title: An alternative method to match planned and achieved positions of implants, after virtual planning using cone-beam CT data and surgical guide templates--a method reducing patient radiation exposure (part I).
abstract: OBJECTIVE
  The present study describes a new method of evaluating the precision of surgically placed dental implants compared after virtual planning of implant positions using cone-beam computed tomography (CT) data and surgical guide templates. This method reduces radiation exposure for patients participating in scientific studies.
  
  
  METHODS
  Twenty-three implants in 10 patients with a unilateral free-end gap in the mandible (Kennedy Class II) were evaluated. After three-dimensional planning of implant position, the implant bed was prepared with a surgical guide template and transmucosal drilling. Preoperative cone-beam CT images were matched with postoperative images of the master cast with implant replicas. Deviations between planned and achieved positions were measured in position and axis.
  
  
  RESULTS
  On average, the match between planned and placed implant axis was within 4.2 degrees (range, 0.0-10.0). The mean difference in distance at the implant shoulder was 0.9 mm (range, 0.0-4.5). The mean difference in distance at the implant apex was 0.6mm (range, 0.0-2.7) in the lateral/medial direction and 0.9 mm (range, 0.0-3.4) in the anterior/posterior direction.
  
  
  CONCLUSIONS
  This alternative matching method provides reliable postoperative evaluation of differences in position and axis of planned and placed implants while reducing patient radiation exposure.
authors: Department of Prosthodontics, University Hospital Erlangen, Erlangen, Germany. Dr.A.Nickenig@t-online.de
authors: Hans-Joachim
authors: HJ
authors: Nickenig
authors: Stephan
authors: S
authors: Eitner
mesh_terms: D000328:Adult; D054893:Cone-Beam Computed Tomography; D003758:Dental Implantation, Endosseous / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007576:Jaw, Edentulous, Partially / Q000000981:diagnostic imaging* / Q000601:surgery; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery*; D008875:Middle Aged; D008953:Models, Anatomic; D003765:Models, Dental; D010347:Patient Care Planning; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012984:Software; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014584:User-Computer Interface; D055815:Young Adult