Retrieval of Prefabricated Zirconia Crowns with Er,Cr:YSGG Laser from Primary and Permanent Molars

Abstract

(1) Background: Prefabricated zirconia crowns are used to restore teeth in children. The purpose of this study was to evaluate the removal of these crowns with the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser; (2) Methods: A total of 12 primary and 12 permanent teeth were prepared and prefabricated zirconia crowns were passively fitted and cemented with two resin modified glass-ionomer (RMGI) cements. Surface areas of prepared teeth and crowns were calculated. Crowns were removed using two laser settings: 4.5 Watts, 15 Hertz, 20 water/20 air, and 5 Watts, 15 Hertz, 50 water/50 air. The retrieval time and temperature changes were tested recorded. Data were analyzed using ANOVA with Tukey’s adjusted post hoc pairwise comparison t-test; (3) Results: The average time for crown removal was: 3 min, 47.7 s for permanent; and 2 min 5 s for primary teeth. The mean temperature changes were 2.48 °C (SD = 1.43) for permanent; and 3.14 °C (SD = 1.88) for primary teeth. The time to debond was significantly positively correlated with tooth inner surface area and volume, outer crown volume, and the cement volume; (4) Conclusions: Use of the Er,Cr:YSGG laser is an effective, safe and non-invasive method to remove prefabricated zirconia crowns cemented with RMGI cements from permanent and primary teeth.

In Vitro Study of Laser-Assisted Prefabricated Ceramic Crown Debonding as Compared to Traditional Rotary Instrument Removal

“…Two different methods were used and compared for crown removal: laser irradiation versus air rotary handpiece removal ( Figure 1 ). Laser crown removal was similar to previous studies [ 6 , 17 ]. Laser irradiation was performed using an Er,Cr:YSGG laser (Waterlase iPlus ® , Biolase ® , CA, USA) using settings: 5.0 Watts, 15 Hertz, the fluence in pulse: 39.32 J/cm 2 , power density: 786.3 W/cm 2 , with 50 water and 50 air, with the Turbo handpiece and MX9 laser tip (spot size 900 μm) ( Figure 1 A).…”

“…The abutment teeth were prepared based on the prefabricated zirconia crown manufacturer’s instructions (NuSmile ® , Houston, TX, USA) using an 850012-C tapered-diamond bur (Premier ® , Plymouth Meeting, PA, USA) in an Adec TG-97L air-driven handpiece (Henry Schein ® , Melville, NY, USA), allowing for a minimum of 1 mm of ceramic thickness to ensure a passive seat for a crown [ 17 ]. Teeth were numbered consecutively and divided into four groups: Group 1: Anterior Laser retrieval (AL, n = 18); Group 2: Anterior Rotary retrieval (AR, n = 17); Group 3: Posterior Laser retrieval (PL, n = 13); Group 4: Posterior Rotary retrieval (PR, n = 13) ( Figure 1 ).…”

“…Teeth were numbered consecutively and divided into four groups: Group 1: Anterior Laser retrieval (AL, n = 18); Group 2: Anterior Rotary retrieval (AR, n = 17); Group 3: Posterior Laser retrieval (PL, n = 13); Group 4: Posterior Rotary retrieval (PR, n = 13) ( Figure 1 ). Prefabricated zirconia crowns were cemented with designated resin-modified glass ionomer (RMGI), BioCem cement (BioCem Universal BioActive Cement; NuSmile: Houston, TX, USA) [ 17 , 23 ]. Finger pressure was used to stabilize the crown on the tooth during the setting of the cement.…”

“…Prefabricated zirconia crowns can be removed with erbium lasers in an atraumatic manner [ 17 , 18 ]. Laser irradiation offers a predictable method for debonding zirconia crowns, creating minimal to no damage to the tooth or crown surfaces.…”

“…Zirconia crowns can be retrieved undamaged and can be recemented again if necessary. Studies have shown that laser irradiation can be an efficient and predictable removal method for prefabricated zirconia crowns from permanent and primary molars; however, no studies to date has been conducted on primary anterior teeth or compared the laser method to rotary handpiece removal [ 17 ].…”