• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.1
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• pp.51-62
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• 1994

The sagittal split osteotomy of the mandibular ramus is a common procedure which has been used in the correction of mandibular deformities for a few decades. Although the technical improvements have increased the reliability and stability of SSRO procedure, the postoperative relapse is imperative and clinically more significant than any other complication. One of the major causes of the relapse is due to the displacement of the proximal segment during SSRO procedure, which is well documented in the literature. Therefore it is important to preserve the original position of the proximal segment during SSRO proced and maxillofacial fixation period. In the case of mandibular asymmetry, if one side of mandible is advanced and the other side of mandible is setback during SSRO procedure, the proximal segment in the advancement site will rotate laterally and the proximal segment in the setback site will rotate medially. For the prevention of the lateral rotation or flaring of the proximal segment in the advancment site. we deliberately fracture the posterior protion of the distal segment in green-stick fashion during SSRO procedure, and there is no need to fix the fractured lingual segment. We fix the two osteotomized bony segments in the buccal cortex area rigidly with adjustable monocortical plates and screws. During SSRO procedure the lingual fracture technique was applied to nine patients with severe mandibular asymmetry who underwent orthognathic surgery in our hospital since march, 1992. These clinical experiencies enable us to find the lingual fracture technique has the following advantages. 1. The proximal segment is displaced minimally. 2. The osteotomized bony segments are contacted intimately. 3. The postoperative relapse and the healing period are decreased.

• The korean journal of orthodontics
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• v.53 no.2
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• pp.99-105
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• 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
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• v.41 no.2
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• pp.102-108
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• 2015

In surgery for facial asymmetry, mandibles can be classified into two types, rotational and translational, according to the required mandibular movements for surgery. During surgery for rotational mandibular asymmetry, a bilateral sagittal split ramus osteotomy (BSSRO) may cause a large bone gap between the proximal and distal segments as well as condylar displacement, resulting in a relapse of the temporomandibular joint disorder, especially in severe cases. The intraoral vertical ramus osteotomy has an advantage, in this respect, because it causes less rotational displacement of the proximal segment on the deviated side and even displaced or rotated condylar segments may return to their original physiologic position. Unilateral intraoral vertical ramus osteotomy (UIVRO) on the short side combined with contralateral SSRO was devised as an alternative technique to resolve the spatial problems caused by conventional SSRO in cases of severe rotational asymmetry. A series of three cases were treated with the previously suggested protocol and the follow-up period was analyzed. In serial cases, UIVRO combined with contralateral SSRO may avoid mediolateral flaring of the bone segments and condylar dislocation, and result in improved condition of the temporomandibular joint. UIVRO combined with contralateral SSRO is expected to be a useful technique for the treatment of rotational mandibular asymmetry.

• The korean journal of orthodontics
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• v.43 no.6
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• pp.263-270
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• 2013

Objective: To evaluate condylar head remodeling after mandibular set-back sagittal split ramus osteotomy (SSRO) with rigid fixation in skeletal class III deformities. The correlation between condylar head remodeling and condylar axis changes was determined using cone-beam computed tomography (CBCT) superimposition. Methods: The CBCT data of 22 subjects (9 men and 13 women) who had undergone mandibular set-back SSRO with rigid fixation were analyzed. Changes in the condylar head measurements and the distribution of the signs of condylar head remodeling were evaluated by CBCT superimposition. Results: The subjects showed inward rotation of the axial condylar angle; reduced condylar heights on the sagittal and coronal planes; and resorptive remodeling in the anterior and superior areas on the sagittal plane, superior and lateral areas on the coronal plane, and anterior-middle and anterior-lateral areas on the axial plane (p < 0.05). Conclusions: The CBCT superimposition method showed condylar head remodeling after mandibular set-back SSRO with rigid fixation. In skeletal class III patients, SSRO with rigid fixation resulted in rotation, diminution, and remodeling of the condylar head. However, these changes did not produce clinical signs or symptoms of temporomandibular disorders.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.4
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• pp.563-569
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• 1996

Skeletal and dental changes were examined in 38 patients of mandibular prognathism who been treated by a bilateral sagittal split osteotomy(SSRO) and internal fixation using titanium mini-screws. All patients were followed up for over 8 months after the surgeries, and postoperative cephalometric measurements were compared at 2 months and at 8 months. Linear measurements of the "Pog-most posterior screws" and angular measurementsts of "SN-Pog'were compared to figure out the change of bony fragments. The significancy of data were tested by unpaired T-test. The results were as follows : 1. The fixation screws were changed in cephalometric position as little as $0.32{\pm}2.51mm$ in SSRO and $0.15{\pm}1.00mm$ in SSRO & Le Fort I Osteotomy.(P<0.05) 2. Mandibular set-back over 5mm resulted in less stability of the fixation screws and higher relapse tendency. 3. The internal fixation using two screws along the inferior border and one on the superior ridge is considered to be very resistant to postoperative relapse of the repositioned bony segments.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.8.1-8.6
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• 2019

Background: Resorbable devices have recently been adopted in the field of orthognathic surgery with controversies about their postoperative skeletal stability. Hence, we determined the long-term skeletal stability of unsintered hydroxyapatite/poly-ʟ-lactic acid (HA/PLLA) mesh for osteofixation of mandibular sagittal split ramus osteotomy (SSRO), and compared it with that of titanium miniplate. Methods: Patients were divided into resorbable mesh and titanium miniplate fixation groups. A comparative study of the change in the mandibular position was performed with preoperative, 1-day, 6-month, and 2-year postoperative lateral cephalograms. Results: At postoperative 6 months-compared with postoperative 1 day, point B (supra-mentale) was significantly displaced anteriorly in the titanium-fixation group. Moreover, at postoperative 2 years-compared with postoperative 6 months, point B was significantly displaced inferiorly in the titanium-fixation. However, the HA/PLLA mesh-fixation group did not show any significant change with respect to point B postoperatively. Conclusions: The HA/PLLA mesh-fixation group demonstrated superior long-term skeletal stability with respect to the position of mandible, when compared with the titanium-fixation group.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.19 no.2
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• pp.130-134
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• 1997

The sagittal split ramus osteotomy(SSRO) of the mandible has used one of the most popula methods for the correction of various dentofacial deformities, especially mandibular prognathism. In SSRO, there are produced bony gap following mandible setback because of mandibular flaring. For this reason, the condylar axis may be changed due to bony approximation both segment in three dimension more mesio-laterally. According to change of condylar position, the condition of TMJ structure are changed and change of TMJ symptoms are suggested theoretically, and the correction of malocclusion by SSRO may improve the TMJ symptoms by improvement of feeding difficulties. The pupose of this study was to determine relationship between expected alterations in condylar position and suggested TMJ symptoms produced by change of condylar position. TMJ symptoms of 15patients who had operated SSRO are checked at about postoperative 6 month ranging $5{\sim}11$ month. Anterior-posterior position of condyle which was comparison preoperative with postoperative position, was classified 5 groups. The author tried to identify relationship between positional change of condyle and TMJ discomfort.

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

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.5
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• pp.373-381
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• 2021

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.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.239-249
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• 2001

The purpose of this study is to evaluate the relationship of the factors which could be influenced by orthognathic surgery especillay SSRO. We measured the amounts of the maximum opening, lateral movements, maximum velocity and pattern of mandibular path during the opening and closing of mandible at the following times ; preoperative, 1 month after operation, 6 months after operation respectively using MKG. And the results were compared according to the categorized subgroups. Following results were obtained : 1. The change of the amounts of mandibular lateral movement and maximum opening velocity were statistically different between male and female (p<0.05), but the others were not. 2. According to the method of operation, there was no difference in the change of the mandibular movements between the group of SSRO and SSRO plus LeFort I osteotomy (p>0.05). 3. According to the amounts of mandibular movement, the recovery of left lateral movement of the group of $6{\sim}10mm$ was better than the other groups (p<0.05). 4. In the frontal pattern of the opening and closing of the mandible, the complex deflected type (F5), simple deflected type (F4), complex deviated type (F3), simple deviated type (F2), straight type (F1) were obtained in order at the time of preoperative, simple deflected type, simple deviated type, complex deviated type, straight type, complex deflected type in order at the time of 1 month after surgery, and the result at the time of 6 months after surgery was the same with that of the time of preoperative. In the sagittal pattern, non-coincident type (S2) was predominant at the time of preoperative, and coincident type (S1) was predominant at the time of 1 month after surgery. After 6 months, the result was also the same with that of the preoperative in sagittal pattern. 5. There was not a statistical difference in the change of the mandibular movement between group of presence of the preoperative TMJ symptoms and non-presence group (p>0.05). 6. There was not a statistical difference in the change of the mandibular movement between repositioning device applied group and non-applied group (p>0.05). 7. Sixty three percents of the patients who had preoperative TMJ symptoms were improved after surgery and preoperative TMJ symptoms were more improved after operation in the repositioning device non-applied group statistically (p<0.05).