• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.41 no.3
• /
• pp.133-138
• /
• 2015

Objectives: To evaluate the influence of the type of osteotomy in the inferior aspect of the mandible on the mechanical performance. Materials and Methods: The study was performed on 20 polyurethane hemimandibles. A sagittal split ramus osteotomy (SSRO) was designed in 10 hemimandibles (group 1) with a vertical osteotomy in the buccal side (second molar level) and final osteotomy was performed horizontally on the lingual aspect, while the mandible body osteotomy was finalized as a straight osteotomy in the basilar area, perpendicular to the body. For group 2, the same osteotomy technique was used, but an oblique osteotomy was done in the basilar aspect of the mandibular body, forming continuity with the sagittal cut in the basilar area. Using a surgical guide, osteosynthesis was performed with bicortical screws using an inverted L scheme. In both groups vertical compression tests were performed with a linear load of 1 mm/min on the central fossa of the first molar and tests were done with models made from photoelastic resin. Data were analyzed using Student's t-test, establishing a statistical significance when P<0.05. Results: A statistical difference was not observed in the maximum displacements obtained in the two osteotomies (P<0.05). In the extensiometric analysis, statistically significant differences were identified only in the middle screw of the fixation. The photoelastic resin models showed force dissipation towards the inferior aspect of the mandible in both SSRO models. Conclusion: We found that osteotomy of the inferior aspect did not influence the mechanical performance for osteosynthesis with an inverted L system.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.36 no.2
• /
• pp.94-99
• /
• 2010

The purpose of this study was to examine the soft tissue changes in skeletal class II patients after mandibular advancement by bilateral sagittal split ramus osteotomy (BSSRO). In Asian population, the incidence of skeletal class II malocclusion is lower than that of skeletal class III malocclusion unlike the caucasians. This study was conducted to figure out the ratio at which hard tissue and soft tissue changes after mandibular advancement by analyzing cephalograms of 13 patients that have undergone the mandibular advancement surgery. As a result, change ratios of Li, B', Pog' according to the movement of li, B, Pog were found to be 0.59, 1.06, 0.82. Also, vertical height of vermilion zone (Si-Vb) and lower lip and chin (Si-Me') were measured to evaluate vertical changes. Vermilion zone showed tendency to decrease by 1.02 mm on the average postoperatively, whereas vertical length of lower lip and chin showed tendency to increase by 3.57 mm on the average.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.22 no.4
• /
• pp.271-281
• /
• 2006

Long term prediction of surgical result of skeletal class III has not been evaluated adequately because the stability of orthognathic surgery would be affected by not only set back amount of mandible but also many other factors like skeletal pattern, hyoid position, and airway size. The aimof this study is to discriminate the factors which affect the stability of post-treatment result of surgical outcome of sagittal split ramus osteotomy. We have collected 37 patients (male: 17, female: 20) from patients who have been treated at Orthodontic Department in Dankook University. The patients underwent 3 times Cephalometric X-ray taking at pre-, post-orthognathic surgery and after 12 months retention. The subjects were divided into 2 groups (Stable group: 21, Relapse group: 16) according to their relapse amount. We have taken following results from Students t-test and discriminant analysis. The discriminant factors which discern relapse and stable groupe among treatment change variables were BX and Ba-HY. Hyoid bone moved to posterior and inferior position due to surgery and repositioned superiorly and posteriorly during retention period. Skeletal patterns of the relapse group are smaller mandibular plane angle, anterior mandibular position, and greater distance from hyoid bone to cervical bone and mandible respectively.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.33 no.3
• /
• pp.218-224
• /
• 2011

Purpose: The purpose of this study is to evaluate the post-operative skeletal stability after surgical correction of patients with mandibular prognathism by bilateral sagittal split ramus osteotomy (BSSRO) and to evaluate the horizontal relapse tendency after the surgery. Methods: Twenty-six patients with Class III dental and skeletal malocclusion were selected for this retrospective study. Fifteen of them underwent BSSRO for mandibular setback and eleven of them underwent two-jaw surgery (Lefort I and BSSRO). In each patient, lateral cephalometric radiographs were taken pre-operatively, post-operatively within 1 week, and post-operatively after eight months. After tracing of the cephalometric radiographs, various parameters were measured. The analyses were done by linear measurement to evaluate the change in position of hard tissue B point, pogonion and mandibular plan angle by examination on lateral cephalograms. Results: The horizontal relapse rate was 27.1% at B point and 31.6% at pogonion in patients who underwent BSSRO. The horizontal relapse rate of the group where the amount of correction exceeded 10 mm was 25.69% at B point. Conclusion: There were no statistical differences on the magnitude of setback and direction of rotation of the mandible in mandibular stability. There were also no statistical differences between single mandibular surgery and two-jaw surgery for mandibular stability.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.31 no.6
• /
• pp.496-500
• /
• 2005

A 22-year-old male patient had developed a submasseteric abscess secondary to a mandibular osteomyelitis at the age of 7 years old. The initial presentation at that time seems to be acute suppurative parotitis. The computed tomographic scans taken before surgery demonstrated diffuse deformity, sclerotic change and osteolytic lesion in the mandible. There was no marrow space on both sides of mandibular ramus and thin-walled cortical bone was seen. So, from the results of the computed tomography, the surgery was performed intraoral vertical ramus osteotomy (IVRO) instead of performing the more commonly used bilateral sagittal split ramus osteotomy (BSSRO). In this report, we present a case of surgical correction of mandibular prognathism with fibrous-osseous lesion of mandible with using IVRO.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.37 no.6
• /
• pp.539-544
• /
• 2011

Maxillary canting and vertical shortening of the unilateral mandibular ramus height is common in cases of severe facial asymmetry. Normally, mandibular distraction osteogenesis (DO) with horizontal osteotomy at the ascending ramus is used for vertical lengthening of the mandibular ramus to correct facial asymmetry with an absolute shortened ascending ramus. In this case report, vertical lengthening of the ascending ramus was performed successfully with unilateral DO and sagittal split ramus osteotomy (SSRO), where the posterior part of the distal segment can be distracted simultaneously in an inferior direction with maxillary DO, resulting in a lengthening of the medial pterygoid muscle. This case describes the acquired unilateral mandibular hypoplasia caused by a condylar fracture at an early age, which resulted in abnormal mandibular development that ultimately caused severe facial trismus. The treatment of this case included two-stage surgery consisting of bimaxillary distraction osteogenesis for gradual lengthening of the unilateral facial height followed by secondary orthognathic surgery to correct the transverse asymmetry. At the one year follow-up after SSRO, the vertical length was maintained without complications.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.42
• /
• pp.21.1-21.6
• /
• 2020

Background: Fibula free flap mandible reconstruction is the standard procedure after wide resection of the mandible. Establishment and maintenance of normal occlusion are important in mandible reconstruction both intraoperatively and after surgery. However, scar formation on the surgical site can cause severe fibrosis and atrophy of soft tissue in the head and neck region. Case presentation: Here, we report a case of severe soft tissue atrophy that appeared along with scar formation after mandibular reconstruction through the fibular free flap procedure. This led to normal occlusion collapse after it was established, and the midline of the mandible became severely deviated to the affected side that was replaced with the fibula free flap, leading to facial asymmetry. We corrected the malocclusion with a secondary operation: a sagittal split ramus osteotomy on the unaffected side and a sliding osteotomy on the previous fibula graft. After a healing time of 3 months, implants were placed on the fibula graft for additional occlusal stability. Conclusion: We report satisfactory results from the correction of malocclusion after fibula reconstruction using sliding fibula osteotomy and sagittal split ramus osteotomy. The midline of the mandible returned to its original position and the degree of facial asymmetry was reduced. The implants reduced difficulties that the patient experienced with masticatory function.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.21 no.1
• /
• pp.35-40
• /
• 1999

Recently, sagittal split ramus oseotomy and intraoral vertical ramus osteotomy have been commonly performed for the correction of mandibular prognathism, occurred to abundant oriental people. Many authors have studied the soft tissue change after orthognathic surgery, especially between mandibular hard tissues and soft tissue of lower lip, but the study of upper lip change is comparatively little. Therefore, we studied the 12 patients, operated only sagittal split ramus osteotomy without genioplasty or maxillary osteotomy in department of oral and maxillofacial surgery, Hanyang university hospital from 1996. 1. 1. to 1998. 7. 20. Preoperative and postoperative cephalometric view was measured to know the change of upper lip position and shape after mandibular setback. The result were obtained as follows. 1. The ratio of upper lip change amount to lower incisor horizontal movement was 15.1%. 2. The ratio of lower facial profile between Sn-Stm and Stm-Mes was changed from 1 : 2.352 to 1 : 2.069 after operation. 3. Post-operative upper lip was flattened 72.4% compared with pre-operative one. 4. The vermilion zone of the upper lip increased 56 % horizontally, 5.8% vertically after operation. 5. The vermilion zone ratio of the lower lip to the upper lip was changed from 1 : 1.253 to 1 : 1.348. 6. The distance between esthetic line and Ls was changed from -3.958mm to -1.15mm.

• The korean journal of orthodontics
• /
• v.53 no.2
• /
• pp.99-105
• /
• 2023

Objective: The study aimed to evaluate the changes in mandibular width after sagittal split ramus osteotomy (SSRO) in patients with mandibular asymmetric prognathism using cone-beam computed tomography (CBCT). Methods: Seventy patients who underwent SSRO for mandibular setback surgery were included in two groups, symmetric (n = 35) and asymmetric (n = 35), which were divided according to the differences in their right and left setback amounts. The mandibular width was evaluated three-dimensionally using CBCT images taken immediately before surgery (T1), 3 days after surgery (T2), and 6 months after surgery (T3). Repeated measures analysis of variance was applied to verify the differences in mandibular width statistically. Results: Both groups showed a significant increase in the mandibular width at T2, followed by a significant decrease at T3. No significant difference was observed between T1 and T3 in any of the measurements. No significant differences were found between the two groups (p > 0.05). Conclusions: After mandibular asymmetric setback surgery using SSRO, the mandibular width increased immediately but returned to its original width 6 months after surgery.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.38 no.6
• /
• pp.354-359
• /
• 2012

Objectives: The purpose of this study was to investigate whether the age factor would be related with stability of mandibular setback surgery for patients with mandibular prognathism. Materials and Methods: We compared the relapse patterns of 47 patients divided into three age groups (termed younger, adult, and older). The younger group consisted of patients between 15 and 17 years old; the adult group was made up of patients between 21 and 23 years old, and the older group was made up of patients more than 40 years old. The positional change of B point was evaluated at preoperative, postoperative, and follow-up states. Results: The horizontal relapse ratio was 21.7% in the younger group, 15.3% in the adult group, and 15.7% in the older group. Although relatively higher degrees of relapse were found in the younger group, this increase was not statistically significant. Spearman's correlation analysis was performed to explore other factors contributing to relapse. We subsequently found that the amount of relapse was related to horizontal setback. Conclusion: Although the degree of relapse in younger patients is not significant;y higher compared to other groups. The major contributing factor to relapse after sagittal split ramus osteotomy is amount of setback rather than age when the surgery was performed to patients over than 15 years of age.