Otosclerosi: indagine morfologica e microchimica quantitativa

The degree of mineralization in 35 footplates (28 otosclerotic obtained from patients who underwent stapedectomy and 6 normal obtained from patiens who underwent labirintectomy for sever Menieres disease, as control group) has been detected by quantitaive electron microprobe analysis. The optimal section of samples for the analysis were obtained by grinding the footplates (embedded in Epoxic resin) with Boron Carbide and then polished with a diamond past. A scanning electron microscope (SEC) ETEC autoscan, operating at 15 KV, and an energy dispersive system (EDS) EEDS ORTEC for the X-ray analysis, were employed to analyze elements with athomic number higher than 10. Natural chloro.apatite was used as standard and a modified computer program was used to convert the X-ray counts to wight percent oxides. Several points of analysis were carried out between core and rim, or rim to rim, of samples; this method gives an accurate evaluation of spot chemical composition. The total ammount of demineralized tissue (Δ), the Ca/P ratio (competent to Octacalciumphosphate OCP) increased and well-defined Aluminium content. Sclerotic footplates show a modified structure due to numerous irregular lacunae enclosed by well mineralized bone with Ca/P ratio (copetent to Hydroxyapatite HA) and absence of aluminium. Even though at present we cannot explain the presence of Aluminium, the finding of OCP in the spongiotic lesion may play an important role in the explanation of chrystallochemical action of Sodium FLuoride in the treatment of otosclerosis.