title: A novel conversion method for radiographic guide into surgical guide.
abstract: BACKGROUND
  The study proposed a novel method for converting a radiographic guide into a surgical guide and evaluated its accuracy.
  
  
  METHODS
  Radiographic guide was reformed with the addition of index rods for geometric conversion method (GCM). Planning implants were projected on geometric projection planes, and the implant positions were measured. The radiographic guide was converted into surgical guide using a generic bench drill machine with GCM data. Two experiments were designed to validate the GCM. (1) In vitro test: Twenty implants were placed on five edentulous dental models by using the GCM (group 1) and Stereolithography (SLA) method (group 2), respectively. The deviations of planned and placed implant were calculated, and the precision error (PE) value was calculated to evaluate the stability of the GCM and SLA. (2) In vivo test: Nine edentulous subjects were selected for clinical implant surgery with the GCM guide. Two level of the index rods of radiographic guides were prepared for surgical guides forming. The differences between the planned and actual implants were calculated in implant head, apex, and angulation.
  
  
  RESULTS
  The in vitro test revealed no significant differences in the planned and placed angulations between groups 1 and 2 (P > .05). The PE was not significantly different between groups 1 and 2 (P > .05). The in vivo test revealed a successful treatment of the subjects, and 16 implant sites were evaluated. The results indicated that GCM guide could achieve the three-dimensional (3D) offset deviations of 1.03 ± 0.27 mm and 1.17 ± 0.24 mm at the implant head and apex, respectively, and 1.37° ± 0.21° for the 3D angulation.
  
  
  CONCLUSIONS
  The novel method for converting a radiographic guide into a surgical guide appears accurate and stable compared with SLA.
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan City, Taiwan.|Metal Industries Research & Development Centre, Kaohsiung City, Taiwan.
authors.forename: Yao-Te
authors.initials: YT
authors.lastname: Peng
authors.affiliation: Department of Dentistry, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan.
authors.forename: Chung-Chih
authors.initials: CC
authors.lastname: Tseng
authors.affiliation: Department of Electrical Engineering, Southern Taiwan University of Science and Technology, Tainan City, Taiwan.
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Du
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan City, Taiwan.
authors.forename: Yen-Nien
authors.initials: YN
authors.lastname: Chen
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan City, Taiwan.
authors.forename: Chih-Han
authors.initials: CH
authors.lastname: Chang
mesh_terms: D003758:Dental Implantation, Endosseous / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D003765:Models, Dental; D011861:Radiography, Dental / Q000379:methods*; D000076227:Stereolithography
keywords: computer-aided design and manufacturing; dental implant; dental surgical guide; geometric projection method; precision error