Kinetic study of release of silicon compounds from polysiloxane tissue expanders.

The release behavior of typical commercial tissue expanders has been examined by carrying out two kinds of experiments: 1) Determination of chemical nature and its modification after in vivo use by X-ray photoelectron spectroscopy for chemical analysis. This study has been paralleled by scanning electron microscopy with associated energy dispersive X-ray analysis of surface, as well as by silicon compounds analysis of tissues around implants. 2) Kinetic examination of silicon compounds released by the biomaterial in physiologic solution at 36 +/- 0.3 degrees C. Results of these investigations have shown independently that the starting material was not a filler-free, pure polymer, but a composite, reinforced elastomer, with the reinforcing agent most seemingly represented by silicon dioxide. Release of latter, with a relatively fast kinetics, is compatible with data of the simulating laboratory runs in the physiologic solution. All these facts seem to rule out any hypothesis of a prevailing siloxane oligomer migration. The correlation of kinetic and physicochemical tests with the in vivo behavior is discussed.