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Objective:To investigate the effect of mandibular angle osteotomy on the morphological changes of mandible by using cone beam computed tomography (CBCT) scanning data and three-dimensional cephalometry.Methods:According to included and excluded criteria, the complete CBCT data of 20 female patients (aged 20-35 years with an average age of 25.5 years) from January 2016 to June 2018 who underwent curved mandibular angle osteotomy combined with splitting cortiectomy were selected. Seven items reflecting mandibular morphology before and after surgery were measured respectively. All the data were analyzed by the means of SPSS 12.0; linear correlation analysis and paired t test were used to evaluate the change of andibular morphology.Results:The measurement results of the mandible pre- and post-operative 10 days showed as follows: Go-Go decreased, both sides of Cd-Go, Go-Ri and MR-MA decreased, both sides of Go-Me became longer, both sides of Ar-Go-Me and MP-FH increased. The paired t-test results showed that there was significant difference before and after operation ( P<0.05), but there was no significant difference between the left and right measurement items ( P>0.05). Compared with that in 10 days after operation, the measurement items also changed 6 months after operation. There was no statistical difference between the above measurement items 6 months after surgery and 10 days after surgery ( P>0.05), and no statistical difference between the left and right sides ( P>0.05). Conclusions:The mandibular three-dimensional model which is reconstructed based on CBCT data, not only displays the three-dimensional anatomical structure that cannot be presented on X-ray film visually and comprehensively by means zoom, rotation and other operations, but also precisely and accurately shows the change of the shape of the mandible from the sagittal, coronal and horizontal plane with arbitrary cutting and rotation. The measurement of mandible is more accurate and reliable, and the surgical plan of mandibular angle osteotomy can be accurately planned preoperatively, and the operative effect can be quantitatively evaluated postoperatively.
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Objective@#To design the aesthetic new gonion and osteotomy line for patients with prominent mandibular angle patients using computer-aided techniques, and to investigate the application of three-dimensional digital planning in gonioplasty.@*Methods@#From April 2016 to April 2017, 14 female patients with prominent mandibular angle underwent preoperative surgical design and surgical simulation using digital technology. Gonioplasty was performed under the guide of surgical templates, preoperative, surgical simulation and postoperative data were measured including bilateral mandibular angles, the height of ramus(Co-Go) and the length of mandibular body(Go-Me). Paired t test was used to compare the differences between surgical simulation and postoperative measurements.@*Results@#Gonioplasty was performed in 14 patients successfully, and all were satisfied with their facial outcomes. The mandibular angle was improved from 113.86°±4.11° to 124.52°±1.26° on the left side, and 114.30°±4.01° to 124.29°±1.24° on the right side respectively. The average ratio of Go-Me/Co-Go was 2.011 on both sides after operation, which was very close to surgical planning. No significant differences were found between surgical planning and postoperative measurements with respect to mandibular angle or the ratio of Go-Me/Co-Go on both sides(P>0.05). The deviations between them were 1.00°±0.68° and 0.058±0.038 on the left side, and 0.85°±0.63° and 0.072±0.053 on the right side respectively.@*Conclusions@#Computer-assisted gonioplasty could improve the efficiency and accuracy of surgery, reduce the risk of surgical complications, and attain higher patients′ satisfaction.
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Objective Cephalometry has been used to measure the changes of mandibular shape before and after the surgery.The aim of this study was to evaluate the effect of mandibular angle osteotomy.Methods A lot of 42 cases with complete data were selected,cephalometric analysis were performed before operation and one week and 6 months after surgery,respectively.Furthermore,the data of six months postoperatively were compared to those of the beauty people reported in the literature.Results At one week after surgery,the average distance between the gonions decreased (17.70± 8.46) mm,the average length of the mandibular ramus reduced (5.84±3.26) mm,the average mandibular body length increased (4.61±2.74) mm,the average gonial angle increased (14.78±6.65)°,and the average mandibular plane angle increased (10.29±3.82)° (P＜0.05).At six months postoperatively,the first three linear measurements increased (3.68±2.91) mm,(1.66±2.51) mm and (2.10±2.37) mm,respectively;however,the last two angular measurements reduced (2.86±3.02)°and (1.77±2.62)° respectively.The data of six months postoperatively were compared to those of the beauty people reported in the literature,and there were statistically differences between the linear measurements,but no statistically differences between the angular measurements.Conclusions Re duction mandibuloplasty can modificate mandibular contouring three-dimensionally.Despite bone regeneration resuhs in linear or angular measurements change,postoperative angular shape is predominantly maintained,and so the patients can reach the level of beauty papulation.
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Objective To explore the clinical effect of endoscopic-assisted intraoral reduction mandibuloplasty.Methods From January 2010 to December 2014,a total of 186 patients with prominent mandibular angles underwent one stage long-curved ostectomy combined with splitting corticectomy through an intraoral approach with endoscopic assistence according to preoperative design for reduction mandible three-dimensionally,and achieved reduced width of the lower face with smooth curve of mandibular edge.The distance between both gonions was measured and the complications recorded to evaluate the clinical effect of the surgery during follow-up.Results All the 186 patients had no complications of bleeding and infection.The mean distance between both gonions measurement was (117.3±2.5) mm before surgery and (102.6±2.3) mm after operation;it was reduced (14.1 ±2.4)mm.After 1 month to 2 years of follow up,the width of the lower face was reduced in the frontal view and the mandibular angle appeared natural and inconspicuous in the lateral view.The patients were satisfied with both their frontal and lateral appearances.Conclusions Intraoral approach mandibular ostectomy with endoscopic-assisted allows surgeons to perform accurate,safe and reproducible ostectomies and to recontour mandible symmetrically and reduce the complications.
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Objective To explore the clinical method and effect of ultrasonic osteotomy in mandibular angle reduction.Methods Under intronasal approach and general anesthesia,30 patients (5 male patients and 25 female patients) underwent intraoral prominent mandibular angle reductions with ultrasonic osteotomy.The jaw bone under periosteum was explored and the mental nerves protected.According to the clinical features of mandibular angle,curved mandibular angle osteotomy,mandible margin osteotomy or outer cotex splitting osteotomy were performed.Results All the osteotomy of prominent mandibular angle reductions could be completed with ultrasonic osteotomy.There were no complications of bleeding,nerve injury and malfracture happened.After 1 year following-up,the outlines of lower mandible were natural and concordant.Compared with traditional osteotomy devices,ultrasonic osteotomy was smoother and more precisely.Conclusions Ultrasonic osteotomy can improve the precise and safty of mandibular angle reduction.but compared with traditional osteotomy devices,it takes more time for osteotomy procedure.Surgeons need adapt to the different feeling and control methods.
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Objectives To investigate the changes in the masseter muscle following osteotomy of the prominent mandibular angle using real-time three-dimensional (3D) ultrasonography, and to supply guidance for resection of the mandibular angle. Methods Real-time 3D ultrasonography was applied preand post-operatively (over a 6-month follow-up period) to 10 patients who underwent curved osteotomy with the following objectives: (1) to reconstruct the morphological changes of the masseter under different conditions; (2) to assess masseter muscle volume changes, and (3) to obtain the dynamic morphological changes of masseter during mouth opening and closing. Results The reconstructed 3D images revealed that longitudinal diameters of masseter muscle decreased and angle regions changed to be arc-shaped with significant thinning 6 months after operation. The mean volume of masseter muscle was (18. 222 ±3. 028) cm36 months post-operatively, compared with the pre-operation mass of (25. 480 ± 7. 113) cm3,the statistical difference was significant (P＜0.01). Transverse and longitudinal changes of the thickest masseter muscle section 6 months post-operatively were of no statistic difference (P＞0. 01) compared with pre-operation status during mouth opening and closing motions. Conclusion A certain extent of atrophy occurs primarily in the angle region of masseter muscle after mandibular angle ostectomy. However, these changes do not significantly impair masseter muscle function. Real-time 3D ultrasonography offers a novel, safe, and convenient technique for masseter muscle reconstruction and observation of masseter muscle movement.
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Objective To investigate the changes of the constitution and its ratio of collagen fiber in the process of masseter reattachment following different osteotomies of the prominent mandibular angle so as to offer guidance for the resection of mandibular angle. Methods Sixteen adult goats were randomized into four groups. In group A we performed unilateral curved osteotomy of the mandibular angle. In group B unilateral curved ostectomy was performed with partial masseter resection. In group C unilateral angle splitting ostectomy, while in group D unilateral dissection of the masseter muscle was conducted. The constitution and its ratio of collagen fiber in the interface were observed at 1-month, 2-month, 3-month, and 6-month after operation. Results On the changes of collagen fiber in the process of muscular reattachment, at 1-month post-operation, the constitution of collagen fiber (types Ⅰ and Ⅲ) in groups A and B were significantly different from that of control group (P<0.05). However, both groups C and D had no statistic difference from control group (P>0.05). At 2-month, 3-month and 6-month post-operation, those of all experimental groups had no statistic difference from control group. And with time, the percentage of collagen fiber type Ⅰ increased and type Ⅲ decreased gradually. Conclusion The recovery sequences of masseter muscle reattachment in this study are firstly group C, secondly group A and finally group B. It suggests that the recoveries of mastication and other oral activities are different. Group B turns out to be with a slow muscle reattachment. Thus, we recommend treating different kinds of mandibular hypertrophy with different ostectomies.
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Objective Several surgical procedures are available for treatment the prominent mandibular angle. But in some patients, only one procedure is not likely to obtain satisfactory results. This study was to evaluate the effect of curved osteotomy combined with sagittal splitting osteotomy of the mandibular angle by an intraoral approach for treatment the broad lower face. Methods 21 patients with broad lower face were treated with mandibular angle osteotomy plus mandibular angle splitting osteotomy under general aesthesia by intraoral approach. Changes of the distance between the mandibular angles were observed during follow up phase. Questionnaires were used to assess the patents level of satisfaction after operation. Results All the wounds healed without complications of bleeding and infection. After 7 months to 12 months follow up, the distance between the mandibular angles was effectively reduced, the deformity of broad lower face were improved markedly, the curve of the mandibular angle was smooth and the shape was natural. Conclusion This method is worthy to be applied widely because of the good result with effective reduction of the width of the lower face, smooth and gentle outline of the face.
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Objective To investigate the changes of the masseter muscle following osteotomy of the prominent mandibular angle and to provide guidance for the resection of mandibular angle. Methods Ten goats were equally divided into two groups. In group A we performed unilateral curved osteotomy of the mandibular angle, and in group B we performed unilateral dissection of the masseter muscle. The cross section area (CSA) and the sarcomere length of masseter muscle were measured beore and after operation. Results (1) Cross section area (CSA) of masseter muscle fiber in curved ostectomy group decreased at 1,2, 3 and 6 months after operation in different extent. Comparing with the control group, the difference was statistically significant (P<0.01). CSA of masseter muscle fiber in dissection group decreased 1 month postoperatively, which had significantly statistic difference with control group (P<0.01). But, they had no significant difference with control group at 2, 3, and 6 months after operation (P>0.01). (2) Sarcomere length of masseter muscle in curved ostectomy group decreased in 1 week, 1 and 2 months after operation, which had significantly statistic difference with control group (P<0.01). At 3 months after operation, sarcomere length recovered to normal. In dissection group, sarcomere length decreased in 1 week and 1 month after operation, which had significantly statistic difference with control group (P<0.01). At 2 month after operation, it recovered to normal. Conclusion Certain extent of atrophy does happen to masseter muscle after mandibular angle ostectomy. Meanwhile, these changes do not significantly impair the function of masseter muscle. According to this, we suggest a simple mandibular angle ostectomy without partial resection of masseter muscle in case of mild to morderate mandibular angle hypertrophy. Doing so, we can not only achieve the cosmetic effect but also reduce the implications.
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Objective To investigate the application of computer-aided 3D reconstruction and rapid prototyping(RP) technique in the correction of prominent mandibular angle.Methods Computer tomography scanning and 3D reconstruction were performed on 15 square face patients with prominent mandibular angles,then their actual mandible models were made by RP techniques.Surgical programs were made according to the model,including partial mandibular angle osteotomy,outer mandible table sagittal splitting osteotomy,chin augmentation with autogenous mandibule bones,and so on.In 15 cases,mandibular angle partial cutting was performed in 5 cases,sagittal splitting osteotomy in 6 cases,and mandibular angle partial cutting combined with splitting osteotomy in 4 cases.The autogenous mandibule bones were transplanted for chin augmentation in 3 chin microsomia patients.All the cases were treated according to the position and range set by the RP model.Results All the mandibular models produced by RP techniques were real and complete,which could directly and precisely show the state of the mandible.The operations completed smoothly and accomplished with the expected outcomes designed before operation.In all cases,the width of lower face was efficiently reduced and the face was symmetrical after operation.The follow-up period ranged from 3 months to 1 year in 12 patients,during which their facial appearances were in good condition and the results were satisfactory.Conclusion RP techniques is helpful in precise representation of the state of mandible,which providing ideal surgical models for accurate evaluation of prominent mandibular angle,design of surgical procedures as well as surgery instruction.It can provide good assistance to facial contour plastic surgery.