On 606 retrieved oral and cranio-facial implants. An analysis of consecutively received human specimens

Abstract

Aim:The aim of the present thesis was to histologically and histomorphometrically analyse retrieved human specimens of oral and cranio-facial implants, and to address the clinical relevance of a retrieval bank.Materials and methods:The specimens analysed were submitted to the retrieval bank at the Department of Biomaterials / Handicap Research. Samples have continuously been received since the early 1980s and new samples are added to the retrieval bank even today. The analyses performed have all addressed consecutively received samples. The tissue response to the implants was, qualitatively and quantitatively, evaluated in undecalcified cut and ground sections in the light microscope.Results:A variation in degree of bone anchorage was found for the evaluated implants. Bone anchorage, as expressed in percentage of bone to implant contact, was increased for loaded implants compared to unloaded implants. In retrieved samples from grafted sites, the autografts showed a seemingly mixed viability. The evaluation of implants retrieved from irradiated sites demonstrated the possibility to achieve bone anchorage of implants in irradiated tissue. However, due to the limited material further analyses of bone response in relation to radiation dose was not performed.Conclusions:For implants clinically regarded as successfully osseointegrated at the time of removal, a mean value of bone to implant contact for the three best consecutive threads was for maxillary implants 59% ±21 (16-86) and for mandibular implants 80% ±22 (9-100).Due to incomplete clinical records in relation to the submitted implants, it was seldom possible to couple clinical information to the histological results. A close collaboration with the clinicians providing retrieved samples is necessary to secure that ultimate information is submitted in each case. Furthermore, experimental human retrievals studies with clear inclusion/exclusion criteria can be a useful source of information with regard to the tissue response to implants.