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: White spot lesions are esthetic problems caused by subsurface enamel demineralization that seen as white opacity. Aim of the study: This study aimed to evaluate and to compare the color change after the treatment of the white spot lesions with resin nϔtrton and micro abrasion. Materials and Methods: rtϔ white spot lesions were generated on 48 premolar teeth by the use of a demineralization solution. The teeth were randomly divided using the Diagnodent into three study groups (16 teeth for each group) depending on the depth of the induced lesions: outer enamel, inner enamel and outer dentine. Then each group was fatherly subdivided into two groups (8 teeth for each group) the ϔrst group was treated wit
... Show MoreIn this paper, a theoretical study was introduced to discussion the Influence of donor senstizer on efficiency of solar cell with clear focusing on dye senstized solar cell DSSCs applications was presented. Use of donor as -sensitizer dye in solar cells was a viable contender in photovoltaics due to their spectrum of excited state to transfer more elkectrons to conduction band of semiconductor .In this study, two systems Alq3/ZnO and D149/ZnO devices taken with same two solvents .Transtion energy ,coupling strength and transtion parameters are used to calculate the electron current density , it uses to calculate the photovoltic characteristic I-V ,fill factor and the efficiency of th
... Show Moreto evaluate the effect of various Nd:YAG frequency doubled laser parameters on the acid
dissolution and the progression of in vitro caries like lesions in human enamel.
Materials and Methods: Human extracted caries free upper first premolar teeth were collected for
this study. The irradiated teeth were divided into two groups. The first group was irradiated with
continuous Nd:YAG laser radiation, and the second group was irradiated with chopped Nd:YAG laser
radiation. For the first group, power and exposure time were changed while for the second group
power and number of pulses were changed. The spot diameter was kept constant for all the samples.
Results: using 1.5 W and 3 seconds (exposure time), best results among
BACKGROUND: Clavicle fractures are common injuries in young active individuals, the mid third of the clavicle is most commonly fractured part(80% of clavicle fracture) OBJECTIVE: To compare the outcomes of operative and non operative management of displaced and or comminuted closed fracture of the mid third of clavicle in young adults PATIENTS AND METHODS: This prospective observational study of 24 patients of fracture of the mid third of the clavicle was conducted in Alkindy teaching hospital from July 2015 to January 2017 and divided into two groups; one managed by operative treatment with plate and screws and the other by non operative sling immobilization after taking the consent and the patients were seen at 2, 4, 6 weeks,3, 6, and 9 m
... Show MoreThe dynamic thermomechanical properties, sealing ability, and voids formation of an experimental obturation hydroxyapatite-reinforced polyethylene (HA/PE) composite/carrier system were investigated and compared with those of a commercial system [GuttaCore (GC)]. The HA/PE system was specifically designed using a melt-extrusion process. The viscoelastic properties of HA/PE were determined using a dynamic thermomechanical analyser. Human single-rooted teeth were endodontically instrumented and obturated using HA/PE or GC systems, and then sealing ability was assessed using a fluid filtration system. In addition, micro-computed tomography (μCT) was used to quantify apparent voids within the root-canal space. The data were statistically analys
... Show MoreThe influence of sensing element length of no-core fiber strain sensor has been studied and experimentally demonstrated, four different lengths of 125 μm diameter no-core fiber is fused between two standard single-mode fibers and bi-directionally strained, the highest obtained sensitivity was around 16.37 pm με -1 which was exhibited in the shortest no-core fiber segment, to the best of our knowledge this is the first study of the influence of no-core fiber strain sensors length on sensor sensitivity. The proposed sensor can be used in many opto-mechanical applications such as, structural health monitoring, aerospace vehicles and airplane components monitoring.
Accurate description of thermodynamic, structural, and electronic properties for bulk and surfaces of ceria (CeO2) necessitates the inclusion of the Hubbard parameter (U) in the density functional theory (DFT) calculations to precisely account for the strongly correlated 4f electrons. Such treatment is a daunting task when attempting to draw a potential energy surface for CeO2-catalyzed reaction. This is due to the inconsistent change in thermo-kinetics parameters of the reaction in reference to the variation in the U values. As an illustrative example, we investigate herein the discrepancy in activation and reaction energies for steps underlying the partial and full hydrogenation of acetylene over the CeO2(111) surface. Overall, we find th
... Show MoreThe current study entitled (the influence of heritage in the ceramic sculpture of the America Potter Paula Rice)
The study is based on four chapters:
Chapter I included structural find of clarification of the research problem and its importance, also included a mention of the research limits and the aim of this study, which is:
-Identify sculptures Ceramic affected ranges for Potter Paula Rice civilization heritage of intellectual and artistic, whether global or local.
-Trying to detect and intellectual influences the formalism of inherited and which resulted in the latest version of the unfinished ceramic artist.
-Did the artist callback method to the values inherent succeeded in the embodiment of the meaning of originali
Background: Hypertension is a chronic medical condition in which the blood pressure in the arteries is elevated, it's classified as either primary (essential) hypertension or secondary hypertension, and it increases the risk of ischemic heart disease, peripheral vascular disease and other cardiovascular diseases. Several classes of medications collectively referred to as antihypertensive drugs like beta blockers, calcium channel blockers, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers, renin inhibitors and statins (HMG-CoA) reductase inhibitor. Statin medication may have some beneficial effects when subjects have dental plaque or signs of periodontitis as gingival bleeding. The purpose of this study were to as
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