These experiments aimed to investigate and compare the nature of the zone of secondary
damage in calvarial bone defect prepared with either XeCl excimer laser or the erbium: YAG
laser light at 75mJ/pulse. Material & Methods: These experiments were conducted in vitro,
using excised calvarial bone, which was examined by environmental scanning electron
microscopy (ESEM). Results: The excimer laser produced a morphologically different defect
in bone. It was smooth surfaced with extensive scattering of debris and cracking. Were the
Erbium: YAG laser slot showed less charring than XeCl excimer laser and the surface was
smooth with microspheratic pattern. Energy dispersive x-ray analysis showed that the
carbonisation and Ca/P ratio were higher in XeCl excimer laser defects compared to erbium:
YAG laser defects.
Key words. Bone, ESEM, x-ray, carbonisation, Calcium, Phosphate, laser