PURPOSE The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth w...

BACKGROUND AND PURPOSE Despite the longstanding use of micromotion as a measure of implant stability, direct measurement of the micromechanics of implant/bone interfaces from en bloc human retrievals has not been performed. The purpose of this study was to determine the stem-cement and cement-bone micromechanics of functionally loaded, en-bloc retrieved, cemented femoral hip components. METHO...

The aim of this review paper is to define the fixation of the cemented stem. Polymethyl methacrylate, otherwise known as "bone cement", has been used in the fixation of hip implants since the early 1960s. Sir John Charnley, the pioneer of modern hip replacement, incorporated the use of cement in the development of low frictional torque hip arthroplasty. In this paper, the concepts of femoral st...

BACKGROUND AND PURPOSE Many clinical reports have indicated that polished hip stems show better clinical results than rough stems of the same geometry. It is still unknown, however, what the mechanical effects are of different surface finishes on the cement at the cement-bone interface. We compared mechanical effects in an in vitro cemented hip arthroplasty model. METHODS Two sizes of double-...

Distal flow of polymethylmethacrylate (PMMA) bone cement during insertion of the femoral implant results in reduced pressure and cement-bone interdigitation (Markolf, Amstutz, 1976). Insertion of femoral cement plugs in the intramedullary canal to prevent distal flow of PMMA cement in total hip replacement during cementing of femoral prostheses is well accepted and has become current practice (...

Portland cement for high-temperature geothermal applications typically includes 35 to 40 percent crystalline quartz by weight of cement (BWOC) to avoid strength retrogression, which is defined as an increase in permeability and a decrease in compressive strength. Also, because of the reactivity of Portland cement at elevated temperatures, relatively expensive cement-hydration retarders are requ...

We investigate the performance of graphene oxide (GO) in improving mechanical properties of cement composites. A polycarboxylate superplasticizer was used to improve the dispersion of GO flakes in the cement. The mechanical strength of graphene-cement nanocomposites containing 0.1-2 wt% GO and 0.5 wt% superplasticizer was measured and compared with that of cement prepared without GO. We found t...

BACKGROUND Pedicle screws with PMMA cement augmentation have been shown to significantly improve the fixation strength in a severely osteoporotic spine. However, the efficacy of screw fixation for different cement augmentation techniques, namely solid screws with retrograde cement pre-filling versus cannulated screws with cement injection through perforation, remains unknown. This study aimed t...

a case of pleomorphic adenoma in sweat gland is reported here. the histopathologic report confirmed the diagnosis. pleomorphic adenoma is most common in salivary glands but very rare in sweat glands. pleomorphic adenoma in sweat gland and the similar tumors of eccring sweat gland are described that bear a striking resemblance to pleomorphic adenomas of salivary gland. upon closer examination, t...

In order to more accurately determine the mechanism by which retinoic acid causes embryonic defects, we have developed a simple method of locally applying retinoic acid rather than immersing the whole embryo in retinoic acid solutions. Retinoic acid was suspended in corn oil and then injected between the surface and the deep ectodermal layers of an early gastrula Xenopus embryo. When droplets c...