Production of artificial urinary stones from natural materials and their physical properties. First results.

Considered from a clinical point of view, all artificial stones known so far are inappropriate for experimental investigations, because they do not correspond to natural urinary stones in shape, physical properties and chemical composition. A special technique has now been developed for the production of biometric artificial stone models. Standard artificial carbonate apatite stones were produced by a coating technique where several layers of a suspension consisting of pure substance were applied around a core. Density and crushing strength of these ball-shaped artificial stones corresponded to natural apatite stones. Experimental chemolitholysis investigations showed comparable results in respect to the dissolution of artificial apatite stones and of natural stones of the same chemical composition. The disintegration behaviour was studied in ESWL tests which revealed a correlation between generator voltage and number of shock waves necessary for complete disintegration. For the first time, an artificial urinary stone has now been produced which is comparable to a natural stone of the same chemical composition not only in shape but also in its physical properties and lysis behaviour. These stones are suitable for use in systemic scientific investigations on disintegration and chemolitholysis.