OBJECTIVES To investigate the static frictional resistance at the bracket/archwire interface in two recently introduced bracket systems and compare them to conventional ceramic and conventional metal bracket systems. Three variables were considered including the bracket system, archwire type and archwire angulation. MATERIAL AND METHODS Four bracket systems were tested in vitro: Self ligating...

Nowadays in highly competitive precision industries, the micromachining of advanced engineering materials is extremely demand as it has extensive application in the fields of automobile, electronic, biomedical and aerospace engineering. The present work addresses the modeling and optimization study on dimensional deviations of square-shaped microgroove in laser micromachining of aluminum oxide ...

High-strength all-ceramic systems for fixed partial dentures (FPDs) is gaining popularity as an alternative to the well established metal-ceramic FPDs. Several new framework materials and technique such as lithium disilicate, aluminum oxide and yttrium tetragonal zirconia polycrystal have been developed with improved strength, marginal discrepancy and esthetics. Since not every all-ceramic syst...

The ceramic-on-ceramic bearing surface has high wear resistance and good biocompatibility in total hip arthroplasty (THA). However, the postoperative noise problem has been an important issue. The purpose of this retrospective study was to determine the incidence and risk factors of bearing surface-related noises in patients with third-generation ceramic-on-ceramic THAs. One hundred twenty-five...

abstract today, pottery in shahreza of isfahan is a valuable arts with its up and downs which has stabilized  its place among iranian pottery centers. the investigation of contemporary pottery in the course of  history shows that iranian potters have used predecessors' experiences, as well as remained  professions of pottery art such as soheili, bahari and fakhar, and tried to promote qual...

Several conditions in clinical orthopaedic practice can lead to the development of a diaphyseal segmental bone defect, which cannot heal without intervention. Segmental bone defects have been traditionally treated with bone grafting and/or distraction osteogenesis, methods that have many advantages, but also major drawbacks, such as limited availability, risk of disease transmission and prolong...

Creating lightweight, mechanically robust materials has long been an engineering pursuit. Many siliceous skeleton species--such as diatoms, sea sponges and radiolarians--have remarkably high strengths when compared with man-made materials of the same composition, yet are able to remain lightweight and porous. It has been suggested that these properties arise from the hierarchical arrangement of...