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Effects of Nd:YAG lasers on root canal walls: a light and scanning electron microscopic study
F Barbakow1, O Peters, L Havranek
1Department of Preventive Dentistry, Periodontology and Cariology, University of Zurich, Switzerland. barbakow@zzmk.unizh.ch
Objective:
This study evaluated amounts of debris, smear layer, and recrystallized dentin on root canal walls treated with an Nd:YAG laser. The presence of carbonized material was also assessed.
Method And Materials:
The root canals of 36 extracted incisors were prepared by stepdown and stepback techniques and divided into 4 groups. One group was not treated further, while 3 others were exposed to the laser beam at an energy density of 159, 239, or 318 J/cm2. The roots were split longitudinally, photographed, and examined using a scanning electron microscope. The amounts of debris, smear layer, and recrystallized dentin were recorded from horizontal bands around the root, 2, 6, and 10 mm from the apices.
Results:
Mean smear layer scores were similar for all groups at the 3 levels examined, ranging from 2.157 to 2.851 on a scale of 0.0 to 3.0. Mean debris scores were similar for all groups at the 3 levels examined, ranging from 0.774 to 1.408 on a scale of 0.0 to 3.0. Recrystallized dentin was recorded in all 3 irradiated groups at the 2-mm level, but only in the group irradiated with 318 J/cm2 at the 6- and 10-mm levels. Severe carbonization was recorded at the 2-mm level.
Conclusion:
Use of the Nd:YAG laser did not reduce the mean amounts of debris and smear layer compared to a nonirradiated group. Carbonization was recorded in the apical part of the canal, but this is not obvious when only scanning electron photomicrographs are examined.