Heat Treatment Strengthens Human Dentin

2008 ◽  
Vol 87 (8) ◽  
pp. 762-766 ◽  
Author(s):  
M. Hayashi ◽  
E.V. Koychev ◽  
K. Okamura ◽  
A. Sugeta ◽  
C. Hongo ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stress Intensity ◽  
Type I Collagen ◽  
Type I ◽  
Third Molars ◽  
X Ray Diffraction ◽  
Intensity Factors ◽  
X Ray ◽  
Human Dentin ◽  
Triple Helices

The flexural strength of Type I collagen, the major organic component of human dentin, increases with heat. We hypothesized that human dentin can be strengthened by heating, which may help prevent fracture of non-vital teeth after restoration. Beam-shaped dentin specimens were obtained from the crowns of human third molars. The dentinal tubular orientations were arranged to run parallel or perpendicular to loading surfaces. The flexural and microtensile strengths of dentin in the parallel specimens were 2- to 2.4-fold greater after being heated between 110°C and 140°C for 1 hr. The stress intensity factors at fracture also increased after specimens were heated. The x-ray diffraction analyses suggested that shrinking of the lateral packing of the collagen triple-helices from 14 Å to 11 Å was the probable cause of the strengthening of heated dentin. We conclude that heat treatment strengthens human dentin.

A new model for packing of type-I collagen molecules in the native fibril

1981 ◽  
Vol 1 (10) ◽  
pp. 801-810 ◽  
Author(s):  
Karl A. Piez ◽  
Benes L. Trus
Keyword(s):  
Type I Collagen ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Equatorial Region ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Left Handed ◽  
Crystal Model ◽  
Collagen Molecules

A specific fibril model is presented consisting of bundles of five-stranded microfibrils, which are usually disordered (except axially) but under lateral compression become ordered. The features are as follows (where D = 234 residues or 67 nm): (1) D-staggered collagen molecules 4.5 D long in the helical microfibril have a left-handed supercoil with a pitch of 400–700 residues, but microfibrils need not have helical symmetry. (2) Straight-tilted 0.5-D overlap regions on a near-hexagonal lattice contribute the discrete x-ray diffraction reflections arising from lateral order, while the gap regions remain disordered. (3) The overlap regions are equivalent, but are crystallographically distinguished by systematic displacements from the near-hexagonal lattice. (4) The unit cell is the same as in a recently proposed three-dimensional crystal model, and calculated intensities in the equatorial region of the x-ray diffraction pattern agree with observed values.

Effects of Rehydration on Dentin Strengthened by Heating or UV Irradiation

2009 ◽  
Vol 89 (2) ◽  
pp. 154-158 ◽  
Author(s):  
M. Hayashi ◽  
K. Okamura ◽  
E.V. Koychev ◽  
Y. Furuya ◽  
A. Sugeta ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Uv Irradiation ◽  
Type I Collagen ◽  
Control Group ◽  
Type I ◽  
Third Molars ◽  
Flexural Testing ◽  
Human Dentin ◽  
Dentin Collagen ◽  
Original Strength

Type I collagen, the major organic component of human dentin, plays an important role in regulating the mechanical strength of dentin. Collagen in dentin can be strengthened by heating. We hypothesized that UV irradiation could produce similar strengthening effects and might maintain the strength of dentin after rehydration. Beam-shaped dentin specimens from the crowns of human third molars were subjected to flexural testing. Flexural strengths were two and three times greater than those in the control group after 5 minutes’ UV irradiation and heating to 140°C, respectively. After 30 days of rehydration, the heated specimens reverted to their original strength, whereas the UV specimens were 69% stronger than the original. Raman spectra of dental collagen were unchanged after heating, whereas several peaks, including a C-C bond in a proline ring, were amplified by UV irradiation. It is concluded that dentin strengthened by UV irradiation retains strength after rehydration because of chemical changes in collagen.

The Effects of Different Hydroxyapatite/TiO2 Composite Coatings on Protein Expression of Osteoblast

2009 ◽  
Vol 610-613 ◽  
pp. 1104-1108 ◽  
Author(s):  
Jian Ye Han ◽  
Zhen Tao Yu ◽  
Lian Zhou
Keyword(s):  
Protein Expression ◽  
Type I Collagen ◽  
Composite Coatings ◽  
Type I ◽  
X Ray Diffraction ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Compound Formation ◽  
X Ray ◽  
Polymerase Chain

Hydroxyapatite/TiO2 composite material was coated onto Ti25Nb3Mo2Sn3Zr (TLM) alloy substrate. To study the effects of hydroxyapatite/TiO2 composite coatings on bone-related protein expression, the osteoblast were cultured with composite coatings for different times. The phase transformation and compound formation of the HA/TiO2 coatings were investigated using XRD (X-ray diffraction). The mRNA expression of Type I collagen, alkaline phosphatase (ALP) and osteocalcin were studied by RT-PCR (reverse transcriptional polymerase chain reaction). The titania delayed the crystallization of HA. The mRNA expressions of Type I collagen are decreased as the increasing of TiO2 percentage. The mRNA expressions of osteocalcin are approached. The ALP expression on H4 coating (HA/TiO2 mol ration is 5) after the osteoblast cultured with composite coating for 6 days is the highest. The increasing of TiO2 amount decreases the bioactivity of the composite coatings.

Isolation, ultrastructure, and partial characterization of collagen from the perineurium of the Florida lobster, Panulirus argus

1991 ◽  
Vol 69 (8) ◽  
pp. 531-536
Author(s):  
Roy J. Baerwald ◽  
Lura C. Williamson ◽  
E. Stevens ◽  
C. Rike ◽  
S. Trabanino ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Content ◽  
Type I Collagen ◽  
Carbohydrate Content ◽  
Panulirus Argus ◽  
Computer Assisted ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fibril Diameter

Highly concentrated extracellular filaments in the perineurium of the Florida spiny lobster, Panulirus argus, were isolated using ultracentrifugation and linear sucrose gradients. The pellet obtained was highly enriched for the filaments as observed by transmission electron microscopy. Fibril diameter and axial periodicity measurements were obtained from filaments positively and negatively stained with uranyl acetate. A period between 14.0 and 25.0 nm and an average fibril diameter of 15.0 nm were observed. The filaments proved resistant to solubilization by most conventional agents and by several collagenases. NaOH (0.1 M at 100 °C) safely dissolved the filaments for measurements of protein content by the Lowry method and carbohydrate content with anthrone reagent. These tests revealed a protein content of ≈ 84% and a high carbohydrate content of ≈ 15%. Polyacrylamide electrophoresis of an acid-pepsin filament extract revealed a highly concentrated band (approximately 100 000) corresponding to the α-1 and α-2 bands of vertebrate type I collagen. Wide angle X-ray diffraction yielded meridional reflections that confirmed the filaments as collagen when compared with mammalian collagen X-ray diffraction. The amino acid composition was determined with a computer-assisted Beckman amino acid analyzer, which showed a glycine content of 279 residues/1000. Hydroxylysine and hydroxyproline were present in lower concentrations than expected.Key words: perineurium, lobster, collagen, extracellular matrix.

HAp Protein Composites Formed by Hydrolysis of α-TCP

2005 ◽  
Vol 284-286 ◽  
pp. 39-42 ◽  
Author(s):  
Ahmed H. Touny ◽  
Paul W. Brown
Keyword(s):  
Type I Collagen ◽  
Isothermal Calorimetry ◽  
Protein Structures ◽  
Structural Proteins ◽  
Surrounding Tissue ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Of ◽  
Aggressive Effect

Composite material composed of hydroxyapatite (HAp) and structural proteins, such as type I collagen or cross-linked gelatins, were synthesized at 37.4°C by hydrolysis of alpha tricalcium phosphate (α-TCP) in the presence of these protein structures. X-ray diffraction (XRD)and isothermal calorimetry were used as tools to evaluate the rate of HAp formation. Rates of HAp formation depend on protein structure. Gelatin enhances HAp formation while collagen delays it. Changes in pH during the hydrolysis α-TCP are unlikely to have an aggressive effect on the surrounding tissue. The presence of the protein improves the ductility of the HAp/protein composite but it decreases the tensile strength.

scholarly journals X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1154
Author(s):  
Diego E. Lozano ◽  
George E. Totten ◽  
Yaneth Bedolla-Gil ◽  
Martha Guerrero-Mata ◽  
Marcel Carpio ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
High Speed ◽  
Spring Steel ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
X Ray ◽  
Water Chamber ◽  
Hardened Case ◽  
Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

Phase selection in precursor-derived yttrium aluminum garnet and related Al2O3–Y2O3 compositions

2005 ◽  
Vol 20 (4) ◽  
pp. 1017-1025 ◽  
Author(s):  
Ashutosh S. Gandhi ◽  
Carlos G. Levi
Keyword(s):  
Heat Treatment ◽  
Yttrium Aluminum Garnet ◽  
Lattice Parameter ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
Phase Selection ◽  
X Ray ◽  
Yttrium Aluminum ◽  
Rich Side ◽  
Nitrate Solutions

Al2O3–Y2O3 powders were synthesized in the range of 25–55% Y2O3 by reverse coprecipitation of nitrate solutions. All starting powders were amorphous and formed primary yttrium aluminum garnet (YAG) upon crystallization. X-ray diffraction detected only garnet in compositions of 30–40% Y2O3 after heat treatment at 1250 °C. Compositions of 45–55% Y2O3 established a metastable YAG + Y4Al2O9 microstructure. The YAG phase field was metastably extended away from its stoichiometry, as indicated by a systematic increase in lattice parameter with Y2O3 content. Although some Al2O3 enrichment was achieved, YAG appears to tolerate greater off-stoichiometry on the Y2O3-rich side. Possible defect structures accommodating the solubility extension were examined. Phase selection results indicate that compositional inhomogeneity is not the only reason behind the appearance of hexagonal YAlO3, which is frequently reported during YAG synthesis.

In Situ X-Ray Diffraction Studies of Crystallization Growth Behavior in ZnO-Bi2O3-B2O3 Glass as a Route to Functional Optical Devices

MRS Advances ◽  
2018 ◽  
Vol 3 (11) ◽  
pp. 563-567 ◽  
Author(s):  
Quentin Altemose ◽  
Katrina Raichle ◽  
Brittani Schnable ◽  
Casey Schwarz ◽  
Myungkoo Kang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Treatment Temperature ◽  
Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Xrd ◽  
Dsc Measurements ◽  
Transmission Window

ABSTRACTTransparent optical ZnO–Bi2O3–B2O3 (ZBB) glass-ceramics were created by the melt quenching technique. In this work, a melt of the glass containing stoichiometric ratios of Zn/Bi/B and As was studied. Differential scanning calorimeter (DSC) measurements was used to measure the thermal behavior. VIS/NIR transmission measurements were used to determine the transmission window. X-ray diffraction (XRD) was used to determine crystal phase. In this study, we explore new techniques and report a detailed study of in-situ XRD of the ZBB composition in order to correlate nucleation temperature, heat treatment temperature, and heat treatment duration with induced crystal phase.

The Effect of Different Methods to Pretreat Reed Pulp on the Crystallinity of Microcrystalline Cellulose

2014 ◽  
Vol 1056 ◽  
pp. 12-15 ◽  
Author(s):  
Wen Long Zhang ◽  
Wen Long Zhao ◽  
Ya Jie Dai
Keyword(s):  
Crystallite Size ◽  
Microcrystalline Cellulose ◽  
Average Crystallite Size ◽  
Comprehensive Analysis ◽  
Raw Material ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimethyl Acetamide ◽  
Crystal Type

Reed Pulp was Raw Material that Pretreated by Four Methods {ultrasonic, Microwave, N, N-Dimethyl Acetamide (DMAc) and Tetrahydrofuran (THF)}. Reed Microcrystalline Cellulose (MCC) was Prepared by the Dilute Hydrochloric Acid Hydrolysis from Pretreated Reed Pulp. the Influences of Pretreatment Methods on Crystalline Type, Crystallinity and Crystallite Size of MCC were Investigated by X-Ray Diffraction (XRD). the Results Showed that the Crystallinity of MCC with Four Pretreatment Methods was 68.45%, 62.28%, 63.21% and 69.56%, Respectively. the Average Crystallite Size of MCC Prepared by Hydrolysis after Pretreated by Dmac was the Largest. whereas, the Crystal Type of MCC was Not Changed, it was still the Cellulose Type I. Comprehensive Analysis Indicated that the Effects of MCC Prepared by Hydrolysis after Pretreated by Ultrasonic were the Best.

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