نتایج جستجو برای: enamel crack

تعداد نتایج: 34861  

2015
Mona A Montasser Noha A El-Wassefy Mahasen Taha

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 ...

1998
James C. Newman

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...

2012
Masaki J. Honda Ken-ichiro Hata

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...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده فنی 1391

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...

Journal: :Dental materials journal 2015
Soley Arslan Yahya Orcun Zorba Mustafa Altay Atalay Suat Özcan Sezer Demirbuga Kansad Pala Duygu Percin Fusun Ozer

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...

Journal: :تحقیقات مهندسی کشاورزی 0
عباس همت استاد گروه ماشینهای کشاورزی، دانشکده کشاورزی دانشگاه صنعتی اصفهان سیدمجید عطایی دانش آموخته سابق کارشناسی ارشد مکانیک ماشینهای کشاورزی، دانشکده کشاورزی دانشگاه صنعتی اصفهان

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 ...

2014
Joanna Janiszewska-Olszowska Katarzyna Tandecka Tomasz Szatkiewicz Katarzyna Sporniak-Tutak Katarzyna Grocholewicz

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...

2011
Harris L. Marcus

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...

Pahlavan, Ayob, Taheri, Amir hossein,

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...

2011
Ana Carolina Botta Daphne Câmara Barcellos Clovis Pagani Carlos Rocha Gomes Torres José dos Campos

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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