title: Predictable drill-free screw positioning with a graduated 3-dimensional radiographic-surgical guide: a preliminary report.
abstract: BACKGROUND
  Mini-implants are placed in restricted sites, requiring an accurate surgical technique. However, no systematic study has quantified technique accuracy to reliably predict the surgical risks. Therefore, a graduated 3-dimensional radiographic-surgical guide (G-RSG) was proposed, and its inaccuracy and risk index (RI) were estimated.
  
  
  METHODS
  The sample consisted of 6 subjects (4 male, 2 female), who used mini-implant anchorage. Ten drill-free screws (DFS) were placed by using the G-RSG. The central point of the mesiodistal septum width (SW) was the selected implant site on the presurgical radiograph. The distances between DFS and the adjacent teeth (5-DFS and 6-DFS) were measured to evaluate screw centralization and inaccuracy degree (ID). These distances were statistically compared by independent t tests, and inaccuracy was determined by the expression ID = (5-DFS - 6-DFS)/2, which represents deviation of the mini-implant's final position regarding the central point initially selected. Then SW, ID, and screw diameter (SØ) were combined to estimate the surgical risk with RI expressed by RI = SØ/SW - ID.
  
  
  RESULTS
  The 5-DFS and 6-DFS distances were not significantly different. The ID of the G-RSG was 0.17 mm. The low ID ensured a safe RI (<1) in spite of the restricted SW.
  
  
  CONCLUSIONS
  The G-RSG accuracy allowed fine prediction of the final DFS position in the interradicular septum, with a low RI, which is a helpful tool to estimate surgical risks.
authors.affiliation: Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, SP, Brazil. sergioestelita@yahoo.com.br
authors.forename: Sérgio
authors.initials: S
authors.lastname: Estelita
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.forename: Kelly
authors.initials: K
authors.lastname: Chiqueto
authors.forename: Marcos
authors.initials: M
authors.lastname: Janson
authors.forename: Marcos Roberto
authors.initials: MR
authors.lastname: de Freitas
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D017076:Computer-Aided Design; D003758:Dental Implantation, Endosseous / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008312:Malocclusion, Angle Class II / Q000601:surgery*; D008437:Maxilla / Q000601:surgery; D008953:Models, Anatomic; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation / Q000379:methods*; D016382:Orthodontic Appliance Design / Q000379:methods*; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult