A scanning electron microscope study of dentinal tubule continuity in monkey tooth sections

Abstract The American Dental Association (ADA) and Federation Dentaire Internationale (FDI) specifications for the biological evaluation of dental materials in experimental Cavities in dentine require that sections permit dentinal tubules to be followed from cavity floor to pulp lumen. The aim of this study was to investigate this requirement in the specification. Twenty hematoxylin and eosin stained sections of vervet monkey incisor teeth satisfying the ADA and FDI specifications were selected. Adjacent unstained sections of the same specimens were prepared for scanning electron microscopy, and a low power photomicrograph was taken of the dentine between the cavity floor and pulp for each specimen. Two areas on each photomicrograph were selected using a superimposed grid and random number table and this area was re-photographed at higher magnification on the specimen. A histometric analysis of the 40 SEM photomicrographs thus prepared showed that the dentinal tubules in 14 specimens were cut in cross-section, 14 were tangential and only 12 were longitudinal sections. None of die tubules examined in the high power photomicrographs was continuous. It is concluded that serial section evaluation of the area encompassing die entire cavity as well as a few sections before and beyond the cavity zone should be considered for inclusion in die specifications.