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Biomedical subjects

J Zivko-Babić

Publications and source records attributed to J Zivko-Babić.

7 recordsLinked to original sources
PubMed2002

Bite force in subjects with complete dentition.

Bite force is the condition, expression and measure of the masticatory function. The purpose of this study was to examine, by means of a newly constructed electronic gnathodynamometer, the values of maximal bite forces in subjects with complete dentition, the time in which they express 50% and 75% respectively of the total forces value, and the shape of the bite curve during testing. The obtained data was statistically analyzed with respect to gender and age. Analysis of the variance confirmed the finding that there was no statistically significant correlation between the values of forces and subjects' age, but there was a statistically significant difference between males and females in the values of the bite forces in the front segment, as well as between the values of the force on anterior and posterior teeth. The correlation between the time T1 posterior right and T1 posterior left, and between T1 and T2 for anterior teeth are statistically significant. Analysis of the bite curves suggests that males "bite" shorter than females with a sharper peak of the curve. Numerical values and bite curves should be a diagnostic factor in the further follow-up of subjects or in the choice of prosthodontic therapy.

Adult↗
PubMed1998

Quantitative thin-layer chromatographic identification of dental base alloys.

In the corrosively aggressive medium of the oral cavity, the use of identical dental alloys requires identification of the existing metal construction. One of the methods allowing this identification is quantitative thin-layer chromatography with anodic sampling. Using a 4.5-V battery and suitable electrolytes, seven dental alloys for fixed and removable dentures based on cobalt were analysed. Chromatograms of alloy samples were developed with a mixture of acetone and 2 M HCl. Scanning of the thin-layer chromatographic spots produced chromatographic curves and the area under the curve was proportional to the content of cobalt in the alloy studied. Regression analysis showed a very high coefficient of correlation (r=0.999) between the area of the spot and the proportion of cobalt.

Chromatography, Thin Layer↗
PubMed1998

The simulation and calculation of the fatigue of the lower complete denture in function by means of the finite element analysis.

This paper presents a finite element analysis, by which the stress distribution during function of a lower jaw acrylic-resin complete denture can be shown. The geometry of a prosthesis has been approximated by measuring, its elementary dimensions, as well as the dimensions of the characteristic cross-sections, on an already completed denture. Based upon these dimensions a mesh, (a three-dimensional network diagram) of finite elements was made. The results obtained are presented both graphically and numerically. The equivalent fatigue stresses, according to von Mises' energetic theory of firmness, expressed in MPa (or in N/mm2), are also shown. The results obtained enable us to gain an insight into lower complete denture fatigue, and could also be used when optimizing the shape of a denture. Furthermore, they could indicate possible causes of the fatigue fractures of a denture, particularly in the area between the left and the right canines.

Acrylic Resins↗
PubMed1989

[Influence of heat treatment on silver-palladium alloy microstructure].

Cast dental alloys, even those made of precious metals, are not homogeneous. In order to ensure a high-quality cast, it was necessary to determine optimal casting temperature and additional heat treatment to allow for homogenization of the cast in the microarea of the dendritic structure to occur which, in turn, implies chemical inertia of the metal construction to the organic medium of the mouth. A number of melting, homogenizing and aging tests showed the optimal regimen for bringing an Ag-Pd alloy to the level of hardness of the tooth enamel (about 330 HV 0.1) to consist of a technological treatment involving the following procedures: casting at 1100--1150 degrees C, homogenization at 850 degrees C, quenching in water and 20-min precipitation at 350 degrees C.

Dental Alloys↗
PubMed1989

Analysis of metal diffusion from crown to the human teeth.

Proton induced X-ray emission spectroscopy (PIXE) has been used to determine the intensity of metals from crowns in human teeth. In order to measure elements distribution across the tooth section, proton beam (3 MeV) has been collimeted to provide a spatial resolution of 300 microns. The samples were selected according to the time of insertion of crowns and the kind of alloys they were made of. The results show the intensities of gold, zinc and copper in abutment teeth. It was not found any intensity of paladium and amount of silver was not significant.

Crowns↗