A study of human root cementum surfaces as prepared for and examined in the scanning electron microscope

Summary

The morphology of the cementum surface of human teeth was studied directly by scanning electron microscopy of 50 freeze-dried and 170 anorganic specimens. Extrinsic (Sharpey) fibres were found to occupy almost 100% of the surface in acellular cement, about 40% of the surface in cement with intrinsic fibres but no cells, and 15–40% in cellular cement, and averaged 6 μm diameter. Some areas with no extrinsic fibres resembled adult lamellar bone. The mineral front of the intrinsic fibres generally was similar to forming and resting lamellar bone; that of the extrinsic fibres varied according to the activity of the surface, but was normal to the axis of the fibre, even where these entered the surface at a sharp angle. Resorption bays were either small and isolated, often seen in newly erupted teeth; or, more rarely, large and quite deep where excessive force must have occurred.