Defense Date


Document Type


Degree Name

Master of Science in Dentistry



First Advisor

Janina Golob Deeb

Second Advisor

Tiffany Williams

Third Advisor

Caroline Carrico

Fourth Advisor

Kinga Grzech-Leśniak


Purpose: The aim of this study was to compare the time and pulpal temperature changes associated with the removal of prefabricated zirconia crowns from primary anterior teeth using an Er,Cr:YSGG laser compared to a rotary hand-piece.

Methods: This in-vitro study was conducted using extracted primary incisors. Teeth were prepared and restored with prefabricated zirconia crowns (NuSmile®, Houston, TX, USA) sizes 4 and 5 cemented with resin-modified glass-ionomer cement. Restored teeth were stored in a humidor for at least 48 hours prior to removing crowns from the teeth using either an air-rotary hand-piece (HG, N=17) or erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser (LG, N=18). Pulpal temperature was measured inside the pulpal chamber and recorded in 30-second intervals. Removal times and pulpal temperature changes were compared between the two groups. Following crown removal, one tooth and crown from each group was submitted for SEM examination to assess morphological changes.

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 seconds (95% CI: 216.8-328.0, p-value<0.0001) and had higher variability than the rotary hand-piece. 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 of 5.5⁰C (95% CI: 4.6-6.4) higher than the hand-piece (p-value<0.0001).

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


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