Background: Endodontically treated teeth have low resistance to fracture against occlusal forces. The strengthening effect of bonded esthetic onlay restoration on weakened tooth has been reported. This study aimed to assess the fracture resistance of endodontically treated premolars restored with composite with and without cuspal coverage by using direct and indirect techniques. Indirect technique done by CAD/CAM system (computer aided design –computer aided manufacturer) and laboratory processing. Material and methods: Forty human extracted maxillary premolars of approximately comparable sizes were divided into four groups: Group (A): Ten endodontically treated teeth directly filled with Filtek Z250xt without cuspal coverage. Group (B): Ten endodontically treated teeth prepared with onlay cavities and restored directly with Filtek Z250 XT. Group(C): Ten endodontically treated teeth prepared with onlay cavities and restored indirectly with Filtek Z250 XT. Group (D): Ten endodontically treated teeth prepared with onlay cavities and restored indirectly with Paradigm MZ100 CAD/CAM blocks. Fracture strength of the samples was measured by using universal testing machine (an axial compression test). Data were analyzed statistically by one way ANOVA test and least significant difference test, Results showed that Group A has the lowest fracture resistance value than all experimental Groups and the difference are highly significant. While Group B has a high significant fracture resistant value than the indirectly restored groups. Group C and Group D showed an approximate fracture resistant result (1.13KN and 1.07KN respectively) and the difference is statistically not significant. Conclusion All CAD/CAM composite onlay, indirect Filtek z250 XT and direct cuspal coverage survived maximum biting force for posterior single tooth, so these types of onlays provide good reinforcement in an extensive MOD cavities in premolars The mode of fracture for Group D was 90% restorable which is higher than group C (80%) restorable and group B (30%) restorable type of fracture.
Background: The world is in front of two emerging problems being scarceness of virgin re-sources for bioactive materials and the gathering of waste production. Employment of the surplus waste in the mainstream production can resolve these problems. The current study aimed to prepare and characterize a natural composite CaO-SiO2 based bioactive material derived from naturally sustained raw materials. Then deposit this innovative novel bioactive coating composite materials overlying Yttria-stabilized tetragonal zirconia substrate. Mate-rials and method; Hen eggshell-derived calcium carbonate and rice husk-derived silica were extracted from natural resources to prepare the composite coating material. The manufac-tured powder was characterized
... Show MorePromoting the production of industrially important aromatic chloroamines over transition-metal nitrides catalysts has emerged as a prominent theme in catalysis. This contribution provides an insight into the reduction mechanism of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) over the γ-Mo2N(111) surface by means of density functional theory calculations. The adsorption energies of various molecularly adsorbed modes of p-CNB were computed. Our findings display that, p-CNB prefers to be adsorbed over two distinct adsorption sites, namely, Mo-hollow face-centered cubic (fcc) and N-hollow hexagonal close-packed (hcp) sites with adsorption energies of −32.1 and −38.5 kcal/mol, respectively. We establish that the activation of nit
... Show MoreSynthesis, characterization and pharmaceutical studies of schiff base from 2-pyrrolidinone derivative and imidazole-2-carboxaldehyde and corresponding complexes with Metal (||)
The biological activities of some ternary nickel complexes with a Schiff base obtained from 4-dimethylaminobenzaldehyde and 2-aminophenol have been reported. The Schiff base ( HL1) acts as a primary ligand whereas, anthranilic acid ( HL2), 2-nitroaniline ( HL3), alanine ( HL4) and histidine ( HL5) act as secondary ligand or co-ligand. The anticancer activity of these compounds was studied against human colon carcinoma (HCT-116), human hepatocellular liver carcinoma (HEPG-2) and human breast carcinoma (MCF-7) cell lines. As per the results, the compounds were active against the cell lines. The antioxidant activity of the same compounds was evaluated using DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical scavenging and compared with ascorbic aci
... Show MoreIn a hybrid cooling solar thermal systems , a solar collector is used to convert solar energy into heat energy in order to super heat the refrigerant leaving the compressor, and this process helps in the transformation of refrigerant state from gaseous state to the liquid state in upper two-thirds of the condenser instead of the lower two-thirds such as in the traditional air-conditioning systems and this will reduce the energy needed to run the process of cooling .In this research two systems with a capacity of 2 tons each were used, a hybrid air-conditioning system with an evacuated tubes solar collector and a traditional air-conditioning system . The refrigerant of each type was R22.The comparison was in the amou
... Show More The reaction of L-ascorbic acid with the tirchloroacetic acid in the presence of potassium hydroxide gave new product Bis[O,O-2,3;O,O-5,6(chlorocarboxylicmethyliden)]Lascorbic acid (H2L) which was isolated and characterized by 1H,13C-NMR, elemental analysis (C,H,N), UV-Visible and Fourier Transform Infrared (FTIR). The complexes of the ligand (H2L) with metal ions, M+2= (Cu, Co, Ni, Cd and Hg) were synthesized and characterized by FTIR, UV-Visible, molar conductance, atomic absorption, magnetic susceptibility and the molar ratio. The analysis evidence showed the binding of the metal ions with (H2L) through the bicarboxylato group manner resulting in six-coordinated metal ion. The TLC for (H2L) and complexes showed one spot for eac
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