Background: Thermocycling simulates the temperature dynamics in the oral environment. This in vitro study done to measure and compare the effect of thermocycling on the shear bond strength of stainless steel and sapphire brackets bonded to human enamel teeth using light cured orthodontic adhesive and debonded at various time, and to measure adhesive remnant index after debonding. Materials and Methods: one-hundred-twenty extracted upper first premolars for orthodontic reason were used in this study; depending on weather thermocycled or not, the sample was divided into two main groups, then within each group 30 teeth were used for stainless-steel brackets (Bionic®) and for sapphire brackets (Pure®). Both groups were subdivided into three groups (n = 10) according to the debond times: I: debond after 24 hour, II: debond after 7 days and III: debond after 30 days. Within 24 hr, half of the sample was thermocycled manually for 500 complete cycles between 5/55°C and the remaining sample was stored in distilled water at room temperature and water was changed daily until debond time for each group was performed. The adhesive remnant index was tested under 20X magnification lens using stereomicroscope. Results and Conclusions: Both bracket types demonstrated high shear bond strength values before thermocycling (P?0.05), whereas after 500 thermocycles, there were significant changes in shear bond strength resulted in marked reduction in the stainless steel brackets than in the sapphire brackets (P?0.05). Shear bond strength values increased with time for both stainless steel and sapphire brackets with and without thermocycling (P?0.05). The tendency of bond failure was increased at the bracket/adhesive interface rather than enamel/bracket interface in the stainless steel brackets whereas at the enamel/bracket interface rather than bracket/adhesive interface in the sapphire brackets.
KE Sharquie, AA Noaimi, AA Zeena, IOSR J Dent Med Sci, 2015 - Cited by 5
Numerical study is adapted to combine between piezoelectric fan as a turbulent air flow generator and perforated finned heat sinks. A single piezoelectric fan with different tip amplitudes placed eccentrically at the duct entrance. The problem of solid and perforated finned heat sinks is solved and analyzed numerically by using Ansys 17.2 fluent, and solving three dimensional energy and Navier–Stokes equations that set with RNG based k−ε scalable wall function turbulent model. Finite volume algorithm is used to solve both phases of solid and fluid. Calculations are done for three values of piezoelectric fan amplitudes 25 mm, 30 mm, and 40 mm, respectively. Results of this numerical study are compared with previous b
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Background: Oral Lichen Planus (OLP) is a chronic inflammatory mucosal disease, presenting in various clinical forms WHO had regarded OLP as a precancerous conditions in 1978 because of its potential with cancer. Both antigen-specific and nonspecific mechanisms involved in the pathogenesis of OLP. Oral Squamous Cell Carcinoma (OSCC) is the most common malignant neoplasm of the oral cavity representing more than 94% of oral cancer. It occurs in different sites and has many etiological factors. Cyclin Dl is a proto-oncogene which consider as the key protein in the regulation of cell proliferation and its overexpression led to the occurrence and progression of malignant tumors.NF-KB p65 is a member ofNF-kB family of transcription factors that
... Show MoreThe aim of the current research is to study the effect of adding green tea to the edible film prepared from the whey protein isolate on the effectiveness of microorganisms and evaluating the of antimicrobial effectiveness of these films on Iraqi soft cheese packaging during the nine days of storage as an alternative to commercial packaging. At the beginning of the study, the minimum inhibitory concentration was measured by calculate the diameter of the zone of inhibition on growth of the bacteria and it's included the group of Gram negative bacteria (Escherichia coli, Salmonella spp, Pseudomonas Aeruginosa) and the group of Gram positive bacteria (Staphylococcus Aureus, Bacillus spp) and a yeast (Candida Albican). Where the diameter of t
... Show MoreThe world of Contemplations is a controversial concept among scholars, writers, thinkers and the public. The theory of the dialogue of souls indicates that souls communicate and think with each other despite the distances. Islamic studies have researched this concept, and this research paper aims to explain the concept of the world of Contemplations and what is the dialogue between God Almighty and the souls that God brought forth from the back of Adam and took from them the covenant and pledge to unify Him, and its effects on human life in this world. The researcher found that scholars and writers differ in proving the existence of the world of Contemplations despite the existence of examples of it in verses of the Holy Quran, and that the
... Show MoreThe paper tries to explore the grammatical phenomenon of rankshift in Systemic Grammar, a functional grammar that establishes five units or the rank scale , : namely sentence, clause phrase, word and morpheme .Rankshift a Hallidayan term , occurs when a given unit is downgraded or shifted down the rank scale and operates further down its rank or a rank equal to itself as when a clause which has to operate in sentence structure operates at q “ qualifier” in a nominal group. The paper , quite significantly, introduces the systemic background that enunciates the systemic theory whose organising concept system rather than structure. The paper then, grammatically explores rankshifted elements, successive rankshifting, degrees of rankshifting
... Show MoreAim: The purpose of this study is to compare the effect of epineurotomy of median nerve with just division of the transverse carpal ligament in the treatment of carpal tunnel syndrome. Patients & Methods: We conducted a prospective, random study to evaluate the effect of epineurotomy on the outcome of operative treatment of established median-nerve compression in the carpal canal. Fifty hands (forty-four patients) were selected randomly into two groups: group I had a release of the transverse carpal ligament alone, and group II had a release and adjuvant epineurotomy of the median nerve. The groups were similar with regard to age group, gender, duration of symptoms, and preoperative physical findings. All patients had electrophysiological e
... Show MoreOf non-Muslim minorities In the Muslim community