442 - Removal of Prefabricated Zirconia Crowns from Primary Anterior Teeth with Er,Cr:YSGG Laser Compared to a High-Speed Handpiece: an in-vitro study

Purpose: The aim of this study was to compare the time, pulpal temperature changes associated with removal of prefabricated zirconia crowns from primary anterior teeth using an Er,CR:YSGG laser versus a rotary handpiece. 

Methods: This in-vitro study used extracted primary incisors. Teeth were prepared and restored with NuSmile zirconia crowns (sizes 4  and 5) cemented with resin-modified glass-ionomer cement. Crowns were removed using either an air-rotary handpiece (HG, N=17) or Er,Cr:YSGG laser (LG, N=18). Pulpal temperature and removal times were compared between the two groups. Following crown removal, one tooth and crown from each group was submitted for SEM examination. 

Results: The average time for crown removal for HG was 80.9 seconds (SD=19.36); and 353.3 seconds (SD=110.6) for LG. Removal with the laser took significantly longer by an average of 272.4 (95% CI: 216.8-328.0, p-value < 0.0001) and had higher variability than the drill. The maximum observed temperature for HG was 22.2⁰C (SD=0.85) compared to 27.7⁰C (SD=1.60) for LG. Laser-assisted crown removal was associated with a maximum temperature 5.5⁰C (95% CI: 4.6-6.4) higher than that with the handpiece (p-value < 0.0001). 

Conclusions: Er,Cr:YSGG laser and rotary handpiece can both be used predictably to remove zirconia crowns from primary anterior teeth. While a rotary handpiece presents a more efficient method of removal, Er,Cr:YSGG laser offers a viable alternative method.