نتایج جستجو برای: fracture resistance

تعداد نتایج: 466446  

2010
Jong-Hyun Kim Sung-Ho Park Jeong-Won Park Il-Young Jung

The purpose of this study was to determine the effect of post types and sizes on fracture resistance in immature tooth model with various restorative techniques. Bovine incisors were sectioned 8 mm above and 12 mm below the cementoenamel junction to simulate immature tooth model. To compare various postand-core restorations, canals were restored with gutta-percha and resin core, or reinforced d...

2012
Vajihesadat Mortazavi Mohammadhossein Fathi Najmeh Katiraei Shirin Shahnaseri Hamid Badrian Navid Khalighinejad

BACKGROUND With the aim of developing methods that could increase the fracture resistance of structurally compromised endodontically treated teeth, this study was conducted to compare the effect of three esthetic post systems on the fracture resistance and failure modes of structurally compromised and normal roots. MATERIALS AND METHODS Forty five extracted and endodontically treated maxillar...

2012
Jasjit Kaur Navneet Sharma Harpal Singh

STATEMENT OF PROBLEM Techniques and recommendations for the restoration of endodontically treated teeth have changed from the use of custom cast metal post and core system to glass fiber-reinforced (GFRC) post and composite core system. Has this latest prefabricated glass fiber reinforced post and composite core system increased the fracture resistance of teeth and reduced the incidence of unre...

Buckling restrained braced frames (BRBFs) for seismic load resistance have been widely used in recent years. One of the key requirements for a buckling restrained brace is to sustain large plastic deformations under severe ground motions. The core of a buckling restrained brace is prone to fatigue fracture under cyclic loading. The earthquake induced fracture type of the core plate in a bucklin...

2015
G S Amarnath M U Swetha B C Muddugangadhar Radhika Sonika Ashu Garg T R Poonam Rao

BACKGROUND Endodontically treated teeth with posts are more prone to fracture. Hence, the purpose of this study was to investigate the in-vitro fracture resistance of devitalized teeth and mode of failure restored with posts of different materials and different lengths. MATERIALS AND METHODS Sixty freshly extracted human mandibular premolars were endodontically treated and then restored with ...

2017
Ae-Ra Kim Hyun-Pil Lim Hong-So Yang Sang-Won Park

PURPOSE This study evaluated fracture resistance with regard to ferrule lengths and post reinforcement on endodontically treated mandibular premolars incorporating a prefabricated post and resin core. MATERIALS AND METHODS One hundred extracted mandibular premolars were randomly divided into 5 groups (n=20): intact teeth (NR); endodontically treated teeth (ETT) without post (NP); ETT restored...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علم و صنعت ایران - دانشکده مهندسی مکانیک 1384

در این پایان نامه ابتدا به منظور آشنایی بیشتر با مواد سرامیکی، پس از ارایه تاریخچه مختصری از این دسته مواد، به معرفی مختصر از انواع سرامیک ها، خواص و کاربردهای متنوع صنعتی آن ها پرداخته شده است. سپس مفاهیم مکانیک شکست ترد و تاریخچه آن مختصرا شرح داده شده است. همچنین نظریه مکانیک شکست الاستیک خطی، فرضیات آن و پارامترهای موثر نوک ترک معرفی شده اند. در ادامه پس از آشنایی با محدودیت های ابعاد نمونه...

2012
Nadia Z. Fahmy

Statement of problem: A dowel is essential to retain the core in case of severe tooth destruction. However, the placement of a dowel and core may actually weaken teeth and affect their failure pattern depending on their material properties and stress transfer. Purpose: The present study compared the fracture resistance and failure pattern of endodontically treated premolars with different amoun...

2016
Shweta Sharma George Attokaran Kunwar S. Singh Jeethu J. Jerry Naima Ahmed Nirban Mitra

AIM AND OBJECTIVES Use of posts improves the physical properties of endodontically-treated teeth. Different post types are developed such as metal, custom-made, carbon, and quartz. The present study was conducted to evaluate the fracture resistance of glass fiber-reinforced, carbon, and quartz post in endodontically-treated teeth. MATERIALS AND METHODS Forty extracted human maxillary incisor ...

2013
Hyeon-Cheol Kim Sang-Won Kwak Gary Shun-Pan Cheung Dae-Hoon Ko Se-Min Chung WooCheol Lee

The use of reciprocating movement (RM) was claimed to increase the resistance of nickel-titanium (NiTi) file to fatigue in comparison to continuous rotation (CR). Recently two new brands of NiTi file have been marketed for use in a RM mode. The purpose of this study was to compare the cyclic fatigue resistance and torsional resistance of these two files; Reciproc and WaveOne. Cyclic fatigue tes...

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