Evaluation of shape and size changes of bone and remodelled bone substitute after different fixation methods.

Suitable tissue fixation is indispensable to histological analysis. This investigation, therefore, sought to evaluate changes of shape and size of bone specimens and remodelled bone substitute material following different fixation methods. Mandibular bones of 9 pigs (Sus scrofa domesticus) served as specimens. Two mandibular premolars were extracted respectively and the extraction alveoli were filled with synthetic bone substitute material. The samples were collected after 70 days. Fixation of 6 specimens respectively was done for 7 days in 4% formalin (formaldehyde), 70% ethanol and glycerol at 18 degrees C room temperature. The samples were radiographically examined before and after fixation using a reference specimen and subsequently underwent histological analysis. After fixation in formalin, the samples showed no size changes. After fixation in glycerol, morphological analysis revealed minor shape changes. Fixation in ethanol causes shrinking of the tissue specimens. Histological inspection of the tissues shows no morphological changes except slight shrinking. In conclusion there is no universal fixative that could met all requirements and permited proper examination without affecting tissues or bone specimens.