نتایج جستجو برای: enamel crack
تعداد نتایج: 34861 فیلتر نتایج به سال:
BACKGROUND The objective of this study was to study the potential protection effect of different treatments against sound enamel demineralization around orthodontic brackets. METHODS This is an in vitro randomized controlled study; artificial enamel demineralization of human premolars was created and compared with reference to control. The three materials used for enamel treatment were resin ...
An assessment of the plasticity-induced crack-closure concept is made, in light of some of the questions that have been raised on the validity of the concept, and the assumptions that have been made concerning crack-tip damage below the crack-opening stress. The impact of using other crack-tip parameters, such as the cyclic crack-tip displacement, to model crack-growth rate behavior was studied...
Dental scientists are eagerly embracing regenerative medicine using tissue engineering technology. Enamel, one component of teeth, is the hardest tissue in the body. It cannot regenerate by itself, because it is formed by a layer of ameloblasts that is lost by the time the tooth crown has completely formed. Although the enamel is spent during lifetime, it is vulnerable to wear, damage, and deca...
the study of air infiltration into the buildings is important from several perspectives that may be noted to energy and design of hvac systems, indoor air quality and thermal comfort and design of smoke control systems. given the importance of this issue, an experimental and numerical study of air infiltration through conventional doors and windows has been explored in iran. to this end, at fir...
The aim of this study was to evaluate and compare the effects of resin infiltration and sealant type on enamel surface properties and Streptococcus mutans adhesion to artificial enamel lesions. Artificial enamel lesions were produced on the surfaces of 120 enamel specimens, which were divided into two groups: Group A and Group B (n=60 per group). Each group was further divided into four subgrou...
poor stand establishment of canola (brassica napus l.) under flatland mechanized planting and crust-forming soil is a major problem for farmers in central iran. previous research there showed that irrigated cotton emergence on crust-forming soils under flatland planting can be significantly improved using a double-disk planter with zero-pressure press wheel tires and no crust-breaking. in that ...
AIMS Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. MATERIAL AND METHODS Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% sa...
Fatigue crack growth can be strongly influenced by crack closure, i. e., the contacting of the opposing faces of a fatigue crack above the minimum load in a loading cycle. This crack closure shields the crack tip from the full stress field, but different views are held regarding the extent of this shielding. The type of closure, whether it be plasticity-induced, or roughness-induced may also pl...
Role of cusp coverage in the protection of unsupported enamel in posterior composite restorations Dr. A. Pahlavan* /Dr. AH. Taheri** *-Assistant professor of Operative Dentistry Dept-Faculty of Dentistry- Tehran University of Medical Sciences. **- Dentist. Background and aim: Removal of unsupported enamel is one of Block's important principles in cavity preparation. The aim of this study was to...
This study evaluated the effect of antioxidant agents on microtensile bond strengths (μTBS) of composite to bleached enamel. Fifteen freshly extracted human third molars were selected and randomly assigned to 6 groups (n = 5): (NB) enamel not bleached, (B) bleached enamel, (BR7) bleached enamel and restored 7 days later, (BSA) bleached enamel+sodium ascorbate, (BMC) bleached enamel+malvidin chl...
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