Development of hip joint simulators / 中国医疗器械杂志

Currently, hip replacement is an effective treatment for some hip joint diseases. The friction and wear of a prothesis in the human body are the main causes for the failure of joint arthroplasty. It is, therefore, very important to simulate the working conditions of a hip prosthesis in order to get an optimal design and successful clinical applications. This article summarizes wear testing methods of hip prostheses and the developing status of their simulators. Three key aspects of the simulators, i.e., the structures, motions and lubrications, are analyzed in detail. At the end, the developing trend of the simulators are discussed.

Analysis of the fracture processes in all-ceramic crowns by finite element analysis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the effects of core material and design on the fracture mechanism of veneered all-ceramic crowns.</p><p><b>METHODS</b>The fracture process of 6 veneered alumina or zirconia crowns with different core design (well-distributed core, not well distributed core, and core with cervical ring) under load was analyzed by RFPA'2D finite element analysis software.</p><p><b>RESULTS</b>All the six tested crowns fractured due to tension failure, and the crack started at the porcelain in the cusp and spread along the interface between core and porcelain. Under the conditions of this test, the break was only related to the porcelain and not the core, and the crack of porcelain took place earlier in zirconia crowns than in alumina crowns. Minimum stress distribution in cervical ring core design crown and maximum stress distribution in not well distributed core design crown could be seen at the neck area.</p><p><b>CONCLUSIONS</b>Zirconia crowns presented greater stress at the interface between core and porcelain than alumina crowns. The not well distributed core design did not increase the rise of break. The neck area was the weak area with tensile stress concentration in the cervical ring core design.</p>