A scanning electron microscopic observation of etched human peritubular dentine

Thirty permanent human teeth were fractured immediately after extraction and fixed with 10 per cent neutral formalin or cold acetone. The fractured surfaces were etched with 1/20 N and 1/200 N formic acid for 5–20 and 30–200 sec, coated with gold and the fractured surfaces of the dentine were studied with a scanning electron microscope.

In the dentine, intertubular dentine, peritubular dentine and Tomes fibres were distinguishable with these techniques. While the entire peritubular dentine showed a mild resistance to acid treatment, a layer of greater insolubility was also found contiguous upon the dentinal tubules. This probably represents an inner hypomineralized layer.