Radioiodine therapy during the COVID-19 pandemic in a public reference hospital in Brazil: an experience report.

COVID-2019 has resulted in an emerging respiratory infection that has spread as a pandemic since January 2020. Nuclear Medicine Services and its workers experienced a dramatic change in their clinical routine. They were required to adjust protocols for this new health condition. Regarding radioiodine therapy (RIT), initial orientations were to postpone treatments. In Brazil, National Nuclear Energy Commission prepared guidelines. It authorized RIT to employ activities over 1850 MBq in an outpatient setting on an exceptional basis. This study reports the RIT experience of a Brazilian hospital during the COVID-19 pandemic, intending to evaluate the applicability of outpatient treatment employing over 1850 MBq of I-131 on a large scale. During referred period, 106 patients at our service had an indication for RIT, of which 58 agreed to participate in the research and provided informed consent. Majority of patients did not meet the minimum requirements for outpatient treatment using doses > 1850 MBq.

Mechanical integrity of cement- and screw-retained zirconium-lithium silicate glass-ceramic crowns to Morse taper implants.

STATEMENT OF PROBLEM: The improved esthetics of ceramic dental prostheses has increased their popularity, although their high elastic modulus and low fracture toughness and tensile strength may reduce the long-term performance of dental prostheses. PURPOSE: The purpose of this in vitro study was to assess the mechanical integrity of zirconium-lithium silicate glass-ceramic crowns cement- and screw-retained to a titanium implant-abutment after fatigue. MATERIAL AND METHODS: Forty titanium implants were placed in polyacetal to mimic bone support. Abutments were tightened to the implants to 20 Ncm by using a digital handheld torque meter. The implant abutment assemblies received a pressed maxillary premolar crown, either lithium disilicate (LD) or zirconium-lithium silicate glass-ceramic (LZS). The specimens (n=10) were subjected to fatigue at 200 N and 5 Hz for 500 000 cycles in a Ringer electrolytic solution (37°C). After fatigue, the crowns were removed to evaluate removal torque values on the implant-abutment connection. The remaining crown-implant-abutment assemblies were cross-sectioned at 90 degrees to the implant-abutment joint for inspection of cracks and the micro-gaps by scanning electron microscopy. RESULTS: Removal torque values before fatigue were recorded at 18 ±1.63 Ncm for the LD group and 18.2 ±0.81 Ncm for the LZS group. After fatigue, the removal torque values decreased significantly (12.8 ±1.6 Ncm for LD, 14.9 ±1.08 Ncm for LZS; P<.05). Micro-gaps at the implant-abutment connections were measured at 0.9 ±0.3 µm before fatigue and at 4.2 ±0.9 µm after fatigue. Cracks were detected at the crown adhesive or at the adhesive-abutment interface for both systems after fatigue. CONCLUSIONS: Cement- and screw-retained implant zirconium-lithium silicate glass-ceramic crowns revealed effective fatigue resistance on mean cyclic loading in an electrolyte solution. However, mechanical instability of the crown-adhesive-abutment interfaces and implant-abutment joints was detected after fatigue.

Physicochemical and biological assessment of PEEK composites embedding natural amorphous silica fibers for biomedical applications.

The main aim of this study was to assess the physicochemical and biological properties of a novel poly(ether ether ketone) (PEEK) composite containing 30%wt natural amorphous silica fibers (NASF). PEEK and NASF powders were previously functionalized by atomization and citric acid in order to enhance adhesion between polymeric matrix and fillers. Then, composites were produced by cold compression molding technique at 350°C for 3h. Materials were characterized by chemical, microstructural, thermophysical, mechanical and cytotoxic analysis. The results of the mechanical assays showed that the incorporation fibers increased the elastic modulus of the resultant PEEK composite in 56% while its microhardness increased in 26.7%. Chemical and microscopic analyses detected a good interfacial adhesion between PEEK and NASF. The results of the cytotoxicity assays indicated that PEEK/NASF composites stimulated the metabolic activity of fibroblasts and therefore a high cytocompatibility was noticed. PEEK composites embedding natural amorphous silica fibers revealed a high potential to be used in medicine and dentistry replacing several polymeric and composite materials.