Background: This study was conducted to assess the effect of sonic activation and bulk placement of resin composite in comparison to horizontal incremental placement on the fracture resistance of weakened premolar teeth. Materials and method: Sixty sound human single-rooted maxillary premolars extracted for orthodontic purposes were used in this study. Teeth were divided into six groups of ten teeth each: Group 1 (sound unprepared teeth as a control group), Group 2 (teeth prepared with MOD cavity and left unrestored), Group 3 (restored with SonicFill™ composite), Group 4 (restored with Quixfil™ composite), Group 5 (restored with Tertic EvoCeram® Bulk Fill composite) and Group 6 (restored with Universal Tetric EvoCeram® composite using horizontal incremental layering technique). Standardized class II MOD cavity was prepared in all teeth except (group 1).After finishing the restorative procedure of each group according to the manufacturer's instructions, all teeth were stored in deionized distilled water in an incubator at 37°C for seven days.All specimens were subjected to compressive axial loading until fracturein a universal testingmachine.Specimens were examined by a stereomicroscope at a magnification of (20X) to evaluate the mode of fracture . Results: The results of this study revealed that the control group exhibited the highest fracture resistance compared to all prepared teeth groups (restored or unrestored) and the differences were statistically highly significant (P<0.01), except with group 3 (which was restored with SonicFill™ composite) where the difference was statistically significant only (P < 0.05).Additionally the results of this study revealed that the prepared unrestored teeth (Group 2) exhibited the lowest fracture resistance compared to all restored groups and the differences were statistically highly significant (P<0.01). Meanwhile, among the restored teeth groups, teeth restored with SonicFill™ composite (group 3) exhibited the highest fracture resistance as compared with all other restored groups and the difference was statistically highly significant (P<0.01). On the other hand, no statistically significant differences in fracture resistance were found among groups 4, 5 and 6, which were restored with Quixfil™ composite, Tetric EvoCeram® Bulk Fill composite and Universal Tetric EvoCeram® composite, respectively (P > 0.05). Group 3and Group 5 showed mostly mixed mode of failure, while Group 4 showed mostly adhesive mode of failure. On the other hand Group 6 teeth showed different modes of failure. Conclusions: SonicFill™ composite can be considered as a viable treatment modality for the restoration of weakened maxillary premolar teeth. On the other hand, the time-consuming incremental layering technique can be substituted with bulk filling, using bulk fill materials (Quixfil™ and Tetric EvoCeram® Bulk Fill) for reinforcement ofweakened maxillary premolars.
Polymer additives binder system provides many properties useful in thermal energy storage (TES) then developed the efficient energy storage materials and green strength bodies system.
This paper studies the thermal energy storage property for polyvinyl alcohol (PVOH) / paraffin wax (WPw) blends. To enhance paraffin wax thermal conductivity, PVOH as a material which high conductivity was employed. A fixed weight of Paraffin wax was dispersed with PVOH heterogeneously at different additive weights ratios of PVOH/Pw (50/50, 67/33, 75/25, and 80/20) wt. ratio respectively. The composite material was prepared using wetted pressing method.
Both base materials (polyvinyl alcohol and paraffin wax) were scanned using differential
... Show MoreA cantilever beam is made from composite material which is consist of (matrix: polyester) and (particles: Silicon-Carbide) with different volume fraction of particles. A force is applied at the free end of beam with different values. The experimental maximum deflection of beam which occurs at the point of the applied load is recorded. The deflection and slope of beam are analyzed by using FEM modeling. MATLAB paltform is built to assemble the equations, vector and matrix of FEM and solving the unknown variables (deflection and slope) at each node. Also ANSYS platform is used to modeling beam in finite element and solve the problem. The numerical methods are used to compare the results with the theoretical and experimental data. A good ag
... Show MoreThis paper presents an application of a Higher Order Shear Deformation Theory (HOST 12) to problem
of free vibration of simply supported symmetric and antisymmetric angle-ply composite laminated plates.
The theoretical model HOST12 presented incorporates laminate deformations which account for the effects
of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane
displacements with respect to the thickness coordinate – thus modeling the warping of transverse crosssections more accurately and eliminating the need for shear correction coefficients. Solutions are obtained in
closed-form using Navier’s technique by solving the eigenvalue equation. Plates with varying number of
Modern American elegy reveals a change in the attitude of mourning from the traditional lamenting approach to some antielegiac attitudes towards the mourned figure. Many American poets have lamented the pass away of the stately figure of the father. However, some poets attack their dead father, and ridiculed him in a poem that is intended to be an elegy, instead of showing passion, homage and love to him. In this regard, two poetic attitudes to the father can be traced in modern American poetry. The first one takes the form of tributes and praise, offering great admiration, compassion, and love for the father. For these poets, a father is an inspiration. The second voice develops some anger and contempt against the patriarchal authority emb
... Show MoreComics is a visual art (Still and motion pictures) it seeks to provide a Training courses are a series of intensive important educational and complementary programs, based on previous foundation experiences. Create to development the participants in aspects of specialization according to the requirements of the educational system to continue developing the previous scientic and practical experiences. Personally, or adopted by the trainee institution, where the trainee gets a professional skill certicate that contributes to the development his work.Development and Continuous Education Center (DCEC) at the University of Baghdad (UoBaghdad) is a center dedicated to continuing education courses in which the participant is awarded a cert
... Show Moreackground An autoimmune and inflammatory illness called rheumatoid arthritis (RA) occurs when your immune system mistakenly attacks normal cells in your body. Interleukin-35 is a brand-new cytokine that belongs to the immunosuppressive and anti-inflammatory IL-12 family. β -herpesvirus that produces inflammation and stays dormant in its host for life is the human cytomegalovirus. Human herpesvirus (HCMV) has been at the core of several RA-related theories. Objective The current study looked at the association between RA and serum IL-35 levels as well as the association between RA and CMV. Patients and methods Blood samples were taken in the Baghdad Teaching Hospital and Typical Rheumatology Unit from January 2022 to Mars 2022 for the curre
... Show MoreThis study on the plant of Ain –AL Bason Catharanthus roseous showed the ability of callus cells that is produced by In Vitro culture technique and transformed to the accumulated media (MS 40gm/L sucrose ,2gm/L IAA Indole acetic acid , 0.5gm/L Tryptophan) to produce Vinblastine and Vincristine compounds. Extraction, purification and quantitive determination of Vinblastine and Vincristine compounds using High performance liquid chromatography technique (HPLC)were carried out. The results showed that the highest concentration of Vinblastine and Vincristine compounds were ( 4.653,12.5 (ppm /0.5 dry Wight respectively from transformed callus cells from MS 40 gm /L sucrose , 2 gm / L NAA Naphthaline acetic acid .
Solar cells thin films were prepared using polyvinyl alcohol (PVA) as a thin film, with extract of natural pigment from local flower. A concentration of 0.1g/ml of polyvinyl alcohol solution in water was prepared for four samples, with various concentrations of plant pigment (0, 15, 25 and 50) % added to each of the four solutions separately for preparing (PVA with low concentrated dye , PVA with medium concentrated dye and PVA with high concentrated dye ) thin films respectively . Ultraviolet absorption regions were obtained by computerized UV-Visible (CECIL 2700). Optical properties including (absorbance, reflectance, absorption coefficient, energy gap and dielectric constant) via UV- Vis were tested, too. Fourier transform infra
... Show MoreIn this work, the rate of charge transfer (CT) reaction at the N3-ZnS interface was calculated using a quantitative computational model to evaluate the efficiency of N3-ZnS heterojunction dye-sensitized solar cell devices using different types of solvents. This work discussed the influence of the effective driving energy force on the charge transport rate and performance of N3-ZnS devices with various solvents based on a donor-acceptor model. A solar cell model was used to study the optical efficiency when changing some of its parameters, such as the type of material and the thickness of the film, as they are important factors influencing the quality of the solar cell. It was found that the transition energy varies with different so
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