title: Assessment of peripheral dual-energy x-ray absorptiometry measurements in peri-implant bone defects in dogs.
abstract: BACKGROUND
  The goal of this study was to assess the variability of peripheral dual-energy x-ray absorptiometry (pDEXA) measurements in peri-implant bone defects in dogs.
  
  
  METHODS
  Ninety dental implants were inserted in edentulous areas of nine foxhound dogs and standardized peri-implant bone defects were created on the mesial and distal aspect of each fixture (N = 144 total). The animals were sacrificed at 1, 2, and 3 months, respectively. Bone mineral density measurements (BMD) were performed with the use of pDEXA. The calibration of the system was determined by generating four quality control plots using a phantom of known density value. A series of three repeated measurements of the peri-implant sites were made with repositioning of the region of interest. The measurements were performed at the mesial and distal peri-implant sites. The variability of the three BMD measurements was expressed as the coefficient of variation (CV), which is calculated as ([SD/mean] x 100). The difference in the CV between the mesial and distal sites was evaluated using an analysis of variance model for repeated measures accounting for timing of sacrifice (month 1, 2, 3), dog (1 through 9), side (left, right), and adjacent defect regions between implants (1 through 4).
  
  
  RESULTS
  The calibration of the pDEXA measured by means of the phantom resulted in a deviation of 0.17%, 0.52%, -0.17%, and 0.00%, respectively, for each of the four assessments. The average CV for the 72 mesial and 72 distal peri-implant sites was 5.22% +/- 4.22% (median 3.50%; range 0.46% to 18.83%) and 5.37% +/- 3.54% (median 4.64%; range 0.22% to 15.35%), respectively. After accounting for timing of sacrifice, dog, side, and position, there was not a statistically significant difference in the CV between the mesial and distal peri-implant sites (P = 0.75). This indicates that the peri-implant site did not significantly affect the variability of the BMD measurements.
  
  
  CONCLUSIONS
  This study demonstrated that the pDEXA is a non-invasive, convenient, and fast method to assess BMD around dental implants in animal studies. Limitations of the technique may have a negative impact in the precision of pDEXA when measuring small regions.
authors.affiliation: Division of Periodontics, Department of Dental Specialties, Mayo Clinic, Rochester, MN 55905, USA. sanchez.andres@mayo.edu
authors.forename: Andrés R
authors.initials: AR
authors.lastname: Sánchez
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Sheridan
authors.forename: Christine
authors.initials: C
authors.lastname: Lohse
authors.forename: Amy
authors.initials: A
authors.lastname: Weaver
mesh_terms: D015502:Absorptiometry, Photon; D000704:Analysis of Variance; D000818:Animals; D015519:Bone Density / Q000502:physiology; D002138:Calibration; D015921:Dental Implants; D004285:Dogs; D007576:Jaw, Edentulous, Partially / Q000473:pathology / Q000601:surgery; D008334:Mandible / Q000473:pathology / Q000601:surgery; D008336:Mandibular Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D019047:Phantoms, Imaging; D013997:Time Factors; D014945:Wound Healing / Q000502:physiology
chemical_list: D015921:Dental Implants