Morphological changes of rat mandibular bone with ArF excimer laser in vivo.
OBJECTIVE
The purpose of this study was to investigate the morphological changes of bone tissue by ArF excimer laser irradiation in vivo.


BACKGROUND
Recently, it has been demonstrated that soft and hard tissues can be removed by excimer laser irradiation with little thermal damage.


METHODS
ArF excimer laser was irradiated on the surface of the rat mandibular bone using the following parameters: wavelength; 193 nm; output: 0.12 W; pulse repetition rate: 10 Hz; spot size: 1.0 x 4.0 mm; irradiation time: 90 and 120 seconds. The ablation depth was measured at 90 and 120 seconds. Furthermore, the irradiated surface was examined histologically using scanning electron microscopy (SEM).


RESULTS
The relationship between ablation depth and irradiation time was almost linear. Macroscopically, the ArF excimer laser beam produced a defect with clean-cut margins without carbonization in the mandibular bone. Histologically, there was minimal evidence of thermal damage to the surrounding tissue. The bottom of the defect revealed a sawtooth appearance. In SEM observation, mosaic structures corresponded to the sawtooth structures observed with light microscopy.


CONCLUSIONS
These findings suggest that it is possible to remove bone tissue using ArF excimer laser irradiation without thermal damage. The effectiveness of this laser can be attributed to the photoablation of the bone tissue.
Nakamura
Y
Y
Department of Endodontics, School of Dentistry, Showa University, Kitasenzoku, Ohta-ku, Tokyo, Japan.
Hossain
M
M
Watanabe
H
H
Tokonabe
H
H
Matsumoto
N
N
Matsumoto
K
K
D000818:Animals; D007834:Lasers; D008297:Male; D008334:Mandible / Q000528:radiation effects* / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar