gms | German Medical Science

Introduction: For development of new materials for reconstruction of the ossicular chain it is important to represent the position of the prosthesis in situ. Additionally the histological examination of surrounding tissue is essential for the evaluation of biocompatibility of new materials. The micro-grinding procedure allows examination of bony as well as soft tissue structures.

Materials and methods: In an experimental animal study 80 petrous bones were extracted. Specimens were fixated in glutaraldehyd for two hours. An increasing concentration of ethanol was used to dehydrate the preparations. For 8 hours samples were placed in a drying cabinet at 65°C and were then embedded in epoxy resin. A special micro-grinding machine was used for grinding and polishing the surface, which was then stained with a three-fold-colouring by Mann-Dominici. Specimens were examined and photo-documented in at least five different planes by using a light microscope and an external cold light source.

Results: During macroscopic examinations surrounding structures and connection areas of the prostheses could be evaluated three-dimensionally. Additionally the position of the prostheses within the tympanic cavity could be documented optimally. Up to 32-fold magnification joining tissue and cells were differentiated very well by microscopic examination.

Conclusion: Compared with parafine-preparation a reproduction of middle ear structures without any shift of tissue and artefacts could be seen. However, consequent photo-documentation of those single planes is imperativ. This technique will provide valuable, additional information for the development and evaluation of new middle ear implants.