Download or read book Aging and Fracture of Human Cortical Bone and Tooth Dentin written by and published by . This book was released on 2008 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mineralized tissues, such as bone and tooth dentin, serve as structural materials in the human body and, as such, have evolved to resist fracture. In assessing their quantitative fracture resistance or toughness, it is important to distinguish between intrinsic toughening mechanisms which function ahead of the crack tip, such as plasticity in metals, and extrinsic mechanisms which function primarily behind the tip, such as crack bridging in ceramics. Bone and dentin derive their resistance to fracture principally from extrinsic toughening mechanisms which have their origins in the hierarchical microstructure of these mineralized tissues. Experimentally, quantification of these toughening mechanisms requires a crack-growth resistance approach, which can be achieved by measuring the crack-driving force, e.g., the stress intensity, as a function of crack extension ("R-curve approach"). Here this methodology is used to study of the effect of aging on the fracture properties of human cortical bone and human dentin in order to discern the microstructural origins of toughness in these materials.

Download or read book Fatigue and Fracture Properties of Human Coronal Dentin written by Juliana Ivancik and published by . This book was released on 2012 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Failures of restorations resulting from tooth fracture are one of the primary problems to lasting oral health. Fatigue cracks are often present in the dentin of restored teeth and their incidence increases with age of the patient. The primary objective of this investigation was to characterize the influence of microstructure, age and ethnicity on the crack growth resistance of human coronal dentin. Compact tension (CT) specimens were prepared from three regions (i.e. inner, middle and outer dentin) of the crown of 3rd molars obtained from young and old patients of the US and Colombia. Stable crack extension was achieved under Mode I quasi℗Ưstatic and cyclic loading. To understand the fundamental mechanisms of crack growth extension, the fracture surfaces were evaluated using scanning electron microscopy (SEM) and image processing techniques. Metrics related to the microstructure were correlated with the fatigue and fracture responses. Lastly, a hybrid approach was also used to quantify the contribution of toughening mechanisms to the overall toughness.

Download or read book The Fracture Properties and Toughening Mechanisms of Bone and Dentin written by Kurt John Koester and published by . This book was released on 2007 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Anisotropic Changes in Fracture Toughness of Aging Human Cortical Bone written by Jennifer Rebecca Zuba and published by . This book was released on 2006 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dental Biomaterials An Issue of Dental Clinics of North America E Book written by Jack Ferracane and published by Elsevier Health Sciences. This book was released on 2017-09-15 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This issue of Dental Clinics of North America focuses on Dental Materials, and is edited by Drs. Jack Ferracane, Luiz E. Bertassoni, and Carmem S. Pfeifer. Articles will include: Tooth: Its structure and properties; Dental light curing; Bioactive dental materials having remineralizing or antimicrobial characteristics; Materials for regenerating dental pulp and soft tissues; Dental adhesives; Polymer-based direct filling materials; Dental impression materials and techniques; Dental ceramics for restoration and metal-veneering; Dental cements for luting and bonding restorations; Bone augmentation materials; Dental implants, and more!

Download or read book Structure property Relationships for Human Dentin written by Weishi Yan and published by . This book was released on 2020 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increase in number of senior patients has become a major challenge in the field of dentistry. Senior patients are more likely to experience tooth fracture, which often necessitates tooth extraction. Understanding the aging process and its effects on the structure-property relationships of tooth tissue is critical to the development of patient-centric oral healthcare. Previous efforts have focused on the impact of age-related mineralization, known as sclerosis, within the tooth crown. In comparison, few studies have considered age-related degradation of the organic content and its contribution to the structural behavior of dentin. This concern is of greater importance in the radicular dentin, which possesses a higher organic content. Furthermore, the tooth roots are subjected to more invasive treatments as a result of root infection, which could contribute to a unique form of age-related degradation. Therefore, the primary goal of this study is to understand the materials science of aging in the radicular dentin, including the differences in degradation that occur in vital and non-vital teeth. Chapter 1 presents a brief introduction to oral histology that supports the detailed discussions in the following chapters. Chapter 2 to Chapter 6 describe complementary studies performed to answer the overarching research questions: what are the mechanisms of structural degradation in tooth roots with aging and how is this process affected by the loss of the vital pulp? Chapter 7 then addresses the cellular aspects of the aging process in dentin. In Chapter 2 we start by exploring the changes in microstructure, chemical composition, and mechanical properties of radicular dentin as a function of aging. Specifically, the evolution in microstructures associated with sclerosis, mineral-to-collagen ratio and collagen cross-linking were correlated with the mechanical properties as a function of distance from the root apex. The findings indicate that the most severe degradation occurs near the root apex. In Chapter 3 we compare the structural behavior of radicular dentin from vital and non-vital teeth of senior patients using a matched-pair approach. The results indicate that the radicular dentin of teeth with root canal treatment (RCT) followed by oral function undergoes an accelerated degradation in comparison to that in teeth with vital roots. This process appears to be most associated with the extent of collagen cross-linking. Dehydration has been considered as a potential factor in Vertical Root Fractures (VRF) after the RCT. In Chapter 4 we characterized the spatial distribution in shrinkage of tooth roots with respect to donor age and prior RCT using digital image correlation. The RCT treated teeth of senior patients suffered the highest percentage of water loss. Dehydration-induced cracking initiates from the root surface towards the canal as a result of shrinkage. Chapter 5 focuses on acute embrittlement of dentin due to changes in the capacity for viscous deformation in the dentin matrix. Advanced dynamic mechanical analysis was applied to the dentin matrix using scanning mode nanoindentation. The findings revealed degradation in the intertubular component of radicular dentin (i.e. the collagen matrix) with aging, and an acceleration of the extent of age-related degradation near the apex and particularly within the tissue of pulpless (i.e. non-vital) teeth. In Chapter 6, autotransplantation of teeth after cryopreservation is discussed, which is an increasingly viable method for whole tooth replacement. The objective of this effort is to determine whether cryopreservation alters the microstructure of dentin or causes a reduction of its resistance to fracture. Results revealed that hidden damage within the dentin as a result of cryopreservation decreases the fatigue resistance and could render these teeth more susceptible to fracture. In Chapter 7, the role of odontoblasts in the progress of sclerosis and the degradation in strength of dentin with aging is discussed. The biophysical and biochemical alterations in dentin appear to result from changes in the microstructure and chemical composition of the dentinal tubules where odontoblastic extensions reside. The extent of odontoblast apoptosis is assessed along the radial direction of roots from teeth of different ages and is correlated to the chemical composition and mechanical properties of the radicular dentin. Chapter 8 presents a summary of the overall results and conclusions. A brief discussion of future research directions is also included.

Download or read book Bioceramics Materials and Applications V written by Veeraraghavan Sundar and published by John Wiley & Sons. This book was released on 2012-04-17 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings includes papers on ceramics and glasses used in biomedical, dental and biological applications, including biomimetics and natural bioceramic materials. Topics include: materials; applications; biomimetic materials and synthesis; structure/properties of natural ceramic-based materials; behavior in biological environments; and synthesis, processing, characterization, and properties.

Download or read book Fracture Aging and Disease in Bone written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: From a public health perspective, developing a detailed mechanistic understanding of the well-known increase in fracture risk of human bone with age is essential. This also represents a challenge from materials science and fracture mechanics viewpoints. Bone has a complex, hierarchical structure with characteristic features ranging from nanometer to macroscopic dimensions; it is therefore significantly more complex than most engineering materials. Nevertheless, by examining the micro-/nano-structural changes accompanying the process of aging using appropriate multiscale experimental methods and relating them to fracture mechanics data, it is possible to obtain a quantitative picture of how bone resists fracture. As human cortical bone exhibits rising ex vivo crack-growth resistance with crack extension, its fracture toughness must be evaluated in terms of resistance-curve (R-curve) behavior. While the crack initiation toughness declines with age, the more striking finding is that the crack-growth toughness declines even more significantly and is essentially absent in bone from donors exceeding 85 years in age. To explain such an age-induced deterioration in the toughness of bone, we evaluate its fracture properties at multiple length scales, specifically at the molecular and nanodimensions using pico-force atomic-force microscopy, nanoindentation and vibrational spectroscopies, at the microscale using electron microscopy and hard/soft x-ray computed tomography, and at the macroscale using R-curve measurements. We show that the reduction in crack-growth toughness is associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging, and that this occurs at relatively coarse size-scales in the range of tens to hundreds of micrometers. Finally, we briefly describe how specific clinical treatments, e.g., with steroid hormones to treat various inflammatory conditions, can prematurely damage bone, thereby reducing its fracture resistance, whereas regulating the level of the cytokine TGF-beta can offer significant improvements in the stiffness, strength and toughness of bone, and as such may be considered as a therapeutic target to treat increased bone fragility induced by aging, drugs, and disease.

Download or read book Fracture of Nano and Engineering Materials and Structures written by E.E. Gdoutos and published by Springer Science & Business Media. This book was released on 2008-01-08 with total page 1452 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 16th European Conference of Fracture (ECF16) was held in Greece, July, 2006. It focused on all aspects of structural integrity with the objective of improving the safety and performance of engineering structures, components, systems and their associated materials. Emphasis was given to the failure of nanostructured materials and nanostructures including micro- and nano-electromechanical systems (MEMS and NEMS).

Download or read book Effect of Aging on the Toughness of Human Cortical Bone written by and published by . This book was released on 2004 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Age-related deterioration of the fracture properties of bone, coupled with increased life expectancy, are responsible for increasing incidence of bone fracture in the elderly, and hence, an understanding of how its fracture properties degrade with age is essential. The present study describes ex vivo fracture experiments to quantitatively assess the effect of aging on the fracture toughness properties of human cortical bone in the longitudinal direction. Because cortical bone exhibits rising crack-growth resistance with crack extension, unlike most previous studies the toughness is evaluated in terms of resistance-curve (R-curve) behavior, measured for bone taken from wide range of age groups (34-99 years). Using this approach, both the ex vivo crack-initiation and crack-growth toughness are determined and are found to deteriorate with age; the initiation toughness decreases some 40% over six decades from 40 to 100 years, while the growth toughness is effectively eliminated over the same age range. The reduction in crack-growth toughness is considered to be associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging in the wake of the crack.

Download or read book Age Estimation written by Joe Adserias-Garriga and published by Academic Press. This book was released on 2019-04-26 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Age Estimation: A Multidisciplinary Approach is the only reference in the field covering all techniques and methods involving age estimation from different perspectives in just one volume. The book provides comprehensive coverage of all aspects of age estimation: aging the living and the dead, human rights, and skeletal, dental, histological and biochemical techniques and methods available. Each chapter is written by internationally known expert contributors. Age Estimation: A Multidisciplinary Approach is a one of a kind resource for those involved in estimating the age of the living and the dead. Presents a concentration of all techniques and methods involving age estimation in a single volume Provides a multidisciplinary approach that lends itself to researchers, practitioners and students from a variety of different fields Includes contributions by world renowned forensic specialists

Download or read book Traumatic Dental Injuries written by Jens O. Andreasen and published by John Wiley & Sons. This book was released on 2011-10-07 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRAUMATIC DENTAL INJURIES: A MANUAL The third edition of Traumatic Dental Injuries: A Manual builds on the widespread success of the previous two editions. The ultimate guide to dental trauma, the manual preserves its uniquely usable and reader-friendly format, demonstrating step-by-step treatment protocols for commonly occurring traumatic injuries. Several new sections have been added to expand the number of clinical scenarios, describing soft tissue injuries associated with dental trauma, showing how decoronation of ankylosed anterior teeth in adolescents can preserve the alveolar process for later implant placement, and identifying predictors for pulpal and periodontal ligament healing complications as well as for tooth loss. A unique feature of the new edition is the accompanying DVD which presents computer animations of all trauma scenarios, as well as links to the internet-based interactive Dental Trauma Guide to predict healing complications for individual trauma scenarios. KEY FEATURES Written by international authorities on dental trauma Demonstrates treatment protocols in a clear step-by-step format Illustrated throughout with high-quality color images and diagrams Includes more sections to expand number of clinical scenarios Accompanied by a new DVD of trauma scenario animations REVIEWS OF PREVIOUS EDITIONS The text is clear and well written and well referenced ... The chapters on diagnosis of periodontal and pulpal complications are particularly helpful as this is a difficult area for many clinicians. The manual will serve as an excellent reference for practitioners and dental students who have a good working knowledge of dental traumatology. Journal of Orthodontics Overall, this book is excellent and I believe would be an essential member of a dentist’s library. It is the sort of book that can be quickly read, and information and guidance can be located easily when the need arises. The price makes the book very affordable and I wholeheartedly recommend it as an essential reference source for the general dentist and dental student. Australian Endodontic Journal BY THE SAME AUTHORS Textbook and Color Atlas of Traumatic Injuries to the Teeth Fourth Edition Edited by J.O. Andreasen, F.M. Andreasen and L. Andersson ISBN 9781405129541 Oral and Maxillofacial Surgery Edited by L. Andersson, K.E. Kahnberg and M.A. Pogrel ISBN 9781405171199 DVD animations can be found by entering the ISBN at Booksupport.wiley.com

Download or read book The Deformation and Fracture of Human Cortical Bone Across Multiple Length scales written by Elizabeth Ann Zimmermann and published by . This book was released on 2011 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: The complex structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen molecules and hydroxyapatite crystals at the nanoscale to the osteonal structures at near-millimeter dimensions. There is a need to understand how all levels of the structure contribute to the deformation and fracture resistance of cortical bone under physiological loading conditions and how structural changes due to aging and disease lead to diminished mechanical properties. The first part of this thesis addresses the latter by using non-enzymatic crosslinking measurements and in situ small- and wide-angle x-ray scattering/diffraction to characterize changes in the bone structure at sub-micron dimensions, while synchrotron x-ray computed micro-tomography and in situ fracture-toughness measurements in the scanning electron microscope were performed to characterize corresponding changes at micron-scale dimensions. This multi-scale analysis allows us to better understand how load is transferred across multiple length-scales and how biological aging impacts energy absorption throughout the structure. The second part of this thesis addresses the fracture toughness of human cortical bone under multiaxial loading. Most studies to date have only considered the toughness of bone under mode I (tensile) loading conditions; however, due to the complex, anisotropic structure of cortical bone, the mode I fracture toughness is not necessarily the limiting value. Thus, this research investigates the effects of combined tensile and shear loading at the crack tip on the initiation and crack-growth toughnesses to better understand how bone fractures under physiologically relevant loading conditions.

Download or read book Age related Changes in the Plasticity and Toughness of Human Cortical Bone at Multiple Length scales written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen and hydroxyapatite at the nanoscale to osteonal structures at nearmillimeter dimensions, which all provide the basis for its mechanical properties. To resist fracture, bone's toughness is derived intrinsically through plasticity (e.g., fibrillar sliding) at structural-scales typically below a micron and extrinsically (i.e., during crack growth) through mechanisms (e.g., crack deflection/bridging) generated at larger structural-scales. Biological factors such as aging lead to a markedly increased fracture risk, which is often associated with an age-related loss in bone mass (bone quantity). However, we find that age-related structural changes can significantly degrade the fracture resistance (bone quality) over multiple lengthscales. Using in situ small-/wide-angle x-ray scattering/diffraction to characterize sub-micron structural changes and synchrotron x-ray computed tomography and in situ fracture-toughness measurements in the scanning electron microscope to characterize effects at micron-scales, we show how these age-related structural changes at differing size-scales degrade both the intrinsic and extrinsic toughness of bone. Specifically, we attribute the loss in toughness to increased non-enzymatic collagen cross-linking which suppresses plasticity at nanoscale dimensions and to an increased osteonal density which limits the potency of crack-bridging mechanisms at micron-scales. The link between these processes is that the increased stiffness of the cross-linked collagen requires energy to be absorbed by?plastic? deformation at higher structural levels, which occurs by the process of microcracking.

Download or read book On the Mechanistic Role of the Dentin enamel Junction in Preventing the Fracture of Human Teeth written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dentin-enamel junction (DEJ), which is the interface between the dentin and outer enamel coating in teeth, is known for its unique biomechanical properties that provide a crack-arrest barrier for flaws formed in the brittle enamel. In this work, we re-examine how cracks propagate in the proximity of the DEJ, and specifically quantify, using interfacial fracture mechanics, the fracture toughness of the DEJ region. Additionally, we show that the vital function of the DEJ, in preventing cracks formed in enamel from traversing the interface and causing catastrophic tooth fractures, is not necessarily associated with the crack-arrest capabilities of the DEJ itself, but rather with the development of crack-tip shielding, primarily from uncracked-ligament bridging, in the mantle dentin adjacent to the DEJ. Measurements of the toughness of the DEJ region give estimates of G{sub c} (almost equal to) 115 J/m2, i.e., (almost equal to)5 to 10 times higher than enamel and (almost equal to)75 percent of that of dentin.

Download or read book Studies on Age related Changes in Human Cortical Bone written by Edward Donald Simmons and published by . This book was released on 1986 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Engineering Methodologies for Medicine and Sports written by Roberto Montanari and published by Springer Nature. This book was released on with total page 737 pages. Available in PDF, EPUB and Kindle. Book excerpt: