A new osteotomy for the correction of mandibular prognathism: techniques and rationale of the intraoral vertico-sagittal ramus osteotomy.

The sagittal split ramus osteotomy (SSRO) and the intraoral vertical ramus osteotomy (IVRO) are long established methods for correcting mandibular prognathism, each having its own advantages. However, both procedures have the same disadvantage: the potential for postoperative condylar displacement. The displacement of the condyle is mainly due to the fact that the osteotomy plane is not parallel to the original sagittal plane in which the mandible is repositioned. The author has developed a new ramus osteotomy since 1985 in which the osteotomy plane is theoretically parallel to the original sagittal plane and thereby attempting to decrease the incidence of condylar displacement. This osteotomy was designed additionally to decrease neurosensory disturbances and has the advantages of both methods, and therefore has been named 'intraoral vertico-sagittal ramus osteotomy (IVSRO)'. Initial experience with the 24 prognathic patients operated on by means of the IVSRO indicated excellent clinical results. It has been noted clinically that the IVSRO is very effective in reducing postoperative iatrogenic TMJ symptoms and in treating preoperative TMJ symptoms. It has the additional effect of reducing neurosensory disturbances. This osteotomy seems to be more applicable in mandibular prognathism with excessive flaring of the ramus, particularly that associated with TMJ dysfunction, because the IVSRO has a 'condylotomy effect' and its splitting plane diverges less from the original sagittal plane than that of the SSRO and the IVRO.     

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.     

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.     

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.     

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.     

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.     

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.     

Three-dimensional evaluation of positional change of the condyle after mandibular setback by means of bilateral sagittal split ramus osteotomy

OBJECTIVE: The aim of this study was to evaluate condylar displacement in 3 dimensions by means of computed tomography after mandibular setback by sagittal split ramus osteotomy with rigid fixation and to compare these results with those from patients with mandibular advancement. STUDY DESIGN: Thirty Korean subjects with skeletal class III malocclusion who had undergone mandibular setback by sagittal split ramus osteotomy had computed tomographs taken. Tomographs were taken to evaluate the temporomandibular joint 1 month before and approximately 1 month after surgery. The position and angulation of the condyle were measured on axial or sagittal views. These measurements were analyzed to determine any correlations between the amount of mandibular movement and condylar displacement. RESULTS: The results of this study show that the condyle tends to move inferiorly and rotate inward on the axial view and backward on the sagittal view by a statistically significant amount. CONCLUSION: The positional change of the condyle after sagittal split ramus osteotomy was not correlated with the amount of the setback.     

The treatment of hemimandibular hyperplasia preserving enlarged condylar head.

OBJECTIVE: To present a case of hemimandibular hyperplasia (HH) treated with orthognathic surgery that preserves the condyle without disturbing mandibular function. METHODS: A 27-year-old woman with HH was treated with orthognathic surgery preserving the enlarged condylar head. Radiographic examination showed typical enlargement of the right condyle, elongation of the right ascending ramus and mandibular body, and tilted occlusal plane. A mandibular sagittal split osteotomy on the unaffected side and subcondylar ramus osteotomy on the affected side, Le Fort I wedge osteotomy to relevel the tilted occlusal plane, and contouring of the lower mandibular margin were performed. RESULTS: Excellent results in the full-face appearance and occlusion were obtained. There was no change in the size of the reserved condylar head 4 years postoperatively. In a series of examinations of jaw function with electromyography, mandibular kinesiography, and computer-aided diagnostic axiography, more favorable findings were obtained postoperatively. CONCLUSIONS: In a case of HH without abnormally high growth activity, orthognathic surgery preserving hypertrophic condyle produced functional improvement in addition to good occlusal and aesthetic outcomes.     

Surgical orthodontic treatment for a patient with unilateral cleft lip and palate and temporomandibular disorder

The patient was a 12-year-old female who presented with unilateral cleft lip and palate, facial asymmetry, mandibular protrusion, resorption of condyle heads, and transverse maxillary deficiency. At the age of 13 years 10 months, maxillary expansion and autogenous bone graft were performed to improve the maxillary collapsed arch. Aged 14 years 10 months, she described symptoms of temporomandibular joint pain and dysfunction. Segmental Le Fort I osteotomy and intraoral vertical ramus osteotomy (IVRO) were performed at the age of 15 years 11 months. Segmental Le Fort I osteotomy resulted in improved sagittal and transverse discrepancy of the maxilla. After IVRO, facial symmetry, a good facial profile, and disappearance of TMD symptoms were achieved. The occlusion and esthetics were stable after 5 years of retention.     

Hypomobility after maxillary and mandibular osteotomies

A retrospective recall study of forty patients was made to examine mandibular function after orthognathic surgery. Maximum maxillomandibular opening, protrusion, and lateral excursions were measured and compared with similar mandibular movements in a control group of patients of comparable age. Six months to 42 months after maxillary and mandibular osteotomies, the majority of patients demonstrated decreased maxillomandibular opening compared to the control group 54.8 mm (SD 4.7). The decrease was most dramatic in patients previously treated with sagittal split ramus osteotomies. The mean maxillomandibular opening after Le Fort I osteotomy to reposition the maxilla superiorly was 48.7 mm (SD 5.7); after bilateral intraoral vertical ramus osteotomies to retract the mandible it was 48.6 mm (SD 5.7); and after bilateral sagittal split ramus osteotomies to advance the mandible it was 35.1 mm (SD 6.7). The presence of mandibular hypomobility after orthognathic surgery and maxillomandibular immobilization may be due to pre-existing or surgically induced muscle or temporomandibular joint dysfunction. Our findings indicate the need for routine clinical assessment of mandibular function preoperatively and for a systematic regimen of muscular and occlusal rehabilitation postsurgically to normalize muscle function, condylar movement, and range of mandibular motion.     

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.     

颌骨畸形600例正颌手术治疗

目的 总结正颌外科矫正颌骨畸形的临床经验。方法 对600例颌骨畸形患者进行正颌外科手术,其中上颌Le FortⅠ截骨与下颌体部截骨术212例,单纯上颌Le Fort Ⅰ截骨56例,单纯双下颌升支矢状劈开截骨(SSRO)30例,下颌体部截骨145例,行Downfracture或Wassmund法矫治112例,下颌前突伴偏颌畸形行下颌体部截骨45例。结果 60X例中术后部分复发28例,完全复发2例,下唇感觉异常9例,术后感染6例,其余术后面容和咀嚼功能获得满意效果。结论 上颌Le Fort Ⅰ截骨与下颌体部截骨术能较好地矫正上颌后缩及下颌前突畸形,但牙颌关系恢复不良。前牙根尖下截骨是纠正双颌前突畸形的理想术式,SSRO矫正下颌前突畸形效果满意。     

Postoperative stability of bimaxillary surgery in Class III patients with mandibular protrusion and mandibular deviation: a frontal cephalometric study

The aims of this study into bimaxillary surgery were to investigate and compare the postoperative stability of deviated side (lengthened side) and non-deviated side (shortened side), the effect of the type of surgery performed in the mandible, and the changes in signs and symptoms of temporomandibular joint (TMJ) disorders before and after surgery. The sample consisted of 31 Class III patients in whom imbalance between the maxilla and the mandible were corrected by Le Fort I osteotomy combined with bilateral intraoral vertical ramus osteotomy (BIVRO group, n=9), bilateral sagittal split ramus osteotomy (BSSRO group, n=10), or IVRO and SSRO (IVRO+SSRO group, n=12). IVRO+SSRO and BIVRO are more effective in improving TMJ signs and symptoms. There was no significant post-surgical difference between deviated and non-deviated sides in any group. BIVRO and BSSRO showed excellent post-surgical stability on both sides; less was found in the IVRO+SSRO group. The IVRO+SSRO group showed greater transverse displacement in menton point than the BIVRO group. In conclusion, after bimaxillary surgery and in asymmetric patients there were no differences between deviated and non-deviated sides, BIVRO and BSSRO appear to be more stable than IVRO+SSRO.     

Effect of Le Fort III osteotomy on mandibular growth in patients with Crouzon and Apert syndromes

Midface advancement by Le Fort III osteotomy is a common procedure in craniofacial surgery. However, little data exist concerning the effect of midface advancement on mandibular growth. This is a retrospective study of 38 patients from two craniofacial centers who had Le Fort III osteotomy. The aims of this investigation were to document the size and shape of the mandible in Crouzon and Apert syndromes and to determine the effect on these parameters of downward and forward movement of the midface. The syndrome patients had increased gonial angle, increased MP-SN, increased ramus height, and increased ratio of ramus height to body length when compared with normal standards. Patients operated during growth and those operated when growth was completed had similar mandibular size and shape indicating that Le Fort III osteotomy had no measurable effect on these parameters. Inclination of the mandible to the anterior cranial base was increased by the operation and remained unchanged during the follow-up period. The results of this study indicate that the size and morphology of the mandible are similar in Crouzon and Apert syndromes. The pattern of growth is more vertical in the syndrome patients than in normals. Le Fort III osteotomy in growing children does not result in altered mandibular size and shape despite backward rotation of the mandible as a result of midface advancement.     

Treatment of severe mandibular prognathism in combination with maxillary hypoplasia: case report.

We performed a Le Fort I osteotomy and sagittal split ramus osteotomy (Obwegeser-Dal Pont) combined with mandibular anterior segmental osteotomy without tooth extraction for a patient with severe mandibular prognathism accompanied by a hypoplastic maxilla, anterior open bite and normal anterior mandibular vertical dimension. The results of facial appearance and occlusion were excellent. This combined surgical method appears to be satisfactory for treating severe mandibular prognathism with hypoplastic maxilla.     

Computer-assisted osteotomy guides and pre-bent titanium plates improve the planning for correction of facial asymmetry

This study investigated the surgical outcomes and accuracy of computer-assisted osteotomy guides and pre-bent titanium plates in the treatment of patients with facial asymmetry. Thirteen patients with facial asymmetry undergoing bimaxillary orthognathic surgery were included. Virtual simulation of Le Fort I osteotomy, sagittal split ramus osteotomy, and genioplasty, if needed, was conducted on the preoperative three-dimensional model. Computer-assisted osteotomy guides and pre-bent titanium plates were produced and used in the actual operation. The postoperative outcome was assessed for facial symmetry and surgical accuracy. All patients were followed up for at least 18 months and their level of satisfaction was investigated. Use of the computer-assisted osteotomy guides and pre-bent titanium plates was successful in all patients. Maxillary canting, mandibular ramus inclination, and mandibular length were corrected on both sides postoperatively. Superimposition of the surgical simulation and postoperative images demonstrated favourable accuracy. Quantitative analysis revealed a mean linear difference of <0.60 mm in the maxilla and 1.57 mm in the mandible. All patients were satisfied with the surgical outcome; there were no complications or cases of relapse during follow-up. The application of computer-assisted osteotomy guides and pre-bent titanium plates achieved favourable outcomes and accuracy, improving planning for the correction of facial asymmetry.     

Changes in temporomandibular joint and ramus after sagittal split ramus osteotomy in mandibular prognathism patients with and without asymmetry

The purpose of this study was to examine the changes in the temporomandibular joint (TMJ) and ramus after sagittal split ramus osteotomy (SSRO) with and without Le Fort I osteotomy.The subjects consisted of 87 Japanese patients diagnosed with mandibular prognathism with and without asymmetry. They were divided into 2 groups (42 symmetric patients and 45 asymmetric patients). The TMJ disc tissue was assessed by magnetic resonance imaging (MRI) and the TMJ space, condylar and ramus angle were assessed by computed tomography (CT) preoperatively and postoperatively.Medial joint space on the deviation side in the asymmetry group was significantly larger than that in the symmetry group (P = 0.0043), and coronal ramus angle on the non-deviation side in the asymmetry group was significantly larger than that in the symmetry group preoperatively (P = 0.0240). The horizontal condylar angle on the deviation side in the asymmetry group was significantly larger than that in the symmetry group (P = 0.0302), posterior joint space on the non-deviation side in the symmetry group was significantly larger than that in the asymmetry group postoperatively (P = 0.00391).The postoperative anterior joint space was significantly larger than the preoperative value on both sides in both groups (the deviation side in the symmetry group: P = 0.0016, the non-deviation side in the symmetry group: P < 0.0001, the deviation side in the asymmetry group: P = 0.0040, the non-deviation side in the asymmetry group: P = 0.0024). The preoperative disc position could was not changed in either group.These results suggest that significant expansion of anterior joint space could occur on the deviation side and non-deviation side in the asymmetry group as well as on both sides in the symmetry group, although disc position did not change in either group.     

Three-dimensional computed tomography evaluation of postsurgical condylar displacement after mandibular osteotomy

Objective. The purpose of this study was to examine both condylar displacement of the temporomandibular joint after sagittal split ramus osteotomy with rigid osteosynthesis and intraoral vertical ramus osteotomy without osteosynthesis in patients with mandibular prognathism by means of three-dimensional computed tomography.Study design. In this pilot study, five patients treated with sagittal split ramus osteotomy and 5 patients treated with intraoral vertical ramus osteotomy were evaluated. A technique to superimpose a postoperative three-dimensional computed tomography image on its corresponding preoperative image was designed. Postoperative condylar displacement, rotation, and tilting were measured in three-dimensional computed tomography images.Results. Within 3 to 6 months after surgery, changes in the inclination of the condylar axes were distinctly seen, although changes in the position of the condyles within the joints were minimal. In particular, outward rotation of the condylar long axes after intraoral vertical ramus osteotomy was a frequent finding.Conclusions. The three-dimensional computed tomography superimposition technique was a practical method of evaluating post-surgical condylar displacement after mandibular osteotomy.     

Orthognathic treatment for a patient with facial asymmetry associated with unilateral scissors-bite and a collapsed mandibular arch

Subapical mandibular surgeries have been used to correct vertical malocclusion and interdental problems associated with mandibular deformity. Subapical surgery to the anterior part of the mandible is applicable in many patients with anterior open bite and deepbite. Surgery of the posterior part of the mandible is needed less frequently than surgery of the anterior part. This case report describes the surgical-orthodontic treatment of a 21-year-old woman who underwent posterior subapical mandibular surgery. Her chief complaint was facial asymmetry, and she had a collapsed mandibular arch with a scissors-bite of the right premolars and molars. After subapical osteotomy, surgically assisted correction of the collapsed right mandibular arch was performed with a lingual arch appliance. Comprehensive orthodontic treatment was initiated in both arches after this correction. Le Fort I osteotomy and sagittal split ramus osteotomy were used to correct the facial asymmetry. Her facial appearance and temporomandibular problems were markedly improved, and she achieved a functional and stable occlusion after these treatments. This case report demonstrates the efficiency of posterior subapical mandibular surgery for a patient with a collapsed mandibular arch and a scissors-bite.