Speech may be affected by the transition from complete dentures to fixed prosthesis on osseointegrated implants (OIB). If so, is there any correlation between interdental spaces (open or closed) in the prosthodontic construction and deteriorated speech? 21 individuals advocated for maxillary OIB were randomised so that one half of the group got constructions with wide interdental spaces and the other half with minimised interdental spaces. All patients were examined audiologically and their speech was individually tape-recorded before and after treatment. Perceptual, acoustic, model and audiological analyses were made. Approximately 60% of the patients were judged to have indistinct speech after the treatment. The s-sound was perceptually and acoustically distorted. 67% of the patients suffered from hearing defects. No correlation between interdental spaces (open or closed) and deteriorated speech could be found. It is supposed, that hearing plays a part in the effort to adjust speech to a new maxillary OIB, and thus reduced hearing can enhance speech difficulties.