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In this study, the MgAlTiFeNi high entropy alloy was processed by high-energy ball milling under both argon and hydrogen atmospheres. It is shown that this alloy forms a body-centered cubic (BCC) structure when milled under an argon atmosphere (mechanical alloying-MA) and a combination of BCC, FCC, and Mg2NiH4 when milled under hydrogen pressure (reactive milling-RM). The hydrogen storage behavior of the RM samples was evaluated by a combination of thermal analyses and manometric measurements in a Sieverts apparatus. The RM alloy presented a functional hydrogen storage capacity of 0.94 wt% and a very high hydrogen absorption and desorption kinetics at temperatures 100 °C lower than the one for the desorption temperature of the commercial MgH2. Electrochemical discharge of RM samples showed precisely the same hydrogen contend as that obtained in the gas desorption. Electrochemical charging/discharging experiments also were performed in the MA samples, which, however, presented lower electrochemical storage capacity, a behavior probably resulting from the instability of the alloy in the alkaline solution with the formation of a hydroxide layer on its surface that hinders the electrochemical reactions.

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<p align="justify"><span style="font-family: Arial, serif;"><span><span lang="en-US"><strong>Objective</strong></span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US">: The aim was to evaluate influence of different sterilization methods on cutting effectiveness and durability of cylindrical ultrasonic burs compared with conventional cylindrical diamond-coated burs. </span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US"><strong>Material </strong></span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US"><strong>and </strong></span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US"><strong>Methods</strong></span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US">: Fifteen conventional cylindrical diamond-coated (1092) (KG Sorensen) coupled to a high-speed turbine, and fifteen cylindrical ultrasonic (8.2137) (CVDentus</span></span></span>^{<span style="font-family: Arial, serif;"><span><span lang="en-US">®</span></span></span>}<span style="font-family: Arial, serif;"><span><span lang="en-US">) burs coupled to an ultrasound-handpiece were used to perform standardized cavity preparations in healthy bovine tooth fragments, cleaned with rubber cup, pumice stone and water. After every 10 preparations, burs were sterilized 9 times in autoclave (SA), oven (SO), or cleaned with brush, soap and water (C). Fragments were weighed and microphotographs of burs were taken at the beginning and end of experiment. Another 9 conventional diamond-coated and 9 CVD burs underwent the same sterilization cycles in autoclave (SAC), oven (SOC) or washed with soap and water (CC) however, without being used for making cavity preparations, serving as control. Descriptive analyses were made of the values found by weighing and microphotography scores. </span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US"><strong>Results</strong></span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US">: Statistically significant differences (Paired Student’s-</span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US"><em>t </em></span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US">test) were observed among burs after sterilization (p = 0.0001). SO and SA did not influence cutting effectiveness and durability of ultrasonic and conventional diamond-coated burs. The microphotographs showed morphological differences between the burs used for preparation and the control. </span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US"><strong>Conclusion</strong></span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US">: Sterilization by oven and autoclave did not influence cutting effectiveness and durability of CVD and conventional diamond-coated burs. Conventional diamond-coated burs presented greater structural alterations after performing cavity preparations and cleaning/sterilization procedures, irrespective of the process used.</span></span></span></p><p align="justify"><span style="font-family: Arial, serif;"><span><span lang="en-US"><strong>Keywords</strong></span></span></span><span style="font-family: Arial, serif;"><span><span lang="en-US">: cvdentus, sterilization, dental instruments, infection control.</span></span></span></p>

The austenitic stainless steel 316L is the most used metallic biomaterials in orthopedics applications, especially in the manufacture of articulated prostheses and as structural elements in fracture fixation, since it has high mechanical strength. However, because it is biologically inactive, it does not form chemical bond with bone tissue, it is fixed only by morphology. The development of biocomposites of stainless steel with a bioactive material, such as hydroxyapatite -HA, is presented as an alternative to improve the response in the tissue-implant interface. However significant reductions in mechanical properties of the biocomposite can occur. Different compositions of the biocomposite stainless steel 316L/HA (5, 20 and 50 wt. (%) HA) were prepared by mechanical alloying. After milling the powders for 10 hours, the different compositions of the biocomposite were compacted isostatically and sintered at 1200 °C for 2 hours. The mechanical properties of the biocomposites were analyzed by compression tests. The powders and the sintered composites were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

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