This study was performed to evaluate the possibility of pulpal damage by measuring temperature change occured in dentin according to the thickness of dentin, the time of irradiation and the output of laser energy when the dentin surfaces were
irradiated
with Nd-YAG laser under water coolant and no water coolant.
Sound upper and lower molar teeth were sectioned with 1mm, 1.5mm and 2.0mm thickness of dentin discs and divided into 3 groups by dentin thickness. 0.5 watt, 1 watt, 1.5 watt and 2.0 wattenergied beam of pulsed 10 p.p.s of Nd: YAG laser was
applied
respectively to dentin surfaces for 8 secs and 16 secs when water coolant is used or not. And then the temperature changes occured in dentin were measured at opposite surfaces of laser-irradiated dentin surfaces with digital thermometer.
@ES The results were as follows.
@EN 1. When the amount of irradiated energy was same, the temperatue changes of dentin were higher as the thickness of dentin discs was thinner (p<0.01).
2. When the amount of irradiated energy and the thickness of dentin were same, the temperature changes of dentin were lower under water coolant than under no water coolant in all groups (p<0.01).
3. With the increase of time of irradiation, the temperature changes of Dentin became higher in all groups and were steeply increased at initial period of irradiation of laser.
4. Under the same thickness of dentin, the temperature changes of dentin became higher as irradiated energy was increased.
These results suggest that when the beam of Nd: YAG Laser is irradiated to dental hard tissue, amount of irradiating energy, thickness of dentin, using water coolant must be considered in order to minimize thermal damage of the pulp.
|