1.Contralateral mandibular outer cortex "sandwich" bone grafting for correcting lower facial asymmetry with normal occlusal relationship
Guoping WU ; Tong LU ; Yuming QU ; Sheng GAO ; Zhiyang XIE ; Kaili YAN ; Chongxu QIAO ; Shunchao YAN ; Shu WANG ; Wensong SHANGGUAN
Chinese Journal of Plastic Surgery 2024;40(10):1049-1058
Objective:To investigate the clinical outcomes of using autologous mandibular outer cortex "sandwich" grafting to augment mandible for correcting lower facial asymmetry with normal occlusal relationships.Methods:A retrospective analysis was conducted on the clinical data of patients with lower facial asymmetry treated at the Department of Plastic Surgery, the Affiliated Friendship Plastic Surgery Hospital of Nanjing Medical University, from January 2016 to December 2019. Preoperative cone-beam CT (CBCT) scans of the maxillofacial region were obtained to acquire three-dimensional data of the maxillofacial skeleton. Computer-aided design was used to determine the osteotomy range of the mandibular outer cortex and design osteotomy guide template. The outer cortex of the larger mandibular side (donor site) was harvested according to the osteotomy guide template and sectioned. The segmented mandibular outer cortex was then contoured to match the arc of the recipient side’s mandibular outer cortex and fixed to the inner side of the recipient mandibular outer cortex, thus increasing the width and thickness of the expanded mandible. Follow-up was conducted at 7th day and 6 months postoperatively, CBCT scan was performed to measure the changes in ramus height (Co-Go), mandibular body length (Go-Me), and mandibular outer cortex thickness, and volume, and the patient satisfaction with facial appearance (1 to 5 points, with higher scores indicating higher satisfaction), were assessed to evaluate surgical outcomes. Statistical analysis was performed using SPSS 12.0 software. Paired t-tests were used to compare patient satisfaction scores preoperatively and six months postoperatively. Repeated measurement ANOVA was used to compare Co-Go and Go-Me measurements preoperatively, 7th day, and 6 months postoperatively. If a statistically significant difference is found, further analysis using post-hoc testing(Tukey’s HSD test) will be conducted to examine the data. Results:Sixteen patients with lower facial asymmetry were included, comprising of 5 males and 11 females, aged 18 to 40 years, with an average age of 25.2 years. Surgical method included contralateral mandibular outer cortex "sandwich" grafting to the expanded mandible in 9 cases and simultaneous genioplasty in 7 cases. Follow-up ranged from 6 months to 5 years, with an average follow-up of 18.6 months. All patients experienced numbness of the lower lip postoperatively, which resolved within six months, and no severe complications occurred. The symmetry of lower facial contour improved significantly and remained stable. Patient satisfaction score for facial appearance increased from (1.63±0.62) points preoperatively to (4.19±0.75) points six months postoperatively( P<0.01). The differences in Co-Go on the donor side and Go-Me on the recipient side across the three time points(preoperatively, 7th day and 6 months postoperatively) were not statistically significant(all P>0.05). However, the differences in Go-Me on the donor side and Co-Go on the recipient side across the three time points were statistically significant(all P<0.05). On the donor side, the mandibular outer cortex thickness decreased by a maximum of 6 mm on 7th day postoperatively and increased by a maximum of 2 mm at 6 months postoperatively compared to 7th day. On the recipient side, mandibular outer cortex thickness increased by a maximum of 6 mm on 7th day postoperatively and decreased by a maximum of 2 mm at six months postoperatively compared to 7th day. The volume of the mandibular outer cortex on the recipient side increased by (4 415.94±1 017.21)mm 3 at 7th day postoperatively compared to preoperatively, and decreased by (202.63±300.85)mm 3 at 6 months postoperatively. Conclusion:For lower facial asymmetrical with normal occlusal relationships and no occlusal plane deviation, contralateral mandibular outer cortex "sandwich" bone grafting can effectively increase the width and volume of the mandible on the grafted side, achieving favorable clinical outcomes.
2.Contralateral mandibular outer cortex "sandwich" bone grafting for correcting lower facial asymmetry with normal occlusal relationship
Guoping WU ; Tong LU ; Yuming QU ; Sheng GAO ; Zhiyang XIE ; Kaili YAN ; Chongxu QIAO ; Shunchao YAN ; Shu WANG ; Wensong SHANGGUAN
Chinese Journal of Plastic Surgery 2024;40(10):1049-1058
Objective:To investigate the clinical outcomes of using autologous mandibular outer cortex "sandwich" grafting to augment mandible for correcting lower facial asymmetry with normal occlusal relationships.Methods:A retrospective analysis was conducted on the clinical data of patients with lower facial asymmetry treated at the Department of Plastic Surgery, the Affiliated Friendship Plastic Surgery Hospital of Nanjing Medical University, from January 2016 to December 2019. Preoperative cone-beam CT (CBCT) scans of the maxillofacial region were obtained to acquire three-dimensional data of the maxillofacial skeleton. Computer-aided design was used to determine the osteotomy range of the mandibular outer cortex and design osteotomy guide template. The outer cortex of the larger mandibular side (donor site) was harvested according to the osteotomy guide template and sectioned. The segmented mandibular outer cortex was then contoured to match the arc of the recipient side’s mandibular outer cortex and fixed to the inner side of the recipient mandibular outer cortex, thus increasing the width and thickness of the expanded mandible. Follow-up was conducted at 7th day and 6 months postoperatively, CBCT scan was performed to measure the changes in ramus height (Co-Go), mandibular body length (Go-Me), and mandibular outer cortex thickness, and volume, and the patient satisfaction with facial appearance (1 to 5 points, with higher scores indicating higher satisfaction), were assessed to evaluate surgical outcomes. Statistical analysis was performed using SPSS 12.0 software. Paired t-tests were used to compare patient satisfaction scores preoperatively and six months postoperatively. Repeated measurement ANOVA was used to compare Co-Go and Go-Me measurements preoperatively, 7th day, and 6 months postoperatively. If a statistically significant difference is found, further analysis using post-hoc testing(Tukey’s HSD test) will be conducted to examine the data. Results:Sixteen patients with lower facial asymmetry were included, comprising of 5 males and 11 females, aged 18 to 40 years, with an average age of 25.2 years. Surgical method included contralateral mandibular outer cortex "sandwich" grafting to the expanded mandible in 9 cases and simultaneous genioplasty in 7 cases. Follow-up ranged from 6 months to 5 years, with an average follow-up of 18.6 months. All patients experienced numbness of the lower lip postoperatively, which resolved within six months, and no severe complications occurred. The symmetry of lower facial contour improved significantly and remained stable. Patient satisfaction score for facial appearance increased from (1.63±0.62) points preoperatively to (4.19±0.75) points six months postoperatively( P<0.01). The differences in Co-Go on the donor side and Go-Me on the recipient side across the three time points(preoperatively, 7th day and 6 months postoperatively) were not statistically significant(all P>0.05). However, the differences in Go-Me on the donor side and Co-Go on the recipient side across the three time points were statistically significant(all P<0.05). On the donor side, the mandibular outer cortex thickness decreased by a maximum of 6 mm on 7th day postoperatively and increased by a maximum of 2 mm at 6 months postoperatively compared to 7th day. On the recipient side, mandibular outer cortex thickness increased by a maximum of 6 mm on 7th day postoperatively and decreased by a maximum of 2 mm at six months postoperatively compared to 7th day. The volume of the mandibular outer cortex on the recipient side increased by (4 415.94±1 017.21)mm 3 at 7th day postoperatively compared to preoperatively, and decreased by (202.63±300.85)mm 3 at 6 months postoperatively. Conclusion:For lower facial asymmetrical with normal occlusal relationships and no occlusal plane deviation, contralateral mandibular outer cortex "sandwich" bone grafting can effectively increase the width and volume of the mandible on the grafted side, achieving favorable clinical outcomes.
3.Nomogram for predicting the risk of post hepatectomy liver failure was established based on preoperative routine test indexes
Guoping DONG ; Chen CHEN ; Xudong LU ; Jiali WU ; Wenhao ZHENG ; Lin TONG
Chinese Journal of Laboratory Medicine 2024;47(8):895-901
Objective:To establish a risk prediction model of liver failure after liver resection for hepatocellular carcinoma.Method:A retrospective case-control study was designed. Clinical data and laboratory results, including gender, age, and preoperative 18 laboratory indicators, were collected from 320 patients with hepatocellular carcinoma undergoing liver resection in Eastern Hepatobiliary Surgery Hospital Affiliated to Naval Medical University from January 1, 2013 to December 31, 2023. According to the surgical time, 252 cases in the training cohort were divided into 62 and 190 cases with and without postoperative liver failure, respectively. Of the 68 cases in validation cohort, 34 developed postoperative liver failure and 34 did not. Binary Logistic regression analysis was used to conduct univariate analysis of gender, age, and 18 preoperative laboratory indicators, and multivariate analysis was carried out for significant results to determine the influencing factors of liver failure after liver resection for hepatocellular carcinoma, and Logistic regression model was established.Result:In the training cohort, indicators significantly associated with liver failure after liver resection for hepatocellular carcinoma included age ( P=0.016), platelets ( P=0.005), prealbumin ( P<0.001), and alkaline phosphatase ( P<0.001). Logistic regression was used to construct a nomogram model and draw a calibration curve by combining these four indicators. In the training cohort, the nomogram model showed good discriminability in predicting the risk of liver failure after hepatectomy for hepatocellular carcinoma. The area under the curve of was 0.82 (95% CI 0.76-0.88), and the sensitivity was 73% and specificity was 80% when the optimal cut-off value was 0.2646. In the validation cohort, the predictive performance of the nomogram model was comparable to that of the training cohort, with an area under the curve of 0.81 (95% CI 0.71-0.92), sensitivity of 82%, and specificity of 77%. Conclusion:Preoperative platelet and prealbumin decreases, alkaline phosphatase increases, and elderly patients are prone to liver failure after liver resection. The nomogram model constructed with preoperative test data has shows good discriminatory ability and accuracy in predicting liver failure after liver resection for hepatocellular carcinoma.
4.Effect of biomechanics principle on the repair of double eyelid disappearance after blepharoplasty
Kang YIN ; Guoping WU ; Wensong SHANGGUAN ; Shu WANG ; Chao HU ; Tong LU ; Sheng GAO ; Liping ZHAO
Chinese Journal of Medical Aesthetics and Cosmetology 2024;30(6):603-605
Objective:To explore the application of biomechanics principle in the repair of double eyelid disappearance after blepharoplasty.Methods:A retrospective analysis was performed on 47 patients (46 females and 1 male) with double eyelid disappearance after blepharoplasty in the Department of Plastic and Cosmetic Surgery, Friendship Plastic Surgical Hospital from July 2018 to December 2022. The patients aged from 19-42 (28±8) years. The repair surgery was performed by increasing the mechanical factors that promoted the double eyelid formation or weakening the mechanical factors that inhibited the double eyelid formation. The overall satisfaction with ocular appearance, and psychological well-being and social function were evaluated with the Face-Q qustionnaires before or after operation.Results:By following-up for 3-24 months, the morphology of upper eyelids in all 47 patients were remarkably improved. 2 patients complained about asymmetry and 1 patient had multiple creases, for whom satisfactory results achieved after re-operation. The remaining patients presented smooth natural double eyelid line, and concave groove deformity when eyes closed were not noticed. The operative effects were satisfactory. After surgery, the scores for ocular satisfaction with facial appearance, psychological well-being and social function were (69.5±10.3), (75.5±13.6) and (68.3±11.3) scores, which were significantly increased than those before operation [(38.7±9.3), (54.8±10.5) and (52.3±8.7) scores], respectively (all P<0.05). Conclusion:More effective and reliable operation results can be obtained in the repair strategies of double eyelid disappearance after blepharoplasty by utilizing the biomechanical mechanism.
5.Efficacy of W-genioplasty on the broad and short chin
Zhiyang XIE ; Sheng GAO ; Kaili YAN ; Tong LU ; Chao HU ; Shu WANG ; Wensong SHANGGUAN ; Guoping WU
Chinese Journal of Medical Aesthetics and Cosmetology 2023;29(1):19-22
Objective:To investigate the clinical effect of W-shaped genioplasty in the correction of broad and short chin deformity.Methods:Thirty-eight patients (5 males, 33 females, aged 20 to 41 years, mean 27.3 years) complained with broad and short chin were admitted to the Affiliated Friendship Plastic Surgery Hospitalof Nanjing Medical University from January 2019 to December 2021. CBCT scan and three-dimensional reconstruction were performed to design osteotomy line and determine the distance of chin lengthening, narrowing and advancing or retrocession preoperatively. Under general anesthesia, the W-shaped osteotomy was performed using an intraoral incision, and the angle between the bilateral free bone fragments, the distance of downward and forward movement were adjusted to change the curvature, width, length and prominence of the lower edge of the chin according to the preoperative designs. The results were evaluated by clinical appearances and image analyses at a follow-up of 3-24 months.Results:The amount of vertical lengthening of the chin in 38 cases were 2 mm to 5 mm, with an average of 3.02 mm. The horizontal narrowing width distances were 3-7 mm, with an average of 5.6 mm. The patients were followed up for 3-24 months, with an average of 10.6 months. There were no complications such as hematoma, wound dehiscence, accidental fracture, surgical area infection and permanent neurosensory disorder. 38 patients had transient sensory loss in the lower lip region of varying degrees, but all recovered spontaneously during routine follow-up period. All patients were satisfied with the improvement of facial contour.Conclusions:W-shaped geinoplasty preserves the central bone of the chin and the attachment of genioglossus muscle, which does not affect the normal anatomy and physiological function of the oral cavity. After osteotomy, the bone is removed and the bilateral bone fragments move flexibly. It can effectively change the radian, width, length and protrusion of the lower edge of the chin in three dimensions, so as to correct the wide and short deformity of the chin.
6.Effects of eyebrow arch augmentation with personalized PEEK implant assisted by endoscope
Shu WANG ; Zhiyang XIE ; Tong LU ; Chao HU ; Sheng GAO ; Wenwen ZHANG ; Wensong SHANGGUAN ; Yang ZHAO ; Guoping WU
Chinese Journal of Medical Aesthetics and Cosmetology 2022;28(3):185-188
Objective:To investigate the effect of eyebrow arch augmentation with personalized polyether ether ketone (PEEK) implant assisted by endoscope.Methods:From January 2019 to August 2021, 9 patients with low and flat eyebrow arch requiring eyebrow arch augmentation were treated in the plastic surgery department of the Friendship Plastic Surgery Hospital Affiliated to Nanjing Medical University. The cranial and maxillofacial CT scanning data were obtained before operation, the eyebrow arch elevation range and height were designed according to the patient's requirements, and personalized peek implants were manufactured. During the operation, a small temporal hairline incision was used to accurately separate the implantation cavity of individualized peek implants under the periosteum of the eyebrow arch implantation area with the aid of endoscope. Personalized PEEK implants were implanted under endoscope to make them fully fit with the eyebrow arch bone and fixed with titanium nails. Photos were taken and analyzed before and after operation.Results:All patients were followed up for 3 months to 2 years. Their facial expressions were normal, and there were no motor nerve injury, rejection and iatrogenic infection. The patients were satisfied with the postoperative effect. Compared with before operation, the low level of orbital bone in eyebrow area was improved, and the facial contour was three-dimensional and harmonious.Conclusions:The eyebrow arch augmentation with individualized peek implant assisted by endoscope is safe and effective. It can greatly reshape the upper contour of the face, deepen the upper eyelid fossa and improve the convex eye phenomenon, so as to achieve the cosmetic effect of enhancing the three-dimensional sense of the eyebrow orbital area, which is worthy of clinical application.
7.Efficacy of endoscopic-assisted transaxillary breast augmentation with ultrasonic scalpel and electroscalpel
He CHEN ; Shu WANG ; Wenwen ZHANG ; Chao HU ; Tong LU ; Sheng GAO ; Guoping WU
Chinese Journal of Medical Aesthetics and Cosmetology 2022;28(3):189-193
Objective:To evaluate the clinical effects of the dissection of the implant pockets with ultrasonic scalpel or traditional electroscalpel through the axillary approach under endoscopic assistant.Methods:A total of 125 female patients with an average of 32.5 years, ranged from 21 to 44 years, underwent endoscopic-assisted transaxillary breast augmentation in the Department of Plastic Surgery, the Affiliated Friendship Plastic Surgery Hospital of Nanjing Medical University, from January 2019 to December 2020, were analyzed retrospectively. The implant pockets were dissected with ultrasonic scalpel (ultrasonic scalpel group) in 64 patients or with traditional electroscalpel (electroscalpel group) in 61 patients. The operation time, operation speed, postoperative drainage, drainage tube removal time and hospital stay of the two groups were compared and analyzed statistically.Results:Compared with the electroscalpel group, the average operation time of the ultrasonic scalpel group 75(71-90) min was significantly shorter than that of the electroscalpel group 105(80-135) min ( t=4.10, P<0.001), the operation speed (3.27±0.44 ml/min) was faster than that of the electroscalpel group (2.52±0.72 ml/min) ( t=4.71, P<0.001), the postoperative drainage 130.5(98.8-193.3) ml was significantly less than that of the electroscalpel group 281.75(145.5-328.3) ml ( t=2.21, P<0.05), and the drainage tube removal time 3 (3-4) d and hospital stay 3 (3-4) d were remarkablely shorter than that of the electroscalpel group 4 (3-4) d, 5 (4-6) d ( t=3.58; t=4.06, P<0.05). Conclusions:The application of ultrasonic scalpel in endoscopic-assisted transaxillary breast augmentation is safe and reliable. In addtion to improving the surgical efficiency, ultrasonic scalpel can reduce blood loss, shorten the time of hospital stay and reduce complications, which is worthy of further promotion in clinical application.
8.Effect of local gene therapy on expression of Wnt3a and β-catenin in callus of distraction gap during mandibular distraction osteogenesis in rabbits
Tong LU ; Chunli ZHANG ; Wenwen ZHANG ; Shu WANG ; Sheng GAO ; Zhiyang XIE ; Chao HU ; Wensong SHANGGUAN ; Guoping WU
Chinese Journal of Medical Aesthetics and Cosmetology 2022;28(2):144-149
Objective:To investigate the effect of electroporation-mediated local gene therapy on the expression of Wnt3a and β-catenin in callus of distraction gap during mandibular distraction osteogenesis of rabbits.Methods:The experiments were conducted in the laboratory of the Affiliated Friendship Plastic Surgery Hospital of Nanjing Medical University from September 2019 to December 2019. Forty eight New-Zealand rabbits were randomly divided into control group (group A), gene therapy group (group B) and normal saline group (group C), with 16 rabbits in each group. After bilateral mandible osteotomy and distractors were implanted, the distractors were activated at a speed of 0.8 mm/d on 4th day, postoperatively, and lasted for 7 days, followed by consolidation period. Group A distracted only, group B was subject to local injection of recombinant plasmid pIRES-hBMP2-hVEGF165 in the distraction gap and electroporation stimulation at the beginning of activation distractors; and group C local injection of the same dose of normal saline in the distraction gap and electroporation stimulation at the beginning of activation distractors. Four animals in each group were sacrificed on the day at the end of distraction, 7th, 14th, 28th days of consolidation period, respectively. The callus in the distraction gap was taken for immunohistochemical staining and RT-PCR to detect the expression of Wnt3a and β-catenin, and image analysis was performed. SPSS 22.0 statistical software was used for data analysis.Results:Immunohistochemical staining showed that Wnt3a and β-catenin were mainly located in the cytoplasm and nuclei of fibroblasts, chondrocytes and osteoblasts in callus tissue. Immunohistochemistry and RT-PCR showed that the expression of Wnt3a and β-catenin reached a peak at the end of distraction. With the disappearance of distraction tension, the expression of Wnt3a and β-catenin gradually decreased. After gene therapy intervention, the expression of Wnt3a and β-catenin was significantly increased, and the expression of Wnt3a and β-catenin in group B was the highest at each time point, with statistically significant difference compared with groups A and C ( F=96.3, P<0.01). Conclusions:Gene therapy promotes the expression of Wnt3a and β-catenin in the callus of distraction gap, regulating the balance of the bone reconstruction system and thus promoting the formation of new bone in the distraction gap.
9.Comparison of design and clinical outcomes of two different digital osteotomy template for mandibular angle osteotomy
Chao HU ; Guoping WU ; Wensong SHANGGUAN ; Wenwen ZHANG ; Shu WANG ; Tong LU ; Sheng GAO ; Zhiyang XIE ; Xiang QIAO ; Yang ZHAO
Chinese Journal of Plastic Surgery 2022;38(4):392-398
Objective:To evaluate the accuracy and clinical outcomes of two different three-dimensional(3D) printed digital mandibular angle osteotomy templates.Methods:Female patients with a prominent mandibular angle(PMA) admitted to the same surgical team in the Friendship Plastic Surgery Hospital of Nanjing Medical University from March 2019 to July 2020 were selected as the research subjects. They were allocated into Group A and Group B alternately according to the order of admission. Group A was the conventional digital osteotomy template(CDOT) group, and Group B was the novel digital osteotomy template(NDOT) group. All patients underwent cone-beam computed tomography(CBCT) scan and 3D reconstruction before surgery. Preoperative CT data were imported into Mimics 19.0, and personalized mandibular angle osteotomy(MAO) line and digital osteotomy template(DOT) were designed according to patients’ conditions and requirements. In Group A, the DOTs were designed according to the part of mandibular angle to be removed(CDOT). And in Group B, the DOTs were designed according to to the part of reserved mandible(NDOT). The DOTs were created with a 3D printer. All patients were underwent bilateral MAO under the guidance of these DOTs through an intraoral approach. CBCT scan was also performed on all patients within 1 week after surgery, and incision healing, complications and lower facial contouring were observed. The mean time taken for positioning DOT and performing curved osteotomy, the volume of postoperative drainage on one side within 24 hours after surgery, and the deviations between the preoperative design and 3D reconstruction mode lower mandibular margin within 1 week after surgery were compared between the two groups.Results:A total of 20 female patients with PMA were included, including 10 patients in Group A, aged 20-31 years, with an average of 24.3±2.3 years. Group B consisted of 10 patients aged 22-30 years, with an average of 24.6±2.2 years. There was no significant difference in age between 2 groups ( P>0.05). All patients were successfully performed MAO without fracture, massive bleeding, infection and other complications, and the postoperative result were satisfactory. The mean time taken to position the DOT and perform MAO one side in Group A was (18.1±1.0) min, significantly longer than that in Group B (14.2±1.4) min ( P<0.05). The volume of postoperative drainage on one side within 24 hours in Group A and Group B was (107.9±12.5) ml and (112.1±13.8) ml, respectively ( P>0.05). The deviations between preoperative design and postoperative mandibular margin, at the anterior part was (2.7±1.2) mm in Group A, which was significantly larger than that of Group B[(1.6±0.9) mm]( P<0.05), the middle part deviation of Group A and B was (1.9±0.7) mm and (1.8±0.8) mm, respectively ( P>0.05), and the posterior part deviation of Group A was (2.8±1.1) mm, which was significantly higher than that of Group B (1.8±0.8 mm)( P<0.05). Conclusions:DOT assisted MAO can achieve accurate osteotomy and reduce the operative difficulty. The NDOT is easier to be located in the operation with more stable fixation, and the surgical efficiency and accuracy of osteotomy are higher than that of CDOT.
10.Comparison of design and clinical outcomes of two different digital osteotomy template for mandibular angle osteotomy
Chao HU ; Guoping WU ; Wensong SHANGGUAN ; Wenwen ZHANG ; Shu WANG ; Tong LU ; Sheng GAO ; Zhiyang XIE ; Xiang QIAO ; Yang ZHAO
Chinese Journal of Plastic Surgery 2022;38(4):392-398
Objective:To evaluate the accuracy and clinical outcomes of two different three-dimensional(3D) printed digital mandibular angle osteotomy templates.Methods:Female patients with a prominent mandibular angle(PMA) admitted to the same surgical team in the Friendship Plastic Surgery Hospital of Nanjing Medical University from March 2019 to July 2020 were selected as the research subjects. They were allocated into Group A and Group B alternately according to the order of admission. Group A was the conventional digital osteotomy template(CDOT) group, and Group B was the novel digital osteotomy template(NDOT) group. All patients underwent cone-beam computed tomography(CBCT) scan and 3D reconstruction before surgery. Preoperative CT data were imported into Mimics 19.0, and personalized mandibular angle osteotomy(MAO) line and digital osteotomy template(DOT) were designed according to patients’ conditions and requirements. In Group A, the DOTs were designed according to the part of mandibular angle to be removed(CDOT). And in Group B, the DOTs were designed according to to the part of reserved mandible(NDOT). The DOTs were created with a 3D printer. All patients were underwent bilateral MAO under the guidance of these DOTs through an intraoral approach. CBCT scan was also performed on all patients within 1 week after surgery, and incision healing, complications and lower facial contouring were observed. The mean time taken for positioning DOT and performing curved osteotomy, the volume of postoperative drainage on one side within 24 hours after surgery, and the deviations between the preoperative design and 3D reconstruction mode lower mandibular margin within 1 week after surgery were compared between the two groups.Results:A total of 20 female patients with PMA were included, including 10 patients in Group A, aged 20-31 years, with an average of 24.3±2.3 years. Group B consisted of 10 patients aged 22-30 years, with an average of 24.6±2.2 years. There was no significant difference in age between 2 groups ( P>0.05). All patients were successfully performed MAO without fracture, massive bleeding, infection and other complications, and the postoperative result were satisfactory. The mean time taken to position the DOT and perform MAO one side in Group A was (18.1±1.0) min, significantly longer than that in Group B (14.2±1.4) min ( P<0.05). The volume of postoperative drainage on one side within 24 hours in Group A and Group B was (107.9±12.5) ml and (112.1±13.8) ml, respectively ( P>0.05). The deviations between preoperative design and postoperative mandibular margin, at the anterior part was (2.7±1.2) mm in Group A, which was significantly larger than that of Group B[(1.6±0.9) mm]( P<0.05), the middle part deviation of Group A and B was (1.9±0.7) mm and (1.8±0.8) mm, respectively ( P>0.05), and the posterior part deviation of Group A was (2.8±1.1) mm, which was significantly higher than that of Group B (1.8±0.8 mm)( P<0.05). Conclusions:DOT assisted MAO can achieve accurate osteotomy and reduce the operative difficulty. The NDOT is easier to be located in the operation with more stable fixation, and the surgical efficiency and accuracy of osteotomy are higher than that of CDOT.

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