Preparation of extracted natural human teeth for SEM investigations.

Direct and indirect (replica) methods for investigating natural hard tooth tissues by scanning electron microscopy have been compared. The direct method requires an effective dehydration and drying procedure to avoid artefacts. A simple, fast and very effective procedure is described in this investigation. This recommends dehydration with differently concentrated mixtures of water/ethanol followed by mixtures of ethanol/acetone so that critical point drying can be avoided with regard to hard tooth tissues. The indirect method is carried out by taking impressions of the tooth surfaces with an addition-type polysiloxane. A positive model is manufactured from this impression using an epoxy resin. When investigated by scanning electron microscopy, the epoxy model reflects only very obscure pictures of the original tooth surface. The indirect method can only be recommended in cases where direct investigation is impossible. For instance, when non-extracted teeth are investigated or when extracted teeth are expected to be influenced by the dehydration and drying process.