Title:Maximum Temperature Through a Yttrium Stabilized Zirconia Ceramic After Er,Cr:YSGG Laser Irradiation
Volume: 3
Author(s): Laurel Stringer, Sarah Malley, Darrell M. Hutto, Jason A. Griggs and Susana M. Salazar Marocho*
Affiliation:
- Department of Biomedical Materials Science, School of Dentistry, University of Mississippi Medical Center, Jackson, MS,United States
Keywords:
Laser irradiation, zirconia, temperature, laser, Debonding, instrumentation.
Abstract:
Background: The most common approach to remove yttria stabilized zirconia (YSZ)
fixed-dental prostheses (FDPs) is by means of diamond burs attached to a high-speed handpiece.
This process is time-consuming and destructive. The use of lasers over mechanical instrumentation
for removal of FDPs can lead to efficient and predictable restoration retrievability. However, the
heat produced might damage the tooth pulp (>42˚C).
Objective: The purpose of this study was to determine the maximum temperature (T) reached during
the use of different settings of the erbium, chromium:yttrium-scandium-gallium-garnet
Er,Cr:YSGG laser through a YSZ ceramic.
Methods: YSZ slices (1 mm thick) were assigned to 7 groups. For the control group, a diamond
bur was used to cut a 1 mm groove into the YSZ slices. For the 6 experimental groups, the laser
was operated at a constant combination of 33% water and 66% air during 30 s with two different
power settings (W) at three frequencies (PPS), as follows (W/PPS): 2.5/20, 2.5/30, 2.5/45, 4.5/20,
4.5/30, 4.5/45. The T through the YSZ slice was recorded in degrees Celsius by using a digital thermometer
with a K thermocouple.
Results: The median T of the control group was 26.5˚C. The use of 4.5 W resulted in the median T
(˚C) of 44.2 at 20 PPS, 53.3 at 30 PPS, and 58.9 at 45 PPS, while 2.5 W showed 34.6, 31.6, and
25.0 at 20, 30, and 45 PPS, respectively. Kruskal-Wallis one-way ANOVA showed that within
each power setting, the T was similar. The high power and lowest frequency (4.5/20) showed no
significant difference from the 2.5 W settings and the control group.
Conclusion: The lower power setting (2.5 W) is a potential method for the use of the Er,Cr:YSGG
laser to debond YSZ structures. The higher power (4.5 W) with high frequencies (30 and 45 PPS)
is unsuitable.
