Abstract: Objectives: To investigate the effect of temperature elevation on the bonding strength of resin cement to the zirconia ceramic using fractional CO2 laser. Background: Fractional CO2 laser is an effective surface treatment of zirconia ceramic, as it increases the bonding strength of zirconia to resin cement. Methods: Thirty sintered zirconia discs (10 mm diameter, 2 mm thickness) were prepared and divided to three groups (N=10) and five diffident pulse durations were used in each group (0.1, 0.5, 1, 5 and 10 ms). Group A was treated with 10 W power setting, group B with 20 W and group C with 30 W. During laser irradiation, temperature elevation measurement was recorded for each specimen. Luting cement was bonded to the treated zirconia surfaces and cured for 30 seconds. Shear bond strength was evaluated by a testing machine (universal) with bond failure mode determination. Results: The lowest temperature elevation measurement of the irradiated specimen which gave maximum shear bond strength was about 1.6±0.3 Ċ higher than ambient room temperature (27±0.2 ºC). Apparent micromechanical irregularities were seen in the treated samples and cracks formation with increased pulse duration and power setting were also observed. Conclusions: The temperature elevation is a vital factor in the surface roughness of zirconia ceramic with fractional CO2 laser irradiation and the lowest temperature elevation at best shear bond strength of zirconia ceramic to the resin cement is satisfied with the shorter pulse duration of 0.1 millisecond.
the most important purposes and uses of the test results in the educational sector. This is because the quality of tests is related to their ability to predict the learner's behavior in the future, and the accuracy of the educational and administrative decisions that are taken in light of their results. The study aimed accordingly to reveal the predictive ability of the university Grade Point Average (GPA) in the Score of the specialized test for the position of teacher in the Ministry of Education in the Sultanate of Oman. It further aimed to investigate the differences in the predictive ability according to the specialization and academic year using the descriptive approach. The sample of the study consisted of (349) s/he students enro
... Show More
Technology is an important factor for achieving architecture as an impact and vulnerability. It represents one of the significant elements in creating the intellectual framework, as well as having its own intellectual breakdown, while values constitute the most important and obviously factor of the community's intellectual. Research aims was determined accordingly by: investigating the role and impact of values and their relationship to technology in architecture.
In this context, the research investigated values and technology in architecture, through discussing their aspects and dimensions in architecture. In the context of values, the research discussed their concept and the related ones to have a concrete def
... Show MoreMany people, especially among the youth or scholars, wonder about the position of Islam or the scholars of faith on the terminology used by scholars of theology in a certain period of time, and then circulated by people throughout the times and to the present day, such as the terms (the old, the maker, the updated, the cause and the cause) and so on, and this What I felt myself while teaching this subject from some of the students, some of whom consider it blasphemy, and some of them consider it an innovation of speech, and so there were many questions about this subject, which led me to write and research it, after relying on God Almighty, although the research is not long due to the nature of This topic on the one hand, and because I d
... Show MoreToday, more than ever before, the business organizations’ initiatives should seek to design themselves and delivery them to the environment because of its change, and the increasing of uncertainties and the growing opportunities. What is required by the business organizations is that to adopt good approaches to stimulate the modern thinking and non traditional thinking and exploit the valued concepts and overcome the old thinking. Substantially, the scenario planning is the art of thinking about what is unexpected.
Therefore the research’s problem is reflected to answer the following questions:
- What
(1)
The reactions of ozone with 2,3-Dimethyl-2-Butene (CH3)2C=C(CH3)2 and 1,3-Butadiene CH2=CHCH=CH2 have been investigated under atmospheric conditions at 298±3K in air using both relative and absolute rate techniques, and the measured rate coefficients are found to be in good agreement in both techniques used. The obtained results show the addition of ozone to the double bond in these compounds and how it acts as function of the methyl group substituent situated on the double bond. The yields of all the main products have been determined using FTIR and GC-FID and the product studies of these reactions establish a very good idea for the decomposition pathways for the primary formed compounds (ozonides) and give a good information for the effe
... Show More
(12)
(10)
BACKGROUNDS Nasoalveolar molding (NAM) application is among presurgical management (PSM) techniques used for infants with cleft lip and palate (CLP). It helps to approximate the palatal cleft and to reshape the nasoalveolar complex prior to primary lip repair. This study aimed to explore types of PSM and the dental speciality provision for infants with CLP in Baghdad. The status of NAM usage and surgeons’ perceptions toward NAM usage were assessed. MATERIALS AND METHODS This is a cross-sectional paper-based questionnaire study that collected responses of surgeons perform primary lip and nose repair regarding PSM. The questionnaire was distributed amongst public and private hospitals in Baghdad. Twenty surgeons were enrolled (only those su
... Show More
(1)