Histologic evaluation of the effects of Er:YAG laser on bone ablation

The aim of the present study was to compare the healing of bone defects created using an Er:YAG laser with those defects created using a surgical bone drill.

Fourteen Wistar rats were used for this study. Femurs were perforated with a surgical bone drill, coupled to a micromotor (bur group) to create a bone defect. Another defect was created using a 2940 nm wavelength Er:YAG laser on the same femur (Er:YAG Group). The Er:YAG laser was used with a energy density of 1.5 W in noncontact mode under a water coolant. Incisions were then sutured with polyglycolic acid sutures. Seven rats were sacrificed at day ten and the other seven at day 20 to compare the status of bone repair of each group at those post-surgical intervals. The femurs were fixed with 10% neutral buffered formalin and decalcified in 10% EDTA. The specimens were embedded in paraffin and sectioned at a 5 micron thickness and stained with hematoxylin and eosin (H&E) stain. The specimens were examined at a magnification of X100 and scored using a standardized histologic scoring system.

Stages of bone healing including union, spongioza, cortex, and bone marrow development were evaluated and no significant difference between groups were found at days ten and 20 of healing. There was also no significant difference among the two groups in sum of histologic scores on day ten.

Bone can be ablated effectively and precisely using a Er:YAG laser without the vibration associated with steel surgical burs, but it is a slower process than when burs are used. There was no significant difference between the two groups in terms of bone repair at ten and 20 day intervals of healing.

Within the limits of this study a 2940 nm Er:YAG laser at 1.5 W can be used with confidence in cases requiring effective bone ablation.