STRUCTURAL AND FUNCTIONAL-CHANGES IN ROOT DENTIN FOLLOWING EXPOSURE TO KTP 532 LASER/

The use of a new, modified Nd:YAG laser called the KTP/532 laser was e valuated within root canals to determine whether it would modify denti n permeability or alter the scanning electron microscopic appearance o f canal dentin. Energies and exposure times were chosen which did not permit periodontal temperatures to increase above 5-degrees-C (1 W x 1 s-5 W x 0.5 s). Half of the root canals were covered with smear layer and half were treated with EDTA/NaOCl to remove the smear layer. The results showed that this laser did not change the permeability of the smear layer-covered dentin, although scanning electron microscopic exa mination revealed modifications to the surface of smear layer. Lasing of etched dentin produced modest increases in root permeability which were associated with enlargement and cracking of tubule orifices.