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Changes of masticatory function following orthognathic treatment in patients with mandibular prognathism
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025A • Orthognathic, cleft lip~palate and craniofacial surgery
contrast, ifi the last three cases, the distance of distraction was measured directly between the bony segments from the radiographs before ending the distraction. Conclusions The best results with this technique can be achieved by measuring the actual distracted distance directly from the radiographs prior to the consolidation period. Through this approach accuracy is enhanced and the outcome is predictable.
Conclusion LUCAS and SSN are the first highly precise computer-assisted systems to transfer laboratory planning data concerning a repositioning osteotomy of the orbital walls to a surgical site.
4. Changes of Masticatory Function Following Orthognathic Treatment in Patients with Mandibular Prognathism
Kobayashi, T., Shingaki, S., Nakajima, T. First Department of Oral and MaxillofaciaI Surgery, School of Dentistry, Niigata University 3. Computer-Assisted Reconstruction of the Orbit
Marmulla, R., Niederdellmann, H. Department of Cranio-Maxillofacial Surgery, University of Regensburg, Germany Introduction A computer-assisted navigation system for the reconstruction of malformations, named Surgical Segment Navigator (SSN), has been developed at the University of Regensburg by support of Carl Zeiss Germany. The SSN is a system to transfer laboratory planning data concerning a repositioning osteotomy to a surgical site. Initially, the SSN has been used to navigate the maxilla after osteotomy in a Le Fort I fashion, now it is even used to reconstruct malformations of the orbit. Materials and method The SSN is based on an infrared three-dimensional localizer such as the Surgical Tool Navigator (STN) and the Surgical Microscope Navigator (SMN) by Carl Zeiss. Surgical planning can be carried out using stereolithographic models. Another very new method is to perform surgical planning on a workstation by use of a Laboratory Unit for Computer Assisted Surgery (LUCAS), which has been developed as a new software-module for the SSN. Conventional CT scans are vectorized and three-dimensional reconstructed by LUCAS, using about 10,000 cells to render a human skull. The size and osteotomy-lines of the bone segment to be navigated have to be selected on tile workstation. Afterwards, the dislocation of the bone segment can be planned. On the workstation, the spatial displacement between the preoperative and planned postoperative position of the bone segment is described by three vectors. The data for surgical planning can directly be exported from the LUCAS workstation to the SSN. The reconstruction of posttraumatic malpositions of the orbit is planned and carried out using the LUCAS and SSN system. Results Surgical planning and transfer to the surgical site can be performed highly precise with the LUCAS and SSN system, guiding the osteotomied bone segment exactly in the preoperatively planned position. Even more, osteotomy and repositioning of the orbital walls can be performed safer and much faster using the described systems.
Recovery 9 f masticatory function is one of the important objectives of orthognathic treatment of jaw deformities. The purpose of this study was to investigate the changes of masticatory function following orthognathic surgery in patients with mandibular prognathism. The subjects were 26 patients and were examined before treatment, after preoperative orthodontic treatment, and six months, a year, and two years after surgery. Masticatory efficiency was evaluated spectrophotometrically by measuring the amount of adenosine triphosphate eluted from masticated adenosine triphosphate enteric-coated granules. Occlusal contact was evaluated by calculating the number and area of occlusal contacts from the illuminated images of a silicone record o f the occlusion that was stored in the image analysis system. Masticatory rhythm during gum chewing was examined by mean values and coefficient of variation values of 10 masticatory cycle times and integrations on electromyograms of the masseter and anterior temporalis muscles. The mean masticatory efficiency increased significantly from 0.52 abs of the pretreatment value to 0.68 abs two year postoperatively, but it was still significantly lower then the 1.13 abs of the normal occlusion group. Similar changes were observed in the number and area of occlusal contacts. Coefficient of variation values of the cycle times and integrations on electromyograms significantly decreased after surgery. The results indicate that although masticatory efficiency, occlusal contacts and masticatory rhythm were improved by orthognathic treatment, the postoperative masticatory function is not fully recovered when compared with the normal occlusion group.
5. Polymer Technology and Surgical Experience with Resorbable Bone Fixation in the Maxilla and Mandible
Edwards, R., Kiely, K. United States Air Force Research in resorbable science has been well documented in the literature since the early 1970's. Various homopolymers have been investigated including polylactic acid (PLA), polyglycolic acid (PGA), po!ydioxanone (PDS), and more recently a copolymer of PLA-PGA (LactoSorb, Biomet Warsaw, IN). Previous studies have established that PLA, while
025A • Orthognathic, cleft lip~palate and craniofacial surgery
contrast, ifi the last three cases, the distance of distraction was measured directly between the bony segments from the radiographs before ending the distraction. Conclusions The best results with this technique can be achieved by measuring the actual distracted distance directly from the radiographs prior to the consolidation period. Through this approach accuracy is enhanced and the outcome is predictable.
Conclusion LUCAS and SSN are the first highly precise computer-assisted systems to transfer laboratory planning data concerning a repositioning osteotomy of the orbital walls to a surgical site.
4. Changes of Masticatory Function Following Orthognathic Treatment in Patients with Mandibular Prognathism
Kobayashi, T., Shingaki, S., Nakajima, T. First Department of Oral and MaxillofaciaI Surgery, School of Dentistry, Niigata University 3. Computer-Assisted Reconstruction of the Orbit
Marmulla, R., Niederdellmann, H. Department of Cranio-Maxillofacial Surgery, University of Regensburg, Germany Introduction A computer-assisted navigation system for the reconstruction of malformations, named Surgical Segment Navigator (SSN), has been developed at the University of Regensburg by support of Carl Zeiss Germany. The SSN is a system to transfer laboratory planning data concerning a repositioning osteotomy to a surgical site. Initially, the SSN has been used to navigate the maxilla after osteotomy in a Le Fort I fashion, now it is even used to reconstruct malformations of the orbit. Materials and method The SSN is based on an infrared three-dimensional localizer such as the Surgical Tool Navigator (STN) and the Surgical Microscope Navigator (SMN) by Carl Zeiss. Surgical planning can be carried out using stereolithographic models. Another very new method is to perform surgical planning on a workstation by use of a Laboratory Unit for Computer Assisted Surgery (LUCAS), which has been developed as a new software-module for the SSN. Conventional CT scans are vectorized and three-dimensional reconstructed by LUCAS, using about 10,000 cells to render a human skull. The size and osteotomy-lines of the bone segment to be navigated have to be selected on tile workstation. Afterwards, the dislocation of the bone segment can be planned. On the workstation, the spatial displacement between the preoperative and planned postoperative position of the bone segment is described by three vectors. The data for surgical planning can directly be exported from the LUCAS workstation to the SSN. The reconstruction of posttraumatic malpositions of the orbit is planned and carried out using the LUCAS and SSN system. Results Surgical planning and transfer to the surgical site can be performed highly precise with the LUCAS and SSN system, guiding the osteotomied bone segment exactly in the preoperatively planned position. Even more, osteotomy and repositioning of the orbital walls can be performed safer and much faster using the described systems.
Recovery 9 f masticatory function is one of the important objectives of orthognathic treatment of jaw deformities. The purpose of this study was to investigate the changes of masticatory function following orthognathic surgery in patients with mandibular prognathism. The subjects were 26 patients and were examined before treatment, after preoperative orthodontic treatment, and six months, a year, and two years after surgery. Masticatory efficiency was evaluated spectrophotometrically by measuring the amount of adenosine triphosphate eluted from masticated adenosine triphosphate enteric-coated granules. Occlusal contact was evaluated by calculating the number and area of occlusal contacts from the illuminated images of a silicone record o f the occlusion that was stored in the image analysis system. Masticatory rhythm during gum chewing was examined by mean values and coefficient of variation values of 10 masticatory cycle times and integrations on electromyograms of the masseter and anterior temporalis muscles. The mean masticatory efficiency increased significantly from 0.52 abs of the pretreatment value to 0.68 abs two year postoperatively, but it was still significantly lower then the 1.13 abs of the normal occlusion group. Similar changes were observed in the number and area of occlusal contacts. Coefficient of variation values of the cycle times and integrations on electromyograms significantly decreased after surgery. The results indicate that although masticatory efficiency, occlusal contacts and masticatory rhythm were improved by orthognathic treatment, the postoperative masticatory function is not fully recovered when compared with the normal occlusion group.
5. Polymer Technology and Surgical Experience with Resorbable Bone Fixation in the Maxilla and Mandible
Edwards, R., Kiely, K. United States Air Force Research in resorbable science has been well documented in the literature since the early 1970's. Various homopolymers have been investigated including polylactic acid (PLA), polyglycolic acid (PGA), po!ydioxanone (PDS), and more recently a copolymer of PLA-PGA (LactoSorb, Biomet Warsaw, IN). Previous studies have established that PLA, while