Objective:To evaluate the accuracy of L-shaped reduction malarplasty under the guidance of virtual surgical planning (VSP).Methods:The data of adult female patients who were diagnosed with zygomatic protrusion or hypertrophy at Department of Orthognathic and Temporo-mandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University, from January 2018 to December 2020 were analyzed retrospectively. L-shaped reduction malarplasty with or without bone resection and with the mortice and tenon joint structure on the zygomatic arch was conducted either by digital procedures comprising VSP and three-dimensional printing titanium templates (digtal surgery group) or by conventional method (control group). The incidence of postoperative complications and the patient postoperative satisfaction [using a Likert scale with a score ranging from 1 to 5, representing very dissatisfied, dissatisfied, average, satisfied and very satisfied, satisfaction rate = (very satisfied + satisfied)/ total number of patients × 100%] were statistically analyzed in the two groups. The differences in the postoperative symmetry of the zygomatic complex between the digital group and the control group were analyzed by three-dimensional cephalometry. The accuracy of VSP in L-shaped reduction malarplasty was evaluated by comparing the preoperative design model with the actual postoperative model in the digital group. The statistical analyses were conducted using SPSS 24.0 software. The chi-square test was used in the comparison of surgical complications and patient satisfaction rates. The symmetry of bilateral landmarks in the three-dimensional direction between the two groups was evaluated using the independent t-test, and the pre- and post-operative measurements in the digital group were compared using paired t-test. Results:A total of 78 patients were included, with 36 in the digital group, aged (25.2±3.6) years, and 42 in the control group, aged (24.3±2.8) years. Satisfactory reduction of zygomatic protrusion or hypertrophy was recognized among all patients. Compared with the control group, the digital group had lower percentage of complications [25% (9/36) vs. 55% (23/42)] and higher postoperative satisfaction [78% (28/36) vs. 48% (20/42)], both of which were statistically significant (all P<0.01). Regarding the symmetry of bilateral zygomatic complexes, the average deviations of ΔZb (bottom point of zygoma) in the digital group in the horizontal, vertical, and sagittal directions [(1.05±0.24), (1.05±0.24), (1.00±0.88) mm] were significantly smaller than those in the control group [(2.03±0.58), (1.32±0.68), (1.47±0.47) mm], with statistically significant differences (all P<0.05). The bone segment movements of virtual plans and actual result in the digital surgery group were measured and showed no obvious difference for the inward movement [(5.42±0.98) mm vs. (5.33±0.93) mm] and the sagittal overlap [(4.87±1.21) mm vs. (4.77±1.32) mm] at the zygoma roots, along with the step length at the long-arm of the L-shaped osteotomy line [(2.43±1.11) mm vs. (2.39±0.89) mm] (all P>0.05). The mean differences of facial width and protrusion measurements between virtual simulations and actual result in the digital group ranged from (1.13±0.47) mm to (2.07±0.88) mm, with no significant differences( P>0.05). Meanwhile, the high resemblance between virtual plans and actual result was depicted via superimposition models, with a deviation controlled within ±0.5 mm. Conclusion:The application of VSP in reduction malarplasty significantly improved surgical accuracy and reduced difficulties in the operation, which would improve patients’ postoperative satisfaction.

Objective:To evaluate the accuracy of L-shaped reduction malarplasty under the guidance of virtual surgical planning (VSP).Methods:The data of adult female patients who were diagnosed with zygomatic protrusion or hypertrophy at Department of Orthognathic and Temporo-mandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University, from January 2018 to December 2020 were analyzed retrospectively. L-shaped reduction malarplasty with or without bone resection and with the mortice and tenon joint structure on the zygomatic arch was conducted either by digital procedures comprising VSP and three-dimensional printing titanium templates (digtal surgery group) or by conventional method (control group). The incidence of postoperative complications and the patient postoperative satisfaction [using a Likert scale with a score ranging from 1 to 5, representing very dissatisfied, dissatisfied, average, satisfied and very satisfied, satisfaction rate = (very satisfied + satisfied)/ total number of patients × 100%] were statistically analyzed in the two groups. The differences in the postoperative symmetry of the zygomatic complex between the digital group and the control group were analyzed by three-dimensional cephalometry. The accuracy of VSP in L-shaped reduction malarplasty was evaluated by comparing the preoperative design model with the actual postoperative model in the digital group. The statistical analyses were conducted using SPSS 24.0 software. The chi-square test was used in the comparison of surgical complications and patient satisfaction rates. The symmetry of bilateral landmarks in the three-dimensional direction between the two groups was evaluated using the independent t-test, and the pre- and post-operative measurements in the digital group were compared using paired t-test. Results:A total of 78 patients were included, with 36 in the digital group, aged (25.2±3.6) years, and 42 in the control group, aged (24.3±2.8) years. Satisfactory reduction of zygomatic protrusion or hypertrophy was recognized among all patients. Compared with the control group, the digital group had lower percentage of complications [25% (9/36) vs. 55% (23/42)] and higher postoperative satisfaction [78% (28/36) vs. 48% (20/42)], both of which were statistically significant (all P<0.01). Regarding the symmetry of bilateral zygomatic complexes, the average deviations of ΔZb (bottom point of zygoma) in the digital group in the horizontal, vertical, and sagittal directions [(1.05±0.24), (1.05±0.24), (1.00±0.88) mm] were significantly smaller than those in the control group [(2.03±0.58), (1.32±0.68), (1.47±0.47) mm], with statistically significant differences (all P<0.05). The bone segment movements of virtual plans and actual result in the digital surgery group were measured and showed no obvious difference for the inward movement [(5.42±0.98) mm vs. (5.33±0.93) mm] and the sagittal overlap [(4.87±1.21) mm vs. (4.77±1.32) mm] at the zygoma roots, along with the step length at the long-arm of the L-shaped osteotomy line [(2.43±1.11) mm vs. (2.39±0.89) mm] (all P>0.05). The mean differences of facial width and protrusion measurements between virtual simulations and actual result in the digital group ranged from (1.13±0.47) mm to (2.07±0.88) mm, with no significant differences( P>0.05). Meanwhile, the high resemblance between virtual plans and actual result was depicted via superimposition models, with a deviation controlled within ±0.5 mm. Conclusion:The application of VSP in reduction malarplasty significantly improved surgical accuracy and reduced difficulties in the operation, which would improve patients’ postoperative satisfaction.

Objective:To evaluate the stability of the zygomatic complex in reduction malarplasty (RM) with different fixation method.Methods:The clinical data of patients with zygomatic arch protrusion at the Department of Orthognathic and Temporomandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University from January 2018 to January 2021 were analyzed retrospectively. All patients underwent L-shaped osteotomy reduction malarplasty which were divided into zygomatic body fixation (ZBF) and zygomatic arch fixation (ZAF) according to fixation technique. As for ZBF, there were 4 different groups including two bicortical screws (2LS), an L-shaped plate with one bicortical screw (LPLS), an L-shaped plate with short-wing on the zygoma (LPwZ) and an L-shaped plate with short-wing on the maxilla (LPwM). As for ZAF, there were 3 different groups including mortice-tenon (MT), 3-hole plate (3HP) and short screw (SS). CT imaging data of two postoperative periods (1 week later; 6 months later) were collected. ITK-SNAP and 3D Slicer software were applied to evaluate the difference in the displacement distance of relevant landmarks of the zygomatic complex, so as to compare the postoperative stability of RM under different fixation methods. Statistical analyses were performed using IBM SPSS Statistics, version 25.0, and Kruskal-Wallis method was used to compare the difference of relevant landmarks displacement distance between ZBF group and ZAF group. P<0.05 was considered statistically significant. Results:60 patients (120 zygomatic arches) who were composed of 21 men and 39 women, aged (27.1±4.9) years were included. There were 30 samples in each group of ZBF and 40 samples in each group of ZAF. Compared with the single L-shaped plate (LPwZ, LPwM) group, the displacement distance of zygomatic complex in 2LS and LPLS groups was shorter ( P<0.05). The three fixation method of zygomatic arch (MT, 3HP, SS) had similar effects on the displacement of zygomatic complex ( P>0.05). Conclusion:After RM, the "two-bridge" fixation method (2LS and LPLS) provides better stability than the single L-shaped plate. The stability of all ZAF is similar when combined with 2LS or LPLS.

Objective:To evaluate the stability of the zygomatic complex in reduction malarplasty (RM) with different fixation method.Methods:The clinical data of patients with zygomatic arch protrusion at the Department of Orthognathic and Temporomandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University from January 2018 to January 2021 were analyzed retrospectively. All patients underwent L-shaped osteotomy reduction malarplasty which were divided into zygomatic body fixation (ZBF) and zygomatic arch fixation (ZAF) according to fixation technique. As for ZBF, there were 4 different groups including two bicortical screws (2LS), an L-shaped plate with one bicortical screw (LPLS), an L-shaped plate with short-wing on the zygoma (LPwZ) and an L-shaped plate with short-wing on the maxilla (LPwM). As for ZAF, there were 3 different groups including mortice-tenon (MT), 3-hole plate (3HP) and short screw (SS). CT imaging data of two postoperative periods (1 week later; 6 months later) were collected. ITK-SNAP and 3D Slicer software were applied to evaluate the difference in the displacement distance of relevant landmarks of the zygomatic complex, so as to compare the postoperative stability of RM under different fixation methods. Statistical analyses were performed using IBM SPSS Statistics, version 25.0, and Kruskal-Wallis method was used to compare the difference of relevant landmarks displacement distance between ZBF group and ZAF group. P<0.05 was considered statistically significant. Results:60 patients (120 zygomatic arches) who were composed of 21 men and 39 women, aged (27.1±4.9) years were included. There were 30 samples in each group of ZBF and 40 samples in each group of ZAF. Compared with the single L-shaped plate (LPwZ, LPwM) group, the displacement distance of zygomatic complex in 2LS and LPLS groups was shorter ( P<0.05). The three fixation method of zygomatic arch (MT, 3HP, SS) had similar effects on the displacement of zygomatic complex ( P>0.05). Conclusion:After RM, the "two-bridge" fixation method (2LS and LPLS) provides better stability than the single L-shaped plate. The stability of all ZAF is similar when combined with 2LS or LPLS.

Objective:To compare the outcomes of the total mandibular inferior border ostectomy and the T-shape genioplasty for chin narrowing combined with mandibular contouring and to assess the indications of the total mandibular inferior border ostectomy.Methods:In this retrospective study, the clinical data were collected from the patients who received mandibular contouring and chin narrowing at the Department of Orthognathic and Temporomandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University from January 2015 to January 2019. According to the surgical procedure, patients were divided into Total inferior border ostectomy (Group I) and T-shaped genioplasty combined with mandibular contouring (Group II). Computed tomography scans, combined with medical records and photographs, were collected preoperatively and in the final follow-up postoperatively. Lower facial height, chin width, chin symmetry, facial proportions as well as patients’ satisfaction and complications were investigated to assess the clinical outcomes. Statistical analyses were performed using IBM SPSS Statistics, version 20.0 (IBM Corp., Armonk, NY, USA). The measurement data were expressed as Mean±SD, and the counting data were expressed as case (%). T-test was performed to compare the age difference, average satisfaction score and the relative measurements between the two groups. Pearson’s chi squared test was used to compare the sex composition ratio and complication ratio between the two groups. P<0.05 was considered statistically significant. Results:102 patients were involved in this study, including 42 patients in group I, 7 males and 35 females; 60 patients in group Ⅱ, 11 males and 49 females. All patients improved lower facial contours. No severe complications were observed during the follow-up period(6~24 months) Regarding appearance satisfaction, 30 cases were very satisfied, 11 cases were satisfied, and 1 case was neutral in group I. 43 cases were very satisfied, 15 cases were satisfied, and 2 cases were neutral in group II. There was no significant difference ( P >0.05) between group I and group II in age, sex, inferior lip numbness, hematoma, severe swelling, infection, soft tissue ptosisand appearance satisfaction.There was a statistically significant difference ( P < 0.01) in preoperative lower facial height [(63.05±4.15) mm vs. (52.87±4.07) mm], Preoperative lower and midfacial height ratio [(107.89±3.11) % vs. (91.29±7.94) %], and preoperative chin width and lower facial height ratio [(90.31±3.19) % vs. (104.32±5.28) %], chin width change [(12.11±2.59) mm vs. (8.39±1.89) mm], postoperative chin deviation [(0.17±0. 09)mm vs. (0.36±0.20) mm] and Postoperative chin width and lower facial height ratio [(76.80±1.85) % vs. (80.95±3.75) %]. No statistical difference ( P>0.05) was found in preoperative chin deviation, midfacial height, postoperative lower facial heigh, postoperative lower and midfacial height ratio. Conclusion:In conclusion, compared to T-shape genioplasty combined with mandibular contouring, total mandibular inferior border ostectomy had a large amount of chin narrowing and better postoperative symmetry and is well suited for a longer, wider, and more asymmetrical chin. The surgical options should be considered and chosen quantitatively to achieve aesthetically satisfactory results.

Objective:To compare the outcomes of the total mandibular inferior border ostectomy and the T-shape genioplasty for chin narrowing combined with mandibular contouring and to assess the indications of the total mandibular inferior border ostectomy.Methods:In this retrospective study, the clinical data were collected from the patients who received mandibular contouring and chin narrowing at the Department of Orthognathic and Temporomandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University from January 2015 to January 2019. According to the surgical procedure, patients were divided into Total inferior border ostectomy (Group I) and T-shaped genioplasty combined with mandibular contouring (Group II). Computed tomography scans, combined with medical records and photographs, were collected preoperatively and in the final follow-up postoperatively. Lower facial height, chin width, chin symmetry, facial proportions as well as patients’ satisfaction and complications were investigated to assess the clinical outcomes. Statistical analyses were performed using IBM SPSS Statistics, version 20.0 (IBM Corp., Armonk, NY, USA). The measurement data were expressed as Mean±SD, and the counting data were expressed as case (%). T-test was performed to compare the age difference, average satisfaction score and the relative measurements between the two groups. Pearson’s chi squared test was used to compare the sex composition ratio and complication ratio between the two groups. P<0.05 was considered statistically significant. Results:102 patients were involved in this study, including 42 patients in group I, 7 males and 35 females; 60 patients in group Ⅱ, 11 males and 49 females. All patients improved lower facial contours. No severe complications were observed during the follow-up period(6~24 months) Regarding appearance satisfaction, 30 cases were very satisfied, 11 cases were satisfied, and 1 case was neutral in group I. 43 cases were very satisfied, 15 cases were satisfied, and 2 cases were neutral in group II. There was no significant difference ( P >0.05) between group I and group II in age, sex, inferior lip numbness, hematoma, severe swelling, infection, soft tissue ptosisand appearance satisfaction.There was a statistically significant difference ( P < 0.01) in preoperative lower facial height [(63.05±4.15) mm vs. (52.87±4.07) mm], Preoperative lower and midfacial height ratio [(107.89±3.11) % vs. (91.29±7.94) %], and preoperative chin width and lower facial height ratio [(90.31±3.19) % vs. (104.32±5.28) %], chin width change [(12.11±2.59) mm vs. (8.39±1.89) mm], postoperative chin deviation [(0.17±0. 09)mm vs. (0.36±0.20) mm] and Postoperative chin width and lower facial height ratio [(76.80±1.85) % vs. (80.95±3.75) %]. No statistical difference ( P>0.05) was found in preoperative chin deviation, midfacial height, postoperative lower facial heigh, postoperative lower and midfacial height ratio. Conclusion:In conclusion, compared to T-shape genioplasty combined with mandibular contouring, total mandibular inferior border ostectomy had a large amount of chin narrowing and better postoperative symmetry and is well suited for a longer, wider, and more asymmetrical chin. The surgical options should be considered and chosen quantitatively to achieve aesthetically satisfactory results.