Scanning electron microscopy
Cells on dentine were fixed in 4% glutaraldehyde, dehydrated via graded alcohol solutions then graded (50% to 100%) hexamethyldisilazane solutions (Sigma-Aldrich, MO, USA), then air-dried. Dentine slices were then mounted onto aluminium stubs (EMS, Hatfield, PA, USA), sputtered with gold, and examined using a scanning electron microscope (Philips SEM 505, Best, Netherlands).