in this arena, and discussions on safety concerns regarding the use of dental nanomaterials. Details are provided on the cutting-edge properties (morphological, antibacterial, mechanical, fluorescence, antitumoral, and remineralization and regeneration potential) of polymeric, metallic and inorganic nano-based materials, as well as their use as nanocluster fillers, in nanocomposites, mouthwashes, medicines, and biomimetic dental materials. Nanotoxicological aspects, clinical applications, and perspectives for these nanomaterials are also discussed.
Collapse
|
8
|
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.
Collapse
|