Extraoral or intraoral approach in the oblique sliding osteotomy of the mandibular rami? Clinical experience and results

The Versatility of Extraoral Vertical Ramus Osteotomy for Mandibular Prognathism: A Prospective Study

INTRODUCTION

Orthognathic surgery simply means alignment of the jaws. The aim of orthognathic surgery is to normalize the relationship of the jaws between themselves and the rest of the craniofacial complex. Mandibular prognathism is a common clinical problem all over the world. Currently, sagittal ramus osteotomy is the primary choice for correcting most cases of mandibular retrognathism and prognathism. The surgical option for extreme cases of mandibular prognathism is extraoral vertical ramus osteotomy (EVRO) or intraoral vertical ramus osteotomy (IVRO) or inverted L osteotomy.

AIM

The aim of this study was to evaluate the versatility of EVRO for mandibular prognathism.

MATERIALS AND METHODS

Ten patients with the chief complaint of mandibular prognathism with no history of keloid tendency were included in the study. EVRO was done for all patients. The parameters based on which the outcome of the surgical procedure was assessed were time taken for the surgical procedure, facial harmony both in frontal and profile views postoperatively, and intraoperative and postoperative complications, and assessment of the postoperative results was done through orthopantomogram (OPG) and 3D CT scan.

RESULTS

The time taken for the entire surgical procedure, starting from incision to closure, varied between 80 and 94 minutes with the average time taken for the surgery being 90 ± 8.80 minutes. It was found that there was a statistically significant difference between preoperative (M = 53.4, SD = 5.854) and postoperative evaluation (M = 47.5, SD = 5.039) of the posterior nasal spine to nasion 1 (PNS-N 1) horizontal plane (HP) (mm) with p < 0.001. Similarly, there was a statistically significant difference between preoperative (M = 81.4, SD = 2.716) and postoperative evaluation (M = 74.4, SD = 3.627) of mandible body length (mm) with p < 0.001. However, no statistically significant difference exists between the preoperative and postoperative evaluation of anterior nasal spine (ANS) to PNS (mm) and ramus height Ar-Go (mm).

CONCLUSION

EVRO is an acceptable surgical procedure owing to the fact that it is relatively simple to carry out, its lack of complications, and its good results.

Immunohistochemical Analysis on Cortex-to-Cortex Healing After Mandibular Vertical Ramus Osteotomy: A Preliminary Study

PURPOSE

The present study analyzed the expression of specific cytokines in the transforming growth factor (TGF)-β superfamily postoperatively after mandibular vertical ramus osteotomy (VRO).

MATERIALS AND METHODS

Four beagle dogs were enrolled and euthanized at 1, 2, 4, and 8 weeks postoperatively for immunohistochemical analysis using 6 specific antibodies (bone morphogenetic protein [BMP]-2/4, BMP-7, TGF-β2, TGF-β3, matrix metalloproteinase-3, and vascular endothelial growth factor [VEGF]). The results from the surgical site and control (adjacent area) were compared.

RESULTS

Generalized upregulation of BMP-2/4 was observed in all healing periods, and the strongest expression of BMP-7 was observed at 1 week postoperatively. The strongest expression of TGF-β2 was observed at 8 weeks with increasing pattern. The strong expression of TGF-β3 was observed at 1 and 4 weeks, with the strongest expression of VEGF at 1 week, with a decreasing pattern. No notable uptake was detected with the 6 specific antibodies in the adjacent bone (control).

CONCLUSIONS

The absence of internal fixation after VRO led to dynamic healing with a specific expression pattern of BMP-7 and TGF-β2. The anatomic factors, including sufficient preexisting vascularity, led to the earlier expression pattern of VEGF.

Robot-Assisted Surgery for Mandibular Angle Split Osteotomy Using Augmented Reality: Preliminary Results on Clinical Animal Experiment

Mandibular angle split osteotomy (MASO) is a procedure widely used for prominent mandibular angles. However, conventional mandibular plastic surgery is invasive and high risk. It may induce postoperative neurosensory disturbance of the inferior alveolar nerve, fractures and infection due to the complexity of the anatomical structure and the narrow surgical field of view. The success rate of MASO surgery usually depends on the clinical experience and skills of the surgeon. To evaluate the performance of inexperienced plastic surgeons conducting this surgery, a self-developed and constructed robot system based on augmented reality is used. This robot system provides for sufficient accuracy and safety within the clinical environment. To evaluate the accuracy and safety of MASO surgery, an animal study using this robot was performed in the clinical room, and the results were then evaluated. Four osteotomy planes were successfully performed on two dogs; that is, twenty tunnels (each dog drilled on bilaterally) were drilled in the dogs' mandible bones. Errors at entrance and target points were 1.04 ± 0.19 and 1.22 ± 0.24 mm, respectively. The angular error between the planned and drilled tunnels was 6.69° ± 1.05°. None of the dogs experienced severe complications. Therefore, this technique can be regarded as a useful approach for training inexperienced plastic surgeons on the various aspects of plastic surgery.

NO LEVEL ASSIGNED

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Relapse and stability after mandibular setback surgery one year postoperatively: a retrospective study

PURPOSE

A retrospective evaluation was performed of dentoalveolar and skeletal stability 1 year after mandibular setback surgery using intraoral vertical subcondylar osteotomy (IVSO) combined with intermaxillary fixation.

PATIENTS AND METHODS

Twenty-eight patients (16 men, 12 women) with skeletal Angle Class III malocclusions were included. Mean age at start of treatment was 23.9 years. All patients underwent combined surgical and orthodontic treatment. Dental casts and cephalometric measurements were performed for each patient before orthodontic treatment and at 8 weeks and 1 year after surgery.

RESULTS

Treatment changes from 8 weeks to 1 year after surgery were small but significant for the angular relationship between the maxilla and the mandible in the sagittal plane (ANB) (mean difference, -0.5 mm; P = .021), Wits appraisal (mean difference, -0.7 mm; P = .044), the inclination of the mandible in relation to the nasion-sella line (ML-NSL) (mean difference, -0.8 mm; P = .010), and the inclination of the lower incisors in relation to the nasion-point B line (Li-NB) (mean difference, -0.6 mm; P < .001). These findings for cephalometric values indicated a small skeletal relapse in sagittal and vertical relations. No significant dentoalveolar relapse occurred according to the dental cast evaluations.

CONCLUSION

The results clearly show that orthodontic treatment combined with IVSO provides a stable dental and skeletal result 1 year after treatment.

Evaluation of mandibular fracture treatment

A total of 124 patients treated for mandibular fractures were analyzed. Patients were divided into three groups according to treatment: intermaxillary fixation, wire fixation and mini-plate fixation. For each method, the success of treatment was evaluated with respect to surgical approach, fracture site and injury to treatment interval. Five basic parameters were used for evaluation of the outcome: occlusion, appearance, mastication, duration of IMF and complications. The treatment was surveyed based on both the surgeon's and patient's-evaluation. All parameters were scored and average values for every parameter calculated. The most successful treatment was achieved with mini-plate fixation in symphyseal and angle fractures. Intermaxillary fixation is indicated for mandibular body fractures with or without minimal displacement and a sufficient number of teeth. However, mini-plate fixation should be used for fractures with displacement. Wire fixation has been shown to be the poorest choice for all sites. Results showed that the intraoral approach has advantages over the extraoral one. The optimal time for treatment of mandibular fractures is within 72 h from time of injury. Even in fractures older than 7 days we recommended mini-plate fixation.

Techniques for ensuring the lateral position of the proximal segment following intraoral vertical ramus osteotomy

Continual refinements of the surgical technique and instrumentation for the intraoral vertical ramus osteotomy have made it a preferred procedure for mandibular setback, especially in asymmetrical cases. However, there may be intraoperative difficulty in lateral positioning of the proximal segment, which is frequently trapped medially. Three techniques for lateral relocation of the medially displaced proximal segment are described. Techniques designed to prevent this medial displacement also are presented.

Extraoral subcondylar ramus osteotomy for correction of mandibular prognathism. The surgical technique and complications

1178 patients with mandibular prognathism and/or asymmetry, in some cases combined with maxillary retrognathism, were treated by extraoral horizontal or oblique ramus osteotomy during the period from 1939 to 1989. The described percutaneous retromandibular approach is a simple, rapid and reliable technique which can usually be performed under local anaesthesia. Very few complications, particularly neurological, were observed. These aspects justify consideration of this technique when indications for a simple, straight set-back procedure of the mandible exist, and there is no tendency to bite-opening. However, the method demands intermaxillary fixation for 6-9 weeks postoperatively.

Radiographic study of structural changes in the temporomandibular joint after oblique sliding osteotomy: comparison between the extra-oral and intra-oral approaches

Oblique sliding osteotomy of the mandibular rami was performed on 41 patients by either an intra-oral (21 patients) or extra-oral (20 patients) approach. The temporomandibular joints were radiographed preoperatively and then immediately and 18 months postoperatively. Signs of structural changes were recorded so as to compare the two approaches to osteotomy. The most common findings following the operation were signs of sclerosis and bone remodelling in 85% and 73% respectively of the two groups but these differences were not statistically significant.

Anterior skeletal fixation as an adjunct to oblique sliding osteotomy of the mandibular ramus. A cephalometric study

Positional changes of the mandible and upper and lower incisors were studied by means of cephalometric analysis after oblique sliding osteotomy for the correction of mandibular prognathism. In addition to intermaxillary fixation, skeletal fixation between the anterior nasal spine and the chin was used. The patients were followed up for 18 months after surgery. During the fixation period no increase in anterior facial height was observed and at 18 months this had decreased by 2.2 mm. Nevertheless, there was an increase in the mandibular plane angle by 3.8 degrees which mainly occurred during the fixation period. The posterior facial height decreased by 4.0 mm. As to the changes of the incisors these varied between individuals, but the mean values were small. Anterior skeletal fixation prevented increase in anterior facial height and seemed to limit the posterior shortening of the mandible and the extrusion of the mandibular incisors. However, the benefits remained rather limited.