engleski

An analysis of dental magnets retentive force

When planning retention one of the most important tuks is to ensure that the construction, size and shape of the retention element enable the transfer of forces which the underlying tissue can withstand without damage. The aim of this study was to demonstrate the force of the magnetic retetention elements which are most frequently used. The study was performed on an apparatus especially prepared for the purpose. The study included ?8 pairs of Nd-Fe-B magnets. The values of retention forces between two parallelly placed magnets of the same or different dimensions were examined on this sample. The following vuiables were sttdied: diameter zed htigM of the magnets, mmual disutsce and paialklism, and measurement with a without lateral force. The results obtained ware statistically analysed by calculating arithmetic means, standar deviations, minimal and maximal values of vuriables and coefficient of vuriability. Correlation was examined by calculating the linear coefficients of correlation. Large differences in the measured values were observed, depending on whether the mutual force of attraction of the magnets was exposed to lateral force or not. It cen be concluded that the sverage value of retention forces of Nd-Fe-B magnets, at mutual distances of 0 mm amounts 288 cN in the semple with lateral force, and 340 cN in the sample without lateral force. The average value of retention force for Nd-Fe-B magnets, at mutual distances of 0.5 mm amounted to 196 cN in the sample with lateral force, and 230 cN in the sample without lateral force. Supported by Ministry .ef Science usd Txhnology, Republic of Croatia, Procject No.Oti5901.

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