title: Comparison of 4 registration strategies for computer-aided maxillofacial surgery.
abstract: OBJECTIVE
  Surgeons have recently started to use computer-aided surgery (CAS) to assist with maxillofacial reconstructive surgery. This study evaluates four different CAS registration strategies in the maxillofacial skeleton.
  
  
  METHODS
  Fifteen fiducial markers were placed on each of four cadaveric heads. Four registration protocols were used: 1) group 1-invasive markers, 2) group 2-skin surface, 3) group 3-bony landmark, 4) group 4-intraoral splint. Two observers registered each head twice with each of the four protocols and measured the target registration error (TRE). The process was repeated on two different navigation systems for confirmation.
  
  
  RESULTS
  The mean TRE values were: invasive, 1.13 +/- 0.05 mm (P < 0.05); skin, 2.03 +/- 0.07 mm (P < 0.05); bone, 3.17 +/- 0.10 mm (P < 0.05); and splint, 3.79 +/- 0.13 mm (P < 0.05). The TRE values were consistent across CAS systems.
  
  
  CONCLUSIONS
  Of the techniques tested for CAS registration, invasive fiducial markers are the most accurate. Skin surface landmarks, bony landmarks, and an intraoral splint are incrementally less accurate.
authors.affiliation: Department of Craniomaxillofacial Surgery, University Freiburg, Freiburg, Germany.
authors.forename: Marc Christian
authors.initials: MC
authors.lastname: Metzger
authors.forename: Amir
authors.initials: A
authors.lastname: Rafii
authors.forename: Bettina
authors.initials: B
authors.lastname: Holhweg-Majert
authors.forename: Annette M
authors.initials: AM
authors.lastname: Pham
authors.forename: Brad
authors.initials: B
authors.lastname: Strong
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D005145:Face / Q000033:anatomy & histology; D005147:Facial Bones / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D019647:Oral Surgical Procedures / Q000379:methods*; D019651:Plastic Surgery Procedures / Q000379:methods; D012867:Skin / Q000033:anatomy & histology; D013165:Splints; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods; D014584:User-Computer Interface