Non-Invasive Retrieval of Prefabricated Zirconia Crowns with Er,Cr:YSGG Laser from Primary and Permanent Teeth
Master of Science in Dentistry
Janina Golob Deeb, DDS, MS
William Dahlke, DMD
Patrice Wunsch, DDS, MS
Caroline Carrico, PhD
Kinga Grzech-Leśniak DMD, MS, PhD
Purpose: Compromised tooth structure on permanent and deciduous teeth in the pediatric population is increasingly being restored with tooth-colored prefabricated zirconia crowns. These restorations may need to be removed or replaced with permanent crowns. The purpose of this in vitro study was to explore the use of an Er,Cr:YSGG laser for removal of prefabricated zirconia crowns cemented with RMGI as a non-invasive alternative to rotary instruments.
Methods: Thirteen permanent and 12 primary molars were prepared to dentin and prefabricated zirconia crowns were passively fitted and cemented with two resin modified glass ionomer cements. The irradiation parameters for ErCR:YSGG were 4.5 Watts, 15 Hertz, 20 Water, 20 Air; 5 Watts, 15 Hertz, 50 Air, 50 Water with the Turbo Mx9 Handpiece. The experiment was repeated three times for permanent teeth and twice for primary teeth. The debonding time, laser settings and pulpal temperature changes were tested and recorded for all groups. Data were analyzed using repeated measures ANOVA with Tukey’s adjusted post hoc pairwise comparisons t-test.
Results: The average time for permanent molar laser-assisted crown removal was 3 minutes and 47.7 sec. The average time for primary molar crown removal was 2 minutes and 5 sec. The mean temperature changes for permanent teeth were 2.48 (SD=1.43)°C and increased by 3.8°C for higher laser setting; and 3.14 (SD=1.88)°C for primary teeth. The time to debond was significantly positively correlated with inner surface area, inner volume, outer volume, and the cement volume.
Conclusion: The Er,CR;YSGG Erbium laser proved to be an effective, non-invasive tool to remove prefabricated zirconia crowns cemented with RMGI cements and should be considered as a viable alternative to rotary instrumentation.
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