Alteration of the intaglio surface of lithium disilicate glass-ceramic.

STATEMENT OF PROBLEM: Clinical adjustment of a lithium disilicate glass-ceramic (LDGC) restoration may necessitate its return to the laboratory for additional firing. Evidence of how the intaglio surface should be re-etched after internal adjustment, or after refiring, is lacking. PURPOSE: The purpose of this in vitro study was to investigate the effects of different sequences of etching, refiring, diamond rotary instrument adjustment, airborne-particle abrasion, and re-etching on the microstructure and surface roughness of the intaglio surface of heat-pressed LDGCs. MATERIAL AND METHODS: Heat-pressed LDGC specimens were ground with abrasive paper to produce a uniformly flat surface. The groups (n=3) were subjected to different combinations of etching, refiring, diamond rotary instrument adjustment, airborne-particle abrasion, and re-etching. X-ray diffraction was used to characterize the crystalline phases. Scanning electron microscopy and surface profilometry were used to characterize the microstructure and surface roughness. RESULTS: Qualitative differences were observed in the surface texture of specimens etched for different periods. Excessive etching revealed more of the underlying lithium disilicate crystallites and caused surface pitting for the longest etching period studied. Refiring altered the surface condition but did not completely remove the texture created by the original etching. Diamond rotary instrument adjustment resulted in appreciable surface damage and a higher mean value of measured surface roughness (with or without re-etching) than the other groups. Airborne-particle abrasion caused embedding of particles in the specimen surface, likely corresponding to the abrasion media, although this process resulted in qualitatively less surface damage than diamond rotary instrument adjustment. CONCLUSIONS: Excessive etching, refiring, and adjustment by airborne-particle abrasion or diamond rotary instrument result in qualitative changes in surface condition. Adjustment by diamond rotary instrument results in appreciable surface damage.

[Serum prohepcidin and other iron metabolism parameters in healthy adults]. / Ocena stezenia prohepcydyny na tle wybranych parametrów gospodarki zelazem w surowicy krwi ludzi zdrowych.

UNLABELLED: Hepcidin is a newly discovered iron metabolism regulator. It decreases iron absorption from the duodenal enterocytes and inhibits its release from the reticuloendothelial macrophages. The experiments on hepcidin and its precursor--prohepcidin seem very promising and underline the need to establish the reference intervals for these proteins and define the effects of age and sex on their concentrations. AIM: The aim of this study was to assess the impact of age and sex on serum prohepcidin concentration in healthy adults. MATERIAL AND METHODS: The study group consisted of 79 healthy volunteers (F-29, M-50) between 18 to 88 years of age. Healthy adults were divided into three groups according to age: group 1-33 healthy volunteers aged between 18-36, group 2-20 healthy volunteers aged between 38-53, group 3- 26 healthy volunteers aged between 58-88. Prohepcidin and ferritin concentrations were determined by enzyme-linked immunosorbent assays (ELISA). Serum iron concentration was measured on Architect c8000 System. RESULTS: In this work, we demonstrated that prohepcidin concentrations were significantly higher in group 3 (Me = 292,2 ng/ ml) in comparison with group 1 (Me = 150.7 ng/ml; p < 0.000001) or group 2 (Me = 118.1 ng/ml; p < 0.000001). We observed a positive correlation between age and prohepcidin concentration (R = 0.38; p = 0.001). The oldest group of volunteers also revealed significantly higher levels of ferritin and lower levels of serum iron in comparison with two groups of younger adults. Females showed significantly higher level of prohepcidin (Me = 226.51 ng/ml) than males (Me = 142.6 ng/ml; p = 0.01). We observed that females under 50 years of age had significantly higher levels of prohepcidin (Me = 290.9 ng/ml) in comparison with younger females (Me = 150.7 ng/ml; p = 0.0001), similar correlation was noticed in males (212.3 ng/ml vs 128.3 ng/ml; p = 0.007). CONCLUSIONS: Prohepcidin concentration increased significantly with age and was significantly higher in women than men. The results of our study show that serum prohepcidin concentration is age and sex dependent.