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O.045 Orthognathic surgery with the salzburg concept – 23 years of experience
Oral Presentations SS; maxillary, mandibular and facial proportions; and Dahn’s analysis included: ramus height and mandibular corpus length. Results: In 12 patients the there was greater angle Z–AG–J in the range 14–31.5 (mean 21.26) on right side; on the left side in 10 patients there was greater angle 14–38 (mean 22.06) indicating skeletal lingual cross bite. Unmatching of the middle axis of the face (SS plane) were found in all 15 patients. The ramus height (Go-Cd) were increased (from 3 to 22 mm) in 6 patients on the right side and in 7 patients (from 1 to 13 mm) on the left side. The length of the mandibular body (Go-Gn) were increased in 11 patients on the right side and in 3 patients on the left side. Conclusion: The presented analysis enable proper pre-operative planning of skeletal osteotomy and correction of facial asymmetry.
O.045 Orthognathic surgery with the salzburg concept – 23 years of experience T. J¨unger, C. Krenkel. Department of Oral and Maxillofacial Surgery, St. Johanns Spital, Landeskrankenhaus, Paracelsus Medical Private University, Salzburg, Austria Introduction and Objectives: Since Obwegeser’s fundamental ideas, orthognathic surgery now is routinely performed. Nevertheless there are some unsolved problems caused by limited unterstanding in detail, resulting in unfavourable outcome. For better predictability of results the senior author developed the 3-D-OSS in 1983. In this study, long-term experience planning orthognathic surgery with this system is presented. Material and Methods: In 23 years 1237 patients underwent orthognathic surgery. We treated 339 patients with single jaw surgery and 898 patients underwent bimaxillary osteotomies. The idea was to transfer bony and soft tissue reference points to a three-dimensional device (3-D-OSS), enabling the surgeon to divide and visualize planned jaw movements according to 3 linear movement planes and 3 rotation axles. A coordinate system enables the transfer of planned movements to the operation theatre (Face-O-Meter). Results: Mock surgery precisely represents the operation itself and can be correlated with the attending patient. Surgical outcome can be evaluated before surgey, thus enabling the surgeon to concentrate on the procedure. Using the Face-O-Meter the aimed result can reliably be verified and controlled. Deviations can be detected and corrected. Plain congruency was systematically found at the osteotomy sites. Conclusions: With this planning system it is possible to convert a difficult operations into a simple operation, dividing a complex three-dimensional movement into 6 simple movements (3x rotation, 3x linear). All procedures can be repeated at any time. The method helps to gain education quality of trainees and improves planning procedures for the experienced.
O.046 Computer assisted orthognatic surgery based on 3D cephalometry. An alternative approach M. Zinser1 , R. Mischkowski1 , M. Durond2 , J. Z¨oller1 . 1 Department of Craniomaxillofacial and Plastic Surgery, University of Cologne, Germany; 2 Materialise, Leuven, Belgium Introduction: Computerization and radiographic technology in orthognathic surgery have contributed immensely to the stockpile of knowledge. Conventional pre-operative X-ray analysis is limited. Purpose: We present a new technique for 3D-facialsoft tissue-change prediction after simulated orthognatic surgical planning. A new method of computer-assisted-3D-virtual-reality soft tissue planning and prediction is presented. A further objec-
Orthognatic surgery: planning
13
tive is to investigate a new dental splint design to transform the virtual 3D planning to the intraoperative situation. Material and Methods: This study contains 15 patients with orthognatic deformaties. A virtual reality workbench is used for surgical planning based on CT database. The orthognatic surgery procedures (bone segmentation and osteotomy lines) were planned virtually reffering to anatomical landmarks and the soft tissue. Based on this virtual augmented surgeries custom dental splints and surgical templates have been developed to transfer the virtual planning. We used the new software (CMF/Simplant pro 9.21) from Materialise (Leuven, Belgium). All patients underwent a post-operative CT or DVT for evaluation. Results: CAS allowa an ideal pre-operative planning concerning aesthetic and functional aspects. The mean precision of the virtual bone segmentation was 85–90% for horizontal and 80–85% for vertical movements. The facial soft tissue prediction showed an accuracy of nearly 75%. Conclusion: Computer generated image prediction was suitable for patients education and communication. CAS is excellent in complex cases in which change in facial soft tissue shape should be carefully deliberated. The use of CAS templates has resulted in outcomes close to those predicted by the planning process. O.047 Comparison of 3D-visualization, planning and navigation tools in orthognathic surgery P. Juergens, K. Schwenzer-Zimmerer, H.-F. Zeilhofer. Division of Maxillo-Facial Surgery, Clinic for Reconstructive Surgery, University Hospital Basle, Switzerland Introduction: Accurate pre-operative 3D-planning of corrective surgical jaw interventions becomes more and more important in modern orthognathic surgery. The 2D-profile prediction as support of the conventional dental occlusion planning will be replaced by virtual 3D-models of the facial skeleton and the covering soft tissue generated from CT-Scans. The systems differ a lot concerning usability, accuracy and regarding soft tissue also hence a comparison of these systems seems reasonable. Methods: In seven patients mandibulo-maxillary osteotomies were performed after 3D-operation planning with three different planning systems: a commercially available planning system, a newly developed tool for computer-aided preoperative planning and intraoperative navigation and a planning system that allows post-operative soft tissue prediction. All systems were based on Datasets acquired by CT-scan of the midface and the mandible. In three patients intra-operative navigation was performed. The obtained graphics were used to inform the patient about the intended surgical intervention. Results: It could be shown that the three systems vary a lot in the efforts in time and manpower: the commercially available system could be handled by a physician with advanced computer knowledge, the planning with the other two systems had to be performed by computer scientists or mathematicians. The virtual soft tissue model had a very good acceptance by the patients. The third system allows the use as planning and navigation tool and provided the feature of 3D-cephalometry for quick evaluation of facial proportions. Synopsis: The tested systems all provided very accurate planning. We recognized that each had special features that provides unique advantages for different patients and indications.
O.045 Orthognathic surgery with the salzburg concept – 23 years of experience T. J¨unger, C. Krenkel. Department of Oral and Maxillofacial Surgery, St. Johanns Spital, Landeskrankenhaus, Paracelsus Medical Private University, Salzburg, Austria Introduction and Objectives: Since Obwegeser’s fundamental ideas, orthognathic surgery now is routinely performed. Nevertheless there are some unsolved problems caused by limited unterstanding in detail, resulting in unfavourable outcome. For better predictability of results the senior author developed the 3-D-OSS in 1983. In this study, long-term experience planning orthognathic surgery with this system is presented. Material and Methods: In 23 years 1237 patients underwent orthognathic surgery. We treated 339 patients with single jaw surgery and 898 patients underwent bimaxillary osteotomies. The idea was to transfer bony and soft tissue reference points to a three-dimensional device (3-D-OSS), enabling the surgeon to divide and visualize planned jaw movements according to 3 linear movement planes and 3 rotation axles. A coordinate system enables the transfer of planned movements to the operation theatre (Face-O-Meter). Results: Mock surgery precisely represents the operation itself and can be correlated with the attending patient. Surgical outcome can be evaluated before surgey, thus enabling the surgeon to concentrate on the procedure. Using the Face-O-Meter the aimed result can reliably be verified and controlled. Deviations can be detected and corrected. Plain congruency was systematically found at the osteotomy sites. Conclusions: With this planning system it is possible to convert a difficult operations into a simple operation, dividing a complex three-dimensional movement into 6 simple movements (3x rotation, 3x linear). All procedures can be repeated at any time. The method helps to gain education quality of trainees and improves planning procedures for the experienced.
O.046 Computer assisted orthognatic surgery based on 3D cephalometry. An alternative approach M. Zinser1 , R. Mischkowski1 , M. Durond2 , J. Z¨oller1 . 1 Department of Craniomaxillofacial and Plastic Surgery, University of Cologne, Germany; 2 Materialise, Leuven, Belgium Introduction: Computerization and radiographic technology in orthognathic surgery have contributed immensely to the stockpile of knowledge. Conventional pre-operative X-ray analysis is limited. Purpose: We present a new technique for 3D-facialsoft tissue-change prediction after simulated orthognatic surgical planning. A new method of computer-assisted-3D-virtual-reality soft tissue planning and prediction is presented. A further objec-
Orthognatic surgery: planning
13
tive is to investigate a new dental splint design to transform the virtual 3D planning to the intraoperative situation. Material and Methods: This study contains 15 patients with orthognatic deformaties. A virtual reality workbench is used for surgical planning based on CT database. The orthognatic surgery procedures (bone segmentation and osteotomy lines) were planned virtually reffering to anatomical landmarks and the soft tissue. Based on this virtual augmented surgeries custom dental splints and surgical templates have been developed to transfer the virtual planning. We used the new software (CMF/Simplant pro 9.21) from Materialise (Leuven, Belgium). All patients underwent a post-operative CT or DVT for evaluation. Results: CAS allowa an ideal pre-operative planning concerning aesthetic and functional aspects. The mean precision of the virtual bone segmentation was 85–90% for horizontal and 80–85% for vertical movements. The facial soft tissue prediction showed an accuracy of nearly 75%. Conclusion: Computer generated image prediction was suitable for patients education and communication. CAS is excellent in complex cases in which change in facial soft tissue shape should be carefully deliberated. The use of CAS templates has resulted in outcomes close to those predicted by the planning process. O.047 Comparison of 3D-visualization, planning and navigation tools in orthognathic surgery P. Juergens, K. Schwenzer-Zimmerer, H.-F. Zeilhofer. Division of Maxillo-Facial Surgery, Clinic for Reconstructive Surgery, University Hospital Basle, Switzerland Introduction: Accurate pre-operative 3D-planning of corrective surgical jaw interventions becomes more and more important in modern orthognathic surgery. The 2D-profile prediction as support of the conventional dental occlusion planning will be replaced by virtual 3D-models of the facial skeleton and the covering soft tissue generated from CT-Scans. The systems differ a lot concerning usability, accuracy and regarding soft tissue also hence a comparison of these systems seems reasonable. Methods: In seven patients mandibulo-maxillary osteotomies were performed after 3D-operation planning with three different planning systems: a commercially available planning system, a newly developed tool for computer-aided preoperative planning and intraoperative navigation and a planning system that allows post-operative soft tissue prediction. All systems were based on Datasets acquired by CT-scan of the midface and the mandible. In three patients intra-operative navigation was performed. The obtained graphics were used to inform the patient about the intended surgical intervention. Results: It could be shown that the three systems vary a lot in the efforts in time and manpower: the commercially available system could be handled by a physician with advanced computer knowledge, the planning with the other two systems had to be performed by computer scientists or mathematicians. The virtual soft tissue model had a very good acceptance by the patients. The third system allows the use as planning and navigation tool and provided the feature of 3D-cephalometry for quick evaluation of facial proportions. Synopsis: The tested systems all provided very accurate planning. We recognized that each had special features that provides unique advantages for different patients and indications.