J Korean Dent Sci.  2021 Dec;14(2):69-78. 10.5856/JKDS.2021.14.2.69.

Comparison of Temperatures of the Resin Cement in Polycrystalline Ceramic Brackets Irradiated Using a Diode Laser

• Son YT
• Son K
• Kim KM
• Lee JM
• Kim JW
• Yu W
• Lee KB

• KMID: 2525897
• DOI: http://doi.org/10.5856/JKDS.2021.14.2.69

Abstract

Purpose
The primary objective of this study was to evaluate the change in the temperature of the adhesive resin in polycrystalline ceramic brackets irradiated using a diode laser at different irradiation energy levels and times.
Materials and Methods
For the measurement of the temperature of the adhesive resin, it was applied at the base of the ceramic bracket, a thermocouple was placed at the center of the base surface, the bracket was placed on prepared resin specimens for light curing, and a laser was irradiated to the center of the bracket slot at 5, 7, and 10 W. For the measurement of the temperatures of the enamel under the bracket and pulp cavity, extracted premolar was fixed to a prepared mold and the ceramic bracket was bonded to the buccal surface of the premolar. The Kruskal–Wallis H test and Friedman test were used for statistical analysis. Result: At 5 W, the temperature of the adhesive resin did not reach the resin softening temperature of 200°C within 30 seconds. At 7 W, it reached 200°C when the ceramic bracket was irradiated continuously for 28 seconds. At 10 W, it reached 200°C when the ceramic bracket was irradiated continuously for 15 seconds. During laser irradiation, the temperature of the enamel under the bracket increased by over 5°C within 15 seconds.
Conclusion
The use of diode laser irradiation for bracket debonding should be carefully considered because the pulp cavity temperature increases by over 5°C within the irradiation time for resin thermal softening.

Keyword

Bracket debonding; Diode laser; Polycrystalline ceramic bracket; Pulp cavity temperature; Thermal softening