Title: Maximum Temperature Through Y-TZP Ceramic After Er,Cr:YSGG Laser Irradiation
Darrell Hutto, University of Mississippi Medical Center
Laurel Stringer, Millsaps College
Sarah Malley (Presenter)
University of Mississippi Medical Center
Jason Griggs, University of Mississippi
Susana Salazar Marocho, University of Mississippi Medical Center
Objectives: Removing Y-TZP restorations with diamond burs is time-consuming and destructive. Using a laser could be a fast and non-destructive alternative method. However, the heat produced might damage the tooth pulp (>42°C). The aim of this research was to determine the maximum temperature (T) reached during the use of different settings of an Er,Cr:YSGG laser through a Y-TZP ceramic.
Methods: Y-TZP slices (1 mm thick) were prepared and divided into 7 experimental groups (n=5). For the control group, a coarse diamond bur was operated with a high-speed dental handpiece on the Y-TZP slices. For the 6 experimental groups, the Er,Cr:YSGG laser (Waterlase MD) 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, and 4.5/45. The T through Y-TZP was recorded in degrees Celsius by using a digital thermometer (OMEGA HH506R) with a type K thermocouple.
Results: The data were not normally distributed. The median T of the control group was 26.5 °C. The use of 4.5 W resulted in the median T (in °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 regardless of the frequency. The high power and lowest frequency (4.5/20) showed no significant difference from the 2.5 W settings and the control group.
Conclusions: The lower power setting (2.5 W) could be the method of choice for the use of the Er; Cr: YSGG laser with thin Y-TZP structures. The higher power (4.5 W) with high frequencies (30 and 45 PPS) is not suitable due to the potential damage to the pulp.