[The hardness and osseous structure of preserved ear ossicles].

The mechanical rigidity (breaking strength) of normal human ossicles, preserved with cialit and formalin, was studied in a tension compression testing machine. The bony structure of the ossicles before and after crushing was examined via high-grade magnifying radiography. With this new technique, minute bony details of the ossicles, which up to now could be demonstrated only histologically--consequently destroying the object--can be visualised without inflicting any changes to the ossicle. The different preservation methods had no effect on the structure or the mechanical strength of the ossicles. The fracture lines were distributed at random, with no preferential direction. In further experiments, defects in the ossicles' surfaces, which were cut with diamond burrs, were investigated radiographically and with a scanning electron microscope. The compressed bone dust seals up the opened marrow spaces. This reduces bone resorption significantly, as could be demonstrated with removed ossicular transplants similarly prepared, with had been implanted several years ago. The high grade radiographic magnification revealed that several ossicles which were removed during typical middle ear operations, were covered with metallic powder, originating from the intra-operative contact of the burr with the metallic suction tube. The 10% nickel component of the alloy may cause problems in patients with known nickel allergy, considering the intensive contact with the vast surface of the disseminated metallic dust particles.