A scanning electron microscope study of dentinal tubules from un-erupted human teeth.

Twelve fully-formed human third molars were obtained immediately after extraction, the roots removed, the crowns split into buccal and lingual portions fixed in Karnovsky solution and either left in the mineralized state or demineralized in a formic/citric acid solution. Specimens were dehydrated, critical point dried and examined by SEM. Demineralization of the teeth resulted in the loss of peritubular dentine and the appearance within each tubule of a sheet-like structure which extended from the predentine-dentine junction to the dentine-enamel junction. This sheet-like structure, here termed the lamina limitans, may play a role in the control of peritubular dentine formation.