ABSTRACT
In a retrospective study, distance measurements of nine children with craniofacial malformation were analyzed. The accuracy of measurements was compared when measured on a workstation using a 16-slice multidetector spiral computed tomography and on a stereolithographic model. Three different methods of defining distances were investigated: 1) on the stereolithographic plastic models, 14 distances connecting landmarks were identified with a digitizer (Polaris Tracker); 2) the same distances were defined at axial, coronal, and sagittal reformats of the computed tomography data set and measured using a Philips MX View workstation; and 3) the same 14 distances were defined at three-dimensional virtual reality models of the skulls at the same workstation. All measurements were performed with all three methods by three different readers. The following conclusions could be drawn: stereolithographic models provide a highly exact reproduction of the skull in children with craniofacial malformations. They are a reliable basis for all analytic and probatory endeavors preparing complicated surgical corrections. Three-dimensional virtual reality display modes serve significantly better for exact distance measurements on the complex surface of the human skull than planar reformats of the same computed tomography data sets.
Subject(s)
Cephalometry/methods , Computer-Aided Design , Craniofacial Abnormalities/diagnosis , Imaging, Three-Dimensional/methods , Tomography, Spiral Computed/methods , Acrocephalosyndactylia/diagnosis , Cephalometry/statistics & numerical data , Child, Preschool , Cleft Lip/diagnosis , Cleft Palate/diagnosis , Craniosynostoses/diagnosis , Facial Bones/pathology , Humans , Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/statistics & numerical data , Infant , Microcephaly/diagnosis , Models, Anatomic , Observer Variation , Plagiocephaly, Nonsynostotic/diagnosis , Plastics , Radiology Information Systems , Reproducibility of Results , Retrospective Studies , Tomography, Spiral Computed/statistics & numerical data , User-Computer InterfaceABSTRACT
Computed-assisted surgery (CAS) has been designed to improve oral implant planning and positioning and to increase safety and operator comfort. This is especially important in the esthetic zone, at sites with bone deficiency, and when minimally invasive implant placement is the therapy of choice. Current available CAS systems are relatively large and expensive and require a lengthy learning period. This report presents a novel tactile imaging and registration concept that enables the operation of a newly developed computerized implant locating system. An intraoral bone-sounding device maps the surface of the jaw through the soft tissue. Bone contour data are registered over the computerized tomographic image. Guided by treatment preplanning software, a chairside robotic manipulator fabricates guiding sleeves that direct the drill and implant during the osteotomy and implant placement, respectively. The authors' clinical experience shows that tactile registration based the Implant Locating System is simple to use and provides accurate implant design and placement that requires only basic computer experience, minimal operational space, and low infrastructure investment. The system allows final adjustments at the time of operation, transforming each implant surgery into a fully monitored procedure.
