scholarly journals Effectiveness of Nanohydroxyapatite on Demineralization of Enamel and Cementum Surrounding Margin of Yttria-Stabilized Zirconia Polycrystalline Ceramic Restoration

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Niwut Juntavee ◽  
Apa Juntavee ◽  
Preeyarat Plongniras
Keyword(s):  
Multiple Comparisons ◽  
Third Molars ◽  
X Ray Diffraction ◽  
X Ray ◽  
Significant Difference ◽  
Polycrystalline Ceramic ◽  
The Mean ◽  
Mandibular Third Molars ◽  
Post Hoc ◽  
Inducing Surface

Introduction. Prosthetic dentistry has shifted toward prevention of caries occurrence surrounding restorative margin through the anti-demineralization process. This study examines the ability of nanohydroxyapatite (NHA) gel and Clinpro (CP) on enhancing resistance to demineralization of enamel and cementum at margin of restoration. Materials and Methods. Thirty extracted mandibular third molars were segregated at 1 mm above and below cementoenamel junction (CEJ) to separate CEJ portions and substituted with zirconia disks by bonding to crown and root portions with resin adhesive. The enamel and cementum area of 4 × 4 mm2 neighboring zirconia was applied with either NHA or CP, while one group was left no treatment (NT) before demineralized with carbopal. Vickers hardness (VHN) of enamel and cementum was evaluated before material application (BM), after material application (AM), and after demineralization (AD). Analysis of variance (ANOVA) and post hoc multiple comparisons were used to justify for the significant difference (α = 0.05). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were determined for surface evaluations. Results. The mean ± SD of VHN for BM, AM, and AD for enamel and cementum was 393.24 ± 26.27, 392.89 ± 17.22, 155.00 ± 5.68 and 69.89 ± 4.59, 66.28 ± 3.61, 18.13 ± 0.54 for NT groups, respectively, 390.10 ± 17.69, 406.77 ± 12.86, 181.55 ± 7.99 and 56.01 ± 9.26, 62.71 ± 6.15, 19.09 ± 1.16 for NHA groups, respectively, and 387.90 ± 18.07, 405.91 ± 9.83, 188.95 ± 7.43 and 54.68 ± 7.30, 61.81 ± 4.30, 19.22 ± 1.25 for CP groups, respectively. ANOVA indicated a significant increase in anti-demineralization of enamel and cementum upon application of NHA or CP ( p < 0.05 ). Multiple comparisons indicated the capability in inducing surface strengthening to resist demineralization for enamel and cementum of NHA which was comparable to CP ( p > 0.05 ) as evidenced by SEM and XRD data indicating NHA and CP deposition and crystallinity accumulation. Conclusion. NHA and CP were capable of enhancing anti-demineralization for enamel and cementum. The capability in resisting the demineralization process of NHA was comparable with CP. NHA was highly recommended for anti-demineralization for enamel and cementum surrounding restorative margin.

scholarly journals Effect of Galla Chinensis on Remineralization of Early Dentin Lesion

2020 ◽  
Vol 14 (04) ◽  
pp. 651-656
Author(s):  
Hend Mahmoud Abdel-Azem ◽  
Ahmed Fawzy Abo Elezz ◽  
Rehab Khalil Safy
Keyword(s):  
Treatment Time ◽  
Analysis Data ◽  
Environmental Scanning ◽  
X Ray ◽  
Parametric Data ◽  
Significant Difference ◽  
Ph Cycling ◽  
The Mean ◽  
Post Hoc

Abstract Objective This study aimed to investigate the efficacy of the Galla chinensis extract (GCE) on early dentin lesion remineralization. Materials and Methods Seventy-two dentin specimens were divided into three groups according to the treatment solution. In group S1, specimens were treated with GCE; in group S2, the specimens were treated with sodium fluoride (NaF); meanwhile, specimens of group S3 were treated with distilled water (DW). Each group was further subdivided into two subgroups according to the treatment time (1 minute and 5 minutes). An in vitro pH-cycling model for 12 days was done. Subsequently, surface microhardness (SMH) of the specimens, elemental analysis, and their micromorphological appearance were evaluated. Statistical Analysis Data were statistically analyzed. One-way analysis of variance was used to compare numerical (parametric) data between more than two separate groups followed by post hoc Tukey. Results There was no significant difference between the mean SMH of dentin between NaF and GCE groups. Regarding the time, the 5-minute treatment with NaF and DW groups recorded higher mean SMH value of dentin than the 1-minute treatment group. Meanwhile, for GCE groups, the 1-minute immersion recorded higher mean SMH value than the 5-minute immersion without any significant difference between them. The microhardness results were confirmed by environmental scanning electron microscope and energy dispersive X-ray analysis results. Conclusion GCE could be used as an effective alternative for dentin remineralization.

scholarly journals Influence of First Premolar Extraction on Mandibular Third Molar Angulation

2009 ◽  
Vol 79 (6) ◽  
pp. 1143-1148 ◽  
Author(s):  
Suruchi Jain ◽  
Ashima Valiathan
Keyword(s):  
Third Molar ◽  
Positive Influence ◽  
Reference Plane ◽  
Third Molars ◽  
Premolar Extraction ◽  
Mandibular Third Molar ◽  
Significant Difference ◽  
The Mean ◽  
Mandibular Third Molars ◽  
The Right

Abstract Objective: To compare the angular changes in the developing mandibular third molars in both first premolar extraction and nonextraction cases and to determine whether premolar extraction results in a more mesial movement of the mandibular buccal segment and causes favorable rotational changes in the mandibular third molar tilt, which can enhance later eruption of the third molars. Materials and Methods: Pretreatment (T1) and posttreatment (T2) panoramic radiographs were taken of 25 subjects who had been treated by the extraction of all the first premolars and 25 subjects who had been treated with nonextraction. The horizontal reference plane was used to measure and compare the changes in the angles of the developing mandibular third molars. Results: The mean uprighting of the mandibular third molars seen in the extraction group was 8.2 ± 5.4 degrees on the left side and 6.3 ± 6.5 degrees on the right side following treatment (T2 − T1). For the nonextraction group the mean difference was 1.3 ± 4.3 degrees on the left side and 1.7 ± 5.4 degrees on the right side. There was a statistically significant difference between the groups (P = .012 on the right side and P &lt; .001 on the left side). Conclusions: Premolar extractions had a positive influence on the developing third molar angulations. Nonextraction therapy did not have any adverse effects.

scholarly journals Comparing the Effect of Facial Compression Bandage to That of Systemic Dexamethasone on Postsurgical Sequels after Extraction of Impacted Mandibular Third Molars: A Split-mouth Randomized Clinical Trial

2021 ◽  
Vol 9 (D) ◽  
pp. 160-165
Author(s):  
Ibraheem Hamadi ◽  
Nuraldeen Maher Al-Khanati ◽  
Zafin Kara Beit
Keyword(s):  
Third Molar ◽  
Study Groups ◽  
Third Molars ◽  
Dexamethasone Group ◽  
Surgical Extraction ◽  
Significant Difference ◽  
Impacted Mandibular Third Molars ◽  
The Mean ◽  
Mandibular Third Molars ◽  
Present Trial

AIM: The present study aimed to compare the clinical efficiency of facial pressure bandage, to that of intramuscular injection of dexamethasone (8 mg) on postsurgical sequels (swelling, pain, and trismus) of extraction of impacted mandibular third molar. METHODS: The study implemented a randomized split-mouth design. Patients with symmetrical bilateral impacted molars were eligible for the present trial. Sides were randomly assigned to two groups: pressure bandage group and dexamethasone group. The evaluated postsurgical sequels were extraoral swelling, trismus, and pain after 48 h and 7 days. RESULTS: The study included 42 impacted third molars (n = 42) in 21 patients with a mean age of 23.4 years. Most participants were females (66.7%). The mean postoperative swelling rates after 48 h and 7 days in pressure bandage group were found to be comparable to those of dexamethasone group. No significant difference was found in the mean rates of postoperative trismus between study groups after 48 h and 7 days. Differences in mean pain level scores between the pressure bandage group and dexamethasone group were statistically insignificant after 48 h and 7 days. CONCLUSION: The study findings showed that the effect of the pressure bandage was comparable to dexamethasone effect on the postsurgical sequels after surgical extraction of impacted mandibular third molars.

scholarly journals Effects of Extraction and Nonextraction Treatment on Third Molar Angulation

2015 ◽  
Vol 5 (1) ◽  
pp. 17-21
Author(s):  
Ajay Sudhakar Nitturkar ◽  
Sachin Doshi ◽  
Girish Karandikar ◽  
Samay Tahilramani ◽  
Bhavisha Gandhi
Keyword(s):  
Third Molar ◽  
Positive Influence ◽  
Occlusal Plane ◽  
Third Molars ◽  
Premolar Extraction ◽  
The Third ◽  
Significant Difference ◽  
The Mean ◽  
Mandibular Third Molars ◽  
The Right

ABSTRACT Objective To compare the angular changes in the developing third molars in both first premolar extraction and nonextraction cases and to determine if premolar extraction results in greater mesial movement of mandibular buccal segment and also causes favorable rotational changes in the third molar tip, which can improve later eruption of the third molars. Materials and Methods Pretreatment (T1) and post-treatment (T2) panoramic radiographs were obtained 31 subjects were taken who had been treated by extraction of all first premolars and for 21 subjects treated with nonextraction theray. Occlusal plane was used to measure and compare the changes in the angles of the developing maxillary and mandibular third molars. Results The mean uprighting of the third molars seen in the extraction group was 8.7° ± 10.29° and 2.97° ± 11.11° on the right side, and 5.14° ± 9.04° and 2.77° ± 12.10° on the left side following treatment (T2 – T1). For the nonextraction group, the mean difference was – 1.52 ± 6.43 and – 6.430 ± 12.21° on the right side, and – 3.90° ± 7.67° and – 5.7° ± 7.23° on the left side. There was a statistically significant difference between the groups (p < 0.001). Conclusion Premolar extractions had a positive influence on the developing third molar angulations. Nonextraction therapy did not have any adverse effects. How to cite this article Nitturkar AS, Doshi S, Krishnan RV, Karandikar G, Tahilramani S, Gandhi B. Effects of Extraction and Nonextraction Treatment on Third Molar Angulation. J Contemp Dent 2015;5(1):17-21.

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

scholarly journals Deep learning for visualization and novelty detection in large X-ray diffraction datasets

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Lars Banko ◽  
Phillip M. Maffettone ◽  
Dennis Naujoks ◽  
Daniel Olds ◽  
Alfred Ludwig
Keyword(s):  
Thin Film ◽  
Crystal Structure ◽  
Artificial Intelligence ◽  
Deep Learning ◽  
Novelty Detection ◽  
Structural Similarity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Post Hoc

AbstractWe apply variational autoencoders (VAE) to X-ray diffraction (XRD) data analysis on both simulated and experimental thin-film data. We show that crystal structure representations learned by a VAE reveal latent information, such as the structural similarity of textured diffraction patterns. While other artificial intelligence (AI) agents are effective at classifying XRD data into known phases, a similarly conditioned VAE is uniquely effective at knowing what it doesn’t know: it can rapidly identify data outside the distribution it was trained on, such as novel phases and mixtures. These capabilities demonstrate that a VAE is a valuable AI agent for aiding materials discovery and understanding XRD measurements both ‘on-the-fly’ and during post hoc analysis.

scholarly journals Preparation of high-entropy carbides by different sintering techniques

2021 ◽  
Vol 56 (19) ◽  
pp. 11237-11247 ◽  
Author(s):  
Johannes Pötschke ◽  
Manisha Dahal ◽  
Mathias Herrmann ◽  
Anne Vornberger ◽  
Björn Matthey ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Vacuum Sintering ◽  
X Ray ◽  
High Entropy ◽  
Mean Grain Size ◽  
The Mean ◽  
Gas Pressure Sintering ◽  
Hardness Values

AbstractDense (Hf, Ta, Nb, Ti, V)C- and (Ta, Nb, Ti, V, W)C-based high-entropy carbides (HEC) were produced by three different sintering techniques: gas pressure sintering/sinter–HIP at 1900 °C and 100 bar Ar, vacuum sintering at 2250 °C and 0.001 bar as well as SPS/FAST at 2000 °C and 60 MPa pressure. The relative density varied from 97.9 to 100%, with SPS producing 100% dense samples with both compositions. Grain size measurements showed that the substitution of Hf with W leads to an increase in the mean grain size of 5–10 times the size of the (Hf, Ta, Nb, Ti, V,)C samples. Vacuum-sintered samples showed uniform grain size distribution regardless of composition. EDS mapping revealed the formation of a solid solution with no intermetallic phases or element clustering. X-ray diffraction analysis showed the structure of mostly single-phase cubic high-entropy carbides. Hardness measurements revealed that (Hf, Ta, Nb, Ti, V)C samples possess higher hardness values than (Ta, Nb, Ti, V, W)C samples.

Dalnegroite, Tl5–xPb2x(As,Sb)2l–xS34, a new thallium sulphosalt from Lengenbach quarry, Binntal, Switzerland

2009 ◽  
Vol 73 (6) ◽  
pp. 1027-1032 ◽  
Author(s):  
F. Nestola ◽  
A. Guastoni ◽  
L. Bindi ◽  
L. Secco
Keyword(s):  
Polarized Light ◽  
New Mineral ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Concentrations ◽  
Reflected Light ◽  
Mohs Hardness ◽  
The Mean ◽  
The University ◽  
Probable Space

AbstractDalnegroite, ideally Tl4Pb2(As12Sb8)Σ20S34, is a new mineral from Lengenbach, Binntal, Switzerland. It occurs as anhedral to subhedral grains up to 200 μm across, closely associated with realgar, pyrite, Sb-rich seligmanite in a gangue of dolomite. Dalnegroite is opaque with a submetallic lustre and shows a brownish-red streak. It is brittle; the Vickers hardness (VHN25) is 87 kg mm-2(range: 69—101) (Mohs hardness ∼3—3½). In reflected light, dalnegroite is highly bireflectant and weakly pleochroic, from white to a slightly greenish-grey. In cross-polarized light, it is highly anisotropic with bluish to green rotation tints and red internal reflections.According to chemical and X-ray diffraction data, dalnegroite appears to be isotypic with chabournéite, Tl5-xPb2x(Sb,As)21-xS34. It is triclinic, probable space groupP1, witha= 16.217(7) Å,b= 42.544(9) Å,c= 8.557(4) Å, α = 95.72(4)°, β = 90.25(4)°, γ = 96.78(4)°,V= 5832(4) Å3,Z= 4.The nine strongest powder-diffraction lines [d(Å) (I/I0) (hkl)] are: 3.927 (100) (10 0); 3.775 (45) (22); 3.685 (45) (60); 3.620 (50) (440); 3.124 (50) (2); 2.929 (60) (42); 2.850 (70) (42); 2.579 (45) (02); 2.097 (60) (024). The mean of 11 electron microprobe analyses gave elemental concentrations as follows: Pb 10.09(1) wt.%, Tl 20.36(1), Sb 23.95(1), As 21.33(8), S 26.16(8), totalling 101.95 wt.%, corresponding to Tl4.15Pb2.03(As11.86Sb8.20)S34. The new mineral is named for Alberto Dal Negro, Professor in Mineralogy and Crystallography at the University of Padova since 1976.

Plastic deformations in kyanites by tectonometamorphic processes: a single-crystal X-ray diffraction study

2009 ◽  
Vol 73 (3) ◽  
pp. 359-371 ◽  
Author(s):  
G. D. Gatta ◽  
N. Rotiroti ◽  
M. Zucali
Keyword(s):  
Single Crystal ◽  
X Ray Diffraction ◽  
Plastic Deformations ◽  
X Ray ◽  
Deformational History ◽  
Significant Difference ◽  
Elliptical Section ◽  
History Of ◽  
Diffraction Patterns ◽  
Two Stages

AbstractThe crystalch emistry and crystal structure of naturalky anite crystals from the Eclogitic Micaschists Complex of the Sesia-Lanzo Zone, Western Italian Alps, have been investigated by means of optical microscopy, wavelength dispersive X-ray microanalysis, and single-crystal X-ray diffraction. The association of kyanite + garnet + phengitic-mica + chloritoid suggests that the eclogite-facies stages occurred at P ≤ 2.1 GPa and T ≤ 650ºC. Kyanite grains are large (cm-sized) porphyroblasts grown dynamically during one of the deformational events related to the subduction of the Austroalpine continentalcr ust. Under the polarizing microscope, kyanite grains show almost homogeneous cores, whereas rims are sometimes symplectitic aggregates of quartz and kyanite, confirming at least two stages of growth most likely related to the multistage deformational history of these rocks. Chemical analysis shows that Fe3+ is the major substituting cation for Al3+, ranging between 0.038 and 0.067 a.p.f.u.The single-crystal X-ray diffraction investigation of the kyanites shows severely textured patterns on the (h0l)*-plane. Such evidence is not observed in the unwarped diffraction patterns on (0kl)* and (hk0)*. The most significant difference between the structuralp arameters refined in this study, with respect to those of previously published unstrained gem-quality crystals, concerns the displacement parameters. The anisotropic displacement ellipsoids of all the atomic sites are significantly larger than those previously described, and systematically oriented with the largest elliptical section almost perpendicular to [010]. The larger ellipsoids in the kyanite crystal investigated here reflect the displacement of the centre of gravity of the electron distribution, rather than an anomalous atomic thermal motion. The magnitude and orientation of the displacement parameters and the textured/strained diffraction pattern may be the result of two combined effects: (1) that the kyanite crystals are actually composed of several blocks; (2) the crystals are affected by a pervasive residual strain, as a result of tectonometamorphic plastic deformations and re-crystallization.

Mechanical Spectroscopy Investigation of Liquid Pb-Bi Alloys

2012 ◽  
Vol 184 ◽  
pp. 434-439 ◽  
Author(s):  
Roberto Montanari ◽  
Alessandra Varone
Keyword(s):  
Distribution Functions ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
X Ray ◽  
Neutron Spallation Source ◽  
Driven System ◽  
Spallation Source ◽  
Accelerator Driven System ◽  
The Mean ◽  
Diffraction Patterns

Liquid Pb–Bi eutectic alloy has been selected as coolant and neutron spallation source for the development of MYRRHA, an accelerator driven system. The alloy has been characterized in liquid state from melting (125 °C) to 650 °C by mechanical spectroscopy. Experiments have been carried out using hollow reeds of austenitic stainless steel filled with the Pb-Bi alloy and sealed at the extremities. From 350 °C to 520 °C modulus shows a remarkable drop accompanied by a broad internal friction maximum. In the same temperature range radial distribution functions, determined from X-ray diffraction patterns, evidenced variations of the mean distance between the 1st nearest neighbour atoms. The anelastic phenomena have been attributed to a structural re-arrangement of liquid metal. For comparison, other alloys of the Pb-Bi system with hypo-eutectic composition have been investigated.

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