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Houari S, DeRocher K, Thuy TT, Coradin T, Srot V, van Aken PA, Lecoq H, Sauvage T, Balan E, Aufort J, Calemme M, Roubier N, Bosco J, Jedeon K, Berdal A, Joester D, Babajko S. Multi-scale characterization of Developmental Defects of Enamel and their clinical significance for diagnosis and treatment. Acta Biomater 2023; 169:155-167. [PMID: 37574156 DOI: 10.1016/j.actbio.2023.08.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 07/18/2023] [Accepted: 08/08/2023] [Indexed: 08/15/2023]
Abstract
Developmental Defects of Enamel (DDE) such as Dental Fluorosis (DF) and Molar Incisor Hypomineralization (MIH) are a major public health problem. Their clinical aspects are extremely variable, challenging their early and specific diagnosis and hindering progresses in restorative treatments. Here, a combination of macro-, micro- and nano-scale structural and chemical methods, including, among others, Atom Probe Tomography recently applied on tooth enamel, were used to study and compare MIH, DF and healthy teeth from 89 patients. Globally, we show that DF is characterized by an homogenous loss of mineral content and crystallinity mainly disrupting outside layer of enamel, whereas MIH is associated with localized defects in the depth of enamel where crystalline mineral particles are embedded in an organic phase. Only minor differences in elemental composition of the mineral phase could be detected at the nanoscale such as increased F and Fe content in both severe DDE. We demonstrate that an improved digital color measurement of clinical relevance can discriminate between DF and MIH lesions, both in mild and severe forms. Such discriminating ability was discussed in the light of enamel composition and structure, especially its microstructure, organics presence and metal content (Fe, Zn). Our results offer additional insights on DDE characterization and pathogenesis, highlight the potentiality of colorimetric measurements in their clinical diagnosis and provide leads to improve the performance of minimally invasive restorative strategies. STATEMENT OF SIGNIFICANCE: Developmental Defects of Enamel (DDE) are associated to caries and tooth loose affecting billions of people worldwide. Their precise characterization for adapted minimally invasive care with optimized materials is highly expected. Here In this study, first we propose the use of color parameters measured by a spectrophotometer as a means of differential clinical diagnosis. Second, we have used state-of-the-art techniques to systematically characterize the structure, chemical composition and mechanical optical properties of dental enamel teeth affected by two major DDE, Dental Fluorosis (DF) or Molar Incisor Hypomineralization (MIH). We evidence specific enamel structural and optical features for DF and MIH while chemical modifications of the mineral nanocrystals were mostly correlated with lesion severity. Our results pave the way of the concept of personalized dentistry. In the light of our results, we propose a new means of clinical diagnosis for an adapted and improved restoration protocol for these patients.
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Affiliation(s)
- Sophia Houari
- Laboratoire de Pathophysiologie Orale Moleculaire, Centre de Recherche des Cordeliers, INSERM UMRS, Université Paris Cité, Sorbonne Université, Paris 1138, France; Unité de Formation et de Recherche d'Odontologie, Université Paris Cité, APHP, Service d'Odontologie - Hôpital La pitié-Salpetrière, Paris, France; Fédération Hospitalo-Universitaire DDS-ParisNet, INSERM, Université Paris Cité, Assistance Publique-Hôpitaux de Paris, France.
| | - Karen DeRocher
- Department of Materials Science and Engineering, Northwestern University, IL, USA
| | - Tran Thu Thuy
- Faculty of Odonto-stomatology, HochiMinh University of Medicine and Pharmacology, HôchiMinh Ville, Viet Nam
| | - Thibaud Coradin
- Laboratoire de Chimie de la Matière Condensée, Sorbonne Université, CNRS, Paris, France
| | - Vesna Srot
- Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - Peter A van Aken
- Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - Hélène Lecoq
- CNRS UPR3079, Université d'Orléans, Conditions Extrêmes et Matériaux: Haute Température et Irradiation, Orléans, France
| | - Thierry Sauvage
- CNRS UPR3079, Université d'Orléans, Conditions Extrêmes et Matériaux: Haute Température et Irradiation, Orléans, France
| | - Etienne Balan
- Sorbonne Université, CNRS, Institut de Recherche pour le Developpement, Museum National d'Histoire Naturelle, Institut de Minéralogie, Physique des Matériaux et Cosmochimie, Paris, France
| | - Julie Aufort
- Sorbonne Université, CNRS, Institut de Recherche pour le Developpement, Museum National d'Histoire Naturelle, Institut de Minéralogie, Physique des Matériaux et Cosmochimie, Paris, France
| | | | - Nicolas Roubier
- Laboratoire de Mécanique Paris-Saclay, CNRS, Centrale-Supélec, Université Paris-Saclay, Châtenay-Malabry, France
| | - Julia Bosco
- Unité de Formation et de Recherche d'Odontologie, Université Paris Cité, APHP, Service d'Odontologie - Hôpital La pitié-Salpetrière, Paris, France
| | - Katia Jedeon
- Laboratoire de Pathophysiologie Orale Moleculaire, Centre de Recherche des Cordeliers, INSERM UMRS, Université Paris Cité, Sorbonne Université, Paris 1138, France; Fédération Hospitalo-Universitaire DDS-ParisNet, INSERM, Université Paris Cité, Assistance Publique-Hôpitaux de Paris, France
| | - Ariane Berdal
- Laboratoire de Pathophysiologie Orale Moleculaire, Centre de Recherche des Cordeliers, INSERM UMRS, Université Paris Cité, Sorbonne Université, Paris 1138, France; Fédération Hospitalo-Universitaire DDS-ParisNet, INSERM, Université Paris Cité, Assistance Publique-Hôpitaux de Paris, France
| | - Derk Joester
- Department of Materials Science and Engineering, Northwestern University, IL, USA
| | - Sylvie Babajko
- Laboratoire de Pathophysiologie Orale Moleculaire, Centre de Recherche des Cordeliers, INSERM UMRS, Université Paris Cité, Sorbonne Université, Paris 1138, France; Fédération Hospitalo-Universitaire DDS-ParisNet, INSERM, Université Paris Cité, Assistance Publique-Hôpitaux de Paris, France; UR2496, Biomedical research in Odontology, Université Paris Cité, Montrouge, France
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Li P, Zeng B, Xie W, Xiao X, Lin L, Yu D, Zhao W. Enamel Structure Defects in Kdf1 Missense Mutation Knock-in Mice. Biomedicines 2023; 11:biomedicines11020482. [PMID: 36831017 PMCID: PMC9953722 DOI: 10.3390/biomedicines11020482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023] Open
Abstract
The Keratinocyte differentiation factor 1 (KDF1) is reported to take part in tooth formation in humans, but the dental phenotype of Kdf1 mutant mice has not been understood. Additionally, the role of the KDF1 gene in dental hard tissue development is rarely known. In this study, we constructed a Kdf1 missense mutation knock-in mouse model through CRISPR/Cas9 gene-editing technology. Enamel samples from wildtypes (WT) and Kdf1 homozygous mutants (HO) were examined using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), an atomic force microscope (AFM) and Raman microspectroscopy. The results showed that a novel Kdf1 missense mutation (c. 908G>C, p.R303P) knock-in mice model was constructed successfully. The enamel of HO mice incisors appeared chalky and defective, exposing the rough interior of the inner enamel and dentin. Micro-CT showed that HO mice had lower volume and mineral density in their tooth enamel. In addition, declined thickness was found in the unerupted enamel layer of incisors in the HO mice. Using SEM and AFM, it was found that enamel prisms in HO mice enamel were abnormally and variously shaped with loose decussating crystal arrangement, meanwhile the enamel rods were partially fused and collapsed, accompanied by large gaps. Furthermore, misshapen nanofibrous apatites were disorderly combined with each other. Raman microspectroscopy revealed a compromised degree of order within the crystals in the enamel after the Kdf1 mutation. To conclude, we identified enamel structure defects in the Kdf1 missense mutation knock-in mice, which displayed fragmentary appearance, abnormally shaped prism structure, decreased mineral density, altered crystal ordering degree and chemical composition of the enamel layer. This may support the potential role of the KDF1 gene in the natural development of enamel.
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Wu Y, Liu J, Yang Y, Tu S, Liu Z, Wang Y, Peng C, Liu G, Jin Y. Special architecture and anti-wear strategies for giant panda tooth enamel: Based on wear simulation findings. Front Vet Sci 2022; 9:985733. [PMID: 36187810 PMCID: PMC9516319 DOI: 10.3389/fvets.2022.985733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/10/2022] [Indexed: 11/13/2022] Open
Abstract
Giant pandas are the flagship species in world conservation. Due to bamboo being the primary food source for giant pandas, dental wear is common owing to the extreme toughness of the bamboo fiber. Even though research on tooth enamel wear in humans and domestic animals is well-established, research on tooth enamel wear in giant pandas is scarce. The purpose of this study is to evaluate tooth enamel wear resistance in giant pandas to provide a basis for a better understanding of their evolutionary process. From microscopic and macroscopic perspectives, the abrasion resistance of dental enamel in giant pandas is compared with that of herbivorous cattle and carnivorous dogs in this study. This involves the use of micro-scratch and frictional wear tests. The results show that the boundary between the enamel prism and the enamel prism stroma is well-defined in panda and canine teeth, while bovine tooth enamel appears denser. Under constant load, the tribological properties of giant panda enamel are similar to those of canines and significantly different from those of bovines. Test results show that the depth of micro scratches in giant panda and canine enamel was greater than in cattle, with greater elastic recovery occurring in dogs. Scratch morphology indicates that the enamel substantive damage critical value is greater in pandas than in both dogs and cattle. The analysis suggests that giant panda enamel consists of a neatly arranged special structure that may disperse extrusion stress and absorb impact energy through a series of inelastic deformation mechanisms to cope with the wear caused by eating bamboo. In this study, the excellent wear resistance of giant panda's tooth enamel is verified by wear tests. A possible theoretical explanation of how the special structure of giant panda tooth enamel may improve its wear resistance is provided. This provides a direction for subsequent theoretical and experimental studies on giant panda tooth enamel and its biomaterials.
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Affiliation(s)
- Yuanheng Wu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jinxing Liu
- Tsinghua Laboratory of Brain and Intelligence, Nonhuman Primate Research Center Tsingua University, Beijing, China
| | - Yongqiang Yang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Shaotong Tu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zichen Liu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yingyun Wang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Chen Peng
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Gang Liu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
- *Correspondence: Gang Liu
| | - Yipeng Jin
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Yipeng Jin
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Marouane O, Manton DJ. The use of transillumination in mapping demarcated enamel opacities in anterior teeth: A cross-sectional study. Int J Paediatr Dent 2022; 32:49-55. [PMID: 33728689 DOI: 10.1111/ipd.12790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Despite intensive efforts for categorizing demarcated enamel opacities, often related to molar incisor hypomineralization (MIH), there is a lack of descriptive criteria aiming to describe them physically outside the scope of color and size. This is most likely due to the indices focusing on molar, not anterior, teeth. AIM To map and classify demarcated lesions on permanent anterior teeth using reflected and transilluminated light. The association between classification and related lesion characteristics was also examined. DESIGN Permanent anterior teeth with demarcated opacities related to MIH were selected. For each tooth, standardized photographs were taken using transmitted and reflected light. Each lesion was mapped and classified according to its color, lesion size, surface integrity, and type. The data were analyzed using the chi-square and Fisher's exact tests. A logistic regression analysis was performed to identify the risk of PEB. RESULTS There were significant relationships between lesion size, color, and type with surface integrity. Lesion type and size were more important than lesion color for assessing the risk of PEB. There was also a significant relationship between lesion size and lesion color. CONCLUSIONS Lesion size and type are significant clinical parameters for assessing the risk of PEB on enamel opacities related to MIH.
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Affiliation(s)
- Omar Marouane
- Private Practice, Restorative dentistry and Endodontics, Oralys Dental Clinic, Tunis, Tunisia
| | - David J Manton
- Paediatric Dentistry and Cariology, Centrum voor Tandheelkunde en Mondzorgkunde, UMCG, University of Groningen, Groningen, The Netherlands
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Hubbard MJ, Perez VA, Ganss B. 100 Years of Chalky Teeth Research: From Pioneering Histopathology to Social Good. FRONTIERS IN DENTAL MEDICINE 2021. [DOI: 10.3389/fdmed.2020.632534] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
One hundred years ago, histopathology pioneer Bernhard Gottlieb described developmentally disrupted teeth as having “chalky enamel” and “chalky spots” that “crumble” easily. He also asked pivotal questions about the pathogenesis of “enamel hypoplasia” that remained enigmatic for almost a century. Today, breakthrough pathomechanistic investigations of chalky enamel are revealing surprising answers, and an allied translational initiative—The D3 Group for developmental dental defects (“D3s”) —is converting such scientific knowledge into social good surrounding prevention of tooth decay. Molar hypomineralisation (MH) affects 1-in-5 children worldwide and is well-evidenced, but poorly recognised, as a principal risk factor for childhood tooth decay. Given MH is causally linked to infantile illness, an exciting corollary is that medical prevention would lead to substantial reductions in decay. Here we reflect on the past century of chalky teeth research and retrace the path leading to recognition of MH as a global health concern. Five research eras, today's four major D3s, and diverse experimental attacks are outlined alongside translational wins that have benefitted global health. Addressing hopes for medical prevention of MH, this centennial year's pathomechanistic discovery is contextualised against past accomplishments and new opportunities. Finally, we note the translational value of accessible infographics for guiding future work, and forecast exciting prospects for the next century.
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Alkhalaf R, Neves ADA, Banerjee A, Hosey MT. Minimally invasive judgement calls: managing compromised first permanent molars in children. Br Dent J 2020; 229:459-465. [PMID: 33037366 DOI: 10.1038/s41415-020-2154-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/11/2020] [Indexed: 12/23/2022]
Abstract
This paper aims to update the reader on how minimally invasive (MI) techniques may be used to improve the longevity of carious or defective/compromised first permanent molars (cFPMs) in young children. Clinical and radiographic diagnosis and the prognostic factors will be discussed in view of recent studies showing that these teeth can be kept in function and have an improved prognosis as the child gets older. Clinical protocols for their care, based on the latest evidence and techniques for MI restorations, together with longevity information of possible restorative options, are described. This paper also explores the rationale behind enforced extractions and related morbidity, in order to help oral healthcare practitioners to determine the optimal management of these key elements in the dentition for the benefit of the patients.
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Affiliation(s)
- Reem Alkhalaf
- Centre of Oral, Clinical & Translational Science, Faculty of Dentistry, Oral and Craniofacial Research, King's College London, London, UK
| | - Aline de Almeida Neves
- Clinical Lecturer in Paediatric Dentistry, Centre of Oral, Clinical and Translational Research, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, UK; Adjunct Professor in Paediatric Dentistry, Federal University of Rio de Janeiro, Brazil.
| | - Avijit Banerjee
- Professor of Cariology & Operative Dentistry, Honorary Consultant/Clinical Lead, Restorative Dentistry, Conservative & MI Dentistry/Centre of Oral, Clinical and Translational Research, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, UK
| | - Marie Therese Hosey
- Professor of Paediatric Dentistry, Honorary Consultant, Chair of Paediatric Dentistry, Centre of Oral, Clinical and Translational Research, Faculty of Dentistry, Oral and Craniofacial Sciences, King's College London, London, UK
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Mendonça FL, Di Leone CCL, Grizzo IC, Cruvinel T, de Oliveira TM, Navarro MFDL, Rios D. Simplified occlusal replica adapted technique with glass ionomer cement for molar-incisor hypomineralization-affected molars: An 18-month follow-up. J Am Dent Assoc 2020; 151:678-683. [PMID: 32854870 DOI: 10.1016/j.adaj.2020.06.017] [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: 03/09/2020] [Revised: 06/03/2020] [Accepted: 06/10/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND AND OVERVIEW Molar-incisor hypomineralization (MIH) is a qualitative developmental defect of enamel, which has been a daily concern in clinical practice owing to its difficult treatment. CASE DESCRIPTION An 11-year-old girl was admitted to the pediatric dental clinic with a symptom of severe hypersensitivity in the permanent molars owing to MIH. The treatment consisted of a simplified occlusal replica adapted technique with conventional glass ionomer cement in the MIH-affected molars, which involved laboratory and clinical stages. The patient was reexamined every 3 months, and after 18 months there was no additional tooth structure loss, restoration failure, or pain. This technique may be considered a feasible alternative to restore hypomineralized teeth owing to its reduced procedure time and good performance in the follow-up period of 18 months. CONCLUSIONS AND PRACTICAL IMPLICATIONS The technique successfully restored the function and shape of the affected teeth, decreasing the sensitivity by means of covering the demarcated MIH opacities.
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Feltrin-Souza J, Jeremias F, Alaluusua S, Sahlberg C, Santos-Pinto L, Jernvall J, Sova S, Cordeiro RDCL, Cerri PS. The effect of amoxicillin on dental enamel development in vivo. Braz Oral Res 2020; 34:e116. [PMID: 32901731 DOI: 10.1590/1807-3107bor-2020.vol34.0116] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/26/2020] [Indexed: 12/30/2022] Open
Abstract
The exposure to amoxicillin has been associated with molar incisor hypomineralization. This study aimed to determine if amoxicillin disturbs the enamel mineralization in in vivo experiments. Fifteen pregnant rats were randomly assigned into three groups to received daily phosphatase-buffered saline or amoxicillin as either 100 or 500 mg/kg. Mice received treatment from day 13 of pregnancy to day 40 postnatal. After birth, the offsprings from each litter continued to receive the same treatment according to their respective group. Calcium (Ca) and phosphorus (P) content in the dental hard tissues were analyzed from 60 upper first molars and 60 upper incisors by the complexometric titration method and colorimetric analysis using a spectrophotometer at 680 nm, respectively. Lower incisors were analyzed by X-ray microtomography, it was measured the electron density of lingual and buccal enamel, and the enamel and dentin thickness. Differences in Ca and P content and electron density among the groups were analyzed by one-way ANOVA. There was no significant difference on enamel electron density and thickness among the groups (p > 0.05). However, in incisors, the higher dose of amoxicillin decreased markedly the electron density in some rats. There were no statistically significant differences in Ca (p = 0.180) or P content (p = 0.054), although the higher dose of amoxicillin could affect the enamel in some animals. The amoxicillin did not significantly alter the enamel mineralization and thickness in rats.
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Affiliation(s)
- Juliana Feltrin-Souza
- Universidade Federal do Paraná - UFPR, Department of Stomatology, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Fabiano Jeremias
- Universidade Estadual Paulista - Unesp, School of Dentistry, Department of Pediatric Dentistry, Araraquara, SP, Brazil
| | - Satu Alaluusua
- University of Helsinki, School of Medicine, Department of Oral and Maxillofacial Diseases, Helsinki, Finland
| | - Carin Sahlberg
- University of Helsinki, School of Medicine, Department of Oral and Maxillofacial Diseases, Helsinki, Finland
| | - Lourdes Santos-Pinto
- Universidade Estadual Paulista - Unesp, School of Dentistry, Department of Pediatric Dentistry, Araraquara, SP, Brazil
| | - Jukka Jernvall
- University of Helsinki, Institute of Biotechnology, Developmental Biology Program, Helsinki, Finland
| | - Susanna Sova
- University of Helsinki, Institute of Biotechnology, Developmental Biology Program, Helsinki, Finland
| | | | - Paulo Sérgio Cerri
- Universidade Estadual Paulista - Unesp, School of Dentistry, Department of Morphology, Araraquara, SP, Brazil
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Koldehoff J, Swain MV, Schneider GA. The geometrical structure of interfaces in dental enamel: A FIB-STEM investigation. Acta Biomater 2020; 104:17-27. [PMID: 31917293 DOI: 10.1016/j.actbio.2019.12.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 12/20/2019] [Accepted: 12/31/2019] [Indexed: 11/26/2022]
Abstract
In this study a high resolution structural analysis revealed that enamel prisms are surrounded by an interface that is discontinuous with frequent mineral to mineral contact separated by gaps. This contact manifests either by crystallites bridging the boundary between prismatic and interprismatic enamel or continuous crystallites curving and bridging the interprismatic enamel to the prisms. The geometrical resolution of this TEM investigation of the interfaces is ≤2 nm as a basis for micromechanical models. Within this resolution, contrary to existing structural descriptions of dental enamel structure in materials science literature, here the crystallites themselves are shown to be either in direct contact with each other, sometimes even fusing together, or are separated by gaps. Image analysis revealed that on average only 57 ± 15% of the interface consists of points of no contact between crystallites. This work reveals structural features of dental enamel that contribute important understanding to both the architecture and mechanical properties of this biological material. A new structural model is proposed and the implications for the mechanical properties of dental enamel are discussed. STATEMENT OF SIGNIFICANCE: In this study a high resolution structural analysis, employing focused ion beam and transmission electron microscopy revealed that enamel prisms are surrounded by interfaces that are discontinuous with frequent mineral to mineral contact separated by gaps. Although the interfaces in enamel have been investigated previously, existing studies are lacking in detail considering the geometry and morphology of the interfaces. We think that this result is of great importance when it comes to the understanding of the mechanical properties. In our opinion the concept of soft sheaths is no longer feasible. The resulting observations are included in a new structural model which provides new qualitative insights into the mechanical behavior. Existing analytical models were applied to simulate the new geometrical structure.
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Contact damage of human dental enamel under cyclic axial loading with abrasive particles. J Mech Behav Biomed Mater 2020; 102:103512. [DOI: 10.1016/j.jmbbm.2019.103512] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 10/25/2019] [Accepted: 10/28/2019] [Indexed: 12/28/2022]
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Wu SX, Li KQ, Zhu WZ, Wang CY, Chen WL. Machinability of high-speed enamel cutting with carbide bur. J Mech Behav Biomed Mater 2019; 103:103529. [PMID: 31783283 DOI: 10.1016/j.jmbbm.2019.103529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/07/2019] [Accepted: 11/11/2019] [Indexed: 11/30/2022]
Abstract
The cutting of tooth enamel using a high-speed air-turbine handpiece and carbide bur is a key procedure in oral surgeries, such as the minimally invasive extraction. However, presently little is known about the cutting mechanics and material removal mechanism related to tooth enamel machinability. In this study, the machinability of high-speed enamel cutting with carbide bur is studied by a computer-aided numerical control system. The dynamic cutting forces of enamel of the occlusal, buccal/lingual, and proximal surfaces were measured by the force measuring system. The force ratio, cutting torque, rotating speed, specific cutting energy, and bur wear were analyzed. The microstructure of enamel and carbide burs was observed by the scanning electron microscope, and the relationship between enamel microstructures and machinability was further analyzed. The results show that during the high-speed enamel cutting with carbide bur, the chip thickness is on the nano-scale, and the plastic deformation of the machined surface is obvious. With increased material removal rate, the cutting force, torque, specific cutting energy, and bur wear increases accordingly, whereas the rotating speed decelerates (p < 0.05). The different angles between the cutting direction and the axial direction of the enamel rods give rise to the large differences in the cutting mechanics and mechanism of the proximal, buccal/lingual, and occlusal surfaces of the teeth. When the cutting direction is parallel, vertical, and oblique 45° to the axial direction of the enamel rods, the force required for material fracture and crack propagation increases, and the cutting force increases as a consequence. Parallel and oblique 45° cutting are the main modes of tooth segmentation in the minimally invasive extraction. In comparison with the parallel cutting mode, the cutting force, torque, and cutting ratio of the oblique 45° cutting mode can be significantly increased, and the tool wear is obviously accelerated. This is the lowest priority in segmentation surgery, hence the problems of overload and temperature rise need to be considered. The cutting mechanics and cutting mechanism obtained in this study will provide scientific process guidance for dental cutting operations with the air-turbine handpiece driving bur.
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Risnes S, Li C. On the method of revealing enamel structure by acid etching. Aspects of optimization and interpretation. Microsc Res Tech 2019; 82:1668-1680. [PMID: 31259458 DOI: 10.1002/jemt.23333] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/25/2019] [Accepted: 06/15/2019] [Indexed: 01/24/2023]
Abstract
The study aimed at finding an optimal combination of acid concentration and etching time when nitric acid is used as etchant for the study of the finer details of human dental enamel structure. Four hundred 2-3-mm-thick segments of facio-lingually sectioned human third molar crowns were assigned to 20 groups with 20 specimens in each group, each group differing with respect to acid concentration (0.1, 1, 2.5, and 5%) and etching time (15, 30, 45, 90, and 180 s). After etching and preparation, specimens were observed in the scanning electron microscope (SEM). Surface roughness/topography increased with increasing acid concentration and increasing etching time, but not in a linear fashion; generally, prisms tended to go from flat-surfaced to cone-shaped and prism sheaths from fissure-like to wedge-shaped. Intragroup variations and intergroup similarities were considerable. The two major enamel factors determining the etch effect are crystal orientation and prism sheath properties. Other factors, such as distribution of porosities and crystal quality, also contribute probably. Slight to moderate topography is best for observing the finer enamel structure, for example, etching with concentrations in the range 0.1-1% and with etching times in the range 15-90 s, the stronger the acid, the shorter the time. The depth effect of nitric acid is judged to be relatively small. Considerable variations in expression of prism cross-striations were observed. SEM observations of acid-etched enamel in carefully selected planes are a powerful method for the study of enamel structure, bearing in mind the artifactual aspects of the observed surface.
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Affiliation(s)
- Steinar Risnes
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Chunfang Li
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.,School and Hospital of Stomatology, Wuhan University, Wuhan, China
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Marouane O, Douki N. The use of transillumination in detecting subclinical extensions of enamel opacities. J ESTHET RESTOR DENT 2019; 31:595-600. [DOI: 10.1111/jerd.12506] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 04/23/2019] [Accepted: 05/31/2019] [Indexed: 12/01/2022]
Affiliation(s)
- Omar Marouane
- Université de Monastir, Restorative Dentistry Department University Hospital Sahloul Sousse Tunisia
| | - Nabiha Douki
- Université de Monastir, Restorative Dentistry Department University Hospital Sahloul Sousse Tunisia
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Malmberg P, Norén JG, Bernin D. Molecular insights into hypomineralized enamel. Eur J Oral Sci 2019; 127:340-346. [DOI: 10.1111/eos.12619] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Per Malmberg
- Department of Chemistry and Chemical Engineering Chalmers University of Technology Gothenburg Sweden
| | - Jörgen G. Norén
- Department of Pediatric Dentistry Institute of Odontology Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - Diana Bernin
- Department of Chemistry and Chemical Engineering Chalmers University of Technology Gothenburg Sweden
- Swedish NMR Centre University of Gothenburg Gothenburg Sweden
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Rai PM, Jain J, Raju AS, Nair RA, Shashidhar K, Dsouza S. Prevalence of Molar Incisor Hypomineralization among School Children Aged 9 to 12 Years in Virajpet, Karnataka, India. Open Access Maced J Med Sci 2019; 7:1042-1046. [PMID: 30976358 PMCID: PMC6454169 DOI: 10.3889/oamjms.2019.224] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 03/23/2019] [Accepted: 03/24/2019] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND: The molar incisor hypomineralization (MIH) is defined as a qualitative defect of the enamel characterised by the progressive and simultaneous hypomineralization of the enamel structure of the first permanent molars which is of systemic origin, which may be associated frequently with incisors. Although the reported prevalence of MIH ranges from 2.4% to 40.2% worldwide, very little data is available from India. AIM: To determine the prevalence of molar incisor hypomineralization among school children aged 9 to 12 years in virajpet, Karnataka. METHODS: This cross-sectional descriptive study consisted of 1600 school children aged 9-12 years selected by stratified cluster sampling procedure. The European Academy of Pediatric Dentistry criteria were followed for MIH diagnosis. Chi-square test was used to analyse the categorical data. P ≤ 0.05 was considered for statistical significance. RESULTS: The prevalence of MIH is 13.12% with no gender predilection. Ten-year-old children showed the highest prevalence (15%) among all the age group. Majority of children with MIH (70.2%) have lesions in both molars and incisors with demarcated opacities and atypical restorations being the most frequent defect type. CONCLUSION: Prevalence of MIH was 13.12% in the 9-12-year child population in Virajpet. There is a need for a proper planned preventive and restorative program about the increasing prevalence of MIH.
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Affiliation(s)
- Pooja Mali Rai
- Department of Public Health Dentistry, Coorg Institute of Dental Sciences, Virajpet, Karnataka
| | - Jithesh Jain
- Department of Public Health Dentistry, Coorg Institute of Dental Sciences, Virajpet, Karnataka
| | - Ananda Shivamoga Raju
- Department of Public Health Dentistry, Coorg Institute of Dental Sciences, Virajpet, Karnataka
| | - Rohit A Nair
- Department of Public Health Dentistry, Coorg Institute of Dental Sciences, Virajpet, Karnataka
| | - Keerthan Shashidhar
- Department of Orthodontics and Dentofacial Orthopedics, Subbaiah Institue of Dental Sciences, Shivamogga, Karnataka, India
| | - Sheehan Dsouza
- Department of Periodontology, Srinivas Institute of Dental Sciences, Mangalore, Karnataka
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Effect of a self-etching primer containing 4-META and sodium sulfite after phosphoric acid etching on bonding strength of MMA-TBB resin to human enamel. J Prosthodont Res 2018; 63:145-149. [PMID: 30528398 DOI: 10.1016/j.jpor.2018.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/24/2018] [Accepted: 10/30/2018] [Indexed: 11/21/2022]
Abstract
PURPOSE The aim of this study was to evaluate the shear bond strength and durability of MMA-TBB resin to human enamel applied a self-etching primer with phosphoric acid etching. METHODS A self-etching primer (Teeth primer, TP) containing 4-methacryloyloxyethyl trimellitate anhydride (4-META) and sodium sulfite and two etchants having different phosphoric acid concentrations (K-etchant gel, KE, 35-45%: Red gel, RG, 20-25%) were used as treatment agent, and MMA-TBB resin was used as luting agent. Enamel surfaces were treated with six methods which were as follow: KE, RG, TP, KE+TP, and RG+TP. After enamel specimens were bonded with MMA-TBB resin and stored in distilled water for 24h, the shear bond strength test was done at 0 thermocycling or 20,000 thermocycling. These results were statistically verified with Steel-Dwass multiple comparisons and Man-Whitney U test. RESULTS The shear bond strength of TP group, KE+TP group, and RG+TP group were significantly higher than KE group and RG group in pre-thermocycling. KE+TP group and RG+TP group were significantly higher than other groups in post-thermocycling. CONCLUSIONS Applying TP with phosphoric acid etching can increased shear bond durability despite difference of phosphoric acid concentrations (35-45% or 20-25%).
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Liu Z, Weng Z, Zhai ZF, Huang N, Zhang ZJ, Tan J, Jiang C, Jiao D, Tan G, Zhang J, Jiang X, Zhang Z, Ritchie RO. Hydration-induced nano- to micro-scale self-recovery of the tooth enamel of the giant panda. Acta Biomater 2018; 81:267-277. [PMID: 30273740 DOI: 10.1016/j.actbio.2018.09.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/17/2018] [Accepted: 09/27/2018] [Indexed: 11/19/2022]
Abstract
The tooth enamel of vertebrates comprises a hyper-mineralized bioceramic, but is distinguished by an exceptional durability to resist impact and wear throughout the lifetime of organisms; however, enamels exhibit a low resistance to the initiation of large-scale cracks comparable to that of geological minerals based on fracture mechanics. Here we reveal that the tooth enamel, specifically from the giant panda, is capable of developing durability through counteracting the early stage of damage by partially recovering its innate geometry and structure at nano- to micro- length-scales autonomously. Such an attribute results essentially from the unique architecture of tooth enamel, specifically the vertical alignment of nano-scale mineral fibers and micro-scale prisms within a water-responsive organic-rich matrix, and can lead to a decrease in the dimension of indent damage in enamel introduced by indentation. Hydration plays an effective role in promoting the recovery process and improving the indentation fracture toughness of enamel (by ∼73%), at a minor cost of micro-hardness (by ∼5%), as compared to the dehydrated state. The nano-scale mechanisms that are responsible for the recovery deformation, specifically the reorientation and rearrangement of mineral fragments and the inter- and intra-prismatic sliding between constituents that are closely related to the viscoelasticity of organic matrix, are examined and analyzed with respect to the structure of tooth enamel. Our study sheds new light on the strategies underlying Nature's design of durable ceramics which could be translated into man-made systems in developing high-performance ceramic materials. STATEMENT OF SIGNIFICANCE: Tooth enamel plays a critical role in the function of teeth by providing a hard surface layer to resist wear/impact throughout the lifetime of organisms; however, such enamel exhibits a remarkably low resistance to the initiation of large-scale cracks, of hundreds of micrometers or more, comparable to that of geological minerals. Here we reveal that tooth enamel, specifically that of the giant panda, is capable of partially recovering its geometry and structure to counteract the early stages of damage at nano- to micro-scale dimensions autonomously. Such an attribute results essentially from the architecture of enamel but is markedly enhanced by hydration. Our work discerns a series of mechanisms that lead to the deformation and recovery of enamel and identifies a unique source of durability in the enamel to accomplish this function. The ingenious design of tooth enamel may inspire the development of new durable ceramic materials in man-made systems.
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Affiliation(s)
- Zengqian Liu
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China; Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA
| | - Zhaoyong Weng
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Zhao-Feng Zhai
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Nan Huang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Zhen-Jun Zhang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Jun Tan
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Chuanbin Jiang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Da Jiao
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Guoqi Tan
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China; School of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Jian Zhang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China; State Key Laboratory of Advanced Non-ferrous Materials, Lanzhou University of Technology, Lanzhou 730050, China
| | - Xin Jiang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Zhefeng Zhang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
| | - Robert O Ritchie
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, USA.
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Yilmaz ED, Koldehoff J, Schneider GA. On the systematic documentation of the structural characteristics of bovine enamel: A critic to the protein sheath concept. Dent Mater 2018; 34:1518-1530. [DOI: 10.1016/j.dental.2018.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 05/24/2018] [Accepted: 06/07/2018] [Indexed: 11/28/2022]
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Upadhyay S, Kumar G, Dhillon JK, Gill NC. Perception of Indian Dental Surgeons regarding Molar Incisor Hypomineralization. Int J Clin Pediatr Dent 2018; 11:116-121. [PMID: 29991864 PMCID: PMC6034059 DOI: 10.5005/jp-journals-10005-1496] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 02/01/2018] [Indexed: 11/23/2022] Open
Abstract
Aim To determine the perception of Indian dental professionals about prevalence, severity, and etiological factors of molar incisor hypomineralization (MIH). Materials and methods An online survey was mailed to dental professionals encompassing various questions regarding etiology, diagnosis, prevalence, and management of MIH. Results More than 90% of the respondents encounter teeth with hypomineralization in their practice, with less than half of them encountering such teeth on a monthly basis. Among these more than one-third find it difficult to manage one or the other aspect of MIH. The etiology was found to be varying as per the respondents. Conclusion Molar incisor hypomineralization is a common condition encountered by dental professionals with no apparent consensus regarding the anticipated prevalence, severity, and etiology of this condition. Knowledge of clinicians' level of perception could be an incentive for pediatric dentists to become more acquainted with MIH by conducting research into its different aspects.How to cite this article: Upadhyay S, Kumar G, Dhillon JK, Gill NC. Perception of Indian Dental Surgeons regarding Molar Incisor Hypomineralization. Int J Clin Pediatr Dent 2018;11(2):116-121.
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Affiliation(s)
- Sumita Upadhyay
- Assistant Professor, Department of Pediatric Dentistry, Kathmandu University School of Medical Sciences, Dhulikhel Hospital, Dhulikhel, Nepal
| | - Gyanendra Kumar
- Associate Professor, Department of Pedodontics and Preventive Dentistry, Maulana Azad Institute of Dental Sciences, New Delhi, India
| | - Jatinder K Dhillon
- Assistant Professor, Department of Pedodontics and Preventive Dentistry, Maulana Azad Institute of Dental Sciences, New Delhi, India
| | - Namrata C Gill
- Assistant Professor, Department of Pedodontics and Preventive Dentistry Dr. Harvansh Singh Judge Institute of Dental Sciences & Hospital, Panjab University, Chandigarh, India
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Wuollet E, Laisi S, Alaluusua S, Waltimo-Sirén J. The Association between Molar-Incisor Hypomineralization and Dental Caries with Socioeconomic Status as an Explanatory Variable in a Group of Finnish Children. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15071324. [PMID: 29941779 PMCID: PMC6068618 DOI: 10.3390/ijerph15071324] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 06/18/2018] [Accepted: 06/20/2018] [Indexed: 11/21/2022]
Abstract
The aim of this study was to investigate if a developmental enamel defect known as Molar-Incisor Hypomineralization (MIH) is associated with dental caries. Socioeconomic status (SES) was examined as a confounding factor between caries and MIH. In this cross-sectional study, 636 children, aged 8 to 13 years, from three towns (two rural areas and one urban area) in Finland were examined for MIH in line with the criteria of the European Academy of Paediatric Dentistry. Caries status for permanent teeth was recorded as decayed, missing and filled teeth (DMFT). Caries experience (DMFT > 0) in the first permanent molars (FPMs) was set as an outcome. SES was determined using a questionnaire completed by parents. The prevalence of MIH was 18.1%. The mean DMFT in FPMs for children with MIH was higher than for their peers, 1.03 ± 1.25 vs. 0.32 ± 0.80 (p = 0.000, Mann-Whitney U test). In a multivariate analysis using the generalized linear mixed model where locality, SES, age and MIH were taken into account as caries risk indicators, MIH was the strongest risk indicator of caries in FPMs (Odds Ratio: 6.60, 95% Confidence Interval: 3.83–11.39, p = 0.000). According to the study results, children with MIH have a higher risk for dental caries than children without MIH.
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Affiliation(s)
- Emma Wuollet
- Department of Oral and Maxillofacial Diseases, Faculty of Medicine, University of Helsinki, P.O. Box 41, FI-00014 Helsinki, Finland.
| | - Sakari Laisi
- Department of Oral and Maxillofacial Diseases, Faculty of Medicine, University of Helsinki, P.O. Box 41, FI-00014 Helsinki, Finland.
| | - Satu Alaluusua
- Department of Oral and Maxillofacial Diseases, Faculty of Medicine, University of Helsinki, P.O. Box 41, FI-00014 Helsinki, Finland.
| | - Janna Waltimo-Sirén
- Department of Oral and Maxillofacial Diseases, Faculty of Medicine, University of Helsinki, P.O. Box 41, FI-00014 Helsinki, Finland.
- Department of Oral and Maxillofacial Diseases, Helsinki University Hospital, P.O. Box 670, FI-00029 HUS, Finland.
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Kumar H, Palamara JEA, Burrow MF, Manton DJ. An investigation into the effect of a resin infiltrant on the micromechanical properties of hypomineralised enamel. Int J Paediatr Dent 2017; 27:399-411. [PMID: 27813257 DOI: 10.1111/ipd.12272] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Resin infiltration may alter the mechanical properties of enamel hypomineralised lesions (HL); however, variable surface layer (SL) thickness may affect resin penetration. AIMS To determine the thickness of the SL of HL and to investigate the effect of resin infiltration on the mechanical properties of HL. DESIGN The thickness of the SL over HL was determined using polarised light microscopy. Etching time using 15% HCl gel to remove the SL of 52 samples was determined. Selected HL and control areas of 21 teeth were infiltrated with Icon® resin infiltrant, and cross-sectional Knoop microhardness (KHN) measurements were recorded before and after resin infiltration. RESULTS Ninety-six point five per cent of HL had a detectable SL with mean thickness of 58 ± 29 μm. Application of HCl for 120 s produced a mean MIH erosion depth of 58 ± 12 μm. Eleven of 21 samples had evidence of infiltration using visual examination. The infiltrant penetrated some of the HL leading to an increase in KHN (111 ± 75 KHN) which, when compared to adjacent non-infiltrated HL (96 ± 52 KHN), was not statistically significantly different (P = 0.56). CONCLUSIONS There was marked variation in the SL thickness of HL. Resin infiltration of HL did not increase microhardness significantly.
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Affiliation(s)
- Harleen Kumar
- Oral Health Cooperative Research Centre, Melbourne Dental School, The University of Melbourne, Melbourne, Australia.,Boston Children's Hospital and Harvard School of Dental Medicine, Boston, MA, USA
| | | | - Michael Francis Burrow
- Oral Health Cooperative Research Centre, Melbourne Dental School, The University of Melbourne, Melbourne, Australia
| | - David John Manton
- Oral Health Cooperative Research Centre, Melbourne Dental School, The University of Melbourne, Melbourne, Australia
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Gambetta-Tessini K, Mariño R, Ghanim A, Adams GG, Manton DJ. Validation of quantitative light-induced fluorescence-digital in the quantification of demarcated hypomineralized lesions of enamel. ACTA ACUST UNITED AC 2017; 8. [DOI: 10.1111/jicd.12259] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/17/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Karla Gambetta-Tessini
- Oral Health Cooperative Research Centre; Melbourne Dental School; The University of Melbourne; Melbourne Victoria Australia
| | - Rodrigo Mariño
- Oral Health Cooperative Research Centre; Melbourne Dental School; The University of Melbourne; Melbourne Victoria Australia
| | - Aghareed Ghanim
- Oral Health Cooperative Research Centre; Melbourne Dental School; The University of Melbourne; Melbourne Victoria Australia
| | - Geoffrey G. Adams
- Oral Health Cooperative Research Centre; Melbourne Dental School; The University of Melbourne; Melbourne Victoria Australia
| | - David J. Manton
- Oral Health Cooperative Research Centre; Melbourne Dental School; The University of Melbourne; Melbourne Victoria Australia
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Wakasa M, Eshita Y, Nakanishi K, Isobe T, Manago K, Okamoto M, Isshiki T. STEM and HRTEM studies of accumulated deposits on human tooth surface. Microsc Res Tech 2017; 80:511-524. [PMID: 28124499 DOI: 10.1002/jemt.22825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 12/04/2016] [Accepted: 12/07/2016] [Indexed: 11/11/2022]
Abstract
The aim of this study was to clarify the fine structure of accumulated deposits on the surface of teeth that are considered to affect the gloss of teeth. The study was carried out using, as specimens, human incisor teeth having gloss, which were extracted from teenage donors and those incapable of showing gloss even by brushing which were extracted from donors in their 50s. Thin longitudinal sections of tooth enamel with accumulated deposits on the surface were prepared by focused ion beam (FIB) milling, and the fine structure was analyzed using a scanning transmission electron microscope (STEM) and a high resolution transmission electron microscope (HRTEM). By FIB, thin longitudinal sections could be prepared from tooth enamel together with organic and inorganic substances accumulated on the surface without artifacts. The accumulated deposits on the surface of teeth having gloss were composed of organic substances. However, it was first revealed by STEM observation that the accumulated solid deposits on the surface of teeth having no gloss had a complicated structure wherein inorganic and organic substances coexisted. It is suggested that the organic substances contain proteins derived from saliva. The inorganic substances were spherical and needle-like hydroxyapatites (HAs). It is considered that amino acids constituting the proteins affected the nucleus formation and the crystal formation of HA. It is considered that the unevenness of the accumulated deposits existing on the surface of tooth enamel having no gloss causes the decrease in gloss of teeth due to diffuse reflection of light.
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Affiliation(s)
- Masanobu Wakasa
- Analytical Science Research, Kao Corporation, Wakayama, Wakayama Prefecture, 640-8580, Japan
| | - Yoshiyuki Eshita
- Personal Health Care Products Research, Kao Corporation, Sumida-ku, Tokyo, 131-8501, Japan
| | - Kuniyuki Nakanishi
- Analytical Science Research, Kao Corporation, Wakayama, Wakayama Prefecture, 640-8580, Japan
| | - Tsutomu Isobe
- Personal Health Care Products Research, Kao Corporation, Sumida-ku, Tokyo, 131-8501, Japan
| | - Kenji Manago
- Analytical Science Research, Kao Corporation, Wakayama, Wakayama Prefecture, 640-8580, Japan
| | - Masayuki Okamoto
- Analytical Science Research, Kao Corporation, Wakayama, Wakayama Prefecture, 640-8580, Japan
| | - Toshiyuki Isshiki
- Department of Electrical Engineering and Electronics, Kyoto Institute of Technology, Sakyo-ku, Kyoto, 606-8580, Japan
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Enhanced protective role in materials with gradient structural orientations: Lessons from Nature. Acta Biomater 2016; 44:31-40. [PMID: 27503833 DOI: 10.1016/j.actbio.2016.08.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 07/08/2016] [Accepted: 08/04/2016] [Indexed: 12/19/2022]
Abstract
UNLABELLED Living organisms are adept at resisting contact deformation and damage by assembling protective surfaces with spatially varied mechanical properties, i.e., by creating functionally graded materials. Such gradients, together with multiple length-scale hierarchical structures, represent the two prime characteristics of many biological materials to be translated into engineering design. Here, we examine one design motif from a variety of biological tissues and materials where site-specific mechanical properties are generated for enhanced protection by adopting gradients in structural orientation over multiple length-scales, without manipulation of composition or microstructural dimension. Quantitative correlations are established between the structural orientations and local mechanical properties, such as stiffness, strength and fracture resistance; based on such gradients, the underlying mechanisms for the enhanced protective role of these materials are clarified. Theoretical analysis is presented and corroborated through numerical simulations of the indentation behavior of composites with distinct orientations. The design strategy of such bioinspired gradients is outlined in terms of the geometry of constituents. This study may offer a feasible approach towards generating functionally graded mechanical properties in synthetic materials for improved contact damage resistance. STATEMENT OF SIGNIFICANCE Living organisms are adept at resisting contact damage by assembling protective surfaces with spatially varied mechanical properties, i.e., by creating functionally-graded materials. Such gradients, together with multiple length-scale hierarchical structures, represent the prime characteristics of many biological materials. Here, we examine one design motif from a variety of biological tissues where site-specific mechanical properties are generated for enhanced protection by adopting gradients in structural orientation at multiple length-scales, without changes in composition or microstructural dimension. The design strategy of such bioinspired gradients is outlined in terms of the geometry of constituents. This study may offer a feasible approach towards generating functionally-graded mechanical properties in synthetic materials for improved damage resistance.
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Yilmaz ED, Schneider GA. Mechanical behavior of enamel rods under micro-compression. J Mech Behav Biomed Mater 2016; 63:183-194. [PMID: 27415405 DOI: 10.1016/j.jmbbm.2016.06.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/09/2016] [Accepted: 06/17/2016] [Indexed: 11/24/2022]
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Alsayed EZ, Hariri I, Nakashima S, Shimada Y, Bakhsh TA, Tagami J, Sadr A. Effects of coating materials on nanoindentation hardness of enamel and adjacent areas. Dent Mater 2016; 32:807-16. [PMID: 27063457 DOI: 10.1016/j.dental.2016.03.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 12/31/2015] [Accepted: 03/22/2016] [Indexed: 10/22/2022]
Abstract
OBJECTIVES Materials that can be applied as thin coatings and actively release fluoride or other bioavailable ions for reinforcing dental hard tissue deserve further investigation. In this study we assessed the potential of resin coating materials in protection of underlying and adjacent enamel against demineralization challenge using nanoindentation. METHODS Enamel was coated using Giomer (PRG Barrier Coat, PBC), resin-modified glass-ionomer (Clinpro XT Varnish, CXT), two-step self-etch adhesive (Clearfil SE Protect, SEP) or no coating (control). After 5000 thermal cycles and one-week demineralization challenge, Martens hardness of enamel beneath the coating, uncoated area and intermediate areas was measured using a Berkovich tip under 2mN load up to 200μm depth. Integrated hardness and 10-μm surface zone hardness were compared among groups. RESULTS Nanoindentation and scanning electron microscopy suggested that all materials effectively prevented demineralization in coated area. Uncoated areas presented different hardness trends; PBC showed a remarkable peak at the surface zone before reaching as low as the control, while CXT showed relatively high hardness values at all depths. SIGNIFICANCE Ion-release from coating materials affects different layers of enamel. Coatings with fluoride-releasing glass fillers contributed to reinforcement of adjacent enamel. Surface prereacted glass filler-containing PBC superficially protected neighboring enamel against demineralization, while resin-modified glass-ionomer with calcium (CXT) improved in-depth protection. Cross-sectional hardness mapping of enamel on a wide range of locations revealed minute differences in its structure.
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Affiliation(s)
- Ehab Z Alsayed
- Tokyo Medical and Dental University, Cariology and Operative Dentistry Department, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan; Yanbu Dental Center, Saudi Ministry of Health, Al-Madina Health Region, Saudi Arabia
| | - Ilnaz Hariri
- Tokyo Medical and Dental University, Cariology and Operative Dentistry Department, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
| | - Syozi Nakashima
- Tokyo Medical and Dental University, Cariology and Operative Dentistry Department, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
| | - Yasushi Shimada
- Tokyo Medical and Dental University, Cariology and Operative Dentistry Department, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
| | - Turki A Bakhsh
- King Abdulaziz University, Conservative Dental Sciences, P.O. Box 114759, Jeddah 21381, Saudi Arabia
| | - Junji Tagami
- Tokyo Medical and Dental University, Cariology and Operative Dentistry Department, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
| | - Alireza Sadr
- University of Washington School of Dentistry, 1959 NE Pacific St. B162, Seattle, WA 98195, United States.
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28
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Cheng R, Shao J, Gao X, Tao C, Ge J, Liu X. Noninvasive Assessment of Early Dental Lesion Using a Dual-Contrast Photoacoustic Tomography. Sci Rep 2016; 6:21798. [PMID: 26902394 PMCID: PMC4763185 DOI: 10.1038/srep21798] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 02/01/2016] [Indexed: 11/09/2022] Open
Abstract
Dental hard tissue lesions, including caries, cracked-tooth, etc., are the most prevalent diseases of people worldwide. Dental lesions and correlative diseases greatly decrease the life quality of patients throughout their lifetime. It is still hard to noninvasively detect these dental lesions in their early stages. Photoacoustic imaging is an emerging hybrid technology combining the high spatial resolution of ultrasound in deep tissue with the rich optical contrasts. In this study, a dual-contrast photoacoustic tomography is applied to detect the early dental lesions. One contrast, named B-mode, is related to the optical absorption. It is good at providing the sharp image about the morphological and macro-structural features of the teeth. Another contrast, named S-mode, is associated with the micro-structural and mechanical properties of the hard tissue. It is sensitive to the change of tissue properties induced by the early dental lesions. Experiments show that the comprehensive analysis of dual-contrast information can provide reliable information of the early dental lesions. Moreover, the imaging parameter of S-mode is device-independent and it could measure tissue properties quantitatively. We expect that the proposed scheme could be beneficial for improving safety, accuracy and sensitivity of the clinical diagnosis of the dental lesion.
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Affiliation(s)
- Renxiang Cheng
- Key Laboratory of Modern Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Jiaojiao Shao
- Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, 210008, China
| | - Xiaoxiang Gao
- Key Laboratory of Modern Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Chao Tao
- Key Laboratory of Modern Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Jiuyu Ge
- Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, 210008, China
| | - Xiaojun Liu
- Key Laboratory of Modern Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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Noninvasive Assessment of Early Dental Lesion Using a Dual-Contrast Photoacoustic Tomography. Sci Rep 2016. [DOI: 10.1038/srep21798%20https:/www.ncbi.nlm.nih.gov/pmc/articles/pmc4763185/pdf/srep21798.pdf] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
AbstractDental hard tissue lesions, including caries, cracked-tooth, etc., are the most prevalent diseases of people worldwide. Dental lesions and correlative diseases greatly decrease the life quality of patients throughout their lifetime. It is still hard to noninvasively detect these dental lesions in their early stages. Photoacoustic imaging is an emerging hybrid technology combining the high spatial resolution of ultrasound in deep tissue with the rich optical contrasts. In this study, a dual-contrast photoacoustic tomography is applied to detect the early dental lesions. One contrast, named B-mode, is related to the optical absorption. It is good at providing the sharp image about the morphological and macro-structural features of the teeth. Another contrast, named S-mode, is associated with the micro-structural and mechanical properties of the hard tissue. It is sensitive to the change of tissue properties induced by the early dental lesions. Experiments show that the comprehensive analysis of dual-contrast information can provide reliable information of the early dental lesions. Moreover, the imaging parameter of S-mode is device-independent and it could measure tissue properties quantitatively. We expect that the proposed scheme could be beneficial for improving safety, accuracy and sensitivity of the clinical diagnosis of the dental lesion.
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Ţălu Ş, Contreras–Bulnes R, Morozov IA, Rodríguez-Vilchis LE, Montoya-Ayala G. Surface nanomorphology of human dental enamel irradiated with an Er:YAG laser. LASER PHYSICS 2015. [DOI: 10.1088/1054-660x/26/2/025601] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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31
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Abstract
Enamel proteins form a scaffold for growing hydroxyapatite crystals during enamel formation. They are then almost completely degraded during enamel maturation, resulting in a protein content of only 1% (w/v) in mature enamel. Nevertheless, this small amount of remaining proteins has important effects on the mechanical and structural properties of enamel and on the electrostatic properties of its surface. To analyze how enamel proteins affect tooth erosion, human enamel specimens were deproteinated. Surface microhardness (SMH), surface reflection intensity (SRI) and calcium release of both deproteinated and control specimens were monitored while continuously eroding them. The deproteination itself already reduced the initial SMH and SRI of the enamel significantly (p < 0.001 and p < 0.01). During the course of erosion, the progression of all three evaluated parameters differed significantly between the two groups (p < 0.001 for each). The deproteinated enamel lost its SMH and SRI faster, and released more calcium than the control group, but these differences were only significant at later stages of erosion, where not only surface softening but surface loss can be observed. We conclude that enamel proteins have a significant effect on erosion, protecting the enamel and slowing down the progression of erosion when irreversible surface loss starts to occur.
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Abstract
Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization in vitro, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recent findings on amelogenin secondary and tertiary structural properties with a focus on its interactions with different targets including other enamel proteins, apatite mineral, and phospholipids. Following a brief overview of enamel hierarchical structure and its mechanical properties we will present the state-of-the-art strategies in the biomimetic reconstruction of human enamel.
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Affiliation(s)
- Qichao Ruan
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
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Melin L, Lundgren J, Malmberg P, Norén JG, Taube F, Cornell DH. XRMA and ToF-SIMS Analysis of Normal and Hypomineralized Enamel. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2015; 21:407-421. [PMID: 25674916 DOI: 10.1017/s1431927615000033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Molar incisor hypomineralization (MIH) is a developmental disturbance of the enamel. This study presents analyses of hypomineralized and normal enamel in first molar teeth diagnosed with MIH, utilizing time-of-flight secondary ion mass spectrometry area analyses and X-ray microanalysis of area and spot profiles in uncoated samples between gold lines which provide electrical conductivity. Statistical analysis of mean values allows discrimination of normal from MIH enamel, which has higher Mg and lower Na and P. Inductive analysis using complete data sets for profiles from the enamel surface to the enamel-dentin junction found that Mg, Cl and position in the profile provide useful discrimination criteria. Element profiles provide a visual complement to the inductive analysis and several elements also provide insight into the development of both normal and MIH enamel. The higher Mg content and different Cl profiles of hypomineralized enamel compared with normal enamel are probably related to a relatively short period during the development of ameloblasts between birth and the 1st year of life.
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Affiliation(s)
- Lisa Melin
- 1Department of Pediatric Dentistry,Institute of Odontology at the Sahlgrenska Academy,University of Gothenburg,P.O. Box 450,SE 405 30 Gothenburg,Sweden
| | - Jesper Lundgren
- 2Department of Psychology,University of Gothenburg,P.O. Box 500,SE 405 30 Gothenburg,Sweden
| | - Per Malmberg
- 3Department of Chemical and Biological Engineering,Chalmers University of Technology,Kemivägen 10,412 96 Gothenburg,Sweden
| | - Jörgen G Norén
- 1Department of Pediatric Dentistry,Institute of Odontology at the Sahlgrenska Academy,University of Gothenburg,P.O. Box 450,SE 405 30 Gothenburg,Sweden
| | - Fabian Taube
- 4Department of Occupational and Environmental Medicine,Sahlgrenska University Hospital,P.O. Box 414,SE 405 30 Gothenburg,Sweden
| | - David H Cornell
- 5Department of Earth Sciences,University of Gothenburg,P.O. Box 460,SE 405 30 Gothenburg,Sweden
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Yilmaz ED, Jelitto H, Schneider GA. Uniaxial compressive behavior of micro-pillars of dental enamel characterized in multiple directions. Acta Biomater 2015; 16:187-95. [PMID: 25620794 DOI: 10.1016/j.actbio.2015.01.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/15/2014] [Accepted: 01/12/2015] [Indexed: 12/22/2022]
Abstract
In this work, the compressive elastic modulus and failure strength values of bovine enamel at the first hierarchical level formed by hydroxyapatite (HA) nanofibers and organic matter are identified in longitudinal, transverse and oblique direction with the uniaxial micro-compression method. The elastic modulus values (∼70 GPa) measured here are within the range of results reported in the literature but these values were found surprisingly uniform in all orientations as opposed to the previous nanoindentation findings revealing anisotropic elastic properties in enamel. Failure strengths were recorded up to ∼1.7 GPa and different failure modes (such as shear, microbuckling, fiber fracture) governed by the orientation of the HA nanofibers were visualized. Structural irregularities leading to mineral contacts between the nanofibers are postulated as the main reason for the high compressive strength and direction-independent elastic behavior on enamels first hierarchical level.
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Affiliation(s)
- Ezgi D Yilmaz
- Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany
| | - Hans Jelitto
- Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany
| | - Gerold A Schneider
- Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany.
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35
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Yilmaz ED, Schneider GA, Swain MV. Influence of structural hierarchy on the fracture behaviour of tooth enamel. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2014.0130. [PMID: 25713449 DOI: 10.1098/rsta.2014.0130] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Tooth enamel has the critical role of enabling the mastication of food and also of protecting the underlying vital dentin and pulp structure. Unlike most vital tissue, enamel has no ability to repair or remodel and as such has had to develop robust damage tolerance to withstand contact fatigue events throughout the lifetime of a species. To achieve such behaviour, enamel has evolved a complex hierarchical structure that varies slightly between different species. The major component of enamel is apatite in the form of crystallite fibres with a nanometre-sized diameter that extend from the dentin-enamel junction to the oral surface. These crystallites are bound together by proteins and peptides into a range of hierarchical structures from micrometre diameter prisms to 50-100 μm diameter bundles of prisms known as Hunter-Schreger bands. As a consequence of such complex structural organization, the damage tolerance of enamel increases through various toughening mechanisms in the hierarchy but at the expense of fracture strength. This review critically evaluates the role of hierarchy on the development of the R-curve and the stress-strain behaviour. It attempts to identify and quantify the multiple mechanisms responsible for this behaviour as well as their impact on damage tolerance.
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Affiliation(s)
- Ezgi D Yilmaz
- Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany
| | - Gerold A Schneider
- Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany
| | - Michael V Swain
- Prosthetic Department, Freiburg University, 29106 Freiburg, Germany Biomaterials, Faculty of Dentistry, University of Sydney, Sydney, New South Wales 2006, Australia
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36
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Vennat E, Denis M, David B, Attal JP. A natural biomimetic porous medium mimicking hypomineralized enamel. Dent Mater 2015; 31:225-34. [DOI: 10.1016/j.dental.2014.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 11/01/2014] [Accepted: 12/10/2014] [Indexed: 11/17/2022]
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37
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Taube F, Marczewski M, Norén J. Deviations of inorganic and organic carbon content in hypomineralised enamel. J Dent 2015; 43:269-78. [DOI: 10.1016/j.jdent.2014.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/27/2014] [Accepted: 09/05/2014] [Indexed: 11/15/2022] Open
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38
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Ruan Q, Moradian-Oldak J. Amelogenin and enamel biomimetics. J Mater Chem B 2015. [DOI: 10.1039/c5tb00163c and 21=21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mature tooth enamel is acellular and does not regenerate itself.
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Affiliation(s)
- Qichao Ruan
- Center for Craniofacial Molecular Biology
- Herman Ostrow School of Dentistry
- University of Southern California
- Los Angeles
- USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology
- Herman Ostrow School of Dentistry
- University of Southern California
- Los Angeles
- USA
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39
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Song XF, Jin CX, Yin L. Quantitative assessment of the enamel machinability in tooth preparation with dental diamond burs. J Mech Behav Biomed Mater 2015; 41:1-12. [DOI: 10.1016/j.jmbbm.2014.09.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 09/17/2014] [Accepted: 09/27/2014] [Indexed: 11/29/2022]
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40
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Kilpatrick N. New developments in understanding development defects of enamel: optimizing clinical outcomes. J Orthod 2014; 36:277-82. [DOI: 10.1179/14653120723310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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41
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Abstract
‘Bronze teeth' reflect the mechanical properties of natural teeth to a certain extent. Their mechanical properties resemble those of a tough metal, and the gradient of these properties lies in the direction from outside to inside. These attributes confer human teeth with effective mastication ability. Understanding the various mechanical properties of human teeth and dental materials is the basis for the development of restorative materials. In this study, the elastic properties, dynamic mechanical properties (visco-elasticity) and fracture mechanical properties of enamel and dentin were reviewed to provide a more thorough understanding of the mechanical properties of human teeth.
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42
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Dumont M, Tütken T, Kostka A, Duarte M, Borodin S. Structural and functional characterization of enamel pigmentation in shrews. J Struct Biol 2014; 186:38-48. [DOI: 10.1016/j.jsb.2014.02.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/06/2014] [Accepted: 02/11/2014] [Indexed: 10/25/2022]
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43
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Jia Y, Xuan FZ, Yang F. Finite element analysis of depth effect on measuring elastic modulus of a core-shell structure for application of instrumented indentation in tooth enamel. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2014; 37:84-9. [PMID: 24582226 DOI: 10.1016/j.msec.2013.12.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 12/09/2013] [Accepted: 12/27/2013] [Indexed: 11/30/2022]
Abstract
Tooth enamel is a complex structure, consisting of numerous enamel rods surrounded by a protein-rich sheath. Considering the possible effect of the protein-rich sheath on the indentation deformation of an enamel rod and the limitation of the Oliver-Pharr method in measuring the elastic modulus of the enamel rod, we used a finite element method to analyze the indentation deformation of an elastic-perfectly plastic cylinder surrounded by an elastic-perfectly plastic film. A concept of the threshold indentation depth was proposed, at which the percentage error of the measured modulus of the cylinder is ±10%. For the indentation depth less than the threshold indentation depth, the elastic modulus measured from the indentation test can be approximated as the intrinsic elastic modulus of the cylinder. The normalized threshold indentation depth strongly depends on the modulus ratio of the film to the cylinder and the ratio of the film thickness to the cylinder radius. The results can be used to guide the use of the Oliver-Pharr method in characterizing the mechanical properties of tooth enamel and bio-composites with core-shell structures.
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Affiliation(s)
- Yunfei Jia
- Key Laboratory of Pressure System and Safety, MOE, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, People's Republic of China; Materials Program, Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA
| | - Fu-Zhen Xuan
- Key Laboratory of Pressure System and Safety, MOE, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
| | - Fuqian Yang
- Materials Program, Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA.
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44
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Size dependent elastic modulus and mechanical resilience of dental enamel. J Biomech 2014; 47:1060-6. [DOI: 10.1016/j.jbiomech.2013.12.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 12/12/2013] [Accepted: 12/22/2013] [Indexed: 11/22/2022]
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45
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Biswas N, Dey A, Kundu S, Chakraborty H, Mukhopadhyay AK. Mechanical Properties of Enamel Nanocomposite. ACTA ACUST UNITED AC 2013. [DOI: 10.5402/2013/253761] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
For adult Indian premolar teeth, we report for the first time ever the simultaneous evaluations of nanohardness, Young's modulus, and fracture toughness of the enamel nanocomposite. The nanohardness and Young's moduli were evaluated from near the beginning of the middle enamel region to within ~10 μm of the dentino-enamel junction (DEJ) and in the dentin region using the nanoindentation technique. The fracture toughness from near the middle of the enamel region to near the DEJ zone was measured using the microindentation technique. The deformation was studied using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). The relative differences in the extents of biomineralization in the enamel and dentin regions were studied by the energy dispersive X-ray (EDS) technique. The variations of the toughness of the enamel as a function of the toughness of the protein matrix phase have been analyzed which showed that the predicted value of the toughness of the protein present in the nanocomposite was comparable to that of other bioproteins reported in the literature. Further, the work of fracture estimated from the measured value of toughness of the enamel nanocomposite agreed well with the experimental data reported in the literature.
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Affiliation(s)
- Nilormi Biswas
- CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032, India
| | - Arjun Dey
- Thermal Systems Group, ISRO Satellite Centre, Vimanapura, Bangalore 560 017, India
| | - Saugata Kundu
- IBM India Pvt. Ltd., Rajarhat, Kolkata 700156, India
| | - Himel Chakraborty
- School of Materials Science and Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711103, India
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46
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An B, Wang R, Zhang D. Role of crystal arrangement on the mechanical performance of enamel. Acta Biomater 2012; 8:3784-93. [PMID: 22743111 DOI: 10.1016/j.actbio.2012.06.026] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Revised: 06/02/2012] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
Abstract
The superior mechanical properties of enamel, such as excellent penetration and crack resistance, are believed to be related to the unique microscopic structure. In this study, the effects of hydroxyapatite (HAP) crystallite orientation on the mechanical behavior of enamel have been investigated through a series of multiscale numerical simulations. A micromechanical model, which considers the HAP crystal arrangement in enamel prisms, the hierarchical structure of HAP crystals and the inelastic mechanical behavior of protein, has been developed. Numerical simulations revealed that, under compressive loading, plastic deformation progression took place in enamel prisms, which is responsible for the experimentally observed post-yield strain hardening. By comparing the mechanical responses for the uniform and non-uniform arrangement of HAP crystals within enamel prisms, it was found that the stiffness for the two cases was identical, while much greater energy dissipation was observed in the enamel with the non-uniform arrangement. Based on these results, we propose an important mechanism whereby the non-uniform arrangement of crystals in enamel rods enhances energy dissipation while maintaining sufficient stiffness to promote fracture toughness, mitigation of fracture and resistance to penetration deformation. Further simulations indicated that the non-uniform arrangement of the HAP crystals is a key factor responsible for the unique mechanical behavior of enamel, while the change in the nanostructure of nanocomposites could dictate the Young's modulus and yield strength of the biocomposite.
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47
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Dusevich V, Xu C, Wang Y, Walker MP, Gorski JP. Identification of a protein-containing enamel matrix layer which bridges with the dentine-enamel junction of adult human teeth. Arch Oral Biol 2012; 57:1585-94. [PMID: 22609172 DOI: 10.1016/j.archoralbio.2012.04.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 03/12/2012] [Accepted: 04/24/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVE To investigate the ultrastructure and chemical composition of the dentine-enamel junction and adjacent enamel of minimally processed third molar tooth sections. DESIGN Undecalcified human third molar erupted teeth were sectioned and etched with 4% EDTA or 37% phosphoric acid prior to visualization by scanning electron microscopy. Confocal Raman spectroscopy was carried out at 50 μm and more than 400 μm away from the dentine-enamel junction before and after mild etching. RESULTS A novel organic protein-containing enamel matrix layer was identified for the first time using scanning electron microscopy of etched bucco-lingual sections of crowns. This layer resembles a three-dimensional fibrous meshwork that is visually distinct from enamel "tufts". Previous studies have generally used harsher solvent conditions which likely removed this layer and precluded its prior characterization. The shape of the organic enamel layer generally reflected that of sheath regions of enamel rods and extended from the dentine-enamel junction about 100-400 μm into the cuspal enamel. This layer exhibited a Raman CH stretching peak at ∼2931 cm(-1) characteristic of proteins and this signal correlated directly with the presence and location of the matrix layer as identified by scanning electron microscopy. CONCLUSIONS The enamel protein layer was most prominent close to the dentine-enamel junction and was largely absent in cuspal enamel >400 μm away from the dentine enamel junction. We hypothesize that this protein containing matrix layer could provide an important biomechanical linkage between the enamel and the dentine-enamel junction and by extension, with the dentine, of the adult tooth (246 words).
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Affiliation(s)
- Vladimir Dusevich
- Department of Oral Biology, School of Dentistry, University of Missouri-Kansas City, 64108, United States
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48
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An B, Wang R, Arola D, Zhang D. The role of property gradients on the mechanical behavior of human enamel. J Mech Behav Biomed Mater 2012; 9:63-72. [PMID: 22498284 DOI: 10.1016/j.jmbbm.2012.01.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 01/04/2012] [Accepted: 01/14/2012] [Indexed: 11/16/2022]
Abstract
In this study, the mechanical design principles of human enamel were evaluated using a hybrid experimental and computational approach. Nanoindentation was applied to evaluate the load-depth response of human enamel, and Vickers indentations were used to assess the damage behavior. An elastic-plastic numerical model was then developed to analyze the stress and strain distribution about the indentations, and to characterize energy dissipation about indents in three locations including inner, middle and outer enamel. Results confirm that enamel exhibits a gradient in its mechanical behavior. Outer enamel has a limited potential for energy dissipation by inelastic deformation, indicating that the ability of outer enamel to resist fracture is low. While inner enamel, the region close Dentin Enamel Junction (DEJ), possesses less resistance to penetration deformation, it has a much higher capacity to dissipate energy by inelastic deformation than outer enamel. The computational simulations identified that the gradients in mechanical properties of human enamel promote resistance to penetration, energy dissipation and mitigation of fracture, all critical performance requirements of human teeth.
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Affiliation(s)
- Bingbing An
- Shanghai Institute of Applied Mathematics and Mechanics, Shanghai, 200072, PR China
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49
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Arsecularatne JA, Hoffman M. Ceramic-like wear behaviour of human dental enamel. J Mech Behav Biomed Mater 2011; 8:47-57. [PMID: 22402153 DOI: 10.1016/j.jmbbm.2011.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 12/05/2011] [Accepted: 12/07/2011] [Indexed: 11/29/2022]
Abstract
This paper reports a transmission electron microscopy (TEM) analysis of subsurfaces of enamel specimens following in vitro reciprocating wear tests with an enamel cusp sliding on a flat enamel specimen under hydrated conditions. The obtained results show that crack formation occurred in the wear scar subsurface. The path followed by these cracks seems to be dictated either by the histological structure of enamel or by the contact stress field. Moreover, the analysis of a set of enamel wear results obtained from the literature and application of fracture-based models, originally developed for ceramics, correlate well, confirming the similar wear processes taking place in these materials. This analysis also reveals a marked influence of coefficient of friction on the enamel wear rate: for a higher coefficient of friction value, enamel wear can be severe even under forces generated during normal operation of teeth.
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Affiliation(s)
- J A Arsecularatne
- School of Materials Science and Engineering, The University of New South Wales, Sydney 2052, Australia.
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50
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Da Costa-Silva CM, Ambrosano GMB, Jeremias F, De Souza JF, Mialhe FL. Increase in severity of molar-incisor hypomineralization and its relationship with the colour of enamel opacity: a prospective cohort study. Int J Paediatr Dent 2011; 21:333-41. [PMID: 21470321 DOI: 10.1111/j.1365-263x.2011.01128.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Predicting risk of posteruptive enamel breakdown (PEB) of molar-incisor hypomineralization (MIH) opacity is a difficult but important clinical task. Therefore, there is a need to evaluate these aspects through longitudinal studies. OBJECTIVE The aim of this longitudinal study was to analyse the relationship between colours of MIH opacity of children aged 6-12 (baseline) and other clinical and demographic variables involved in the increase in severity of MIH. MATERIALS AND METHODS A blinded prospective 18-month follow-up was conducted with 147 individuals presenting mild MIH. Tooth-based incidence of increase in severity of MIH (PEB or atypical restorations) was used as dependent measurement. Enamel opacities were recorded according to colour shades of white, yellow and brown, allowing assessment of susceptibility to structural loss over time, according to colour of MIH opacity. Poisson regression models were used to adjust the results for demographic and clinical variables. RESULTS Brown and yellow MIH opacities were at higher risk for PEB and atypical restorations than those of white ones, even after adjustment for clinical and demographic variables. CONCLUSION Teeth presenting mild MIH severity associated with yellow and brown enamel opacities were at high risk for increase in severity of MIH than lighter ones. This result could help clinicians determine a risk-based treatment for children with MIH.
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Affiliation(s)
- Cristiane M Da Costa-Silva
- Department of Community Dentistry, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil.
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