title: Correlation of radiographic fractal analysis with implant insertion torque in a rabbit trabecular bone model.
abstract: OBJECTIVE
  Insertion torque and resonance frequency analysis are currently used to assess the initial biomechanical competence of an implant. It would be advantageous to have this information during treatment planning. Therefore, the aim of this study was to assess the correlation between a descriptor of bone architecture, namely the fractal analysis of plain radiographs, and implant insertion torque and resonance frequency.
  
  
  METHODS
  Sixteen femoral condyles from adult rabbits were subjected to conventional radiography and then received an implant each. The final insertion torque and resonance frequency were recorded for each implant. The fractal dimension of the bone area corresponding to the osteotomy was calculated using a box-counting algorithm. The Spearman test was used to evaluate the correlation between the variables examined.
  
  
  RESULTS
  A linear correlation was observed between fractal dimensions and insertion torque values (rs = 0.704; P = .007). No correlation resulted between fractal dimension and resonance frequency. In addition, a receiver operating characteristic analysis defined a fractal dimension breakpoint of 1.83 to detect soft bone quality, as defined by insertion torque values, with a sensitivity of 80%.
  
  
  CONCLUSIONS
  Given its correlation with insertion torque, the box-counting fractal dimension could be useful to evaluate bone quality at implant sites preoperatively and noninvasively. Further studies are needed to confirm the same accuracy for human bone.
authors.affiliation: Department of Oral Surgery, University of Siena, Italy. veltri3@unisi.it
authors.forename: Mario
authors.initials: M
authors.lastname: Veltri
authors.forename: Marco
authors.initials: M
authors.lastname: Ferrari
authors.forename: Piero
authors.initials: P
authors.lastname: Balleri
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology*; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D005270:Femur Head / Q000000981:diagnostic imaging* / Q000502:physiology / Q000601:surgery; D017709:Fractals; D023421:Models, Animal; D010027:Osteotomy; D012372:ROC Curve; D011817:Rabbits; D011859:Radiography; D012680:Sensitivity and Specificity; D019415:Torque; D014732:Vibration
chemical_list: D015921:Dental Implants