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The treatment of mandibular deformities with an anterior open bite is challenging. In this study, skeletal stability after mandibular osteotomies was evaluated to determine the best treatment for mandibular prognathism with an anterior open bite in three procedures: intraoral vertical ramus osteotomy (IVRO), conventional sagittal split ramus osteotomy (conv-SSRO), and SSRO without bone fixation (nonfix-SSRO). Patients who underwent mandibular osteotomy to correct skeletal mandibular protrusion were included. Changes in skeletal and soft tissues were assessed using lateral cephalograms taken before (T1), 3 ± 2 days (T2), and 12 ± 3 months (T3) after surgery. Thirty-nine patients were included: nine in the IVRO group and 11 and 19 in the conv- and nonfix-SSRO groups, respectively. The mandibular plane angles (MPAs) of the T2-T1 were - 2.7 ± 2.0 (p = 0.0040), - 3.7 ± 1.7 (p < 0.0001), and - 2.3 ± 0.7 (p < 0.0001) in the IVRO, conv-SSRO, and nonfix-SSRO groups, respectively. The skeletal relapse of the MPAs was not related to the MPA at T2-T1, and it was approximately 1.3° in the conv-SSRO group. The skeletal relapse of the MAPs was significantly correlated with the MPA of T2-T1 in the IVRO (p = 0.0402) and non-fix-SSRO (p = 0.0173) groups. When the relapse of the MPAs was less than 1.3°, the MPA of T2-T1 was calculated as 2.5° in the nonfix-SSRO group. When the MPA of T2-T1 is less than 2.5°, non-fix SSRO may produce a reliable outcome, and when it is more than 2.5°, conv-SSRO may produce better outcomes.

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OBJECTIVE: To investigate and compare the effect of two orthognathic procedures for mandibular setback, namely, sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), on oral health, mental- and physical health-related quality of life across time. MATERIALS AND METHODS: Patients with mandibular prognathism and planned for orthognathic surgery were recruited in this study. Patients were randomized into two groups (IVRO and SSRO groups). Quality of life (QoL) was assessed with the 14-item Short-Form Oral Health Impact Profile (OHIP-14) and the 36-item Short-Form Health Survey (SF-36) preoperatively (T0), postoperative 2 weeks (T1), 6 weeks (T2), 3 months (T3), 6 months (T4), 12 months (T5), and 24 months (T6). A comparison of OHIP-14 and SF-36 scores between two groups was conducted. RESULTS: Ninety-eight patients (49 SSRO group, 49 IVRO group) participated in this study. There was no significant difference in OHIP-14 scores between SSRO and IVRO throughout the treatment process. SSRO group had significant reduction of OHIP-14 score (i.e., improving oral health-related QoL) since postoperative 2 weeks, whereas IVRO group had significant reduction since postoperative 6 weeks. Starting from postoperative 3 months, the oral health-related QoL of both groups was already significantly better than the baseline level and continued to steadily improve afterwards. For SF-36, both groups had increased physical health summary score starting from postoperative 2 weeks, indicating an early and gradual recovery of physical health-related QoL. The mental health summary score of the SSRO group began to increase from postoperative 2 weeks, but that of the IVRO group only began to increase from postoperative 6 weeks. Patient age at the time of surgery was positively correlated with OHIP scores in the postoperative period. CONCLUSIONS: The study concludes that both SSRO and IVRO contributed to the improvement of QoL in the long term, but oral health- and mental health-related QoL of SSRO groups showed earlier improvement. CLINICAL RELEVANCE: Undergoing orthognathic surgery at early ages is advised, as older age of patients appeared to have worse QoL. TRIAL REGISTRATION: Clinical trial registration number: HKUCTR-1985. Date of Registration: 14 Apr 2015.

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The patterns of the lingula and antilingula are crucial surgical reference points for ramus osteotomy. Cone-beam computed tomography (CBCT) provides three-dimensional images, and patient radiation dose is significantly lower for CBCT than for medical CT. The morphology of the mandibular lingula and antilingula of ninety patients (180 sides) were investigated using CBCT. The lingula were classified as having triangular, truncated, nodular, and assimilated shapes. The antilingula were classified as having hill, ridge, plateau, and plain shapes. The patients' sex, skeletal patterns (Classes I, II, and III), and right and left sides were recorded. The most to least common lingula shapes were nodular (37.8%), followed by truncated (32.8%), triangular (24.4%), and assimilated (5%). The most to least common antilingulae were hill (62.8%), plain (18.9%), plateau (13.9%), and ridge (4.4%) patterns, respectively. The lingula and antilingula had identical patterns on both sides in 47 (52.2%) and 46 patients (51.1%), respectively. Sex and skeletal pattern were not significantly correlated to lingula and antilingula shapes. No significant correlation was observed between lingula and antilingula shapes.

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This study aimed to investigate the changes in preexisting temporomandibular joint (TMJ) clicking and the new incidence of TMJ clicking after orthognathic surgery. A total of 60 patients (30 men and 30 women) with mandibular prognathism underwent intraoral vertical ramus osteotomy (IVRO) for a mandibular setback. The setback amount and TMJ clicking symptoms (preoperative and one year postoperative) were recorded. To assess the risk of new incidence of TMJ clicking in asymptomatic patients, the cutoff value for postoperative mandibular setback was set at 8 mm. The left and right mandibular setbacks were 11.1 and 10.9 mm in men, respectively, and 10.7 and 10.0 mm in women, respectively. Thus, no difference in setback amount on either side was observed between the sexes. The improvement rate in patients with preexisting TMJ clicking was 69.2% (18 of 26 sides); the postoperative improvement rates were 71.4% (setback amount > 8 mm) and 60% (setback amount ≤ 8 mm). IVRO may reduce the severity of preexisting TMJ clicking. A high setback amount (>8 mm) may not be associated with a considerable increase in the risk of postoperative TMJ clicking.

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BACKGROUND/PURPOSE: Postoperative skeletal relapse is the most important issue in patients undergoing orthognathic surgery. This study aimed to investigate clinical skeletal relapse (≥2 mm) after mandibular setback surgery (intraoral vertical ramus osteotomy: IVRO) using receiver operating characteristic curve (ROC curve) analysis. METHODS: Serial cephalograms of 40 patients with mandibular prognathism were obtained at different time points: (1) before surgery (T1), (2) immediately after surgery (T2), and (3) at least with a 2-year follow-up postoperatively (T3). The menton (Me) was used as the landmark for measuring the amount of mandibular setback and postoperative skeletal relapse. Postoperative stability (T32) was divided into groups A and B by skeletal relapse ≥2 mm and <2 mm, respectively. The area under the ROC curve (AUC) was used to determine the cut-off point for mandibular setback. RESULTS: At the immediate surgical setback (T21), the amount of setback in group A (15.55 mm) was significantly larger than in group B (10.97 mm). Group A (T32) showed a significant relapse (4.07 mm), while group B showed a significant posterior drift (1.23 mm). The amount of setback had the highest AUC area (0.788). The cut-off point was 14.1 mm (T21) that would lead to a clinical relapse of 2 mm (T32). CONCLUSION: In IVRO, the postoperative mandibular positions reveal posterior drift and anterior displacement (relapse). The experience of clinical observation and patient perception of postoperative skeletal relapse was ≥2 mm. In the ROC curve analysis, the cut-off point of setback was 14.1 mm.

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BACKGROUND: This study aimed to investigate the changes in facial width according to the ostectomy level of the proximal segment after orthognathic surgery using intraoral vertical ramus osteotomy (IVRO) in patients with mandibular prognathism. METHODS: The participants included 32 individuals who were diagnosed with class III malocclusion prior to surgery. All participants underwent orthognathic surgery using either version of IVRO. The surgery patients were categorized into two groups depending on the type of proximal bone-segment ostectomy technique used: patients whose osteotomy height was at the level of the mandibular tooth occlusal surface (the mandibular tooth surface-level group) and patients whose osteotomy height was at the level of the mandibular inferior border (the mandibular inferior border-level group). The distances between the mandibular width and soft tissue width at the height of the sigmoid notch, mandibular foramen, and alveolar bone and at the anterior-posterior location of the mandibular condyle, mandibular foramen, and coronoid process were compared between the groups. All data were compared to identify differences between preoperative and postoperative measurements. RESULTS: The postoperative change in facial soft tissue width at the intersection of the coronal plane with the coronoid process and the horizontal plane at the height of the mandibular alveolar bone in the group with osteotomy at the level of the mandibular occlusal surface differed significantly from that in the group with osteotomy at the level of the mandibular inferior border, with respective increases (mean ± SD) of 1.3 ± 3.5% and 4.7 ± 5.6%, compared to preoperative measurements (p = 0.050). CONCLUSIONS: Proximal segment ostectomy at the level of the mandibular occlusal surface must be considered with regard to postoperative facial soft tissue width in vertical ramus osteotomy. Additionally, it is necessary to study the visual effect of the width of the mandible appearing small because of the posterior position of the mandible, even when the mandibular facial width is maintained.

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OBJECTIVES: The purpose of this study was to investigate short- and long-term postoperative changes of both morphology and transverse stability in mandibular ramus after intraoral vertical ramus osteotomy (IVRO) in patients with jaw deformity using three-dimensional (3D) orthognathic surgery planning treatment software for measurement of distances and angles. STUDY DESIGN: This retrospective study included consecutive patients with skeletal Class III malocclusion who had undergone intraoral vertical ramus osteotomy and computed tomography images before (T0), immediately after (T1), and 1 year after (T2) surgery. Reference points, reference lines and evaluation items were designated on the reconstructed 3D surface models to measure distances, angles and volume. The average values at T0, T1, T2 and time-dependent changes in variables were obtained. RESULTS: After surgery, the condylar length, ramal height, mandibular body length and mandibular ramus volume were significantly decreased (P < 0.01), while clinically insignificant change was observed from T1 to T2. The angular length was increased immediately after surgery (P < 0.05), but it was decreased 1 year after surgery (P < 0.05). Lateral ramal inclination showed significant increase after surgery (P < 0.05) and maintained at T2. CONCLUSION: Changes in the morphology of the mandibular ramus caused by IVRO do not obviously bring negative effect on facial appearance. Furthermore, despite position and angle of mandibular ramus changed after IVRO, good transverse stability was observed postoperatively. Therefore, IVRO technique can be safely used without compromising esthetic results.

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OBJECTIVES: This study aimed to investigate the mandibular canal of ramus and design a suitable osteotomy line for intraoral vertical ramus osteotomy (IVRO) using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Ninety patients were classified into class I, II, and III skeletal pattern groups. When extended from the horizontal base plane (0 mm, mandibular foramen [MF]), with a 2-mm section interval, to 10 mm above and 10 mm below the MF, the following landmarks were identified: external oblique ridge (EOR), posterior border of the ramus (PBR), and posterior lateral cortex of ramus (PLC): IVRO osteotomy point. RESULTS: In the base plane (0-mm plane), the EOR-PBR distance of class III (34.78 mm) and the IOR-PBR distance of class II (32.72 mm) were significantly higher than those of class I (32.95 mm and 30.03 mm). Compared to the EOR-PLC distance, the designed osteotomy point (two-thirds EOR-PBR length) has a 3.49-mm safe zone at the base plane and ranging from 0.89 mm (+ 10-mm plane) to 8.37 mm (- 10-mm plane). CONCLUSIONS: The position at two-thirds EOR-PBR length (anteroposterior diameter of the ramus) can serve as a reference distance for the IVRO osteotomy position. CLINICAL RELEVANCE: Mandibular setback operations for treating mandibular prognathism mainly include sagittal split ramus osteotomy (SSRO) and IVRO. IVRO has a markedly lower incidence of postoperative lower lip paraesthesia than SSRO. Our design presented a reference point for identification during IVRO, to prevent damage to the inferior alveolar neurovascular bundle.

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PURPOSE: The purpose of present study was to review the literature regarding the postoperative skeletal stability in the treatment of mandibular prognathism after isolated sagittal split ramus osteotomy (SSRO) or intraoral vertical ramus osteotomy (IVRO). MATERIALS AND METHODS: The articles were selected from 1980 to 2020 in the English published databases (PubMed, Web of Science and Cochrane Library). The articles meeting the searching strategy were evaluated based on the eligibility criteria, especially at least 30 patients. RESULTS: Based on the eligibility criteria, 9 articles (5 in SSRO and 4 in IVRO) were examined. The amounts of mandibular setback (B point, Pog, and Me) were ranged from 5.53-9.07 mm in SSRO and 6.7-12.4 mm in IVRO, respectively. In 1-year follow-up, SSRO showed the relapse (anterior displacement: 0.2 to 2.26 mm) By contrast, IVRO revealed the posterior drift (posterior displacement: 0.1 to 1.2 mm). In 2-year follow-up, both of SSRO and IVRO presented the relapse with a range from 0.9 to 1.63 mm and 1 to 1.3 mm respectively. CONCLUSION: In 1-year follow-up, SSRO presented the relapse (anterior displacement) and IVRO posterior drift (posterior displacement). In 2-year follow-up, both of SSRO and IVRO showed the similar relapse distances.

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OBJECTIVES: In the present study, the effects of sagittal split ramus osteotomy (SSRO) combined with intraoral vertical ramus osteotomy (IVRO) for the treatment of asymmetric mandible in class Ⅲ malocclusion patients were assessed and the postoperative stability of the mandibular condyle and the symptoms of temporomandibular joint disorder (TMD) evaluated. MATERIALS AND METHODS: A total of 82 patients who underwent orthognathic surgery for the treatment of facial asymmetry or mandibular asymmetry at the Department of Oral and Maxillofacial Surgery, Dong-A University Hospital, from 2016 to 2021 were selected. The patients that underwent SSRO with IVRO were assigned to Group I (n=8) and patients that received bilateral SSRO (BSSRO) to Group II (n=10, simple random sampling). Preoperative and postoperative three-dimensional computed tomography (CT) axial images obtained for each group were superimposed. The condylar position changes and degree of rotation on the superimposed images were measured, and the changes in condyle based on the amount of chin movement for each surgical method were statistically analyzed. RESULTS: Group I showed a greater amount of postoperative chin movement. For the amount of mediolateral condylar displacement on the deviated side, Groups I and II showed an average lateral displacement of 0.07 mm and 1.62 mm, respectively, and statistically significantly correlated with the amount of chin movement (P=0.004). Most of the TMD symptoms in Group I patients who underwent SSRO with IVRO showed improvement. CONCLUSION: When a large amount of mandibular rotation is required to match the menton to the midline of the face, IVRO on the deviated side is considered a technique to prevent condylar torque. In the present study, worsening of TMD symptoms did not occur after orthognathic surgery in any of the 18 patients.

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OBJECTIVES: The purpose of this study was to compare the changes of the condylar axis, the anteroposterior condylar position relative to the glenoid fossa, after intraoral vertical ramus osteotomy (IVRO). STUDY DESIGN: 21 patients diagnosed as skeletal class III malocclusion underwent IVRO and were followed according to the authors' postoperative management regimen. The three-dimensional positions of the condyles were evaluated by cone-beam computerized tomography (CBCT) at pre-op, post-op, and at follow-up. CBCT images were referenced to assess the condylar axis change and the anteroposterior condylar position in the glenoid fossa. A repeated-measures analysis of variance (P<0.05) also was performed. RESULTS: After surgery, both the axial condylar angles and the anteroposterior condylar position were significantly different (P<0.05). The coronal condylar axis rotated outwardly. The anteroposterior condylar position in the glenoid fossa had moved from the concentric to the anterior position. But the condyle changes between post-op and follow-up (P>0.05) were insignificant. CONCLUSIONS: With postoperative intermaxillary elastic traction, the condyles changed their positions physiologically for newly established jaw movement after IVRO.

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The sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) are two common orthognathic procedures for the treatment of mandibular prognathism. This randomized clinical trial compared the surgical morbidities between SSRO and IVRO for patients with mandibular prognathism over the first 2 years postoperative. Ninety-eight patients (40 male, 58 female) with a mean age of 24.4±3.5 years underwent bilateral SSRO (98 sides) or IVRO (98 sides) as part or all of their orthognathic surgery. IVRO presented less short-term and long-term surgical morbidity in general. The SSRO group had a greater incidence of inferior alveolar nerve deficit at all follow-up time points (P< 0.01). There was more TMJ pain at 6 weeks (P= 0.047) and 3 months (P= 0.001) postoperative in the SSRO group. The SSRO group also presented more minor complications, which were related to titanium plate exposure and infection. There were no major complications for either technique in this study. Despite the need for intermaxillary fixation, IVRO appears to be associated with less surgical morbidity than SSRO when performed as a mandibular setback procedure to treat mandibular prognathism.

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OBJECTIVE: To compare postoperative positional changes in the mandibular proximal segment between the conventional orthognathic surgery (CS) and the surgery-first approach (SF) using intraoral vertical ramus osteotomy (IVRO) in patients with Class III malocclusion. METHODS: Thirty-eight patients with skeletal Class III malocclusion who underwent bimaxillary surgery were divided into two groups according to the use of preoperative orthodontic treatment: CS group (n = 18) and SF group (n = 20). Skeletal changes in both groups were measured using computed tomography before (T0), 2 days after (T1), and 1 year after (T2) the surgery. Three-dimensional (3D) angular changes in the mandibular proximal segment, condylar position, and maxillomandibular landmarks were assessed. RESULTS: The mean amounts of mandibular setback and maxillary posterior impaction were similar in both groups. At T2, the posterior portion of the mandible moved upward in both groups. In the SF group, the anterior portion of the mandible moved upward by a mean distance of 0.9 ± 1.0 mm, which was statistically significant (p < 0.001). There were significant between-group differences in occlusal changes (p < 0.001) as well as in overjet and overbite. However, there were no significant between-group differences in proximal segment variables. CONCLUSIONS: Despite postoperative occlusal changes, positional changes in the mandibular proximal segment and the position of the condyles were similar between CS and SF, which suggested that SF using IVRO achieved satisfactory postoperative stability. If active physiotherapy is conducted, the proximal segment can be adapted in the physiological position regardless of the occlusal changes.

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Important aspects of orthognathic surgery are the effects of skeletal movement and changes in the position of the hyoid bone, tongue, soft palate, and dimensions of the pharyngeal airway. Our aims were to evaluate the 3-dimensional changes in the pharyngeal airway and in the position of the hyoid bone after mandibular setback in 30 patients who were diagnosed with mandibular prognathism and were treated by intraoral vertical ramus osteotomy (IVRO). Three-dimensional cone-beam computed tomographic (CT) images were obtained preoperatively, one month postoperatively, and one year postoperatively. The total pharyngeal volume decreased between the preoperative state and one month and one year afterwards. The hyoid bone had moved 2.0mm posteriorly and 3.15mm superiorly by one month postoperatively. The position of the hyoid bone was affected by changes in posterior and superior movement of the B point at one month (r=0.44, p=0.015 and R=0.63, p=0.000, respectively) and also by superior movement of the B point at one year (r=0.57, p=-0.001). There was an advantageous relation between posterior positional changes in the B point (mandibular setback), and volumetric changes in the hypopharyngeal and total pharyngeal airway, so maxillofacial surgeons should consider the reduction in airway when planning excessive mandibular setback.

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The sagittal split ramus osteotomy (SSRO) is generally associated with greater postoperative stability than the intraoral vertical ramus osteotomy (IVRO); however, it entails a risk of inferior alveolar nerve damage. In contrast, IVRO has the disadvantages of slow postoperative osseous healing and projection of the antegonial notch, but inferior alveolar nerve damage is believed to be less likely. The purposes of this study were to compare the osseous healing processes associated with SSRO and IVRO and to investigate changes in mandibular width after IVRO in 29 patients undergoing mandibular setback. On computed tomography images, osseous healing was similar in patients undergoing SSRO and IVRO at 1year after surgery. Projection of the antegonial notch occurred after IVRO, but returned to the preoperative state within 1year. The results of the study indicate that IVRO is equivalent to SSRO with regard to both bone healing and morphological recovery of the mandible.

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