Thermal effect and morphological changes induced by Er:YAG laser with two kinds of fiber tips to enlarge the root canals.
OBJECTIVE
The aim of this study was to assess the application of Er:YAG laser root canal preparation using two fiber tip systems.


BACKGROUND
Previous studies have not shown the thermal effect of Er:YAG laser using cone-shaped fiber tip.


METHODS
The ability of Er:YAG laser to enlarge root canals at a pulse energy set at 30 or 20 mJ and constant pulse rate of 10 pps (pulses per second) was tested. A cone-shaped (84 degrees top angle) or a flat fiber tip of Er:YAG laser was used for comparison. Four groups of 15 artificial root canals with fixed dimension were prepared from bovine teeth. Irradiation was accompanied by sterilized distilled water spray (2 mL/min). The temperature changes on the root surface were recorded with an infrared apparatus, and the thermal images were captured with a thermocamera. The morphological changes of irradiated root canals were examined by a scanning electron microscope (SEM).


RESULTS
The mean temperature rises were 9.4 degrees C and 7.1 degrees C with the cone-shaped fiber tip at a pulse energy of 30 and 20 mJ, respectively, and were 11.0 degrees C and 6.5 degrees C with flat fiber tip at a pulse energy of 30 and 20 mJ, respectively. Marked difference in temperature change between the cone-shaped and flat fiber tips was noted at pulse energy of 30 mJ, but not at 20 mJ. The thermal distribution using the cone-shaped fiber tip (in contrast to the flat tip) had an elliptical shape around the fiber tip and was limited to the apical end of the root canals. SEM observation found that irradiation with cone-shaped fiber tip (in comparison to the flat tip) produced a cleaner surface.


CONCLUSIONS
Our results suggest that the cone-shaped fiber tip of Er:YAG laser produced fewer thermal effects and morphological changes as compared to the other type of fiber tip.
Department of Endodontics, School of Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan.
Bor Shiunn
BS
Lee
Jiiang Huei
JH
Jeng
Chun Pin
CP
Lin
Shigeru
S
Shoji
Wan-Hong
WH
Lan
D000818:Animals; D002417:Cattle; D003782:Dental Pulp / Q000473:pathology* / Q000528:radiation effects*; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D053685:Laser Therapy / Q000295:instrumentation*; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D009336:Necrosis; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*