Abstract：
:Understanding the mechanical properties of human teeth is important to clinical tooth preparation and to the development of "tooth-like" restorative materials. Previous studies have focused on the macroscopic fracture behavior of enamel and dentin. In the present study, we performed indentation studies to understand the microfracture and deformation and the microcrack-microstructure interactions of teeth. It was hypothesized that crack propagation would be influenced by enamel rods and the dentino-enamel junction (DEJ), and the mechanical properties would be influenced by enamel rod orientation and tooth-to-tooth variation. Twenty-eight human third molars were used for the measurement of hardness, fracture toughness, elastic modulus, and energy absorbed during indentation. We examined the effect of enamel rod orientation by propagating cracks in the occlusal surface, and in the axial section in directions parallel and perpendicular to the occlusal surface. The results showed that the cracks in the enamel axial section were significantly longer in the direction perpendicular to the occlusal surface than parallel. The cracks propagating toward the DEJ were always arrested and unable to penetrate dentin. The fracture toughness of enamel was not single-valued but varied by a factor of three as a function of enamel rod orientation. The elastic modulus of enamel showed a significant difference between the occlusal surface and the axial section. It is concluded that the cracks strongly interact with the DEJ and the enamel rods, and that the mechanical properties of teeth are functions of microstructural orientations; hence, single values of properties (e.g., a single toughness value or a single modulus value) should not be used without information on microstructural orientation.
journal_name
J Dent Resjournal_title
Journal of dental researchauthors
Xu HH,Smith DT,Jahanmir S,Romberg E,Kelly JR,Thompson VP,Rekow EDdoi
10.1177/00220345980770030601subject
Has Abstractpub_date
1998-03-01 00:00:00pages
472-80issue
3eissn
0022-0345issn
1544-0591journal_volume
77pub_type
杂志文章abstract：:Chemotherapeutics are presently considered for use in caries-preventive programs. The laboratory and in vivo testing of these agents, to some extent, parallels the methodology developed for the evaluation of fluoride products. However, fluoride is primarily effective by interfering with the de- and remineralization ba...
journal_title：Journal of dental research
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更新日期：1994-03-01 00:00:00
abstract：:Previous studies have indicated that tooth-bleaching agents contain potentially hazardous chemicals. The present study evaluates the acute toxicity of a commercially available tooth-bleaching agent and carbamide peroxide, which is the active bleaching ingredient. Rats were dosed by stomach gavage, i.e., via a stomach ...
journal_title：Journal of dental research
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更新日期：1995-02-01 00:00:00
abstract：:The resin-dentin interdiffusion zone produced by a dentin-adhesive system that removes the smear layer and concurrently decalcifies superficial dentin was morphologically examined by both scanning and transmission electron microscopy. Cross-sectioned resin-bonded dentin discs were etched with an argon-ion beam to make...
journal_title：Journal of dental research
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更新日期：1993-02-01 00:00:00
abstract：:Previous studies have demonstrated that antibodies against cholinoreceptors of exocrine glands correlate with dry mouth in persons with primary Sjögren syndrome (pSS). The aim of the present investigation was to establish if serum IgG antibodies (pSS IgG) were able to interact with cholinoreceptors in rat submandibula...
journal_title：Journal of dental research
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doi：10.1177/154405910708600905
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abstract：:Cementum is known to be growth-hormone (GH)-responsive, but to what extent is unclear. This study examines the effects of extremes of GH status on cementogenesis in three lines of genetically modified mice; GH excess (giant), GH antagonist excess (dwarf), and GH receptor-deleted (GHR-KO) (dwarf). Age-matched mandibula...
journal_title：Journal of dental research
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更新日期：2004-01-01 00:00:00
abstract：:The aim of this study was to investigate the diffusion dynamics of 25% hydrogen peroxide (H2O2) through enamel-dentin layers and to correlate it with dentin's structural alterations. Micro-Raman Spectroscopy (MRS) and Fourier Transform Infrared Photoacoustic Spectroscopy (FTIR-PAS) were used to measure the spectra of ...
journal_title：Journal of dental research
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journal_title：Journal of dental research
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更新日期：2014-03-01 00:00:00
abstract：:The cariostatic effect of resin-modified glass ionomer (RMGI) on secondary root caries is well-documented. However, this beneficial effect may be dependent upon the mode of cavity surface treatment. To investigate this relationship, we studied 4 cavity surface treatments prior to the placement of RMGI: no treatment (N...
journal_title：Journal of dental research
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更新日期：2003-02-01 00:00:00
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journal_title：Journal of dental research
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更新日期：2011-08-01 00:00:00
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更新日期：1984-03-01 00:00:00
abstract：:The pathophysiology of painful temporomandibular disorders is not fully understood, but evidence suggests that muscle pain modulates motor function in characteristic ways. This study tested the hypothesis that activation of nociceptive muscle afferent fibers would be linked to an increased excitability of the human ja...
journal_title：Journal of dental research
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更新日期：2002-09-01 00:00:00
abstract：:Dental porcelains that are designed to be fused to PFM (porcelain-fused-to-metal) alloys are formulated by their manufacturers to be closely matched in thermal expansion to these alloys. The high thermal expansion of the mineral leucite has been exploited to regulate porcelain expansion. Leucite, however, has been obs...
journal_title：Journal of dental research
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doi：10.1177/00220345000790081101
更新日期：2000-08-01 00:00:00
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journal_title：Journal of dental research
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doi：10.1177/00220345960750090901
更新日期：1996-09-01 00:00:00
abstract：:Recent functional animal studies have reported that the motor control of masticatory muscle function is bilaterally guided by both hemispheres, which may fundamentally differ from the cortical control of limb muscle function. In this study, we investigated whether unilateral cortical brain infarction induces different...
journal_title：Journal of dental research
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更新日期：1999-12-01 00:00:00
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journal_title：Journal of dental research
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更新日期：1976-07-01 00:00:00
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journal_title：Journal of dental research
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更新日期：1980-12-01 00:00:00
abstract：:Continuous etching of aggressive all-in-one adhesives occurs in wet dentin tubules after polymerization of the adhesives. This study challenged the hypothesis that unpolymerized acidic monomers from an aggressive all-in-one self-etching adhesive continue to etch beyond dentin hybrid layers. Dentin surfaces bonded with...
journal_title：Journal of dental research
pub_type： 杂志文章,随机对照试验
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更新日期：2010-05-01 00:00:00
abstract：:Mixed or parotid saliva from caries-active individuals consistently supported better growth of Streptococcus mutans (type c) than that from caries-free individuals. Electrophoretic studies revealed that certain proteins in caries-active salivas were susceptible to microbial attack, but similar proteins in caries-free ...
journal_title：Journal of dental research
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更新日期：1979-10-01 00:00:00
abstract：:Silver cations generated by passing low intensity direct current through pure silver electrodes were found to be sufficiently antibacterial to cause sterilization of samples of infected dentin. The optimal procedure involved a 5 microA current applied for 20 minutes with the anode then left in contact with the sample....
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更新日期：1978-09-01 00:00:00
abstract：:Mutations in ALPL result in hypophosphatasia (HPP), a disease causing defective skeletal mineralization. ALPL encodes tissue nonspecific alkaline phosphatase (ALP), an enzyme that promotes mineralization by reducing inorganic pyrophosphate, a mineralization inhibitor. In addition to skeletal defects, HPP causes dental...
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更新日期：1987-09-01 00:00:00
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journal_title：Journal of dental research
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更新日期：2014-07-01 00:00:00
abstract：:Fibroblast cultures derived from uninjured and reparative rabbit buccal mucosa were compared in terms of extracellular glycosaminoglycan (GAG) content and cellular response to interleukin-1 (IL-1). Under identical growth conditions, proliferation of both cell lines was the same. Both lines incorporated [3H]-glucosamin...
journal_title：Journal of dental research
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更新日期：1989-01-01 00:00:00
abstract：:Genetic approaches are rapidly yielding new information about our sense of taste. This information comes from both molecular studies of genes encoding taste receptors and other taste-signaling components, and from studies of inherited variation in taste abilities. Our understanding of bitter taste has advanced by comb...
journal_title：Journal of dental research
pub_type： 杂志文章,评审
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更新日期：2004-06-01 00:00:00
abstract：:Loss of hybrid layer integrity compromises resin-dentin bond stability. Matrix metalloproteinases (MMPs) may be partially responsible for hybrid layer degradation. Since chlorhexidine inhibits MMPs, we hypothesized that chlorhexidine would decelerate the loss of resin-dentin bonds. Class I preparations in extracted th...
journal_title：Journal of dental research
pub_type： 杂志文章,随机对照试验
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更新日期：2007-01-01 00:00:00
abstract：:Bone marrow-derived mesenchymal stem/progenitor cells (BMSCs) are commonly used in regeneration therapy. The current primary source of BMSCs is the iliac crest; however, the procedure is associated with various burdens on the patient, including the risk of pain and infection. Hence, the possibility to collect BMSCs fr...
journal_title：Journal of dental research
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更新日期：2014-11-01 00:00:00
abstract：:Extracellular matrix (ECM) mineralization is regulated by mineral ion availability, proteins, and other molecular determinants. To investigate protein regulation of mineralization in tooth dentin and cementum, and in alveolar bone, we expressed matrix Gla protein (MGP) ectopically in bones and teeth in mice, using an ...
journal_title：Journal of dental research
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更新日期：2008-09-01 00:00:00
abstract：:The ability of adhesive resins to restore the physical properties of demineralized dentin has not been well-documented. The unfilled resins that are used for adhesion have relatively low moduli of elasticity and limited ability to increase dentin stiffness, although they may increase the ultimate tensile strength of d...
journal_title：Journal of dental research
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更新日期：1995-04-01 00:00:00
abstract：:Bifidobacteria are aciduric bacteria that might play a role in the caries process. To test the hypothesis that Bifidobacteria behave as caries-associated organisms, as predicted by the ecological plaque hypothesis, we determined salivary levels of Bifidobacteria and caries-associated organisms for 156 older adults. Sa...
journal_title：Journal of dental research
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更新日期：2010-09-01 00:00:00
