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Chai H. Edge chipping patterns in posterior teeth of hominins and apes. J Mech Behav Biomed Mater 2024; 156:106582. [PMID: 38781774 DOI: 10.1016/j.jmbbm.2024.106582] [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: 02/20/2024] [Revised: 05/11/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024]
Abstract
Chip scars in fossil teeth are a lasting evidence that bears on human evolution. Chip dimensions in posterior teeth of hominins, apes and white-lipped peccary (Tayassu pecari) are measured from published occlusal images. The results are plotted as D/Dm vs. h/Dm, where h, D and Dm denote indent distance, chip width and mean tooth crown diameter. The hominin species follow a similar pattern where D/Dm monotonically increases up to h/Dm ≈ 0.3. The behavior for the apes is characterized by two phases. In the first, h/Dm monotonically increases up to h/Dm ≈ 0.26 while in the second (h/Dm ≈ 0.26 to 0.42), D/Dm experiences a drastic change in behavior. The interpretation of chip morphology is assisted by results from controlled spherical indentation tests on extracted human molars. This study shows that in addition to the commonly recognized chipping due to cusp loading, a chip may also initiate from the inner wall of the tooth's central fossa. Accordingly, it is suggested that the chipping in hominins generally initiates from a (worn) cusp while that in apes involves cusp loading up to h/Dm ≈ 0.26 and fossa loading thereafter. The behavior for T. pecari is much similar to that of the apes. The fossa chipping is facilitated by a consumption of hard, large-size diet (e.g., plants, roots, barks and nuts) and presence of broad central fossa, conditions that are met in apes. Finally, a simple expression for the critical chipping force Pch due to fossa loading is developed.
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Affiliation(s)
- Herzl Chai
- School of Mechanical Engineering, Tel-Aviv University, Tel-Aviv, Israel.
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2
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Xie Y, Chen S, Sheng L, Sun Y, Liu S. A New Landscape of Human Dental Aging: Causes, Consequences, and Intervention Avenues. Aging Dis 2023:AD.2022.1224. [PMID: 37163430 PMCID: PMC10389823 DOI: 10.14336/ad.2022.1224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/24/2022] [Indexed: 05/12/2023] Open
Abstract
Aging is accompanied by physical dysfunction and physiologic degeneration that occurs over an individual's lifetime. Human teeth, like many other organs, inevitably undergo chronological aging and age-related changes throughout the lifespan, resulting in a substantial need for preventive, restorative as well as periodontal dental care. This is particularly the case for seniors at 65 years of age and those older but economically disadvantaged. Dental aging not only interferes with normal chewing and digestion, but also affects daily appearance and interpersonal communications. Further dental aging can incur the case of multiple disorders such as oral cancer, encephalitis, and other systemic diseases. In the next decades or even hundreds of years, the proportion of the elderly in the global population will continue to rise, a tendency that attracts increasing attention across multiple scientific and medical disciplines. Dental aging will bring a variety of problems to the elderly themselves and poses serious challenges to the medical profession and social system. A reduced, but functional dentition comprising 20 teeth in occlusion has been proposed as a measurement index of successful dental aging. Healthy dental aging is critical to healthy aging, from both medical and social perspectives. To date, biomedical research on the causes, processes and regulatory mechanisms of dental aging is still in its infancy. In this article, updated insights into typical manifestations, associated pathologies, preventive strategies and molecular changes of dental aging are provided, with future research directions largely projected.
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Affiliation(s)
- Yajia Xie
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Shanghai Stomatological Hospital, Fudan University, Shanghai, China
- Department of Endodontics, Shanghai Stomatological Hospital, Fudan University, Shanghai, China
| | - Shuang Chen
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Shanghai Stomatological Hospital, Fudan University, Shanghai, China
| | - Lu Sheng
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Shanghai Stomatological Hospital, Fudan University, Shanghai, China
| | - Yu Sun
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, China
- Department of Pharmacology, Institute of Aging Medicine, Binzhou Medical University, Yantai, Shandong, China
- Department of Medicine and VAPSHCS, University of Washington, Seattle, WA 98195, USA
| | - Shangfeng Liu
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Shanghai Stomatological Hospital, Fudan University, Shanghai, China
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Oh C, Lee H, Kim J, Lee JH, Nguyen T, Kim KH, Chung CJ. The influence of age and orthodontic debonding on the prevalence and severity of enamel craze lines. J Am Dent Assoc 2023:S0002-8177(23)00207-6. [PMID: 37204377 DOI: 10.1016/j.adaj.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 03/09/2023] [Accepted: 04/05/2023] [Indexed: 05/20/2023]
Abstract
BACKGROUND Craze lines may cause esthetic concerns, especially when noted on the incisors. Various light sources with additional recording apparatus have been proposed to visualize craze lines, but a standardized clinical protocol is yet to be determined. This study aimed to validate the application of near-infrared imaging (NIRI) from intraoral scans to evaluate craze lines and to determine the influence of age and orthodontic debonding on their prevalence and severity. METHODS The NIRI of maxillary central incisors from a full-mouth intraoral scan and photographs from an orthodontic clinic (N = 284) were collected. The prevalence of craze lines and influence of age and orthodontic debonding history on severity were evaluated. RESULTS Craze lines were detected reliably as white lines distinguishable from dark enamel using the NIRI from intraoral scans. The craze line prevalence was 50.7%, which was significantly higher in patients 20 years or older than in patients younger than 20 years (P < .001), with more frequent severe craze lines for those 40 years or older than in patients younger than 30 years (P < .05). Prevalence or severity was similar between patients with and without an orthodontic debonding history regardless of the type of appliance. CONCLUSION The prevalence of craze lines in the maxillary central incisor was 50.7%, with a higher prevalence in adults than in adolescents. Orthodontic debonding did not affect the severity of craze lines. PRACTICAL IMPLICATIONS Craze lines were reliably detected and documented by means of applying NIRI from intraoral scans. Intraoral scanning can provide new clinical information on enamel surface characteristics.
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Dorado S, Arias A, Jimenez-Octavio JR. Biomechanical Modelling for Tooth Survival Studies: Mechanical Properties, Loads and Boundary Conditions-A Narrative Review. MATERIALS (BASEL, SWITZERLAND) 2022; 15:7852. [PMID: 36363451 PMCID: PMC9657341 DOI: 10.3390/ma15217852] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/02/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
Recent biomechanical studies have focused on studying the response of teeth before and after different treatments under functional and parafunctional loads. These studies often involve experimental and/or finite element analysis (FEA). Current loading and boundary conditions may not entirely represent the real condition of the tooth in clinical situations. The importance of homogenizing both sample characterization and boundary conditions definition for future dental biomechanical studies is highlighted. The mechanical properties of dental structural tissues are presented, along with the effect of functional and parafunctional loads and other environmental and biological parameters that may influence tooth survival. A range of values for Young's modulus, Poisson ratio, compressive strength, threshold stress intensity factor and fracture toughness are provided for enamel and dentin; as well as Young's modulus and Poisson ratio for the PDL, trabecular and cortical bone. Angles, loading magnitude and frequency are provided for functional and parafunctional loads. The environmental and physiological conditions (age, gender, tooth, humidity, etc.), that may influence tooth survival are also discussed. Oversimplifications of biomechanical models could end up in results that divert from the natural behavior of teeth. Experimental validation models with close-to-reality boundary conditions should be developed to compare the validity of simplified models.
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Affiliation(s)
- Saúl Dorado
- Department of Mechanical Engineering, Escuela Técnica Superior de Ingeniería ICAI, Universidad Pontificia Comillas, 28015 Madrid, Spain
| | - Ana Arias
- Department of Conservative and Prosthetic Dentistry, School of Dentistry, Complutense University, 28040 Madrid, Spain
| | - Jesus R. Jimenez-Octavio
- Instituto de Investigación Tecnológica, Escuela Técnica Superior de Ingeniería ICAI, Universidad Pontificia Comillas, 28015 Madrid, Spain
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Recent Advances in the Diagnosis of Enamel Cracks: A Narrative Review. Diagnostics (Basel) 2022; 12:diagnostics12082027. [PMID: 36010379 PMCID: PMC9407313 DOI: 10.3390/diagnostics12082027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/08/2022] [Accepted: 08/13/2022] [Indexed: 11/17/2022] Open
Abstract
Cracked teeth can pose a diagnostic dilemma for a clinician as they can mimic several other conditions. The constant physiological stress along with any pathological strain like trauma or iatrogenic causes can lead to the development of microcracks in the teeth. Constant exposure to immense stress can cause the progression of these often-undiagnosed tooth cracks to cause tooth fractures. This review aims to outline the etiology of tooth cracks, their classification, and recent advances in the diagnosis of enamel cracks. Diagnosing a cracked tooth can be an arduous task as symptoms differ according to the location and extension of the incomplete fracture. Early detection is critical because restorative treatment can prevent fracture propagation, microleakage, pulpal or periodontal tissue involvement, and catastrophic cusp failure. Older methods of crack detection are not sensitive or specific. They include clinical examination, visual inspection, exploratory excavation, and percussion test. The dye test used blue or gentian violet stains to highlight fracture lines. Modern methods include transillumination, optical coherence tomography Swept-Source Optical Coherence Tomography (SSOCT), near-infrared imaging, ultrasonic system, infrared thermography, and near-infrared laser. These methods appear to be more efficacious than traditional clinical dental imaging techniques in detecting longitudinal tooth cracks. Clinically distinguishing between the various types of cracks can be difficult with patient-reported signs and symptoms varying according to the location and extension of the incomplete fracture. Cracks are more common in restored teeth. Technological advances such as transillumination allow for early detection and enhanced prognosis.
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Juntavee N, Juntavee A, Srisontisuk S. Flexural Strength of Various Provisional Restorative Materials for Rehabilitation After Aging. J Prosthodont 2022; 32:20-28. [PMID: 35638396 DOI: 10.1111/jopr.13549] [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: 01/13/2022] [Accepted: 05/21/2022] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Durability of provisional restoration is crucial for full-mouth reconstruction, which may be influenced by aging. This study evaluated the effect of aging on the flexural strength of provisional materials for oral rehabilitation. MATERIALS AND METHODS Bar specimens (2×2×25 mm) were fabricated from CAD-CAM [Vita CAD-Temp® (VC), Telio® CAD (TC), artBloc® (RC)], autopolymerized [Protemp™IV (PA), Luxatemp® (LA), Unifast™Trad (UA)], and heat-polymerized polymer [Major® C & B; (MH)]. Each was divided into aging (AG, 5000 thermocycles of 5°/55°C) and nonaging groups (NG, n = 15/group). Flexural strength (σ, MPa) was determined in a universal testing machine at 1 mm/min crosshead speed. An analysis of variance and multiple comparisons were determined for significant difference (α = 0.05). RESULTS TCNG indicated the highest mean of σ (133.49 ±4.32), whereas VCNG indicated the lowest mean of σ (84.62 ±3.73) for nonaging. Upon aging process, TCAG revealed the highest mean of σ (123.11 ±4.55), while VCAG possessed the lowest mean of σ (84.05 ±6.39). Significant differences among various provisional materials were indicated (p = 0.001). Aging significantly affected flexural strength (p = 0.001). CONCLUSIONS The CAD-CAM provisional material possessed higher flexural strength than heat-polymerized PMMA and autopolymerized PMMA, which was suggested as a provisional material for rehabilitation. Aging reduced strength for all materials tested.
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Affiliation(s)
- Niwut Juntavee
- Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Apa Juntavee
- Division of Pediatric Dentistry, Department of Preventive Dentistry, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Supichaya Srisontisuk
- Division of Biomaterials and Prosthodontics Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
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Renteria C, Yan W, Huang YL, Arola DD. Contributions to enamel durability with aging: An application of data science tools. J Mech Behav Biomed Mater 2022; 129:105147. [DOI: 10.1016/j.jmbbm.2022.105147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/08/2022] [Accepted: 02/26/2022] [Indexed: 10/19/2022]
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Peña-Oyarzún D, San Martin C, Hernández-Cáceres MP, Lavandero S, Morselli E, Budini M, Burgos PV, Criollo A. Autophagy in aging-related oral diseases. Front Endocrinol (Lausanne) 2022; 13:903836. [PMID: 35992149 PMCID: PMC9390882 DOI: 10.3389/fendo.2022.903836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 07/13/2022] [Indexed: 11/17/2022] Open
Abstract
Autophagy is an intracellular degradation mechanism that allows recycling of organelles and macromolecules. Autophagic function increases metabolite availability modulating metabolic pathways, differentiation and cell survival. The oral environment is composed of several structures, including mineralized and soft tissues, which are formed by complex interactions between epithelial and mesenchymal cells. With aging, increased prevalence of oral diseases such as periodontitis, oral cancer and periapical lesions are observed in humans. These aging-related oral diseases are chronic conditions that alter the epithelial-mesenchymal homeostasis, disrupting the oral tissue architecture affecting the quality of life of the patients. Given that autophagy levels are reduced with age, the purpose of this review is to discuss the link between autophagy and age-related oral diseases.
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Affiliation(s)
- Daniel Peña-Oyarzún
- Physiology Department, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- Interdisciplinary Center for Research in Territorial Health of the Aconcagua Valley (CIISTe Aconcagua), School of Medicine, Faculty of Medicine, San Felipe Campus, Universidad de Valparaíso, San Felipe, Chile
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile
| | - Carla San Martin
- Interdisciplinary Center for Research in Territorial Health of the Aconcagua Valley (CIISTe Aconcagua), School of Medicine, Faculty of Medicine, San Felipe Campus, Universidad de Valparaíso, San Felipe, Chile
| | - María Paz Hernández-Cáceres
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile
| | - Sergio Lavandero
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- Cardiology Division, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Eugenia Morselli
- Department of Basic Sciences, Faculty of Medicine and Sciences, Universidad San Sebastián, Santiago de Chile, Chile
- Autophagy Research Center, Universidad de Chile, Santiago de Chile, Chile
| | - Mauricio Budini
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile
- Autophagy Research Center, Universidad de Chile, Santiago de Chile, Chile
| | - Patricia V. Burgos
- Autophagy Research Center, Universidad de Chile, Santiago de Chile, Chile
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
- Centro de Envejecimiento y Regeneración (CARE-UC), Facultad de Ciencias Biológicas, Pontificia Universidad Católica, Santiago, Chile
- Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Alfredo Criollo
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Autophagy Research Center, Universidad de Chile, Santiago de Chile, Chile
- *Correspondence: Alfredo Criollo,
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Yan W, Renteria C, Huang Y, Arola DD. A machine learning approach to investigate the materials science of enamel aging. Dent Mater 2021; 37:1761-1771. [PMID: 34625295 DOI: 10.1016/j.dental.2021.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 08/25/2021] [Accepted: 09/11/2021] [Indexed: 11/30/2022]
Abstract
Understanding aging of tooth tissues is critical to the development of patient-centric oral healthcare. Yet, the traditional methods for analyzing the composition-structure-property relationships of hard tissues have limitations when considering aging and other factors. OBJECTIVE To apply unsupervised machine learning tools to pursue an understanding of relationships between the composition and mechanical behavior of aging enamel. METHODS Molar teeth were collected from primary (age ≤ 8), young adult (24 ≤ age ≤ 46) and old adult (55 ≤ age) donors. The hardness and elastic modulus were quantified using nanoindentation as a function of distance from the Dentin Enamel Junction (DEJ) within the cervical, cuspal and inter-cuspal regions of the enamel crown. Similarly, a co-located analysis of the chemical composition and structure was performed using Raman spectroscopy. A Self-Organizing Maps (SOMs) algorithm was implemented to identify multi-dimensional composition-property relationships. RESULTS The hardness and elastic modulus are positively correlated to crystallinity and negatively correlated with carbonate substitution. Furthermore, the effects from fluoridation on the age-dependent properties of enamel is non-linear and depends on its location. The contributions of fluoridation to the enamel properties are different in the cervical and non-cervical regions and appear to be unique within primary and senior adult teeth. SIGNIFICANCE Based on the findings, unsupervised learning methods can reveal complicated non-linear structure-property relationships in tooth tissues and help to understand the materials science of aging and its consequences.
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Affiliation(s)
- W Yan
- Department of Materials Science and Engineering, University of Washington, United States
| | - C Renteria
- Department of Materials Science and Engineering, University of Washington, United States
| | - Y Huang
- Department of Materials Science and Engineering, University of Washington, United States
| | - Dwayne D Arola
- Department of Materials Science and Engineering, University of Washington, United States; Department of Restorative Dentistry, School of Dentistry, University of Washington, United States; Department of Oral Health Sciences, School of Dentistry, University of Washington, United States.
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Maeda H. Aging and Senescence of Dental Pulp and Hard Tissues of the Tooth. Front Cell Dev Biol 2020; 8:605996. [PMID: 33330507 PMCID: PMC7734349 DOI: 10.3389/fcell.2020.605996] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/04/2020] [Indexed: 01/05/2023] Open
Abstract
The ability to consume a meal using one's own teeth influences an individual's quality of life. In today's global aging society, studying the biological changes in aging teeth is important to address this issue. A tooth includes three hard tissues (enamel, dentin, and cementum) and a soft tissue (dental pulp). With advancing age, these tissues become senescent; each tissue exhibits a unique senescent pattern. This review discusses the structural alterations of hard tissues, as well as the molecular and physiological changes in dental pulp cells and dental pulp stem cells during human aging. The significance of senescence in these cells remains unclear. Thus, there is a need to define the regulatory mechanisms of aging and senescence in these cells to aid in preservation of dental health.
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Affiliation(s)
- Hidefumi Maeda
- Department of Endodontology and Operative Dentistry, Kyushu University, Fukuoka, Japan.,Department of Endodontology, Kyushu University Hospital, Fukuoka, Japan
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Bauer LJ, Mustafa HA, Zaslansky P, Mantouvalou I. Chemical mapping of teeth in 2D and 3D: X-ray fluorescence reveals hidden details in dentine surrounding fillings. Acta Biomater 2020; 109:142-152. [PMID: 32294552 DOI: 10.1016/j.actbio.2020.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/24/2020] [Accepted: 04/03/2020] [Indexed: 01/15/2023]
Abstract
X-rays are frequently used for characterizing both tooth tissues and dental materials. Whereas radiographs and tomography utilize absorption contrast for retrieving details, chemical mapping is usually achieved by energy dispersive X-ray (EDX) analysis that is stimulated under vacuum in electron microscopes. However, the relatively dense mineralized composition of teeth, and the frequent inclusion of a large range of elements in filling materials raise the possibility that other X-ray based techniques such as X-ray fluorescence (XRF) spectroscopy may strongly contribute to investigations of a large variety of dental structures. By exploiting the fluorescence excited by micron sized X-rays (µXRF) it is possible to map minute quantities of a large range of elements (from aluminum to uranium), where spectra containing signals from multiple different elements can be resolved non-destructively and concomitantly. The high penetration depth of X-rays makes XRF highly effective at detecting variable compositions with information emerging from tooth tissues situated well beneath the sample surface. The method supports minimal sample preparation and, different from electron microscopy, it facilitates investigation of hydrated dental materials. Direct comparison of µXRF and confocal µXRF (CµXRF) with SEM-EDX reveals micro zones of chemical heterogeneity in the complex 3D architecture of root canal fillings. These methods reproducibly clarify the mutual arrangement of biomaterials in both fresh fillings as well as in repeatedly treated old teeth of unknown history. The results showcase the complementarity of X-ray and electron based elemental mapping for dental materials research. STATEMENT OF SIGNIFICANCE: Chemical characterization of mineralized tissues such as tooth dentine is often performed using energy dispersive X-ray spectroscopy (EDS/EDX) analysis by scanning electron microscopy (SEM). The widespread use of electron microscopes and simplified detector designs have made this form of chemical and structural analysis extremely popular. However, excitation by electrons is limited to the upper microns of the tissue, and these may not well represent the chemical composition of the bulk. Especially when heavier elements are of interest and when dental filling materials exhibit diffusion into the tooth, little is known about the spatial distribution. Here we show how complementary X-ray fluorescence data originating by electron and X-ray excitation can help visualize the distribution and impregnation of heavy elements through teeth, e.g. for root canal treatment.
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Affiliation(s)
- Leona J Bauer
- Institute for Optics and Atomic Physics, Technical University of Berlin, Hardenbergstr. 36, Berlin 10623, Germany
| | - Hawshan A Mustafa
- Department for Restorative and Preventive Dentistry, Centrum für Zahn-, Mund- und Kieferheilkunde, Charité-Universitätsmedizin Berlin, Aßmannshauser Str. 4-6, Berlin 14197, Germany
| | - Paul Zaslansky
- Department for Restorative and Preventive Dentistry, Centrum für Zahn-, Mund- und Kieferheilkunde, Charité-Universitätsmedizin Berlin, Aßmannshauser Str. 4-6, Berlin 14197, Germany.
| | - Ioanna Mantouvalou
- Institute for Optics and Atomic Physics, Technical University of Berlin, Hardenbergstr. 36, Berlin 10623, Germany; Current affiliation: Helmholtz Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin, Germany
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12
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Lainović T, Margueritat J, Martinet Q, Dagany X, Blažić L, Pantelić D, Rabasović MD, Krmpot AJ, Dehoux T. Micromechanical imaging of dentin with Brillouin microscopy. Acta Biomater 2020; 105:214-222. [PMID: 31988041 DOI: 10.1016/j.actbio.2020.01.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 01/10/2023]
Abstract
The structure of teeth can be altered by diet, age or diseases such as caries and sclerosis. It is very important to characterize their mechanical properties to predict and understand tooth decay, design restorative dental procedures, and investigate their tribological behavior. However, existing imaging techniques are not well suited to investigating the micromechanics of teeth, in particular at tissue interfaces. Here, we describe a microscope based on Brillouin light scattering (BLS) developed to probe the spectrum of the light scattered from tooth tissues, from which the mechanical properties (sound velocity, viscosity) can be inferred with a priori knowledge of the refractive index. BLS is an inelastic process that uses the scattering of light by acoustic waves in the GHz range. Our microscope thus reveals the mechanical properties at the micrometer scale without contact with the sample. BLS signals show significant differences between sound tissues and pathological lesions, and can be used to precisely delineate carious dentin. We also show maps of the sagittal and transversal planes of sound tubular dentin that reveal its anisotropic microstructure at 1 µm resolution. Our observations indicate that the collagen-based matrix of dentine is the main load-bearing structure, which can be considered as a fiber-reinforced composite. In the vicinity of polymeric tooth-filling materials, we observed the infiltration of the adhesive complex into the opened tubules of sound dentine. The ability to probe the quality of this interfacial layer could lead to innovative designs of biomaterials used for dental restorations in contemporary adhesive dentistry, with possible direct repercussions on decision-making during clinical work. STATEMENT OF SIGNIFICANCE: Mechanical properties of teeth can be altered by diet, age or diseases. Yet existing imaging modalities cannot reveal the micromechanics of the tooth. Here we developed a new type of microscope that uses the scattering of a laser light by naturally-occurring acoustic waves to probe mechanical changes in tooth tissues at a sub-micrometer scale without contact to the sample. We observe significant mechanical differences between healthy tissues and pathological lesions. The contrast in mechanical properties also reveals the microstructure of the polymer-dentin interfaces. We believe that this new development of laser spectroscopy is very important because it should lead to innovative designs of biomaterials used for dental restoration, and allow delineating precisely destructed dentin for minimally-invasive strategies.
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The potential of three-dimensional printing technologies to unlock the development of new ‘bio-inspired’ dental materials: an overview and research roadmap. J Prosthodont Res 2019; 63:131-139. [DOI: 10.1016/j.jpor.2018.10.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 10/05/2018] [Accepted: 10/26/2018] [Indexed: 11/23/2022]
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14
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An B, Sun W. A theory of biological composites undergoing plastic deformations. J Mech Behav Biomed Mater 2019; 93:204-212. [PMID: 30826697 DOI: 10.1016/j.jmbbm.2019.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 01/25/2019] [Accepted: 02/09/2019] [Indexed: 11/26/2022]
Abstract
Natural biological composites such as bone, dentin, nacre and enamel exhibit anisotropic microstructures, giving rise to orientation-dependent mechanical properties. Although the mechanical properties of these materials have been studied extensively, there is limited progress on modeling the common features associated with the orientation-dependent plastic deformation of biological composites. In this study, we develop a continuum theory for elastic-viscoplastic deformations of anisotropic biological composites. The pressure-sensitive and plastically dilatant plastic flow is incorporated into the theory, and the plastic spin related to the kinematics of the underlying substructure during macroscopic plastic deformation is explicitly taken into account. A special set of constitutive equations are implemented in a finite element program. Furthermore, the material parameters have been calibrated and numerical simulations of elastic-plastic deformation in bone are performed. It is found that the theory can capture the major features of plastic deformation of biological composites. The numerical simulations are in good agreement with experiments, demonstrating that the model is capable of predicting the complex plastic deformation of bone.
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Affiliation(s)
- Bingbing An
- Department of Mechanics, Shanghai University, Shanghai 200444, People's Republic of China; Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai 200072, People's Republic of China.
| | - Wenhao Sun
- Shanghai Institute of Applied Mathematics and Mechanics, Shanghai 200072, People's Republic of China
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15
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Kruzic JJ, Arsecularatne JA, Tanaka CB, Hoffman MJ, Cesar PF. Recent advances in understanding the fatigue and wear behavior of dental composites and ceramics. J Mech Behav Biomed Mater 2018; 88:504-533. [PMID: 30223214 DOI: 10.1016/j.jmbbm.2018.08.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 08/06/2018] [Accepted: 08/08/2018] [Indexed: 12/30/2022]
Abstract
Dental composite and ceramic restorative materials are designed to closely mimic the aesthetics and function of natural tooth tissue, and their longevity in the oral environment depends to a large degree on their fatigue and wear properties. The purpose of this review is to highlight some recent advances in our understanding of fatigue and wear mechanisms, and how they contribute to restoration failures in the complex oral environment. Overall, fatigue and wear processes are found to be closely related, with wear of dental ceramic occlusal surfaces providing initiation sites for fatigue failures, and subsurface fatigue crack propagation driving key wear mechanisms for composites, ceramics, and enamel. Furthermore, both fatigue and wear of composite restorations may be important in enabling secondary caries formation, which is the leading cause of composite restoration failures. Overall, developing a mechanistic description of fatigue, wear, and secondary caries formation, along with understanding the interconnectivity of all three processes, are together seen as essential keys to successfully using in vitro studies to predict in vivo outcomes and develop improved dental restorative materials.
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Affiliation(s)
- Jamie J Kruzic
- School of Mechanical and Manufacturing Engineering, UNSW Sydney, Sydney, NSW 2052, Australia.
| | | | - Carina B Tanaka
- School of Mechanical and Manufacturing Engineering, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Mark J Hoffman
- School of Mechanical and Manufacturing Engineering, UNSW Sydney, Sydney, NSW 2052, Australia; School of Materials Science and Engineering, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Paulo F Cesar
- Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil
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16
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Abstract
This article provides a brief review of recent investigations concerning the structure and properties of the tooth. The last decade has brought a greater emphasis on the durability of the tooth, an improved understanding of the fatigue and fracture behavior of the principal tissues, and their importance to tooth failures. The primary contributions to tooth durability are discussed, including the process of placing a restoration, the impact of aging, and challenges posed by the oral environment. The significance of these findings to the dental community and their importance to the pursuit of lifelong oral health are highlighted.
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Affiliation(s)
- Dwayne D Arola
- Department of Materials Science and Engineering, University of Washington School of Dentistry, Roberts Hall, 333, Box 352120, Seattle, WA 98195-2120, USA; Department of Oral Health Sciences, University of Washington School of Dentistry, Seattle, WA 98195-2120, USA; Department of Restorative Dentistry, Box 357456, University of Washington School of Dentistry, Seattle, WA 98195-7456, USA.
| | - Shanshan Gao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Renmin South Road, Chengdu, 610041, China
| | - Hai Zhang
- Department of Restorative Dentistry, Box 357456, University of Washington School of Dentistry, Seattle, WA 98195-7456, USA
| | - Radi Masri
- Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland School of Dentistry, 650 West Baltimore Street, 4th Floor, Suite 4228, Baltimore, MD 21201, USA
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17
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Enamel Microcracks Induced by Simulated Occlusal Wear in Mature, Immature, and Deciduous Teeth. BIOMED RESEARCH INTERNATIONAL 2018; 2018:5658393. [PMID: 29850534 PMCID: PMC5926526 DOI: 10.1155/2018/5658393] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 02/12/2018] [Indexed: 11/17/2022]
Abstract
Enamel wear, which is inevitable due to the process of mastication, is a process in which the microcracking of enamel occurs due to the surface contacting very small hard particles. When these particles slide on enamel, a combined process of microcutting and microcracking in the surface and subsurface of the enamel takes place. The aim of this study was to detect microscopic differences in the microcrack behavior by subjecting enamel specimens derived from different age groups (immature open-apex premolars, mature closed-apex premolars, and deciduous molars) to cycles of simulated impact and sliding wear testing under controlled conditions. Our findings indicated that the characteristics of the microcracks, including the length, depth, count, orientation, and relation to microstructures differed among the study groups. The differences between the surface and subsurface microcrack characteristics were most notable in the enamel of deciduous molars followed by immature premolars and mature premolars whereby deciduous enamel suffered numerous, extensive, and branched microcracks. Within the limitations of this study, it was concluded that enamel surface and subsurface microcracks characteristics are dependent on the posteruptive age with deciduous enamel being the least resistant to wear based on the microcrack behavior as compared to permanent enamel.
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18
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Ghaffari H, Mirhashemi A, Baherimoghadam T, Azmi A, Rasooli R. Effect of Surface Treatment on Enamel Cracks After Orthodontic Bracket Debonding: Er,Cr:YSGG Laser-Etching Versus Acid-Etching. JOURNAL OF DENTISTRY (TEHRAN, IRAN) 2017; 14:259-266. [PMID: 29296111 PMCID: PMC5748453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVES This study sought to compare enamel cracks after orthodontic bracket debonding in the surfaces prepared with erbium, chromium: yttrium-scandium-galliumgarnet (Er,Cr:YSGG) laser and the conventional acid-etching technique. MATERIALS AND METHODS This in-vitro experimental study was conducted on 60 sound human premolars extracted for orthodontic purposes. The teeth were randomly divided into two groups (n=30). The teeth in group A were etched with 37% phosphoric acid gel, while the teeth in group B were subjected to Er,Cr:YSGG laser irradiation (gold handpiece, MZ8 tip, 50Hz, 4.5W, 60μs, 80% water and 60% air). Orthodontic brackets were bonded to the enamel surfaces and were then debonded in both groups. The samples were inspected under a stereomicroscope at ×38 magnification to assess the number and length of enamel cracks before bonding and after debonding. Independent-samples t-test was used to compare the frequency of enamel cracks in the two groups. Levene's test was applied to assess the equality of variances. RESULTS No significant difference was noted in the frequency or length of enamel cracks between the two groups after debonding (P>0.05). CONCLUSIONS Despite the same results of the frequency and length of enamel cracks in the two groups and by considering the side effects of acid-etching (demineralization and formation of white spot lesions), Er,Cr:YSGG laser may be used as an alternative to acid-etching for enamel surface preparation prior to bracket bonding.
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Affiliation(s)
- Hassanali Ghaffari
- Assistant Professor, Department of Orthodontics, School of Dentistry, Shahed University of Medical Sciences, Tehran, Iran
| | - Amirhossein Mirhashemi
- Associate Professor, Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran; Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
| | - Tahereh Baherimoghadam
- Assistant Professor, Department of Orthodontics, School of Dentistry, Yasuj University of Medical Sciences, Yasuj, Iran
| | - Amir Azmi
- Dentist, Private Practice, Shiraz, Iran
| | - Reza Rasooli
- Assistant Professor, Department of Orthodontics, School of Dentistry, Shahed University of Medical Sciences, Tehran, Iran,Corresponding author: R. Rasooli, Department of Orthodontics, School of Dentistry, Shahed University of Medical Sciences, Tehran, Iran,
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