Thermotransduction and heat stress in dental structures during orthodontic debonding : Effectiveness of various cooling strategies.
OBJECTIVE
Recent studies have indicated possible thermal damage to pulpal tissue during orthodontic debonding. This study aimed to analyze the thermal loads acting upon dental structures and their transfer to the pulp during orthodontic debonding. Specific goals were to analyze temperature changes in local dental tissues, thermotransduction to the pulp cavity, and the effectiveness of common cooling strategies and of simulated intrapulpal circulation.


METHODS
Metal brackets were bonded to five extracted human molars and subsequently removed. While a carbide bur was applied to debond the residual composite from the tooth surface, various cooling strategies (no/air/water cooling) were employed with or without simulated intrapulpal circulation, accompanied by temperature measurements with a thermographic infrared camera on the enamel surface and with measuring probes in the pulp cavity. Appropriate evaluation software was used to calculate the enamel-to-pulp temperature gradients and for statistical analysis.


RESULTS
Significant differences in temperature rise and heat development over time, both on the enamel surfaces and in the pulp cavities were found. The mean temperature rises associated with no/air/water cooling were 90.7/46.6/9.2 °C on the enamel surface versus 9/8/4.6 °C inside the pulp. However, thermotransduction from enamel to pulp remained below 10 % of the surface measurements in all groups. Simulated intrapulpal microcirculation was found to significantly reduce intrapulpal temperature levels.


CONCLUSIONS
During debonding of residual bracket adhesives, provided that a carbide bur is properly used, our data indicate a low risk of reaching critical intrapulpal temperatures even in the absence of dedicated cooling and no risk if the instrumentation is accompanied by air or water cooling.
Department of Orthodontics, University of Bonn, Bonn, Germany.
Philipp
P
Kley
Department of Operative Dentistry and Periodontology, University of Bonn, Bonn, Germany.
Matthias
M
Frentzen
Department of Orthodontics, University of Bonn, Bonn, Germany.|Private Orthodontic Office, Kieferorthopädie am Friesenplatz, Cologne, Germany.
Katharina
K
Küpper
Department of Operative Dentistry and Periodontology, University of Marburg, Marburg, Germany.
Andreas
A
Braun
Department of Operative Dentistry and Periodontology, University of Bonn, Bonn, Germany.
Susann
S
Kecsmar
Department of Orthodontics, University of Bonn, Bonn, Germany.
Andreas
A
Jäger
Department of Orthodontics, University of Bonn, Bonn, Germany. michael.wolf@ukb.uni-bonn.de.|Department of Orthodontics, University of Jena, Jena, Germany. michael.wolf@ukb.uni-bonn.de.
Michael
M
Wolf
D000268:Adhesiveness; D001831:Body Temperature / Q000502:physiology*; D003080:Cold Temperature; D003738:Dental Cements / Q000737:chemistry*; D017005:Dental Debonding / Q000379:methods*; D003786:Dental Pulp Cavity / Q000502:physiology*; D003799:Dental Stress Analysis; D004735:Energy Transfer; D018869:Heat-Shock Response / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D066298:In Vitro Techniques; D008963:Molar / Q000502:physiology*; D016910:Orthodontic Brackets; D013314:Stress, Mechanical; D013814:Thermal Conductivity
D003738:Dental Cements
Dental debonding; Dental models; Orthodontic brackets; Pulp temperature; Teeth