title: An investigation of heat transfer to the implant-bone interface when drilling through a zirconia crown attached to a titanium or zirconia abutment.
abstract: BACKGROUND
  Thermal injury to the implant-bone interface may lead to bone necrosis and loss of osseointegration. This is a concern during manipulation of the implant throughout the restorative phase of treatment. The risk of heat transfer to the implant-bone interface during abutment preparation or prosthesis removal should be considered.
  
  
  OBJECTIVE
  The purpose of the study was to examine the amount of heat transferred to the implant-bone interface when a zirconia crown is drilled to access the screw channel or section a crown with a high-speed dental handpiece.
  
  
  METHODS
  Of the 64 ceramic-veneered zirconia crowns fabricated, 32 had a coping thickness of 0.5 mm and 32 had a coping thickness of 1.0 mm. The crowns were cemented on either titanium stock abutments or zirconia stock abutments. Each group was further subdivided to evaluate heat transfer when the screw channel was accessed or the crown was sectioned with a high-speed handpiece with or without irrigation. Temperature change was recorded for each specimen at the cervical and apical aspect of the implant with thermocouples and a logging thermometer. ANOVA was used to assess the statistical significance in temperature change between the test combinations, and nonparametric Mann-Whitney U tests were used to evaluate the findings.
  
  
  RESULTS
  The use of irrigation during both crown removal processes yielded an average temperature increase of 3.59 ±0.35°C. Crown removal in the absence of irrigation yielded an average temperature increase of 18.76 ±3.09°C. When all parameter combinations in the presence of irrigation were evaluated, the maximum temperature change was below the threshold of thermal injury to bone. The maximum temperature change was above the threshold for thermal injury at the coronal aspect of the implant and below the threshold at the apical aspect in the absence of irrigation.
  
  
  CONCLUSIONS
  Within the limitations of this investigation, the use of irrigation with a high-speed dental handpiece to remove a ceramic-veneered zirconia crown results in a temperature increase at the implant-bone interface insufficient to cause irreversible damage. Conversely, a lack of irrigation may yield a temperature increase capable of producing irreversible damage at the coronal aspect of the implant.
authors.affiliation: Resident, United States Air Force Postgraduate Dental School, Lackland Air Force Base, Joint Base San Antonio, San Antonio, Texas.
authors.forename: Amy G
authors.initials: AG
authors.lastname: Mason
authors.affiliation: Director of Maxillofacial Prosthetics, United States Air Force Postgraduate Dental School, Lackland Air Force Base, Joint Base San Antonio, San Antonio, Texas.
authors.forename: Alan
authors.initials: A
authors.lastname: Sutton
authors.affiliation: Assistant Professor and Director, Dental School Implant Clinic, Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas. Electronic address: turkyilmaz@uthscsa.edu.
authors.forename: Ilser
authors.initials: I
authors.lastname: Turkyilmaz
mesh_terms: D000069343:Bone-Implant Interface / Q000502:physiology*; D003442:Crowns; D000044:Dental Abutments; D003754:Dental High-Speed Equipment; D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D019094:Dental Prosthesis, Implant-Supported; D003801:Dental Veneers; D004735:Energy Transfer; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D007507:Therapeutic Irrigation; D013821:Thermometers; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015921:Dental Implants; D003764:Dental Materials; D003776:Dental Porcelain; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide