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Prediction of soft tissue profile changes after mandibular set-back surgery
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024-C10rthognathic surgery
0 2 4 - C 1 0 r t h o g n a t h i e surgery 3. A New Method for Transfer of Cephalometric Data in the Orthognathic Surgery Patients 1. Prediction of Soft Tissue Profile Changes after Mandibular Set-back Surgery Kwon, T. G., Lee, S. H., Lee, H. If.
Puricelli, E. Department of Oral and Maxillofacial Surgery, UFRGS, Porto Alegre, Brazil
Department of Oral and Maxillofacial Surgery, Kyungpook National University, Taegu, Korea A randomized clinical study was carried out on patients who underwent a BSSO set-back operation with regard to soft and hard tissue changes. Cephalometric data were obtained before orthodontic treatment, immediately before and after surgery, and 6 and 12 months postoperatively. Cephalometric changes were referenced to a cranial base coordinate system. Differences in soft and hard tissue changes among time intervals were examined using analysis of variance. The associations between immediate surgical changes in chin landmarks and subsquent short and long term soft and hard tissue changes were examined using linear regression analysis.
2. Cephalometric Norms for Orthognathic Surgery in Japanese Adults Alcalde, R. E. a, Jinno, T.2, Pogrel, M. A. 3, Sasaki, A. 1, Nishiyama, A. 1, Matsumura, T.1
1Department of Oral and MaxilloJacial Surgery IT, Okayama University Dental School, Okayama, Japan, 2Private practice, Okayama, Japan, 3Department of Oral and Maxillofacial Surgery, University of California, San Francisco, USA Knowledge of the normal dentofacial patterns of adults belonging to various ethnic and age groups is important for clinical and research purposes. Lateral cephalometric standards of Japanese normal adults were developed using the Burstone and Legan comprehensive cephalometric analyses that are specific for orthognathic surgery. Cephalometric radiographs of 217 Japanese adults were analyzed and the mean values of their hard and soft tissue measurements were compared with those of Caucasian American adults. Statistically significant differences were found in the Japanese sample that presented a shorter maxilla, larger upper anterior face height and lower posterior dental height than Burstone's Caucasian sample. A less prominent chin was observed in the Japanese male group. Soft tissue analysis of the Japanese subjects showed a retrognathic maxilla and mandible in relation to the soft tissue glabella and bilabial protrusion when compared to the white adult standards.
Transfer of individualized cephalometric data to the actural, surgical situation still poses some problems. If one wants to achieve predictable results from orthognathic surgery, reliable tranfer, however, is necessary. This presentation suggests a modification of existing analyses. Once the bony corrections are defined, points to be transferred and angles are determined. From the intersection, at a right angle to a line parallel to the mandibular base and a perpendicular line accross the first lower molar, the current position and the prediction of the mandibular position are determined. The standard reference is given by a specially designed registering instrument. The intersection of the two perpendiculars, starting from the mandible base and S.N. lines, define the angles which serve as a comparison. With a metallic instrument, similar to the registering one, we transfer the references to the vestibular cortex of the mandible at surgery. Once the sagittal osteotomy is carried out and the distal fragment is positioned, fixation is achieved with miniplates. Maxillary surgery, if necessary, follows the mandibular surgery.
4. Upper Lip Change Following Orthognathic Surgery Using Rigid Fixation Arpornmaeklong, p.l, Heggie, A. A. C.z
1Department 03"MOS, Prince of Songkla University, Songkhla, Thailand, 2Department of MOS, The Royal Children's Hospital of Melbourne, Melbourne, Australia A retrospective cephalometric analysis of the upper lip change following maxillary repositioning was performed in 85 non-growing (13-43 years) patients. The patients were divided into three groups: A - maxillary advancement (26 cases), B - maxillary advancement and mandibular reduction (30 cases), and C - maxillary superior repositioning and mandibular advancement (29 cases). A "figure 8" alar cinch suture and V Y advancement closure were performed in all cases. Serial cephalometric tracings pre-operatively (T1) and at a minimum of one year follow up (T3) were superimposed using the anatomical best fit technique. Digitization, measurement and the analysis were performed using "Quick Ceph Image" software. In group A, the upper lip moved anteriorly and inferiorly (P<0.001) and became thinner (5.7% of the original thickness, P<0.05). The highest ratio of change was 0.85:1 between the Upper lip point (ULP/X) and Maxillary central incisor edge (MXl), and 0.75:1 between soft tissue A-point (SA/X) and MX1.
024-C10rthognathic surgery
0 2 4 - C 1 0 r t h o g n a t h i e surgery 3. A New Method for Transfer of Cephalometric Data in the Orthognathic Surgery Patients 1. Prediction of Soft Tissue Profile Changes after Mandibular Set-back Surgery Kwon, T. G., Lee, S. H., Lee, H. If.
Puricelli, E. Department of Oral and Maxillofacial Surgery, UFRGS, Porto Alegre, Brazil
Department of Oral and Maxillofacial Surgery, Kyungpook National University, Taegu, Korea A randomized clinical study was carried out on patients who underwent a BSSO set-back operation with regard to soft and hard tissue changes. Cephalometric data were obtained before orthodontic treatment, immediately before and after surgery, and 6 and 12 months postoperatively. Cephalometric changes were referenced to a cranial base coordinate system. Differences in soft and hard tissue changes among time intervals were examined using analysis of variance. The associations between immediate surgical changes in chin landmarks and subsquent short and long term soft and hard tissue changes were examined using linear regression analysis.
2. Cephalometric Norms for Orthognathic Surgery in Japanese Adults Alcalde, R. E. a, Jinno, T.2, Pogrel, M. A. 3, Sasaki, A. 1, Nishiyama, A. 1, Matsumura, T.1
1Department of Oral and MaxilloJacial Surgery IT, Okayama University Dental School, Okayama, Japan, 2Private practice, Okayama, Japan, 3Department of Oral and Maxillofacial Surgery, University of California, San Francisco, USA Knowledge of the normal dentofacial patterns of adults belonging to various ethnic and age groups is important for clinical and research purposes. Lateral cephalometric standards of Japanese normal adults were developed using the Burstone and Legan comprehensive cephalometric analyses that are specific for orthognathic surgery. Cephalometric radiographs of 217 Japanese adults were analyzed and the mean values of their hard and soft tissue measurements were compared with those of Caucasian American adults. Statistically significant differences were found in the Japanese sample that presented a shorter maxilla, larger upper anterior face height and lower posterior dental height than Burstone's Caucasian sample. A less prominent chin was observed in the Japanese male group. Soft tissue analysis of the Japanese subjects showed a retrognathic maxilla and mandible in relation to the soft tissue glabella and bilabial protrusion when compared to the white adult standards.
Transfer of individualized cephalometric data to the actural, surgical situation still poses some problems. If one wants to achieve predictable results from orthognathic surgery, reliable tranfer, however, is necessary. This presentation suggests a modification of existing analyses. Once the bony corrections are defined, points to be transferred and angles are determined. From the intersection, at a right angle to a line parallel to the mandibular base and a perpendicular line accross the first lower molar, the current position and the prediction of the mandibular position are determined. The standard reference is given by a specially designed registering instrument. The intersection of the two perpendiculars, starting from the mandible base and S.N. lines, define the angles which serve as a comparison. With a metallic instrument, similar to the registering one, we transfer the references to the vestibular cortex of the mandible at surgery. Once the sagittal osteotomy is carried out and the distal fragment is positioned, fixation is achieved with miniplates. Maxillary surgery, if necessary, follows the mandibular surgery.
4. Upper Lip Change Following Orthognathic Surgery Using Rigid Fixation Arpornmaeklong, p.l, Heggie, A. A. C.z
1Department 03"MOS, Prince of Songkla University, Songkhla, Thailand, 2Department of MOS, The Royal Children's Hospital of Melbourne, Melbourne, Australia A retrospective cephalometric analysis of the upper lip change following maxillary repositioning was performed in 85 non-growing (13-43 years) patients. The patients were divided into three groups: A - maxillary advancement (26 cases), B - maxillary advancement and mandibular reduction (30 cases), and C - maxillary superior repositioning and mandibular advancement (29 cases). A "figure 8" alar cinch suture and V Y advancement closure were performed in all cases. Serial cephalometric tracings pre-operatively (T1) and at a minimum of one year follow up (T3) were superimposed using the anatomical best fit technique. Digitization, measurement and the analysis were performed using "Quick Ceph Image" software. In group A, the upper lip moved anteriorly and inferiorly (P<0.001) and became thinner (5.7% of the original thickness, P<0.05). The highest ratio of change was 0.85:1 between the Upper lip point (ULP/X) and Maxillary central incisor edge (MXl), and 0.75:1 between soft tissue A-point (SA/X) and MX1.