1
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Zhang S, Liu J, Feng F, Jia Y, Xu F, Wei Z, Zhang M. Rational design of viscoelastic hydrogels for periodontal ligament remodeling and repair. Acta Biomater 2024; 174:69-90. [PMID: 38101557 DOI: 10.1016/j.actbio.2023.12.017] [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: 08/16/2023] [Revised: 11/14/2023] [Accepted: 12/07/2023] [Indexed: 12/17/2023]
Abstract
The periodontal ligament (PDL) is a distinctive yet critical connective tissue vital for maintaining the integrity and functionality of tooth-supporting structures. However, PDL repair poses significant challenges due to the complexity of its mechanical microenvironment encompassing hard-soft-hard tissues, with the viscoelastic properties of the PDL being of particular interest. This review delves into the significant role of viscoelastic hydrogels in PDL regeneration, underscoring their utility in simulating biomimetic three-dimensional microenvironments. We review the intricate relationship between PDL and viscoelastic mechanical properties, emphasizing the role of tissue viscoelasticity in maintaining mechanical functionality. Moreover, we summarize the techniques for characterizing PDL's viscoelastic behavior. From a chemical bonding perspective, we explore various crosslinking methods and characteristics of viscoelastic hydrogels, along with engineering strategies to construct viscoelastic cell microenvironments. We present a detailed analysis of the influence of the viscoelastic microenvironment on cellular mechanobiological behavior and fate. Furthermore, we review the applications of diverse viscoelastic hydrogels in PDL repair and address current challenges in the field of viscoelastic tissue repair. Lastly, we propose future directions for the development of innovative hydrogels that will facilitate not only PDL but also systemic ligament tissue repair. STATEMENT OF SIGNIFICANCE.
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Affiliation(s)
- Songbai Zhang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi'an 710032, PR China; The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Jingyi Liu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Fan Feng
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi'an 710032, PR China
| | - Yuanbo Jia
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Feng Xu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Zhao Wei
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China.
| | - Min Zhang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi'an 710032, PR China.
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2
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Zhong J, Shibata Y, Wu C, Watanabe C, Chen J, Zheng K, Hu J, Swain MV, Li Q. Functional non-uniformity of periodontal ligaments tunes mechanobiological stimuli across soft- and hard-tissue interfaces. Acta Biomater 2023; 170:240-249. [PMID: 37634832 DOI: 10.1016/j.actbio.2023.08.047] [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: 04/10/2023] [Revised: 08/09/2023] [Accepted: 08/22/2023] [Indexed: 08/29/2023]
Abstract
The bone-periodontal ligament-tooth (BPT) complex is a unique mechanosensing soft-/hard-tissue interface, which governs the most rapid bony homeostasis in the body responding to external loadings. While the correlation between such loading and alveolar bone remodelling has been widely recognised, it has remained challenging to investigate the transmitted mechanobiological stimuli across such embedded soft-/hard-tissue interfaces of the BPT complex. Here, we propose a framework combining three distinct bioengineering techniques (i, ii, and iii below) to elucidate the innate functional non-uniformity of the PDL in tuning mechanical stimuli to the surrounding alveolar bone. The biphasic PDL mechanical properties measured via nanoindentation, namely the elastic moduli of fibres and ground substance at the sub-tissue level (i), were used as the input parameters in an image-based constitutive modelling framework for finite element simulation (ii). In tandem with U-net deep learning, the Gaussian mixture method enabled the comparison of 5195 possible pseudo-microstructures versus the innate non-uniformity of the PDL (iii). We found that the balance between hydrostatic pressure in PDL and the strain energy in the alveolar bone was maintained within a specific physiological range. The innate PDL microstructure ensures the transduction of favourable mechanobiological stimuli, thereby governing alveolar bone homeostasis. Our outcomes expand current knowledge of the PDL's mechanobiological roles and the proposed framework can be adopted to a broad range of similar soft-/hard- tissue interfaces, which may impact future tissue engineering, regenerative medicine, and evaluating therapeutic strategies. STATEMENT OF SIGNIFICANCE: A combination of cutting-edge technologies, including dynamic nanomechanical testing, high-resolution image-based modelling and machine learning facilitated computing, was used to elucidate the association between the microstructural non-uniformity and biomechanical competence of periodontal ligaments (PDLs). The innate PDL fibre network regulates mechanobiological stimuli, which govern alveolar bone remodelling, in different tissues across the bone-PDL-tooth (BPT) interfaces. These mechanobiological stimuli within the BPT are tuned within a physiological range by the non-uniform microstructure of PDLs, ensuring functional tissue homeostasis. The proposed framework in this study is also applicable for investigating the structure-function relationship in broader types of fibrous soft-/hard- tissue interfaces.
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Affiliation(s)
- Jingxiao Zhong
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006, Australia
| | - Yo Shibata
- Department of Biomaterials and Engineering, Showa University School of Dentistry, Tokyo, Japan
| | - Chi Wu
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006, Australia
| | - Chie Watanabe
- Department of Biomaterials and Engineering, Showa University School of Dentistry, Tokyo, Japan
| | - Junning Chen
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Keke Zheng
- Institute for Mechanical, Process and Energy Engineering, School of Engineering and Physical Sciences, Heriot Watt University, Edinburgh, UK
| | - Jingrui Hu
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Michael V Swain
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006, Australia
| | - Qing Li
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006, Australia.
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3
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Armijo L, Mancl L, Dennison CR, Houg K, Romanyk D, Popowics T. In-fiber Bragg sensor measurements assess fluid effects on strain in the periodontal space of an ex-vivo swine incisor complex under mechanical loading. J Biomech 2023; 157:111729. [PMID: 37473706 DOI: 10.1016/j.jbiomech.2023.111729] [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: 10/12/2022] [Revised: 06/14/2023] [Accepted: 07/14/2023] [Indexed: 07/22/2023]
Abstract
The purpose of this study is to determine whether in-fiber Bragg grating (FBG) sensors detect changes within the periodontal ligament (PDL) of ex-vivo swine tooth-PDL-bone complex (TPBC) when manipulating fluid content. Recording strain will allow for a better understanding of the biomechanics of viscoelastic load transfer from the tooth to the PDL during chewing and/or orthodontic tooth movement, as well as replication of these dynamics in regenerated PDL tissues. FBG sensors placed within the PDL of swine incisor teeth were used to measure strain resulting from an intrusive load. Specimens were mounted in a custom platform within an MTS machine and a compressive load was applied at 0.3 mm/s to a depth of 0.5 mm and held for 10 s. Median peak strain and load and median absolute deviation (MAD) were compared: dry vs. saline (n = 19) with bias-corrected bootstrap 95% CI. Dry vs. saline conditions did not statistically differ (median peaks of 5με, 103-105 N) and recorded strains showed high repeatability (MAD of 0.82με, 0.72με, respectively). FBG sensors did not detect the fluid changes in this study, suggesting that the deformation of tissues in the PDL space collectively determine FBG strain in response to tooth loading. The repeatability of measurements demonstrates the potential for FBG sensors to assess the strain in the PDL space of an in vivo swine model.
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Affiliation(s)
- Leigh Armijo
- Dept. of Orthodontics, University of Washington School of Dentistry, Seattle, WA 98195, USA.
| | - Lloyd Mancl
- Dept. of Oral Health Sciences, University of Washington School of Dentistry, Seattle, WA 98195, USA.
| | | | - Kathryn Houg
- Dept. of Mechanical Engineering and School of Dentistry, University of Alberta, Edmonton, Alberta, Canada.
| | - Dan Romanyk
- Dept. of Mechanical Engineering and School of Dentistry, University of Alberta, Edmonton, Alberta, Canada.
| | - Tracy Popowics
- Box 357475, Dept. of Oral Health Sciences, 1959 Pacific Ave. NE, University of Washington School of Dentistry, Seattle, WA 98195, USA.
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4
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Ansbacher T, Tohar R, Cohen A, Cohen O, Levartovsky S, Arieli A, Matalon S, Bar DZ, Gal M, Weinberg E. A novel computationally engineered collagenase reduces the force required for tooth extraction in an ex-situ porcine jaw model. J Biol Eng 2023; 17:47. [PMID: 37461028 DOI: 10.1186/s13036-023-00366-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 07/05/2023] [Indexed: 07/20/2023] Open
Abstract
The currently employed tooth extraction methods in dentistry involve mechanical disruption of the periodontal ligament fibers, leading to inevitable trauma to the bundle bone comprising the socket walls. In our previous work, we have shown that a recombinantly expressed truncated version of clostridial collagenase G (ColG) purified from Escherichia coli efficiently reduced the force needed for tooth extraction in an ex-situ porcine jaw model, when injected into the periodontal ligament. Considering that enhanced thermostability often leads to higher enzymatic activity and to set the basis for additional rounds of optimization, we used a computational protein design approach to generate an enzyme to be more thermostable while conserving the key catalytic residues. This process generated a novel collagenase (ColG-variant) harboring sixteen mutations compared to ColG, with a nearly 4℃ increase in melting temperature. Herein, we explored the potential of ColG-variant to further decrease the physical effort required for tooth delivery using our established ex-situ porcine jaw model. An average reduction of 11% was recorded in the force applied to extract roots of mandibular split first and second premolar teeth treated with ColG-variant, relative to those treated with ColG. Our results show for the first time the potential of engineering enzyme properties for dental medicine and further contribute to minimally invasive tooth extraction.
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Affiliation(s)
- Tamar Ansbacher
- Department of Oral Biology, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
- Hadassah Academic College, 91010, Jerusalem, Israel
| | - Ran Tohar
- Department of Oral Biology, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Adi Cohen
- Department of Oral Biology, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Orel Cohen
- Department of Oral Biology, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Shifra Levartovsky
- Department of Oral Rehabilitation, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Adi Arieli
- Department of Oral Rehabilitation, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Shlomo Matalon
- Department of Oral Rehabilitation, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Daniel Z Bar
- Department of Oral Biology, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Maayan Gal
- Department of Oral Biology, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel.
| | - Evgeny Weinberg
- Department of Oral Biology, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel.
- Department of Periodontology and Oral Implantology, Goldschleger School of Dental Medicine, Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel.
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5
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Dall'Ara E, Bodey AJ, Isaksson H, Tozzi G. A practical guide for in situ mechanical testing of musculoskeletal tissues using synchrotron tomography. J Mech Behav Biomed Mater 2022; 133:105297. [PMID: 35691205 DOI: 10.1016/j.jmbbm.2022.105297] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 05/03/2022] [Accepted: 05/25/2022] [Indexed: 02/07/2023]
Abstract
Musculoskeletal tissues are complex hierarchical materials where mechanical response is linked to structural and material properties at different dimensional levels. Therefore, high-resolution three-dimensional tomography is very useful for assessing tissue properties at different scales. In particular, Synchrotron Radiation micro-Computed Tomography (SR-microCT) has been used in several applications to analyze the structure of bone and biomaterials. In the past decade the development of digital volume correlation (DVC) algorithms applied to SR-microCT images and its combination with in situ mechanical testing (four-dimensional imaging) have allowed researchers to visualise, for the first time, the deformation of musculoskeletal tissues and their interaction with biomaterials under different loading scenarios. However, there are several experimental challenges that make these measurements difficult and at high risk of failure. Challenges relate to sample preparation, imaging parameters, loading setup, accumulated tissue damage for multiple tomographic acquisitions, reconstruction methods and data processing. Considering that access to SR-microCT facilities is usually associated with bidding processes and long waiting times, the failure of these experiments could notably slow down the advancement of this research area and reduce its impact. Many of the experimental failures can be avoided with increased experience in performing the tests and better guidelines for preparation and execution of these complex experiments; publication of negative results could help interested researchers to avoid recurring mistakes. Therefore, the goal of this article is to highlight the potential and pitfalls in the design and execution of in situ SR-microCT experiments, involving multiple scans, of musculoskeletal tissues for the assessment of their structural and/or mechanical properties. The advice and guidelines that follow should improve the success rate of this type of experiment, allowing the community to reach higher impact more efficiently.
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Affiliation(s)
- E Dall'Ara
- Department of Oncology and Metabolism, Mellanby Centre for Bone Research, University of Sheffield, UK; INSIGNEO Institute for in Silico Medicine, University of Sheffield, UK.
| | | | - H Isaksson
- Department of Biomedical Engineering, Lund University, Lund, Sweden
| | - G Tozzi
- School of Engineering, London South Bank University, London, UK
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6
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Latimer JM, Maekawa S, Yao Y, Wu DT, Chen M, Giannobile WV. Regenerative Medicine Technologies to Treat Dental, Oral, and Craniofacial Defects. Front Bioeng Biotechnol 2021; 9:704048. [PMID: 34422781 PMCID: PMC8378232 DOI: 10.3389/fbioe.2021.704048] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 06/29/2021] [Indexed: 01/10/2023] Open
Abstract
Additive manufacturing (AM) is the automated production of three-dimensional (3D) structures through successive layer-by-layer deposition of materials directed by computer-aided-design (CAD) software. While current clinical procedures that aim to reconstruct hard and soft tissue defects resulting from periodontal disease, congenital or acquired pathology, and maxillofacial trauma often utilize mass-produced biomaterials created for a variety of surgical indications, AM represents a paradigm shift in manufacturing at the individual patient level. Computer-aided systems employ algorithms to design customized, image-based scaffolds with high external shape complexity and spatial patterning of internal architecture guided by topology optimization. 3D bioprinting and surface modification techniques further enhance scaffold functionalization and osteogenic potential through the incorporation of viable cells, bioactive molecules, biomimetic materials and vectors for transgene expression within the layered architecture. These computational design features enable fabrication of tissue engineering constructs with highly tailored mechanical, structural, and biochemical properties for bone. This review examines key properties of scaffold design, bioresorbable bone scaffolds produced by AM processes, and clinical applications of these regenerative technologies. AM is transforming the field of personalized dental medicine and has great potential to improve regenerative outcomes in patient care.
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Affiliation(s)
- Jessica M Latimer
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA, United States
| | - Shogo Maekawa
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA, United States.,Department of Periodontology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yao Yao
- Department of Periodontics & Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI, United States.,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
| | - David T Wu
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA, United States.,Laboratory for Cell and Tissue Engineering, Harvard John A. Paulson School of Engineering and Applied Sciences, Boston, MA, United States.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States
| | - Michael Chen
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA, United States
| | - William V Giannobile
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA, United States
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7
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Zhong J, Pierantoni M, Weinkamer R, Brumfeld V, Zheng K, Chen J, Swain MV, Weiner S, Li Q. Microstructural heterogeneity of the collagenous network in the loaded and unloaded periodontal ligament and its biomechanical implications. J Struct Biol 2021; 213:107772. [PMID: 34311076 DOI: 10.1016/j.jsb.2021.107772] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 07/02/2021] [Accepted: 07/19/2021] [Indexed: 01/17/2023]
Abstract
The periodontal ligament (PDL) is a highly heterogeneous fibrous connective tissue and plays a critical role in distributing occlusal forces and regulating tissue remodeling. Its mechanical properties are largely determined by the extracellular matrix, comprising a collagenous fiber network interacting with the capillary system as well as interstitial fluid containing proteoglycans. While the phase-contrast micro-CT technique has portrayed the 3D microscopic heterogeneity of PDL, the topological parameters of its network, which is crucial to understanding the multiscale constitutive behavior of this tissue, has not been characterized quantitatively. This study aimed to provide new understanding of such microscopic heterogeneity of the PDL with quantifications at both tissue and collagen network levels in a spatial manner, by combining phase-contrast micro-CT imaging and a purpose-built image processing algorithm for fiber analysis. Both variations within a PDL and among the PDL with different shapes, i.e. round-shaped and kidney-shaped PDLs, are described in terms of tissue thickness, fiber distribution, local fiber densities, and fiber orientation (namely azimuthal and elevation angles). Furthermore, the tissue and collagen fiber network responses to mechanical loading were evaluated in a similar manner. A 3D helical alignment pattern was observed in the fiber network, which appears to regulate and adapt a screw-like tooth motion under occlusion. The microstructural heterogeneity quantified here allows development of sample-specific constitutive models to characterize the PDL's functional and pathological loading responses, thereby providing a new multiscale framework for advancing our knowledge of this complex limited mobility soft-hard tissue interface.
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Affiliation(s)
- Jingxiao Zhong
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia
| | - Maria Pierantoni
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel; Department of Biomedical Engineering, Lund University, Lund, Sweden
| | - Richard Weinkamer
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Vlad Brumfeld
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Keke Zheng
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia; College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Junning Chen
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Michael V Swain
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia
| | - Steve Weiner
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Qing Li
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia.
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8
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Otani T, Koga T, Nozaki K, Kobayashi Y, Tanaka M. Mechanical effects of distributed fibre orientation in the periodontal ligament of an idealised geometry. Comput Methods Biomech Biomed Engin 2020; 24:1-10. [PMID: 33225747 DOI: 10.1080/10255842.2020.1847277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 10/09/2020] [Accepted: 11/03/2020] [Indexed: 10/22/2022]
Abstract
In this study, we computationally assess the effects of the distributed fibre orientation in the periodontal ligament (PDL) on mechanical responses of the tooth-PDL complex. An idealised axial-symmetric geometry of a tooth-PDL complex was constructed. The fibre orientation in the PDL was modelled as a trigonometric function based on anatomical knowledge, and the PDL was modelled as a transversely isotropic hyperelastic material dependent on fibre orientations. Parametric studies of the fibre orientation on the mechanical responses of the tooth-PDL complex were conducted. Obtained results showed that the anatomically consistent fibre orientation functions as a supporting structure against not only vertical but also horizontal loads.
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Affiliation(s)
- Tomohiro Otani
- Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
| | - Taiki Koga
- Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
| | - Kazunori Nozaki
- Division of Medical Information, Osaka University Dental Hospital, Osaka, Japan
| | - Yo Kobayashi
- Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
| | - Masao Tanaka
- Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Japan
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9
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Bemmann M, Schulz-Kornas E, Hammel JU, Hipp A, Moosmann J, Herrel A, Rack A, Radespiel U, Zimmermann E, Kaiser TM, Kupczik K. Movement analysis of primate molar teeth under load using synchrotron X-ray microtomography. J Struct Biol 2020; 213:107658. [PMID: 33207268 DOI: 10.1016/j.jsb.2020.107658] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 10/23/2022]
Abstract
Mammalian teeth have to sustain repetitive and high chewing loads without failure. Key to this capability is the periodontal ligament (PDL), a connective tissue containing a collagenous fibre network which connects the tooth roots to the alveolar bone socket and which allows the teeth to move when loaded. It has been suggested that rodent molars under load experience a screw-like downward motion but it remains unclear whether this movement also occurs in primates. Here we use synchroton micro-computed tomography paired with an axial loading setup to investigate the form-function relationship between tooth movement and the morphology of the PDL space in a non-human primate, the mouse lemur (Microcebus murinus). The loading behavior of both mandibular and maxillary molars showed a three-dimensional movement with translational and rotational components, which pushes the tooth into the alveolar socket. Moreover, we found a non-uniform PDL thickness distribution and a gradual increase in volumetric proportion of the periodontal vasculature from cervical to apical. Our results suggest that the PDL morphology may optimize the three-dimensional tooth movement to avoid high stresses under loading.
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Affiliation(s)
- Maximilian Bemmann
- Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max-Planck-Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Department of Cariology, Endodontics and Periodontology, University of Leipzig, Liebigstrasse 12, 04103 Leipzig, Germany
| | - Ellen Schulz-Kornas
- Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max-Planck-Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Department of Cariology, Endodontics and Periodontology, University of Leipzig, Liebigstrasse 12, 04103 Leipzig, Germany; Center of Natural History (CeNak), University of Hamburg, Hamburg, Germany
| | - Jörg U Hammel
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
| | - Alexander Hipp
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
| | - Julian Moosmann
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
| | - Anthony Herrel
- UMR 7179 C.N.R.S/M.N.H.N., Département Adaptations du Vivant, Bâtiment d'Anatomie Comparée, 55 rue Buffon, 75005 Paris, France
| | - Alexander Rack
- ESRF The European Synchrotron, 71 Rue des Martyrs, 38000 Grenoble, France
| | - Ute Radespiel
- Institute of Zoology, University of Veterinary Medicine Hannover, Buenteweg 17, 30559 Hannover, Germany
| | - Elke Zimmermann
- Institute of Zoology, University of Veterinary Medicine Hannover, Buenteweg 17, 30559 Hannover, Germany
| | - Thomas M Kaiser
- Center of Natural History (CeNak), University of Hamburg, Hamburg, Germany
| | - Kornelius Kupczik
- Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max-Planck-Institute for Evolutionary Anthropology, 04103 Leipzig, Germany.
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10
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Connizzo BK, Sun L, Lacin N, Gendelman A, Solomonov I, Sagi I, Grodzinsky AJ, Naveh GRS. Nonuniformity in Periodontal Ligament: Mechanics and Matrix Composition. J Dent Res 2020; 100:179-186. [PMID: 33043806 DOI: 10.1177/0022034520962455] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The periodontal ligament (PDL) plays a critical role in providing immediate response to abrupt high loads during mastication while also facilitating slow remodeling of the alveolar bone. The PDL exceptional functionality is permitted by the unique nonuniform structure of the tissue. Two distinct areas that are critical to PDL function were previously identified: the furcation and the dense collar. Despite their hypothesized functions in tooth movement and maintenance, these 2 regions have not yet been compared within the context of their native environment. Therefore, the objective of this study is to elucidate the extracellular matrix (ECM) structure, composition, and biomechanical function of the furcation and the collar regions while maintaining the 3-dimensional (3D) structure in the murine PDL. We identify significant difference between the collar and furcation regions in both structure and mechanical properties. Specifically, we observed unique longitudinal structures in the dense collar that correlate with type VI collagen and LOX, both of which are associated with increased type I collagen density and tissue stiffness and are therefore proposed to function as scaffolds for tooth stabilization. We also found that the collar region is stiffer than the furcation region and therefore suggest that the dense collar acts as a suspense structure of the tooth within the bone during physiological loading. The furcation region of the PDL contained more proteins associated with reduced stiffness and higher tissue remodeling, as well as a dual mechanical behavior, suggesting a critical function in loads transfer and remodeling of the alveolar bone. In summary, this work unravels the nonuniform nature of the PDL within the 3D structural context and establishes understanding of regional PDL function, which opens new avenues for future studies of remodeling, regeneration, and disease.
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Affiliation(s)
- B K Connizzo
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - L Sun
- Department of Oral Medicine, Infection and Immunity, School of Dental Medicine, Harvard University, Boston, MA, USA
| | - N Lacin
- Department of Oral Medicine, Infection and Immunity, School of Dental Medicine, Harvard University, Boston, MA, USA
| | - A Gendelman
- Department of Oral Medicine, Infection and Immunity, School of Dental Medicine, Harvard University, Boston, MA, USA
| | - I Solomonov
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - I Sagi
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - A J Grodzinsky
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.,Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - G R S Naveh
- Department of Oral Medicine, Infection and Immunity, School of Dental Medicine, Harvard University, Boston, MA, USA
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11
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Connizzo BK, Naveh GRS. In situ AFM-based nanoscale rheology reveals regional non-uniformity in viscoporoelastic mechanical behavior of the murine periodontal ligament. J Biomech 2020; 111:109996. [PMID: 32861150 DOI: 10.1016/j.jbiomech.2020.109996] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/04/2020] [Accepted: 08/08/2020] [Indexed: 12/16/2022]
Abstract
The periodontal ligament (PDL) is a critical player in the maintenance of tooth health, acting as the primary stabilizer of tooth position. Recent studies have identified two unique regions within the PDL, the 'dense collar' region and the 'furcation' region, which exhibit distinct structural and compositional differences. However, specific functional differences between these regions have yet to be investigated. We adapted an AFM-based nanoscale rheology method to regionally assess mechanical properties and poroelasticity in the mouse PDL while minimizing the disruption of the 3-dimensional native boundary conditions, and then explored tissue mechanical function in four different regions within the dense collar as well as in the furcation region. We found significant differences between the collar and furcation regions, with the collar acting as a stabilizing ligamentous structure and the furcation acting as both a compressive cushion for vertical forces and a conduit for nutrient transport. While this finding supports our hypothesis, based on previous studies investigating structural and compositional differences, we also found surprising inhomogeneity within the collar region itself. This inhomogeneity supports previous findings of a tilting movement in the buccal direction of mandibular molar teeth and the structural adaptation to prevent lingual movement. Future work will aim to understand how different regions of the PDL change functionally during biological or mechanical perturbations, such as orthodontic tooth movement, development, or aging, with the ultimate goal of better understanding the mechanobiology of the PDL function in health and disease.
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Affiliation(s)
- Brianne K Connizzo
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
| | - Gili R S Naveh
- Department of Oral Medicine, Infection and Immunity, School of Dental Medicine, Harvard University, Boston, MA 02115, United States
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12
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Ortún-Terrazas J, Cegoñino J, Pérez Del Palomar A. In silico study of cuspid' periodontal ligament damage under parafunctional and traumatic conditions of whole-mouth occlusions. A patient-specific evaluation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 184:105107. [PMID: 31629157 DOI: 10.1016/j.cmpb.2019.105107] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/28/2019] [Accepted: 10/01/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND AND OBJECTIVE Although traumatic loading has been associated with periodontal ligament (PDL) damage and therefore with several oral disorders, the damage phenomena and the traumatic loads involved are still unclear. The complex composition and extremely thin size of the PDL make experimentation difficult, requiring computational studies that consider the macroscopic loading conditions, the microscopic composition and fine detailed geometry of the tissue. In this study, a new methodology to analyse the damage phenomena in the collagen network and the extracellular matrix of the PDL caused by parafunctional and traumatic occlusal forces was proposed. METHODS The entire human mandible and a portion thereof containing a full cuspid tooth were separately modelled using finite element analysis based on computed tomography and micro-computed tomography images, respectively. The first model was experimentally validated by occlusion analysis and subjected to the muscle loads produced during hard and soft chewing, traumatic cuspid occlusion, grinding, clenching, and simultaneous grinding and clenching. The occlusal forces computed by the first model were subsequently applied to the single tooth model to evaluate damage to the collagen network and the extracellular matrix of the PDL. RESULTS Early occlusal contact on the left cuspid tooth guided the mandible to the more occluded side (16.5% greater in the right side) and absorbed most of the lateral load. The intrusive occlusal loads on the posterior teeth were 0.77-13.3% greater than those on the cuspid. According to our findings, damage to the collagen network and the extracellular matrix of the PDL could occur in traumatic and grinding conditions, mainly due to fibre overstretching (>60%) and interstitial fluid overpressure (>4.7 kPa), respectively. CONCLUSIONS Our findings provide important biomechanical insights into the determination of damage mechanisms which are caused by mechanical loading and the key role of the porous-fibrous behaviour of the PDL in parafunctional and traumatic loading scenarios. Besides, the 3D loading conditions computed from occlusal contacts will help future studies in the design of new orthodontics appliances and encourage the application of computing methods in medical practice.
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Affiliation(s)
- Javier Ortún-Terrazas
- Group of Biomaterials, Aragon Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain.
| | - José Cegoñino
- Group of Biomaterials, Aragon Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
| | - Amaya Pérez Del Palomar
- Group of Biomaterials, Aragon Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
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13
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Three-dimensional ultrastructural imaging and quantitative analysis of the periodontal ligament. Anat Sci Int 2019; 95:1-11. [DOI: 10.1007/s12565-019-00502-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 09/01/2019] [Indexed: 12/16/2022]
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14
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Zhong J, Chen J, Weinkamer R, Darendeliler MA, Swain MV, Sue A, Zheng K, Li Q. In vivo effects of different orthodontic loading on root resorption and correlation with mechanobiological stimulus in periodontal ligament. J R Soc Interface 2019; 16:20190108. [PMID: 31039696 PMCID: PMC6544889 DOI: 10.1098/rsif.2019.0108] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 04/01/2019] [Indexed: 12/26/2022] Open
Abstract
Orthodontic root resorption is a common side effect of orthodontic therapy. It has been shown that high hydrostatic pressure in the periodontal ligament (PDL) generated by orthodontic forces will trigger recruitment of odontoclasts, leaving resorption craters on root surfaces. The patterns of resorption craters are the traces of odontoclast activity. This study aimed to investigate resorptive patterns by: (i) quantifying spatial root resorption under two different levels of in vivo orthodontic loadings using microCT imaging techniques and (ii) correlating the spatial distribution pattern of resorption craters with the induced mechanobiological stimulus field in PDL through nonlinear finite-element analysis (FEA) in silico. Results indicated that the heavy force led to a larger total resorption volume than the light force, mainly by presenting greater individual crater volumes ( p < 0.001) than increasing crater numbers, suggesting that increased mechano-stimulus predominantly boosted cellular resorption activity rather than recruiting more odontoclasts. Furthermore, buccal-cervical and lingual-apical regions in both groups were found to have significantly larger resorption volumes than other regions ( p < 0.005). These clinical observations are complemented by the FEA results, suggesting that root resorption was more likely to occur when the volume average compressive hydrostatic pressure exceeded the capillary blood pressure (4.7 kPa).
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Affiliation(s)
- Jingxiao Zhong
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia
| | - Junning Chen
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Richard Weinkamer
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - M. Ali Darendeliler
- Faculty of Dentistry, Discipline of Orthodontics, University of Sydney, Sydney, Australia
| | - Michael V. Swain
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia
- Faculty of Dentistry, Discipline of Orthodontics, University of Sydney, Sydney, Australia
| | - Andrian Sue
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia
| | - Keke Zheng
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia
| | - Qing Li
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia
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15
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Abstract
3D analysis of animal or human whole teeth and alveolar bone can be performed with high sensitivity in a nondestructive manner by microcomputed tomography. Here we describe the protocols to be followed for the most common applications in the developmental studies of dental and craniofacial tissues. Emphasis is placed on the basis of choosing settings for image acquisition, such as voxel resolution (Fig. 1), or beam energy (Fig. 2) and for processing, such as segmentation method (Fig. 3), parameters. The limitations to take into account for optimal efficiency and image quality are also explained.
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Affiliation(s)
- Kostas Verdelis
- Department of Restorative Dentistry/Comprehensive Care, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
- Department of Endodontics and Center for Craniofacial Regeneration, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Phil Salmon
- Department of Restorative Dentistry/Comprehensive Care, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Bruker microCT, Kontich, Belgium
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16
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Abstract
Ligaments serve as compliant connectors between hard tissues. In that role, they function under various load regimes and directions. The 3D structure of ligaments is considered to form as a uniform entity that changes due to function. The periodontal ligament (PDL) connects the tooth to the bone and sustains different types of loads in various directions. Using the PDL as a model, employing a fabricated motorized setup in a microCT, we demonstrate that the fibrous network structure within the PDL is not uniform, even before the tooth becomes functional. Utilizing morphological automated segmentation methods, directionality analysis, as well as second harmonic generation imaging, we find high correlation between blood vessel distribution and fiber density. We also show a structural feature in a form of a dense collar around the neck of the tooth as well as a preferred direction of the fibrous network. Finally, we show that the PDL develops as a nonuniform structure, with an architecture designed to sustain specific types of load in designated areas. Based on these findings, we propose that ligaments in general should be regarded as nonuniform entities, structured already at developmental stages for optimal functioning under variable load regimes.
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17
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Hirashima S, Ohta K, Kanazawa T, Okayama S, Togo A, Miyazono Y, Kusukawa J, Nakamura KI. Three-dimensional ultrastructural analysis and histomorphometry of collagen bundles in the periodontal ligament using focused ion beam/scanning electron microscope tomography. J Periodontal Res 2018; 55:23-31. [PMID: 30035304 DOI: 10.1111/jre.12592] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/07/2018] [Accepted: 06/13/2018] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND OBJECTIVE The periodontal ligament (PDL) is an essential tissue for tooth function. However, the 3-dimensional ultrastructure of these PDL collagen bundles on a mesoscale is not clear. We investigated the 3-dimensional ultrastructure of these collagen bundles and quantitatively analyzed their histomorphometry using focused ion beam/scanning electron microscope (FIB/SEM) tomography. MATERIAL AND METHODS The PDLs of the first mandibular molar of male C57BL/6 mice were analyzed using FIB/SEM tomography. The serial images of the collagen bundles so obtained were reconstructed. The collagen bundles were analyzed quantitatively using 3-dimensional histomorphometry. RESULTS Collagen bundles of the PDL demonstrated multiple branched structures, rather than a single rope-like structure, and were wrapped in cytoplasm sheets. The structure of the horizontal fiber of the collagen bundle was an extensive meshwork. In contrast, the oblique and apical fibers of the collagen bundle showed a chain-like structure. The area and the minor and major axis lengths of cross-sections of the horizontal fiber, as determined from 3-dimensional images, were significantly different from those of the oblique and apical fibers. CONCLUSION These findings indicate that collagen bundles in horizontal fiber areas have high strength and that the tooth is firmly anchored to the alveolar bone by the horizontal fibers, but is not secured evenly to the alveolar bone. The tooth is firmly anchored around the cervical area, creating a "slingshot-like structure." This study has provided further insights into the structure of the PDL and forms the basis for the development of more effective therapies for periodontal tissue regeneration.
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Affiliation(s)
- Shingo Hirashima
- Division of Microscopic and Developmental Anatomy, Department of Anatomy, Kurume University School of Medicine, Kurume, Japan.,Dental and Oral Medical Center, Kurume University School of Medicine, Kurume, Japan
| | - Keisuke Ohta
- Division of Microscopic and Developmental Anatomy, Department of Anatomy, Kurume University School of Medicine, Kurume, Japan.,Advanced Imaging Research Center, Kurume University School of Medicine, Kurume, Japan
| | - Tomonoshin Kanazawa
- Division of Microscopic and Developmental Anatomy, Department of Anatomy, Kurume University School of Medicine, Kurume, Japan
| | - Satoko Okayama
- Division of Microscopic and Developmental Anatomy, Department of Anatomy, Kurume University School of Medicine, Kurume, Japan
| | - Akinobu Togo
- Advanced Imaging Research Center, Kurume University School of Medicine, Kurume, Japan
| | - Yoshihiro Miyazono
- Dental and Oral Medical Center, Kurume University School of Medicine, Kurume, Japan
| | - Jingo Kusukawa
- Dental and Oral Medical Center, Kurume University School of Medicine, Kurume, Japan
| | - Kei-Ichiro Nakamura
- Division of Microscopic and Developmental Anatomy, Department of Anatomy, Kurume University School of Medicine, Kurume, Japan
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18
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Sartori J, Köhring S, Witte H, Fischer MS, Löffler M. Three-dimensional imaging of the fibrous microstructure of Achilles tendon entheses in Mus musculus. J Anat 2018; 233:370-380. [PMID: 29920671 PMCID: PMC6081500 DOI: 10.1111/joa.12837] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2018] [Indexed: 12/20/2022] Open
Abstract
The whole-organ, three-dimensional microstructure of murine Achilles tendon entheses was visualized with micro-computed tomography (microCT). Contrast-enhancement was achieved either by staining with phosphotungstic acid (PTA) or by a combination of cell-maceration, demineralization and critical-point drying with low tube voltages and propagation-based phase-contrast (fibrous structure scan). By PTA-staining, X-ray absorption of the enthesial soft tissues became sufficiently high to segment the tendon and measure cross-sectional areas along its course. With the fibrous structure scans, three-dimensional visualizations of the collagen fiber networks of complete entheses were obtained. The characteristic tissues of entheses were identified in the volume data. The tendon proper was marked as a segment manually. The fibers within the tendon were marked by thresholding. Tendon and fiber cross-sectional areas were measured. The measurements were compared between individuals and protocols for contrast-enhancement, using a spatial reference system within the three-dimensional enthesis. The usefulness of the method for investigations of the fibrous structure of collagenous tissues is demonstrated.
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Affiliation(s)
- Julian Sartori
- Institut für Zoologie und EvolutionsforschungFriedrich‐Schiller‐Universität JenaJenaGermany
| | - Sebastian Köhring
- Fachgebiet BiomechatronikFakultät für Maschinenbau / IMN MacroNano®Technische Universität IlmenauIlmenauGermany
| | - Hartmut Witte
- Fachgebiet BiomechatronikFakultät für Maschinenbau / IMN MacroNano®Technische Universität IlmenauIlmenauGermany
| | - Martin S. Fischer
- Institut für Zoologie und EvolutionsforschungFriedrich‐Schiller‐Universität JenaJenaGermany
| | - Markus Löffler
- Dresden Center for Nanoanalysis (DCN)Center for Advancing Electronics Dresden (cfaed)Technische Universität DresdenDresdenGermany
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19
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Zebrafish skeleton development: High resolution micro-CT and FIB-SEM block surface serial imaging for phenotype identification. PLoS One 2017; 12:e0177731. [PMID: 29220379 PMCID: PMC5722281 DOI: 10.1371/journal.pone.0177731] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 05/02/2017] [Indexed: 12/03/2022] Open
Abstract
Although bone is one of the most studied living materials, many questions about the manner in which bones form remain unresolved, including fine details of the skeletal structure during development. In this study, we monitored skeleton development of zebrafish larvae, using calcein fluorescence, high-resolution micro-CT 3D images and FIB-SEM in the block surface serial imaging mode. We compared calcein staining of the skeletons of the wild type and nacre mutants, which are transparent zebrafish, with micro-CT for the first 30 days post fertilization embryos, and identified significant differences. We quantified the bone volumes and mineral contents of bones, including otoliths, during development, and showed that such developmental differences, including otolith development, could be helpful in identifying phenotypes. In addition, high-resolution imaging revealed the presence of mineralized aggregates in the notochord, before the formation of the first bone in the axial skeleton. These structures might play a role in the storage of the mineral. Our results highlight the potential of these high-resolution 3D approaches to characterize the zebrafish skeleton, which in turn could prove invaluable information for better understanding the development and the characterization of skeletal phenotypes.
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20
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Coyac BR, Falgayrac G, Baroukh B, Slimani L, Sadoine J, Penel G, Biosse-Duplan M, Schinke T, Linglart A, McKee MD, Chaussain C, Bardet C. Tissue-specific mineralization defects in the periodontium of the Hyp mouse model of X-linked hypophosphatemia. Bone 2017; 103:334-346. [PMID: 28764922 DOI: 10.1016/j.bone.2017.07.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 07/22/2017] [Accepted: 07/27/2017] [Indexed: 01/28/2023]
Abstract
X-linked hypophosphatemia (XLH) is a dento-osseous disorder caused by inactivating mutations in the PHEX gene, leading to renal phosphate wasting and hypophosphatemia, and impaired mineralization of bones and teeth. In the oral cavity, recent reports suggest a higher susceptibility of XLH patients to periodontitis, where patients present with impaired tooth cementum - a bone-like tissue involved in tooth attachment to the jaw bones and post-eruption tooth positioning - and a higher frequency of intrabony defects. In the present study, the pathobiology of alveolar bone and tooth cementum was investigated in the Hyp mouse, the murine analog of XLH. PHEX deficiency in XLH/Hyp dramatically alters the periodontal phenotype, with hypoplasia of tooth root cementum associated with a lack of periodontal ligament attachment and the presence of an immature apatitic mineral phase of all periodontal mineralized tissues. Challenging the Hyp periodontium in two surgical experimental models - ligature-induced periodontal breakdown and repair, and a model of tooth movement adaptation inducing cementum formation - we show that bone and cementum formation, and their healing, are altered. Bone and cementum mineralization appear similarly disturbed, where hypomineralized pericellular matrix surrounds cells, and where the protein osteopontin (OPN, a mineralization inhibitor) accumulates in a tissue-specific manner, most notably in the perilacunar matrix surrounding osteocytes. Although the pathobiology is different between XLH/Hyp bone and cementum, our results show a major XLH phenotype in oral mineralized tissues consistent with variations in patient susceptibility to periodontal disorders.
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Affiliation(s)
- Benjamin R Coyac
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France; Department of Periodontology, U.F.R. of Odontology, Rothschild Hospital, AP-HP, Paris Diderot University, Paris, France
| | - Guillaume Falgayrac
- Univ. Lille, Univ. Littoral Côte d'Opale, EA 4490 - PMOI - Physiopathologie des Maladies Osseuses Inflammatoires, F-59000 Lille, France
| | - Brigitte Baroukh
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France
| | - Lotfi Slimani
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France
| | - Jérémy Sadoine
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France
| | - Guillaume Penel
- Univ. Lille, Univ. Littoral Côte d'Opale, EA 4490 - PMOI - Physiopathologie des Maladies Osseuses Inflammatoires, F-59000 Lille, France
| | - Martin Biosse-Duplan
- Department of Odontology, Bretonneau Hospital PNVS, AP-HP, Paris, France; APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Plateforme d'Expertise Maladies Rares Paris-Sud, Hôpital Bicêtre Paris Sud, Le Kremlin Bicêtre, France
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Agnès Linglart
- APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Plateforme d'Expertise Maladies Rares Paris-Sud, Hôpital Bicêtre Paris Sud, Le Kremlin Bicêtre, France; INSERM U1169, Hôpital Bicêtre, Le Kremlin Bicêtre, and Université Paris-Saclay, France
| | - Marc D McKee
- Faculties of Dentistry and Medicine, Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
| | - Catherine Chaussain
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France; Department of Odontology, Bretonneau Hospital PNVS, AP-HP, Paris, France; APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Plateforme d'Expertise Maladies Rares Paris-Sud, Hôpital Bicêtre Paris Sud, Le Kremlin Bicêtre, France
| | - Claire Bardet
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France.
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21
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Three-dimensional ultrastructural analysis of cells in the periodontal ligament using focused ion beam/scanning electron microscope tomography. Sci Rep 2016; 6:39435. [PMID: 27995978 PMCID: PMC5171660 DOI: 10.1038/srep39435] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 11/21/2016] [Indexed: 01/29/2023] Open
Abstract
The accurate comprehension of normal tissue provides essential data to analyse abnormalities such as disease and regenerative processes. In addition, understanding the proper structure of the target tissue and its microenvironment may facilitate successful novel treatment strategies. Many studies have examined the nature and structure of periodontal ligaments (PDLs); however, the three-dimensional (3D) structure of cells in normal PDLs remains poorly understood. In this study, we used focused ion beam/scanning electron microscope tomography to investigate the whole 3D ultrastructure of PDL cells along with quantitatively analysing their structural properties and ascertaining their orientation to the direction of the collagen fibre. PDL cells were shown to be in contact with each other, forming a widespread mesh-like network between the cementum and the alveolar bone. The volume of the cells in the horizontal fibre area was significantly larger than in other areas, whereas the anisotropy of these cells was lower than in other areas. Furthermore, the orientation of cells to the PDL fibres was not parallel to the PDL fibres in each area. As similar evaluations are recognized as being challenging using conventional two-dimensional methods, these novel 3D findings may contribute necessary knowledge for the comprehensive understanding and analysis of PDLs.
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22
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Pabisch S, Akabane C, Wagermaier W, Roschger A, Ogura T, Hyodo R, Kataoka S, Tobori N, Okano T, Murakami S, Fratzl P, Weinkamer R. The nanostructure of murine alveolar bone and its changes due to type 2 diabetes. J Struct Biol 2016; 196:223-231. [PMID: 27637572 DOI: 10.1016/j.jsb.2016.09.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 06/14/2016] [Accepted: 09/12/2016] [Indexed: 12/29/2022]
Abstract
Alveolar bone - the bony ridge containing the tooth sockets - stands out by its remodeling activity where bone is being formed and resorbed at a much higher rate than in any other bony tissue. Teeth that are anchored in the jaw through the periodontal ligament exert very large localized loads during mastication that could lead to a unique adaptation of the collagen/mineral structure in the bone. Our aim was to characterize the nanostructure of alveolar bone and to determine the influence of diabetes on structural characteristics of the mineralized matrix. Using small- and wide-angle X-ray scattering (SAXS/WAXS), we studied a spontaneous diabetic mouse model (KK+) and its corresponding healthy controls (KK-) (n=6) to determine the size and mutual alignment of the mineral nanoparticles embedded in the collagen matrix. On cross-sections (buccal-lingual) of the first molar multiple line scans with a spatial resolution of 30μm were performed on each sample, from the lingual to the buccal side of the mandible. Mineral particle thickness and length are decreasing towards the tooth in both buccal and lingual sides of alveolar bone. While mineral particles are well aligned with the long axis of the tooth on the buccal side, they are in a quarter of the measurements oriented along two preferred directions on the lingual side. These nanostructural differences can be interpreted as the result of an asymmetric loading during mastication, leading to a tilting of the tooth in its socket. In diabetic mice particle thicknesses are smaller compared to control animals.
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Affiliation(s)
- Silvia Pabisch
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Chika Akabane
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany; Functional Materials Science Research Laboratories, Research & Development Headquarters, LION Corporation, Tokyo, Japan
| | - Wolfgang Wagermaier
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Andreas Roschger
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
| | - Taku Ogura
- Functional Materials Science Research Laboratories, Research & Development Headquarters, LION Corporation, Tokyo, Japan
| | - Ryo Hyodo
- Functional Materials Science Research Laboratories, Research & Development Headquarters, LION Corporation, Tokyo, Japan
| | - Shinsuke Kataoka
- Life Science Research Laboratories, Research & Development Headquarters, LION Corporation, Kanagawa, Japan
| | - Norio Tobori
- Functional Materials Science Research Laboratories, Research & Development Headquarters, LION Corporation, Tokyo, Japan
| | - Tomomichi Okano
- Research & Development Headquarters, LION Corporation, Tokyo, Japan
| | - Shinya Murakami
- Department of Periodontology, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Peter Fratzl
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Richard Weinkamer
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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23
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José Ricardo Kina, Yumi Umeda Suzuki T, Fumico Umeda Kina E, Kina J, Kina M. Non-Inflammatory Destructive Periodontal Disease. Open Dent J 2016; 10:50-7. [PMID: 27053968 PMCID: PMC4787315 DOI: 10.2174/1874210601610010050] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 09/17/2015] [Accepted: 10/27/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Non-Inflammatory Destructive Periodontal Disease (NIDPD), is a severe destructive periodontal disease, that is characterized by the attachment loss and alveolar bone loss, without signs of the gingival inflammation, and the periodontal pocket development. OBJECTIVE Despite the fact that various cases of NIDPD have been reported; their etiology and disease evolution is still indefinite, and therefore, are open for discussion. METHOD An NIDPD case was studied in order to demonstrate features of the disease, and discuss the possible etiology and treatment. RESULTS In this clinical case, the etiology of NIDPD seems to be an association of endogenous opportunist bacteria with anatomical aspects, occlusion pattern, emotional stress and mouth breathing condition. CONCLUSION In spite of all cases described in the literature are comparable and may have similar etiology as related in this clinical case, additional research is needed to identify and clarify the role of the etiologic factors which determine the disease.
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Affiliation(s)
- José Ricardo Kina
- Department of Surgery and Integrated Clinic, Araçatuba School of Dentistry, São Paulo State University - UNESP, Araçatuba, SP, Brazil
| | - Thaís Yumi Umeda Suzuki
- Department of Dental Materials and Prosthodontics, Araçatuba School of Dentistry, São Paulo State University - UNESP, Araçatuba, SP, Brazil
| | | | - Juliana Kina
- Department of Pediatric Dentistry and Public Health, Araçatuba School of Dentistry, São Paulo State University - UNESP, Araçatuba, SP, Brazil
| | - Mônica Kina
- DDS, Private Practice, Araçatuba, SP, Brazil
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Self CJ. Dental root size in bats with diets of different hardness. J Morphol 2015; 276:1065-74. [PMID: 26011087 DOI: 10.1002/jmor.20400] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 03/23/2015] [Accepted: 04/27/2015] [Indexed: 11/06/2022]
Abstract
The relationship between tooth roots and diet is relatively unexplored, although a logical relationship between harder diets and increased root surface area (RSA) is suggested. This study addresses the interaction between tooth morphology, diet, and bite force in small mammals, phyllostomid bats. Using micro computed tomography (microCT), tooth root morphology of two fruit-eating species (Carollia perspicillata and Chiroderma villosum) and two insect-eating species (Mimon bennettii and Macrotus californicus) was compared. These species did not differ in skull or estimated body size. Food hardness, rather than dietary classification, proved to be the strongest grouping factor, with the two insectivores and the seed-processing frugivore (C. villosum) having significantly larger RSAs. Bite force was estimated using skull measurements; bite force significantly correlated with tooth RSA but not with body size. Although the three durophagous species did exhibit larger crowns, the area of the occlusal surface did not vary among the four species. There was a linear relationship between root size and crown size, indicating that the roots were not expanded disproportionately; instead the entire tooth was larger in the hard diet species. MicroCT allows the nondestructive quantification of previously difficult-to-access tooth morphology; this method shows the potential for tooth roots to provide valuable dietary, behavioral, and ecological information in small mammals. J. Morphol. 276:1065-1074, 2015. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Casey J Self
- Department of Biology, University of Washington, Seattle, Washington
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Terranova L, Libouban H, Mallet R, Chappard D. Analysis of β-tricalcium phosphate granules prepared with different formulations by nano-computed tomography and scanning electron microscopy. J Artif Organs 2015; 18:338-45. [DOI: 10.1007/s10047-015-0838-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/15/2015] [Indexed: 12/17/2022]
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Bartold PM, McCulloch CA. Information generation and processing systems that regulate periodontal structure and function. Periodontol 2000 2015; 63:7-13. [PMID: 23931050 DOI: 10.1111/prd.12037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2013] [Indexed: 01/16/2023]
Abstract
The periodontium is a very dynamic organ that responds rapidly to mechanical and chemical stimuli. It is very complex in that it is composed of two hard tissues (cementum and bone) and two soft connective tissues (periodontal ligament and gingiva). Together these tissues are defined by the molecules expressed by the resident periodontal cells in each compartment and this determines not only the structure and function of the periodontium but also how it responds to infection and inflammation. The biological activity of these molecules is tightly regulated in time and space to preserve tissue homeostasis, influence inflammatory responses and participate in tissue regeneration. In this issue of Periodontology 2000 we explore new experimental approaches and data sets which help to understand the molecules and cells that regulate tissue form and structure in health, disease and regeneration.
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Naveh GRS, Weiner S. Initial orthodontic tooth movement of a multirooted tooth: a 3D study of a rat molar. Orthod Craniofac Res 2015; 18:134-42. [DOI: 10.1111/ocr.12066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2014] [Indexed: 11/29/2022]
Affiliation(s)
- G. R. S. Naveh
- Department of Structural Biology; Weizmann Institute of Science; Rehovot Israel
| | - S. Weiner
- Department of Structural Biology; Weizmann Institute of Science; Rehovot Israel
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LPS from P. gingivalis and hypoxia increases oxidative stress in periodontal ligament fibroblasts and contributes to periodontitis. Mediators Inflamm 2014; 2014:986264. [PMID: 25374447 PMCID: PMC4211166 DOI: 10.1155/2014/986264] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/21/2014] [Indexed: 11/20/2022] Open
Abstract
Oxidative stress is characterized by an accumulation of reactive oxygen species (ROS) and plays a key role in the progression of inflammatory diseases. We hypothesize that hypoxic and inflammatory events induce oxidative stress in the periodontal ligament (PDL) by activating NOX4. Human primary PDL fibroblasts were stimulated with lipopolysaccharide from Porphyromonas gingivalis (LPS-PG), a periodontal pathogen bacterium under normoxic and hypoxic conditions. By quantitative PCR, immunoblot, immunostaining, and a specific ROS assay we determined the amount of NOX4, ROS, and several redox systems. Healthy and inflamed periodontal tissues were collected to evaluate NOX4 and redox systems by immunohistochemistry. We found significantly increased NOX4 levels after hypoxic or inflammatory stimulation in PDL cells (P < 0.001) which was even more pronounced after combination of the stimuli. This was accompanied by a significant upregulation of ROS and catalase (P < 0.001). However, prolonged incubation with both stimuli induced a reduction of catalase indicating a collapse of the protective machinery favoring ROS increase and the progression of inflammatory oral diseases. Analysis of inflamed tissues confirmed our hypothesis. In conclusion, we demonstrated that the interplay of NOX4 and redox systems is crucial for ROS formation which plays a pivotal role during oral diseases.
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Tuna M, Sunbuloglu E, Bozdag E. Finite element simulation of the behavior of the periodontal ligament: A validated nonlinear contact model. J Biomech 2014; 47:2883-90. [DOI: 10.1016/j.jbiomech.2014.07.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/05/2014] [Accepted: 07/22/2014] [Indexed: 11/30/2022]
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Pinto VI, Senini VW, Wang Y, Kazembe MP, McCulloch CA. Filamin A protects cells against force-induced apoptosis by stabilizing talin- and vinculin-containing cell adhesions. FASEB J 2014; 28:453-63. [PMID: 24097310 DOI: 10.1096/fj.13-233759] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In mechanically loaded tissues such as weight-bearing joints, myocardium, and periodontal ligament, pathophysiological forces can disrupt cell-matrix contacts, which can induce cell death, leading to tissue and organ dysfunction. Protection against force-induced cell death may be mediated by filamin A (FLNa), an actin-binding protein that regulates β1 integrin-mediated cell adhesion. We examined the affect of filamin expression on collagen distribution and cell death in the periodontal ligament, a force-loaded tissue. Conditional deletion of FLNa in fibroblasts was associated with 2-fold increase of acellular areas in periodontal ligament and 7-fold higher proportions of apoptotic cells. In cultured fibroblasts with FLNa knockdown, we examined the affect of supraphysiological forces (1 pN/μm(2) cell area; applied through the β1 integrin) on recruitment of talin and vinculin to focal adhesions and on apoptosis. Compared with the wild type, FLNa-knockdown cells exhibited 3-fold increases in floating cells after overnight force application and a 2-fold increase in cell detachment. Force induced time-dependent reductions (P<0.05) in the numbers of activated β1 integrin-, talin-, and vinculin-stained adhesions in FLNa-knockdown compared with those in wild-type cells. We conclude that FLNa protects against apoptosis in force-loaded cells, and this protection is mediated by enhanced formation and maturation of matrix adhesions.
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Affiliation(s)
- Vanessa I Pinto
- 1Room 244, Fitzgerald Building, 150 College St., University of Toronto, Toronto, ON, M5S 3E2, Canada.
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Naveh GRS, Brumfeld V, Dean M, Shahar R, Weiner S. Direct microCT imaging of non-mineralized connective tissues at high resolution. Connect Tissue Res 2014; 55:52-60. [PMID: 24437605 DOI: 10.3109/03008207.2013.867333] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The 3D imaging of soft tissues in their native state is challenging, especially when high resolution is required. An X-ray-based microCT is, to date, the best choice for high resolution 3D imaging of soft tissues. However, since X-ray attenuation of soft tissues is very low, contrasting enhancement using different staining materials is needed. The staining procedure, which also usually involves tissue fixation, causes unwanted and to some extent unknown tissue alterations. Here, we demonstrate that a method that enables 3D imaging of soft tissues without fixing and staining using an X-ray-based bench-top microCT can be applied to a variety of different tissues. With the sample mounted in a custom-made loading device inside a humidity chamber, we obtained soft tissue contrast and generated 3D images of fresh, soft tissues with a resolution of 1 micron voxel size. We identified three critical conditions which make it possible to image soft tissues: humidified environment, mechanical stabilization of the sample and phase enhancement. We demonstrate the capability of the technique using different specimens: an intervertebral disc, the non-mineralized growth plate, stingray tessellated radials (calcified cartilage) and the collagenous network of the periodontal ligament. Since the scanned specimen is fresh an interesting advantage of this technique is the ability to scan a specimen under load and track the changes of the different structures. This method offers a unique opportunity for obtaining valuable insights into 3D structure-function relationships of soft tissues.
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Kalajzic Z, Peluso EB, Utreja A, Dyment N, Nihara J, Xu M, Chen J, Uribe F, Wadhwa S. Effect of cyclical forces on the periodontal ligament and alveolar bone remodeling during orthodontic tooth movement. Angle Orthod 2013; 84:297-303. [PMID: 23937517 DOI: 10.2319/032213-234.1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE To investigate the effect of externally applied cyclical (vibratory) forces on the rate of tooth movement, the structural integrity of the periodontal ligament, and alveolar bone remodeling. METHODS Twenty-six female Sprague-Dawley rats (7 weeks old) were divided into four groups: CTRL (unloaded), VBO (molars receiving a vibratory stimulus only), TMO (molars receiving an orthodontic spring only), and TMO+VB (molars receiving an orthodontic spring and the additional vibratory stimulus). In TMO and TMO+VB groups, the rat first molars were moved mesially for 2 weeks using Nickel-Titanium coil spring delivering 25 g of force. In VBO and TMO+VB groups, cyclical forces at 0.4 N and 30 Hz were applied occlusally twice a week for 10 minutes. Microfocus X-ray computed tomography analysis and tooth movement measurements were performed on the dissected rat maxillae. Tartrate-resistant acid phosphatase staining and collagen fiber assessment were performed on histological sections. RESULTS Cyclical forces significantly inhibited the amount of tooth movement. Histological analysis showed marked disorganization of the collagen fibril structure of the periodontal ligament during tooth movement. Tooth movement caused a significant increase in osteoclast parameters on the compression side of alveolar bone and a significant decrease in bone volume fraction in the molar region compared to controls. CONCLUSIONS Tooth movement was significantly inhibited by application of cyclical forces.
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Affiliation(s)
- Zana Kalajzic
- a Postdoctoral Fellow, Department of Craniofacial Sciences, University of Connecticut Health Center, Farmington, Conn
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