Background: The purpose of this study was to verify the influence of post- pressing time of acrylic resin (immediate, 6, 12 and 24 hour) on the dimensional accuracy of denture base whish is a critical factor in the retention and stability of the complete denture that may occur during polymerization shrinkage. Materials and Methods: Forty maxillary stone casts were poured in plastic mold (Columbia Dentoform corp. NEW YORK, type III dental stone (Geastone, Zeus Sri Loc.Tamburine Roccastrada, GR, Italy). The stone casts were randomly assigned into 4 groups of 10 specimens each according to the post-pressing times into (immediate, 6, 12 and 24 h.). Heat cure acrylic resin denture base was constructed according to the previously mentioned pressing time, the resin base-stone cast sets were transversally sectioned with a manual saw device at the distal aspect of the molar area, anterior to the posterior palatal seal area. The gap between the resin base and stone cast was measured at five points in the right (point B) and left (point D) ridge crests, at the midline (point C), and at the right (point A) and left (point E) marginal limits (A), using a Leitz linear optical comparator microscope with a travelling stage capable of measuring 0.001 mm. Each measurement was repeated three times and the average was used as the linear gap distance for that point. The data were submitted to ANOVA. Result: there was statistically significant difference between the pressing time in which the mean values of gap space in point E for 24h shows lowest value then point A, point B, and point D than the other post pressing time. The mean value in point C shows highest values which mean the greater gap space in palatal area.
The effect of considering the third dimension in mass concrete members on its cracking behavior is investigated in this study. The investigation includes thermal and structural analyses of mass concrete structures. From thermal analysis, the actual temperature distribution throughout the mass concrete body was obtained due to the generation of heat as a result of cement hydration in addition to the ambient circumstances. This was performed via solving the differential equations of heat conduction and convection using the finite element method. The finite element method was also implemented in the structural analysis adopting the concept of initial strain problem. Drying shrinkage volume changes were calculated using the procedure suggested
... Show MoreBackground: The mechanical properties of 3D-printed denture base resins are crucial factors for determining the quality and performance of dentures inside a patient’s mouth. Tensile strength and diametral compressive strength are two properties that could play significant roles in assessing the suitability of a material. Although they measure different aspects of material behavior, a conceptual link exists between them in terms of overall material strength and resilience. Aim: This study aims to investigate the correlation between tensile strength and diametral compressive strength after incorporating 2% ZrO2 nanoparticles (NPs) by weight into 3D-printed denture base resin. Methods: A total of 40 specimens (20 dumbbell-shaped and
... Show More
(3)
Experimental and numerical studies have been conducted for the effect of injected air bubbles on the heat transfer coefficient through the water flow in a vertical pipe under the influence of uniform heat flux. The investigated parameters were water flow rate of (10, 14 and 18) lit/min, air flow rate of (1.5, 3 and 4) lit/min for subjected heat fluxes of (27264, 36316 and 45398) W/m2. The energy, momentum and continuity equations were solved numerically to describe the motion of flow. Turbulence models k-ε was implemented. The mathematical model is using a CFD code Fluent (Ansys15). The water was used as continuous phase while the air was represented as dispersed. phase. The experimental work includes design, build and instrument a test
... Show MoreBackground: This study designed to shade light on the important role of CBCT in accurate localization of the impacted maxillary canines. Materials and method: Fifty two unilateral and bilateral impacted maxillary canines from 30 patients (24 females and 6 males) were evaluated by a volumetric 3D images obtained from cone beam CT. All samples attended to the specialist health center of dentistry in Al-Sadder City referred to CBCT by oral surgeons or orthodontists to detect the exact position of impacted upper canine in cases when there was no bulging buccally or palatally which aids to detect the exact position. Results: Mesio-palatal angulations had the highest rate (63.5%) followed by mesio-labial (19.2%), vertical (labial) (9.6%), disto-p
... Show MoreBackground Microorganisms and fungal growth especially Candida albicans, on soft denture lining material are the most common problem which can lead to chronic mucosal inflammation. The aim of this study was to evaluate the effect of zirconium nanoparticles into acrylic-based heat cured soft denture lining material against Candida albicans, and the amount of zirconium ion release of soft liner/ZrNPs composite. Furthermore, evaluate shear bond strength after ZrNPs addition to soft liner. Materials and methods: Zirconium nanoparticles were added into acrylic-based soft denture liner in various percentages (1%, and 1.5% by weight). Two hundred and fifty specimens were arranged and isolated into four groups as per the test to be done The antifu
... Show More
(13)
(2)
(2)
The study aims to identify the symptoms of PTSD among displaced Yazidi women according to age, marital status, educational level, and type of status (displaced or survivor). The study also seeks to identify the effect of the relaxation program on reducing PTSD among displaced Yazidi women. The research sample included (60) Yazidis for the statistical analysis sample and (5) for the experimental sample in the Dohuk governorate. For achieving the research objectives, a scale was used from the PTSD Checklist for DSM-5 (PCL-5), as well as a relaxation program was prepared. The researchers reached the following results that there is an average level of PTSD symptoms among displaced Yazidi women, there are no statistically significant differen
... Show MoreThis research is carried out to study the effect of the external post-tensioning technique on the flexural capacity of simply supported composite castellated beam experimentally. In this research, seven composite castellated beams having the same dimensions and material properties were cast and tested up to failure by applied two concentrated loads at 700 mm from each end. Two external strands of 12.7 mm diameter were fixed at each side of the web of strengthening beams and located at depth 180 mm from top fiber of the section (dps) at each end of the beam. The strands have been tensioned by using a hydraulic jack with a constant stress of 100 MPa. This research aims to study the effect of the strengthening by different shapes of st
... Show More
(1)
(1)
(1)
Successive waves and generations of terrorists attacked the Iraqis in the years following the fall of the regime in Iraq in 2003, after the US invasion of the country under the pretext of weapons of mass destruction. Hence, the Iraqi people enrolled in ongoing war with these armed groups which led to massive casualties due to blasts and missile injuries.
Mechanism of blasts injury can be classified into primary, secondary, tertiary, and quaternary. While bullet injuries can be classified into low and high-energy injuries, the type and severity of the injury will influence the type of management, together with facilities available in
(1)
(1)