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https://www.readbyqxmd.com/read/28645670/fracture-resistance-of-cad-cam-monolithic-ceramic-and-veneered-zirconia-molar-crowns-after-aging-in-a-mastication-simulator
#1
Merve Bankoğlu Güngör, Secil Karakoca Nemli
STATEMENT OF PROBLEM: The demand for ceramic restorations has increased over the past years, and now various machinable materials can be used for chairside computer-aided design and computer aided manufacturing (CAD-CAM) systems. Limited studies of these new materials make it difficult to evaluate their mechanical performance, advantages, and limitations. PURPOSE: The purpose of this in vitro study was to investigate the fracture resistance of CAD-CAM monolithic ceramic and veneered zirconia molar crowns after thermomechanical aging...
June 20, 2017: Journal of Prosthetic Dentistry
https://www.readbyqxmd.com/read/28645667/effect-of-different-restorative-crown-and-customized-abutment-materials-on-stress-distribution-in-single-implants-and-peripheral-bone-a-three-dimensional-finite-element-analysis-study
#2
Necati Kaleli, Duygu Sarac, Safak Külünk, Özgür Öztürk
STATEMENT OF PROBLEM: In recent years, the use of resin-matrix ceramics and polyetheretherketone (PEEK) abutments has been suggested to absorb excessive stresses on dental implants. However, only a few studies have evaluated the effect of these materials on stress distribution in implants and peripheral bone structure. PURPOSE: The purpose of this finite element analysis was to evaluate the biomechanical behaviors of resin-matrix ceramics and PEEK customized abutments in terms of stress distribution in implants and peripheral bone...
June 20, 2017: Journal of Prosthetic Dentistry
https://www.readbyqxmd.com/read/28645665/experimental-evaluation-of-stress-distribution-with-narrow-diameter-implants-a-finite-element-analysis
#3
Sezgi Cinel, Ersan Celik, Elcin Sagirkaya, Onur Sahin
STATEMENT OF PROBLEM: Narrow diameter implants were developed to allow placement in narrow alveolar ridges. Clinicians may have concerns about the durability and function of such implants. PURPOSE: The purpose of this finite element study was to compare the stress values occurring on the implant and at the implant bone interface after the application of the static and dynamic forces on narrow diameter, titanium and titanium-zirconia implants in the maxillary and mandibular second premolar region...
June 20, 2017: Journal of Prosthetic Dentistry
https://www.readbyqxmd.com/read/28645095/tooth-coronal-index-and-pulp-tooth-ratio-in-dental-age-estimation-on-digital-panoramic-radiographs-a-comparative-study
#4
Supreet Jain, Ravleen Nagi, Minal Daga, Ashutosh Shandilya, Aastha Shukla, Abhinav Parakh, Afshan Laheji, Rahul Singh
BACKGROUND: Assessment of an age of an individual whether living or dead through teeth is one of the most reliable and simple method to calculate age than skeletal remains especially when they are in poor conditions. OBJECTIVES: The study was carried out with aim of (i) to evaluate reliability of dental age assessment through two different methods for adults i.e. tooth coronal index and pulp/tooth ratio using digital panoramic radiographs and (ii) to compare these methods for their accuracy in age determination...
May 12, 2017: Forensic Science International
https://www.readbyqxmd.com/read/28644612/suppressing-isomerization-of-phosphine-protected-au9-cluster-by-bond-stiffening-induced-by-a-single-pd-atom-substitution
#5
Seiji Yamazoe, Shota Matsuo, Satoru Muramatsu, Shinjiro Takano, Kiyofumi Nitta, Tatsuya Tsukuda
The fluxional nature of small gold clusters has been exemplified by reversible isomerization between [Au9(PPh3)8](3+) with a crown motif (Au9(C)) and that with a butterfly motif (Au9(B)) induced by association and dissociation with compact counteranions (NO3(-), Cl(-)). However, structural isomerization was suppressed by substitution of the central Au atom of the Au9 core in [Au9(PPh3)8](3+) with a Pd atom: [PdAu8(PPh3)8](2+) with a crown motif (PdAu8(C)) did not isomerize to that with a butterfly motif (PdAu8(B)) upon association with the counteranions...
June 23, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28643923/micro-anatomical-responses-in-periodontal-complexes-of-mice-to-calibrated-orthodontic-forces-on-the-crown
#6
A Pal, L Chen, L Yang, F Yang, B Meng, A H Jheon, S P Ho
OBJECTIVE: Correlating mechanical forces with quantifiable physical changes in the dentoalveolar complex. SETTING AND SAMPLE POPULATION: Male 6-week C57BL/6 mice (N=3), micro X-ray-computed tomography; post-analysis software to extract physical changes in periodontal ligament (PDL)-space. MATERIALS AND METHODS: Silicone-elastic bands were placed between maxillary molars for 1 week, with the contralateral side as internal control. Average displacements between crowns and roots, and changes in PDL-spaces were evaluated by registering X-ray tomograms of experimental and control hemi-maxillae...
June 2017: Orthodontics & Craniofacial Research
https://www.readbyqxmd.com/read/28643836/host-guest-driven-ligand-replacement-on-monodisperse-inorganic-nanoparticles
#7
B Shirmardi Shaghasemi, E S Dehghani, E M Benetti, E Reimhult
We demonstrate that crown ether-assisted ligand replacement on Fe3O4 NPs using halide salts leads to quantitative stripping of an existing stabilizer shell with unprecedented (complete) efficiency; this allows subsequent re-grafting of functional ligands at maximal surface density. The mechanism of the anion-driven ligand replacement is elucidated by varying the halide salt and the versatility by varying the re-grafted ligand.
June 23, 2017: Nanoscale
https://www.readbyqxmd.com/read/28642930/a-novel-etching-technique-for-surface-treatment-of-zirconia-ceramics-to-improve-adhesion-of-resin-based-luting-cements
#8
Eystein Ivar Ruyter, Nalini Vajeeston, Torbjørn Knarvang, Ketil Kvam
Objectives: Bonding of zirconia crowns and bridges to abutments is important, not only bonding of the thin resin layer to the abutment, but also bonding to the zirconia ceramic is crucial. Both mechanical and chemical adhesion are desired. Mechanical retention of dental porcelain achieved by etching with moderately concentrated hydrofluoric acid is not possible with zirconia ceramics. The purpose of this study was to show that etching is possible with relative low melting fluoride compounds such as ammonium hydrogen difluoride and potassium hydrogen difluoride...
January 2017: Acta Biomaterialia Odontologica Scandinavica
https://www.readbyqxmd.com/read/28642921/fracture-behavior-of-single-structure-fiber-reinforced-composite-restorations
#9
Kohji Nagata, Sufyan K Garoushi, Pekka K Vallittu, Noriyuki Wakabayashi, Hidekazu Takahashi, Lippo V J Lassila
Objective: The applications of single-structure fiber-reinforced composite (FRC) in restorative dentistry have not been well reported. This study aimed to clarify the static mechanical properties of anterior crown restorations prepared using two types of single-structure FRC. Materials and methods: An experimental crown restoration was designed for an upper anterior incisor. The restorations were made from IPS Empress CAD for CEREC (Emp), IPS e.max(®) CAD (eMx), experimental single-structure all-FRC (a-FRC), Filtek™ Supreme XTE (XTE), and commercially available single-structure short-FRC (everX Posterior™) (n = 8 for each material) (s-FRC)...
December 2016: Acta Biomaterialia Odontologica Scandinavica
https://www.readbyqxmd.com/read/28642920/elastic-viscoelastic-and-viscoplastic-contributions-to-compliance-during-deformation-under-stress-in-prosthodontic-temporization-materials
#10
Tritala K Vaidyanathan, Jayalakshmi Vaidyanathan, David Arghavani
Purpose: The goal of this investigation was to characterize the compliance properties in selected polymers used for temporary (provisional crown and bridge) applications. Method: Polymethyl methacrylate (PMMA)- and polyethyl methacrylate (PEMA)-based JET and TRIM II were investigated along with two bisacryl composite resins (LUXATEMP and PROTEMP 3 GARANT). Rectangular samples of the resins were subjected to creep-recovery tests in a dynamic mechanical analyzer at and near the oral temperature (27 °C, 37 °C and 47 °C)...
December 2016: Acta Biomaterialia Odontologica Scandinavica
https://www.readbyqxmd.com/read/28642911/a-retrospective-multicenter-study-comparing-metal-ceramic-and-composite-single-crowns-performed-in-public-general-dentistry-5-year-results
#11
Jennie Overmeer, Birger Narby, Lars Hjalmarsson, Kristina Arnrup, Alf Eliasson
Objective The aim of this study was to evaluate and compare the 5-year survival and complication rate of metal-ceramic (MC) and composite single crowns performed within Public Dental Service, general dentistry, in three Swedish counties and with patients' gender, tooth position, root canal treatment and the presence of a post-and-core taken into account. Methods Data were collected from dental records of 600 patients who had received either an MC (n = 300) or a composite (n = 300) crown on a premolar or molar tooth in the year 2005 and where 5 years of follow-up data were available...
December 2016: Acta Biomaterialia Odontologica Scandinavica
https://www.readbyqxmd.com/read/28642551/aesthetic-preformed-crowns-for-primary-teeth
#12
Greig D Taylor
Data sourcesMedline, Cochrane central register of controlled trials, US National Institutes of Health Trials Register and the World Health Organization International Clinical Trials Registry Platform.Study selectionEnglish language randomised clinical trials comparing APCs with conventional restorative techniques for primary teeth.Data extraction and synthesisStudy selection and data abstraction were conducted independently by two reviewers. Risk of bias was assessed using the Cochrane risk of bias tool. Study characteristics and results were described qualitatively...
June 23, 2017: Evidence-based Dentistry
https://www.readbyqxmd.com/read/28641822/interim-rehabilitation-of-occlusal-vertical-dimension-using-a-double-crown-retained-removable-dental-prosthesis-with-polyetheretherketone-framework
#13
Sebastian Hahnel, Christian Scherl, Martin Rosentritt
Polyetheretherketone (PEEK) is a polymeric material that has recently been introduced in dentistry and can be used as framework material for fixed and removable dental prostheses. This clinical report describes the fabrication of a double-crown-retained prosthesis with a PEEK framework in a patient with a substantially diminished occlusal vertical dimension. The insertion of the removable dental prosthesis with a PEEK framework resulted in the functional and esthetic rehabilitation of the patient; however, removable dental prostheses fabricated from PEEK should currently be regarded as interim restorations because of the limited available scientific evidence...
June 20, 2017: Journal of Prosthetic Dentistry
https://www.readbyqxmd.com/read/28640827/the-application-of-multi-baseline-digital-close-range-photogrammetry-in-three-dimensional-imaging-and-measurement-of-dental-casts
#14
Xiaoming Fu, Chun Peng, Zan Li, Shan Liu, Minmin Tan, Jinlin Song
OBJECTIVE: To explore a new technique for reconstructing and measuring three-dimensional (3D) models of orthodontic plaster casts using multi-baseline digital close-range photogrammetry (MBDCRP) with a single-lens reflex camera. STUDY DESIGN: Thirty sets of orthodontic plaster casts that do not exhibit severe horizontal overlap (>2 mm) between any two teeth were recorded by a single-lens reflex camera with 72 pictures taken in different directions. The 3D models of these casts were reconstructed and measured using the open source software MeshLab...
2017: PloS One
https://www.readbyqxmd.com/read/28638775/host-guest-complexes-of-c-ethyl-2-methylresorcinarene-and-aromatic-n-n-dioxides
#15
Rakesh Puttreddy, Ngong Kodiah Beyeh, Robin H A Ras, Kari Rissanen
The C-ethyl-2-methylresorcinarene (1) forms 1:1 in-cavity complexes with aromatic N,N'-dioxides, only if each of the aromatic rings has an N-O group. The structurally different C-shaped 2,2'-bipyridine N,N'-dioxide (2,2'-BiPyNO) and the linear rod-shaped 4,4'-bipyridine N,N'-dioxide (4,4'-BiPyNO) both form 1:1 in-cavity complexes with the host resorcinarene in C4v crown and C2v conformations, respectively. In the solid state, the host-guest interactions between the 1,3-bis(4-pyridyl)propane N,N'-dioxide (BiPyPNO) and the host 1 stabilize the unfavorable anti-gauche conformation...
June 2017: ChemistryOpen
https://www.readbyqxmd.com/read/28638623/the-genetic-architecture-of-growth-traits-in-salix-matsudana-under-salt-stress
#16
Jian Zhang, Huwei Yuan, Qingshan Yang, Min Li, Ying Wang, Yujuan Li, Xiangjian Ma, Feng Tan, Rongling Wu
Willow (Salix) is one of the most important ornamental tree species in landscape plants. One species, Salix matsudana, is widely used as a shade tree and border tree because of its soft branches and plump crown. Some varieties of S. matsudana were salt tolerant and could grow normally in coastal regions. However, the molecular mechanisms of salt tolerance for S. matsudana have been less clear. Here, we addressed this issue by performing a mapping experiment containing 195 intraspecific F1 progeny of S. matsudana, derived from salt-sensitive 'yanjiang' and salt-tolerant '9901', grown by cuttings in a 100 mM NaCl solution...
2017: Horticulture Research
https://www.readbyqxmd.com/read/28638048/maternal-folate-deficiency-causes-inhibition-of-mtor-signaling-down-regulation-of-placental-amino-acid-transporters-and-fetal-growth-restriction-in-mice
#17
Fredrick J Rosario, Peter W Nathanielsz, Theresa L Powell, Thomas Jansson
Maternal folate deficiency is linked to restricted fetal growth, however the underlying mechanisms remain to be established. Here we tested the hypothesis that mTOR functions as a folate sensor in vivo in mice and that maternal folate deficiency inhibits placental mTOR signaling and amino acid transporter activity and causes fetal growth restriction. Folate deficient mice had lower serum folate (-60%). In late pregnancy, fetal weight in the folate deficient group was decreased (-17%, p < 0.05), whereas placental weight, litter size and crown rump length were unaltered...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28637273/gingival-recession-in-mandibular-incisors-and-symphysis-morphology-a-retrospective-cohort-study
#18
Katarina Mazurova, Jean-Baptiste Kopp, Anne Marie Renkema, Nikolaos Pandis, Christos Katsaros, Piotr S Fudalej
Objective: To evaluate if the morphology of the mandibular symphysis is associated with the development of gingival recession. Materials and methods: A cohort of 177 patients was followed longitudinally for up to 5 years post-treatment. Based on the width of the symphysis, participants were divided into three groups: narrow (n = 57); average (n = 63), and wide symphysis (n = 57). Morphology of the symphysis and inclination of incisors were measured on lateral cephalometric radiographs before treatment (Ts), at the end of treatment (T0) and 5 years after treatment (T5)...
June 15, 2017: European Journal of Orthodontics
https://www.readbyqxmd.com/read/28637223/millions-of-years-behind-slow-adaptation-of-ruminants-to-grasslands
#19
Olja Toljagic, Kjetil L Voje, Michael Matschiner, Lee Hsiang Liow, Thomas F Hansen
The Late-Cretaceous appearance of grasses, followed by the Cenozoic advancement of grasslands as dominant biomes, has contributed to the evolution of a range of specialized herbivores adapted to new diets, as well as to increasingly open and arid habitats. Many mammals including ruminants, the most diversified ungulate suborder, evolved high-crowned (hypsodont) teeth as an adaptation to tooth-wearing diets and habitats. The impact of different causes of tooth wear is still a matter of debate, and the temporal pattern of hypsodonty evolution in relation to the evolution of grasslands remains unclear...
June 20, 2017: Systematic Biology
https://www.readbyqxmd.com/read/28636600/hidden-morphological-diversity-among-early-tetrapods
#20
Jason D Pardo, Matt Szostakiwskyj, Per E Ahlberg, Jason S Anderson
Phylogenetic analysis of early tetrapod evolution has resulted in a consensus across diverse data sets in which the tetrapod stem group is a relatively homogenous collection of medium- to large-sized animals showing a progressive loss of 'fish' characters as they become increasingly terrestrial, whereas the crown group demonstrates marked morphological diversity and disparity. The oldest fossil attributed to the tetrapod crown group is the highly specialized aïstopod Lethiscus stocki, which shows a small size, extreme axial elongation, loss of limbs, spool-shaped vertebral centra, and a skull with reduced centres of ossification, in common with an otherwise disparate group of small animals known as lepospondyls...
June 21, 2017: Nature
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