To rehabilitate most cases of
conductive hearing loss closure of ear drum perforations and rebuilding of the ossicular chain can be performed. Due to the great number of biocompatible
bone substitute materials available it is occasionally difficult for the surgeon to choose the most favorable substitute. Autogenous structures (ossicles, cortical bone, cartilage) and allogenous tissues (ossicles, cortical bone, cartilage, dentin) are possible
bone replacement materials. Xenogenic tissue is currently not used in middle ear surgery. Ionomer cement is a hybrid material for replacement of bone but does not fit direct classification of the various classes of alloplastic materials in current use: that is, metals (
gold, steel wire,
platinum,
titanium), plastics (
polyethylene, polytetrafluorethylene) and ceramics (ceramic
oxide,
carbon,
calcium-phosphate ceramic, vitreous ceramic). For restoration of the sound conductive apparatus preference is given to autogenous ossicles because cortical bone is resorbed and cartilage weakens over time. Most surgeons do not use allogenous tissue, because of the possible transmission of such
infectious disease as immunodeficiency syndrome or
Creutzfeldt-Jakob disease. Only dentin deserves special attention as a possible
bone substitute in the middle ear because its form can be preserved during sterilization. Based on the observations available to date, it becomes apparent that
titanium implants hold greater promise than
gold. Form-stable synthetic materials are not generally recommended due to
foreign body reactions which have been confirmed by many investigators. Ceramic materials (e.g. ceramic
oxide,
carbon,
calcium-phosphate ceramic, glass ceramic) are well tolerated in the middle ear and have also proved to be useful over time. Hybrid
bone substitute ionomer cement is easily workable and well integrated, showing a good functional outcome. For many years good results in
otosclerosis surgery have been achieved with a
prosthesis made of
platinum-wire and
Teflon. Short-term follow-up periods hold great promise with pistons made of
gold. Autogenous ossicles, ionomer cement and recently
titanium protheses--as far as usable--are employed by the author for reconstructing the middle ear. For the time being
platinum-
Teflon prostheses and
gold are used in
otosclerosis surgery.