Effects of erbium,chromium:YSGG laser irradiation on canine mandibular bone.
BACKGROUND
Only relatively few reports have described the morphological effects on bone produced by erbium,chromium: yttrium,scandium,gallium,garnet (Er,Cr:YSGG) laser irradiation, and none has investigated the atomic changes or estimated the temperature increases involved. The objectives of this study were to investigate the morphological, atomic, and temperature changes in irradiated areas during and after laser irradiation, and to evaluate the cutting effect on canine mandibular bone in vitro.


METHODS
Two canine mandibular bones were cut into 3 to 5 cm pieces and irradiated by an Er,Cr:YSGG laser utilizing a water-air spray at 5 W and 8 Hz for 10 or 30 seconds. During and after laser irradiation, temperature increases in the irradiated areas were measured by thermography. The samples were then observed by stereoscopy and scanning electron microscopy to determine morphological changes and by energy dispersive x-ray spectroscopy to evaluate atomic alterations.


RESULTS
Regular holes or grooves having sharp edges and smooth walls were produced, but no melting or carbonization was observed. The maximum temperature increase was an average 12.6 degrees C for 30-second irradiation. The continuous time of a temperature increase of more than 10 degrees C was consistently less than 10 seconds. An atomic analytical examination revealed that the calcium:phosphorus ratio was not significantly changed between the lased and unlased areas (P>0.0 1).


CONCLUSIONS
These results showed that the Er,Cr:YSGG laser cuts canine mandibular bone effectively without burning, melting, or altering the calcium:phosphorus ratio of the irradiated bone.
Kimura
Y
Y
Department of Endodontics, Showa University School of Dentistry, Tokyo, Japan. yukimura@senzoku.showa-u.ac.jp
Yu
D G
DG
Fujita
A
A
Yamashita
A
A
Murakami
Y
Y
Matsumoto
K
K
D000818:Animals; D002118:Calcium / Q000032:analysis; D002857:Chromium; D004285:Dogs; D004577:Electron Probe Microanalysis; D004871:Erbium; D006358:Hot Temperature; D007834:Lasers; D008334:Mandible / Q000737:chemistry / Q000528:radiation effects*; D008855:Microscopy, Electron, Scanning / Q000379:methods; D010758:Phosphorus / Q000032:analysis; D013817:Thermography
D002857:Chromium; D010758:Phosphorus; D004871:Erbium; D002118:Calcium