Cyclic Fatigue of Different Nickel-Titanium Rotary Instruments: A Comparative Study

Since the introduction of nickel-titanium alloy to endodontics, there have been many changes in instrument design, but no significant improvements in the raw material properties, or enhancements in the manufacturing process. Recently, a new method to produce nickel-titanium rotary (NTR) instruments has been developed, in an attempt to obtain instruments that are more flexible and resistant to fatigue. NTR instruments produced using the process of twisting (TF, SybronEndo, Orange, CA) were compared to NTR instruments from different manufacturers produced by a traditional grinding process. The aim of the study was to investigate whether cyclic fatigue resistance is increased for TF NTR files. Tests were performed with a cyclic fatigue device that evaluated cycles to failure of rotary instruments inside curved artificial canals. Results indicated that size 06-25 TF instruments showed a significant increase (P< .05). In the mean number of cycles to failurewhen compared to the other tested 06-25 NTR. Hence, it can be concluded that size 06-25 TF NTR instruments were found to be significantly more resistant to fatigue than those produced with the traditional grinding process

HYGIENIC-SANITARY PROFILE OF HANDLED MEAT SOLD IN BULK IN SUPERMARKET CHAINS IN TERESINA-PI

This study objective was to characterize the hygienic-sanitary profile in ground beef, chilled chicken, ham and sausage manipulated and sold in bulk at supermarket chains in Teresina-PI. Samples of sausage, ham, braised chicken and ground beef sold in bulk were collected at five large supermarket chains in Teresina-PI, identified as SM1, SM2, SM3, SM4 and SM5. Forty samples were analyzed by Faust, Willis and Faust method adapted with alcohol-ether solution in triplicates. Fungus spores, hyphae fragments, eggs (hookworm and Ascaris lumbricoides) and parasite cysts (Entamoeba coli) were found in three of the five supermarket evaluated, as well as many body parts of insects as well as whole insects, these being fleas, mites and ants, in much greater quantities than permitted by law. In two of the five supermarkets chosen for the research no structures were found that could harm human health. It is necessary to implement good hygiene and care practices of meat storage at the analyzed supermarkets and to improve regulatory agencies inspections. In addition, it’s important to promote health education for supermarket workers, in order to avoid food contamination