نتایج جستجو برای: universal testing machine

تعداد نتایج: 682925  

شهریار جلالیان متین هداوند

زمینه و هدف: هدف این پژوهش، مقایسۀاستحکام باند برشی بین کامپوزیت رزین و گلاس اینومر اصلاح­شده با رزین (RMGI) با استفاده از باندینگ­های مختلف، در ضمن استفاده ازSandwich Technique  می‌باشد. روش بررسی: در این مطالعۀ آزمایشگاهی، 60 بلوک از جنس RMAGI به شکل مربع cm1×1 و ارتفاع mm 5 تهیه و به 5 گروه 12 تایی تقسیم شد. استوانه‎های کامپوزیتی به قطر mm5/2 و ارتفاع mm5 ...

Azin Jahan Nia Hamideh Sadat Mohammadipour Mohammad Javad Moghaddas, Roya Amiri Daluyi

Introduction: To achieve acceptable clinical performance, a ceramic veneer must be bonded to enamel by well-polymerized resin cement. Among different factors, thickness and translucency of the ceramic may affect the resin cement polymerization. Thus, the current study evaluated the effect of the thickness and translucency of lithium disilicate ceramic on light-cured resin cement bond strength t...

Farhood Massoumi , Akram Mossaei, Alireza Hadi,

Objectives: Metal-ceramic restorations are the standard by which all esthetic restorations are measured. Fracture of dental restorations is a multifactorial problem, which is serious and costly. Debonding of porcelain from metal substructure and the bond strength depend on many factors. The purpose of this study was to determine whether or not the opaque porcelain thickness has a significant ef...

ژورنال: مجله دندانپزشکی 2006
یوسفی, محمدحسین, دانش‌کاظمی, علیرضا , داوری, عبدالرحیم , یاسائی, صغری ,

Background and Aim: With the introduction of different bondable restorative materials in dentistry, various methods have been suggested to enhance the polymerization and shear bond strength of these materials. The aim of this study was to determine the effects of different methods of enamel conditioning on bond strength of orthodontic brackets and on the bracket/ adhesive failure mode. Material...

Abolfazl Sabouri, Farhad Tabatabaian, Negar Barjini ,

Objectives: The present study evaluated the effect of bar and ball attachment designs on retention and stability of a mandibular overdenture supported by four implants. Methods: An edentulous mandibular acrylic resin model with four implants in the anterior part of the ridge (A, B, D and E) was fabricated. A metal framework simulating the overdenture was also fabricated. Totally, 30...

A wide range of materials and scaffolding fabrication methods for bone tissue engineering have beenexplored recently. Fiber reinforced polymers (FRP) system appears to be a suitable system. By the exclusiveuse of biocompatible or bio-absorbable polymers and fibers, novel generation of scaffolds for applicationsin tissue engineering can be prepared. Mulberry Silk as highlighted...

Introduction:Various methods are applied in order to restore maxillary premolar teeth which show much decay, though some inconsistencies have been reported in regard with the rate of fracture strength in different studies. Therefore, in this study, fracture resistance of buccal cusp was compared via 5 different types of restorations. Methods: In this experimental study, 75 intact extracted max...

جعفر زاده کاشی, طاهره سادات, عطایی, ابراهیم, فاضل, اکبر, مقتدر نژاد, ساحل,

Introduction: The purpose of this in vitro study was to introduce the fiber reinforced composite bridges and evaluate the most suitable site and position for placement of fibers in order to get maximum strength. Methods: The study included 20 second premolars and 20 second molars selected for fabricating twenty fiber reinforced composite bridges. Twenty specimens were selected for one fiber la...

Journal: :Journal of prosthodontics : official journal of the American College of Prosthodontists 2004
Periklis Proussaefs

PURPOSE This study evaluated the effect of different cements on resistance to dislodgment of crowns cemented on preparations lacking geometric resistance form. MATERIALS AND METHODS A preparation that offered no geometric resistance form, with 20 degrees total occlusal convergence (TOC), 0.9 mm wide shoulder finish line, and a 2.5 mm axial wall height was created on an ivorine tooth using a m...

2007
Eva Fǐserová

A linear regression model, when a design matrix has not full column rank and a covariance matrix is singular, is considered. The problem of testing hypotheses on mean value parameters is studied. Conditions when a hypothesis can be tested or when need not be tested are given. Explicit forms of test statistics based on residual sums of squares are presented.

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