Bon(n)-stones - Standard stones for lithotripsy and chemolysis

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, struvite and brushite stones were produced by a coating technique where several layers of a suspension consisting of pure substance were applied around a core. Scanning electron microscopy investigations showed identical crystalline structures in artificial and natural stones. Density and crushing strength of these ball-shaped artificial stones corresponded to natural apatite and struvite stones (e.g. density struvite artificial vs. natural = 1.18-1.44 g/cm(3) vs. 1.12-1.89 g/cm(3); crushing strength carbonate apatite artificial vs. natural = 11.1 - 13.0 kp vs. 9.2-19.8 kp). Experimental chemolitholysis investigations showed comparable results in respect to the dissolution of artificial stones and of natural stones of the same chemical composition (e.g. struvite artificial vs. natural = 19.6 vs. 17.2 ml/h, p < 0.05). The disintegration behaviour was studied in ESWL tests which revealed a correlation between generator voltage and number of shock waves necessary for complete disintegration. These artificial stones (Bon(n)-Stones) fulfill all norms for a standard stone model and are suitable for use in systemic scientific investigations on disintegration and chemolitholysis.