Soft tissue changes after a mandibular osteotomy for symmetric skeletal class III malocclusion

The soft tissue profile is crucial to esthetics after orthognathic surgery. The aim of this study was to assess the soft tissue changes of the subnasal and submental regions more than 1 year after a sagittal split ramus osteotomy (SSRO) in patients with skeletal class III malocclusion. A total of 22 patients with mandibular prognathism were included in this study. Patients had lateral cephalograms before and more than 1 year after they underwent an isolated SSRO. Soft and hard tissue changes were assessed using the lateral cephalograms. The lower lip, labiomenton, and soft tissue menton moved posteriorly by 85, 89, and 88% compared with the corresponding hard tissue, and the movement of the soft tissue B point and the top of the chin nearly reflected the displacement of the hard tissues, at 96 and 99%, respectively. The labiomenton, stomions, and naso-labial angles were changed after the mandibular set-back and the changes in these angles correlated with either the width of the soft tissue or skeletal displacement. The naso-labial angle could be altered even if an isolated mandibular osteotomy is performed. Changes to the stomions and naso-labial angles were affected by hard tissue movement, while changes to the labiomental angle were affected by the width of the soft tissue after the mandibular osteotomy. It is important to create an accurate preoperative prediction of the esthetic outcomes after a mandibular osteotomy by considering the interrelations between the hard and soft tissues.     

Evaluation of treatment with unilateral mandibular sagittal split ramus osteotomy and maxillary osteotomy in patients with condylar osteochondroma and mandibular asymmetry: A retrospective case series

The aim of the study was to describe an approach where condylar resection with condylar neck preservation was combined with Le Fort I osteotomy and unilateral mandibular sagittal split ramus osteotomy (SSRO).Patients with a unilateral condylar osteochondroma combined with dentofacial deformity and facial asymmetry who underwent surgery between January 2020 and December 2020 were enrolled. The operation included condylar resection, Le Fort I osteotomy and contralateral mandibular sagittal split ramus osteotomy (SSRO). Simplant Pro 11.04 software was used to reconstruct and measure the preoperative and postoperative craniomaxillofacial CT images. The deviation and rotation of the mandible, change in the occlusal plane, position of the “new condyle” and facial symmetry were compared and evaluated during follow-up. Three patients were included in the present study. The patients were followed up for 9.6 months on average (range, 8–12). Immediate postoperative CT images showed that the mandible deviation and rotation and occlusion plane canting decreased significantly postoperatively; facial symmetry was improved but still compromised. During the follow-up, the mandible gradually rotated to the affected side, the position of the “new condyle” moved further inside toward the fossa, and both the mandible rotation and facial symmetry were more significantly improved.Within the limitations of the study it seems that for some patients a combination of condylectomy with condylar neck preservation and unilateral mandibular SSRO can be effective in achieving facial symmetry.     

Evaluation of condylar resorption rates after orthognathic surgery in class II and III dentofacial deformities: A systematic review

The purpose of this study was to perform a systematic review of morphological alterations in the condyles after orthographic surgery involving a sagittal split ramus osteotomy (SSRO), with or without surgery on the maxilla. Searches were performed on three databases and registered in the PROSPERO. The selected studies fulfilled the criteria established by the following PICO model: (1) population: individuals with skeletal dentofacial deformities (class II or III facial patterns), without asymmetry; (2) intervention: orthognathic surgery for mandibular setback using an SSRO, with or without a Le Fort I osteotomy, and fixed with bicortical screws or plates and screws; (3) comparison: orthognathic surgery for mandibular advancement using an SSRO, with or without a Le Fort I osteotomy, and fixed with plates and screws or bicortical screws; and (4) outcome: condylar resorption rate and relapse. Initially, 1,371 articles were identified and 636 articles were screened after elimination of duplicates, and 6 articles were selected for qualitative analysis based on the inclusion and exclusion criteria. Five studies had data regarding the rate of condylar resorption, varying from 0.0% to 4.2%. In conclusion, condylar resorption and relapses were present in a small percentage of patients studied.     

Stability of sagittal split ramus osteotomy used to correct Class III malocclusion: review of the literature

Setback of the mandible to correct mandibular prognathism is a well-known procedure. The 2 most frequently used techniques are the intraoral vertical ramus osteotomy (IVRO) and the sagittal split ramus osteotomy (SSRO). Although SSRO has been performed for many years, few data exist concerning long-term skeletal stability, and different hypotheses have been suggested to explain potential relapse. The literature published between 1985 and the present concerning this procedure was reviewed, and the authors analyze and discuss skeletal stability and factors contributing to relapse.     

Changes in skeletal asymmetry after sagittal split ramus osteotomy for patients with mandibular prognathism: three-dimensional computed tomographic assessment

Objectives We evaluated the clinical utility of a three-dimensional computed tomography (3D-CT) system to assess changes in the symmetry of patients undergoing sagittal split ramus osteotomy (SSRO) for mandibular prognathism. Methods Nine patients who underwent SSRO for mandibular prognathism were analyzed before and after their treatment using a 3D-CT system that we developed for evaluating maxillofacial skeletal asymmetry. Asymmetry indices for selected landmarks were calculated before and after treatment and compared with those of normal controls. Three regions were assessed: the maxillary, mandibular body, and mandibular ramus regions. Based on these regional assessments before and after treatment, changes in asymmetry types were determined for each patient. Results The asymmetry index was frequently improved for tooth-related landmarks, whereas no changes were observed in the anterior nasal spine, orbitale, or porion. In the maxillary and mandibular body regions, all nine patients showed improvement or no change in asymmetry. Deterioration was observed only in the mandibular ramus region of three patients who had preoperative asymmetry in the maxillary region. Conclusion Our 3D-CT system is effective for postoperative evaluation of facial asymmetry in patients with mandibular prognathism.     

Change in condylar long axis and skeletal stability following sagittal split ramus osteotomy and intraoral vertical ramus osteotomy for mandibular prognathia.

PURPOSE: The purpose of this study was to compare postsurgical time course changes in condylar long axis and skeletal stability between sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO). PATIENTS AND METHODS: Of 40 Japanese patients with a diagnosed jaw deformity, 20 underwent IVRO without internal fixation and 20 underwent SSRO with rigid internal fixation. The time course change in condylar long axis and skeletal stability were assessed with axial, frontal, and lateral cephalograms. RESULTS: A significant difference in the rotation direction of condylar long axis was seen in horizontal axial cephalogram images (P <.01). In Pog-N perpendicular to SN, the IVRO group showed gradual decrease, although SSRO group showed gradual increase in lateral cephalogram (P <.05). CONCLUSION: The present results suggest a significant difference between SSRO and IVRO in time course changes in proximal segment including condyle and distal segment.     

Changes in border movement of the mandible in skeletal Class III before and after orthognathic surgery

The purpose of this study was to examine the changes in border movement of the mandible before and after mandibular ramus osteotomy in patients with prognathism. The subjects were 73 patients with mandibular prognathism who underwent sagittal split ramus osteotomy (SSRO) with and without Le Fort I osteotomy. Border movement of the mandible was recorded with a mandibular movement measure system (K7) preoperatively and at 6 months postoperatively. Of the 73 patients, 21 had measurements taken at 1.5 years postoperative. Data were compared between the pre- and postoperative states, and the differences analyzed statistically. There was no significant difference between SSRO alone and SSRO with Le Fort I osteotomy in the time-course change. The values at 6 months postoperative were significantly lower than the preoperative values for maximum vertical opening (P = 0.0066), maximum antero-posterior movement from the centric occlusion (P = 0.0425), and centric occlusion to maximum opening (P = 0.0300). However, there were no significant differences between the preoperative and 1.5 years postoperative measurements. This study suggests that a postoperative temporary reduction in the border movement of the mandible could recover by 1.5 years postoperative, and the additional procedure of a Le Fort I osteotomy does not affect the recovery of mandibular motion after SSRO.     

Maxillary stability following Le Fort I osteotomy in combination with sagittal split ramus osteotomy and intraoral vertical ramus osteotomy: a comparative study between titanium miniplate and poly-L-lactic acid plate.

PURPOSE: The purpose of this study was to compare changes in maxillary stability after Le Fort I osteotomy with titanium miniplate and poly-L-lactic acid (PLLA) plate (Fixsorb-MX; Takiron Co, Osaka, Japan). PATIENTS AND METHODS: The subjects were composed of 47 Japanese patients with diagnosed jaw deformity: 24 underwent Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO); and 23 underwent Le Fort I osteotomy intraoral vertical ramus osteotomy without internal fixation. Each group was divided into titanium plate and PLLA plate groups. Time course changes between plate groups were compared using lateral and posteroanterior cephalography. RESULTS: Significant differences were identified between titanium plate and PLLA plate groups in A point after Le Fort I osteotomy and SSRO (P < .05). Significant differences existed between titanium plate and PLLA plate groups in vertical component of posterior nasal spine after Le Fort I osteotomy in both combinations with SSRO and intraoral vertical ramus osteotomy (P < .05). However, no significant differences were identified in measurements on posteroanterior cephalography. CONCLUSION: These results suggest a slight tendency for vertical impaction after Le Fort I osteotomy both in combination with SSRO and intraoral vertical ramus osteotomy with PLLA plates, although differences in time course changes were not clinically apparent, and normal occlusion was established in all patients.     

Is skeletal stability after bimaxillary surgery for skeletal class III deformity related to surgical occlusal contact?

A stable occlusion at the time of surgery is considered important for post-surgical stability after orthognathic surgery. The aim of this study was to determine whether skeletal stability after bimaxillary surgery using a surgery-first approach for skeletal class III deformity is related to the surgical occlusal contact or surgical change. Forty-two adult patients with a skeletal class III deformity corrected by Le Fort I osteotomy and bilateral sagittal split osteotomy with a surgery-first approach were studied. Dental models were set and used to measure the surgical occlusal contact, including contact distribution, contact number, and contact area. Cone beam computed tomography was used to measure the surgical change (amount and rotation) and post-surgical skeletal stability. The relationship between skeletal stability and surgical occlusal contact or surgical change was evaluated. No relationship was found between maxillary or mandibular stability and surgical occlusal contact. However, a significant relationship was found between maxillary and mandibular stability and the amount and rotation of surgical change. The results suggest that in the surgical-orthodontic correction of skeletal class III deformity with a surgery-first approach, the post-surgical skeletal stability is not related to the surgical occlusal contact but is related to the surgical change.     

Tongue–palatal contact changes in patients with skeletal mandibular prognathism after sagittal split ramus osteotomy: an electropalatography study

The purpose of this study was to investigate the changes in tongue–palatal contact patterns using electropalatography (EPG) before and after sagittal split ramus osteotomy (SSRO) in patients with mandibular prognathism. Nine clients who underwent SSRO for mandibular setback and seven control subjects were participated in this study. Tongue–palatal contact patterns for /t/, /s/ and /k/ production were investigated using EPG before surgery and 3 months after surgery. The mean value of whole total of palate contact (WT) in the maximum contact frame was examined before and after SSRO. The correlation quantity between the change of center of gravity (COG) value and the amount of mandibular setback was also evaluated. The mean value of WT for /t/ and /s/ significantly increased after SSRO, and the EPG pattern became normal. However, a remarkable change in WT for /k/ was not observed, and the mean value was significantly larger in the SSRO group before and after surgery than in the control group. A negative correlation between COG variation and the amount of mandibular setback for /t/ and positive correlation for /s/ was observed. This study demonstrated that tongue–palatal contact patterns for /t/ and /s/ articulation improved clearly after SSRO. There was a significant correlation between COG variation and the amount of mandibular setback. However, no significant change was detected through perceptual assessment before and after SSRO. Further investigation is needed to determine whether these results will change over time.     

Postoperative stability of two common ramus osteotomy procedures for the correction of mandibular prognathism: A randomized controlled trial

The aim of this randomized controlled trial was to compare the skeletal stability between sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) in the treatment of mandibular prognathism. Patients presenting with mandibular prognathism and scheduled for orthognathic surgery were randomized into either the SSRO group or the IVRO group. Changes at B-point were assessed by serial tracing of lateral cephalograms, which were taken preoperatively, and at 2 weeks, 6 months, 1 year, and 2 years postoperatively. Ninety-eight patients were recruited, with 49 patients in each group. Between 2 weeks and 6 months postoperatively, there was significantly more surgical relapse in the horizontal direction (anterior movement) in the SSRO group when compared with the IVRO group (1.83 mm (SD 2.91 mm) vs 0.49 mm (SD 2.32 mm); p = 0.019). At 2 years, there was more surgical relapse in the horizontal direction in the SSRO group than in the IVRO group (0.27 mm (SD 0.34 mm) vs 0.10 mm (SD 0.29 mm); p = 0.014). There were also more absolute changes (irrespective of direction) at B-point in the SSRO group than in the IVRO group at postoperative 6 months, 1 year, and 2 years (p = 0.016, 0.049, and 0.045, respectively). The amounts of change at B-point as percentages of total mandibular setback were 1.3% and 3.5% in the IVRO group and SSRO group, respectively. There were no differences in vertical changes between the two groups at any time points. In conclusion, the horizontal stability at B-point was shown to be superior in the IVRO group compared with the SSRO group in the correction of mandibular prognathism during the 2-year follow-up. Although the exact clinical importance of this difference is unknown at this time, this possible benefit may be an important key factor when deciding which osteotomy technique to employ for mandibular setback.     

One-stage approach to the correction of facial skeletal deformity with malocclusion

A total of 40 patients with varying degrees of facial skeletal deformity and Class III malocclusion were treated by bimaxillary osteotomy combining maxillo-malar augmentation and/or osseous genioplasty at the same sitting by the author. In all patients, the maxillary advancement and mandibular set back were performed, using Le Fort I maxillary osteotomy and bilateral sagittal split osteotomy of the mandibular rami. In additional bimaxillary osteotomy, simultaneous maxillo-malar augmentation and genioplasty in 20 patients, genioplasty in 12 patients, maxillo-malar augmentation in eight patients, were performed to improve facial harmony. All patients were followed clinically and radiographically for at least 1 year and as much as 5 years after undergoing surgical correction. No cases with relapse or other major complications have been encountered up to now. There were, however, persisting unilateral inferior alveolar nerve damage in two patients, prolonged nerve anesthesia or hypoesthesia in four patients, and short period anesthesia or hypoesthesia in 11 patients, wide alar base in three patients and slight deviation of cartilage septum in two patients. There were no other complications encountered and an unexpected result. The facial skeletal deformity and malocclusion were always treated satisfactorily as patient and plastic surgeon's expectations in one-stage operation, without significant complications and morbidity.     

Midfacial soft-tissue changes after mandibular setback surgery with or without paranasal augmentation: Cone-beam computed tomography (CBCT) volume superimposition

The aim of this article is to compare the soft-tissue changes in the midfacial areas of patients who had undergone mandibular setback sagittal split ramus osteotomy (SSRO) with that of mandibular setback SSRO with paranasal augmentation. The subjects included 15 patients (group I), SSRO with paranasal augmentation and 20 patients (group II), SSRO alone. To evaluate the difference of the midfacial soft-tissue changes between groups, cone-beam computed tomography superimposition was utilized and the soft-tissue changes were measured both preoperatively and postoperatively by a 10 × 27 grid. In group I, the soft tissues were changed at the areas bounded superiorly by the infraorbital foramen, zygomatic eminence, posteriorly by the masseteric muscle and medially by the lateral aspect of the nose and following the nasolabial fold. In group II, the midfacial soft-tissue measurements were unchanged. This study may help clinicians to predict improvement in the midfacial region from mandibular setback SSRO with or without a paranasal augmentation procedure in class III deformities.     

Changes in occlusal force after mandibular ramus osteotomy with and without Le Fort I osteotomy

The purpose of this study was to evaluate the differences in bite force changes and occlusal contacts after sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) with and without Le Fort I osteotomy. Sixty female patients with diagnosed mandibular prognathism with or without asymmetry were divided into four groups (SSRO, IVRO, SSRO with Le Fort I osteotomy and IVRO with Le Fort I osteotomy). Bite force and occlusal contacts were measured preoperatively and at 1, 3, 6 and 12 months after surgery with pressure-sensitive sheets. The differences among surgical procedures were examined statistically. Maximum bite force and occlusal contacts returned to preoperative levels after between 3 and 6 months. Regarding time-dependent changes in bite force and occlusal contact area, there were no significant differences among the groups. In conclusion, this study suggests that the combination of IVRO or SSRO and Le Fort I osteotomy does not affect postoperative time-dependent changes.     

Long-term changes in pharyngeal airway morphology after mandibular setback surgery.

Long-term changes in pharyngeal airway morphology were evaluated after mandibular setback surgery in 10 women who were diagnosed as having skeletal mandibular prognathism and underwent mandibular setback surgery by bilateral sagittal split ramus osteotomy (SSRO) and orthodontic multi-bracket treatment. The subjects were assessed before treatment (T1), 3-6 months after SSRO (T2), and 2 or more years after SSRO (T3). From T1 to T2, the pharyngeal airway constricted significantly. On the other hand, from T2 to T3, the lower facial morphology showed no significant changes. The pharyngeal airway morphology showed significant changes in soft-palate length and posterior reference line to point of posterior tongue, indicating a tendency for relapse. These results suggest that, although the lower facial morphology and the pharyngeal airway morphology showed marked changes after SSRO, the pharyngeal airway morphology exhibited gradual physiologic readaptation. However, because the lower facial morphology after surgery was retained and stable for a long period, it was considered normal for the pharyngeal airway morphology to adapt after surgery to the improved hard tissue relationship.     

Condylar and temporomandibular joint disc positions after mandibular osteotomy for prognathism

PURPOSE: The purpose of this study was to compare the changes in temporomandibular joint (TMJ) morphology and clinical symptoms after sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) with and without a Le Fort I osteotomy. PATIENTS AND METHODS: Of 43 patients with a diagnosed jaw deformity, 20 underwent IVRO without internal fixation and 23 underwent SSRO with rigid internal fixation. Some operations were performed in combination with a Le Fort I osteotomy. The TMJ symptoms and joint morphology, including the disc position, were assessed preoperatively and postoperatively using magnetic resonance imaging (MRI) and axial cephalography. RESULTS: A significant difference in the direction of condylar rotation was seen in horizontal axial cephalography images (P <.01). Fewer or no TMJ symptoms were reported postoperatively by 88% of the patients who underwent IVRO with or without a Le Fort I osteotomy and by 66.7% of patients who underwent SSRO with or without a Le Fort I osteotomy. In sagittal images, no change was seen in anterior disc displacement after SSRO; however, improvement was seen in 44.4% of patients with anterior disc displacement who underwent IVRO with or without a Le Fort I osteotomy. CONCLUSION: These results suggest that SSRO does not improve anterior disc displacement; IVRO improves anterior disc displacement in the initial postsurgical period, and both procedures may improve TMJ symptoms.     

Postoperative mandibular stability after orthognathic surgery in patients with mandibular protrusion and mandibular deviation

Skeletal stability and temporomandibular joint (TMJ) signs and symptoms were analyzed in 23 patients in whom mandibular protrusion and mandibular deviation had been corrected using bilateral sagittal split ramus osteotomy (BSSRO group, n = 10) and unilateral SSRO and intraoral vertical ramus osteotomy (USSRO+IVRO group, n = 13). Miniplate fixation was used in SSRO but no fixation was used in IVRO. The ratio of condylar bony change was 30.4% (7/23) and all condylar bony changes were seen on the deviated side. All preoperative signs and symptoms of TMJ disorders (4/13 patients in the USSRO+IVRO group and 2/10 patients in the BSSRO group) disappeared after surgery. Comparing the USSRO+IVRO group and the BSSRO group, in patients without condylar bony change, the mandible in both groups was stable anteriorly and horizontally after surgery, even though there was a larger horizontal mandibular movement in the USSRO+IVRO group during surgery. Comparing patients with condylar bony change versus no condylar bony change in the USSRO+IVRO group, postoperative horizontal mandibular displacement was significantly larger in the condylar bony change group than in the no condylar bony change group. These results support the idea that USSRO+IVRO can be useful in correcting mandibular deviation as well as improving signs and symptoms of TMJ disorders. However, it also seems important to be aware of the possibility of horizontal mandibular relapse in patients with condylar bony change.     

下颌升支矢状劈开截骨术后退和前徙下颌骨对下颌运动范围的影响

作者对接受下颌升支矢状劈开截骨术患者（下颌骨后退１１例，下颌骨前徙１０例）手术前自下颌运动范围进行了测量，并对颞下颌关节进行了临床检查。发现在术后６个月时，后退组患者的张口度已恢复到术前水平，前徙组患者的张口度仍低于术前，且差异有高度显著性（Ｐ＜０．０１），术后两组患者下颌前伸和侧向运动（左右）均无明显变化。提示下颌升支矢状劈开截骨术后退下颌骨对患者张口度影响较小，且术后恢复较快。     

下颌前突患者升支矢状劈开术前后咀嚼肌的肌电分析

目的测量下颌前突患者行正颌手术前后的肌电值，分析矢状劈开截骨术（SSRO）后咀嚼肌系统的变化，进一步探讨肌电的改变与术后咀嚼肌适应性改建之间的关系。方法选取18例接受SSRO治疗的下颌前突患者，记录术前及术后3个月、1年时主要咀嚼肌在功能运动中的电生理指标，计算相关参数并进行统计分析。结果下颌前突患者在正常状态下，大部分肌电指标低于健康对照组；行SSRO治疗后3个月，咀嚼肌的肌电指标有所下降，部分指标明显低于术前；术后1年，肌电指标较术前有明显上升，但部分仍低于健康对照组。结论正颌术后，咀嚼肌系统的重建是一个长期的过程，与术前相比较，咀嚼肌的性能得到了一定程度的改善。     

Assessment of skeletal stability of intraoral vertical ramus osteotomy with one-day maxillary–mandibular fixation followed by early jaw exercise

PurposeIntraoral vertical ramus osteotomy (IVRO) is an effective surgical technique for cases of mandibular setback, is simpler and has a lower incidence of mental paraesthesia when compared to sagittal split ramus osteotomy (SSRO). However, IVRO has a disadvantage in the prolonged duration of postoperative maxillary–mandibular fixation (MMF) required due to the absence of rigid bone fixation. To avoid an extended MMF period, we developed a postoperative management protocol for our IVRO patients, using jaw exercises with elastic bands starting on the second day after surgery.MethodsWe evaluated the cephalometric skeletal and dental stabilities of 16 IVRO patients as they followed our protocol.ResultsThe stabilities were confirmed and were similar to those of previous reports.ConclusionOne-day MMF and early initiation of jaw exercise after IVRO did not affect the jaw position stability. Moreover, our findings suggest that starting jaw exercise earlier after IVRO surgery is beneficial, as it allows patients to avoid a long period of rigid MMF so that they can resume their normal daily activities sooner.