Sagittal Split Ramus Osteotomy Group Research Articles

Comparison of the quality of life changes of patients receiving sagittal split ramus osteotomy or intraoral vertical subsigmoid osteotomy for mandibular prognathism.

To investigate and compare the effect of two orthognathic procedures for mandibular setback, namely, sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), on oral health, mental- and physical health-related quality of life across time. Patients with mandibular prognathism and planned for orthognathic surgery were recruited in this study. Patients were randomized into two groups (IVRO and SSRO groups). Quality of life (QoL) was assessed with the 14-item Short-Form Oral Health Impact Profile (OHIP-14) and the 36-item Short-Form Health Survey (SF-36) preoperatively (T0), postoperative 2weeks (T1), 6weeks (T2), 3months (T3), 6months (T4), 12months (T5), and 24months (T6). A comparison of OHIP-14 and SF-36 scores between two groups was conducted. Ninety-eight patients (49 SSRO group, 49 IVRO group) participated in this study. There was no significant difference in OHIP-14 scores between SSRO and IVRO throughout the treatment process. SSRO group had significant reduction of OHIP-14 score (i.e., improving oral health-related QoL) since postoperative 2weeks, whereas IVRO group had significant reduction since postoperative 6weeks. Starting from postoperative 3months, the oral health-related QoL of both groups was already significantly better than the baseline level and continued to steadily improve afterwards. For SF-36, both groups had increased physical health summary score starting from postoperative 2weeks, indicating an early and gradual recovery of physical health-related QoL. The mental health summary score of the SSRO group began to increase from postoperative 2weeks, but that of the IVRO group only began to increase from postoperative 6weeks. Patient age at the time of surgery was positively correlated with OHIP scores in the postoperative period. The study concludes that both SSRO and IVRO contributed to the improvement of QoL in the long term, but oral health- and mental health-related QoL of SSRO groups showed earlier improvement. Undergoing orthognathic surgery at early ages is advised, as older age of patients appeared to have worse QoL. Clinical trial registration number: HKUCTR-1985. Date of Registration: 14 Apr 2015.

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.

Surgical morbidities of sagittal split ramus osteotomy versus intraoral vertical ramus osteotomy for the correction of mandibular prognathism: a randomized clinical trial

The sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) are two common orthognathic procedures for the treatment of mandibular prognathism. This randomized clinical trial compared the surgical morbidities between SSRO and IVRO for patients with mandibular prognathism over the first 2 years postoperative. Ninety-eight patients (40 male, 58 female) with a mean age of 24.4±3.5 years underwent bilateral SSRO (98 sides) or IVRO (98 sides) as part or all of their orthognathic surgery. IVRO presented less short-term and long-term surgical morbidity in general. The SSRO group had a greater incidence of inferior alveolar nerve deficit at all follow-up time points (P< 0.01). There was more TMJ pain at 6 weeks (P= 0.047) and 3 months (P= 0.001) postoperative in the SSRO group. The SSRO group also presented more minor complications, which were related to titanium plate exposure and infection. There were no major complications for either technique in this study. Despite the need for intermaxillary fixation, IVRO appears to be associated with less surgical morbidity than SSRO when performed as a mandibular setback procedure to treat mandibular prognathism.

Improvement in quality of life after skeletal advancement surgery in patients with moderate-to-severe obstructive sleep apnoea: a longitudinal study

Skeletal advancement surgery with sagittal split ramus osteotomy (SSRO) or mandibular distraction osteogenesis (MDO) is effective in treating patients with obstructive sleep apnoea (OSA) and may improve their quality of life (QoL). This study aimed to evaluate the longitudinal QoL changes in moderate-to-severe OSA patients after skeletal advancement surgery. Eighteen patients were randomized to receive SSRO (n=9) or MDO (n=9) alone or as part of the skeletal advancement surgery. Baseline QoL was compared with that of a control group (n=36). QoL was compared between the SSRO group and MDO group over a period of 2 years postoperative. The Epworth Sleepiness Scale (ESS), Calgary Sleep Apnea Quality of Life Index (SAQLI), Functional Outcomes of Sleep Questionnaire (FOSQ), and Short Form Health Survey (SF-36) were used as instruments. The OSA group had worse ESS, SF-36, FOSQ, and SAQLI preoperatively than the control group. The MDO and SSRO groups showed significant improvements in ESS at all postoperative time points (P≤0.021). The FOSQ, SAQLI, and SF-36 of both groups at 2 years postoperative were similar to those of the control group. No differences in QoL were found between the SSRO and MDO groups. This study showed QoL was improved in patients with moderate-to-severe OSA after skeletal advancement surgery by SSRO or MDO.

Mandibular distraction osteogenesis versus sagittal split ramus osteotomy in managing obstructive sleep apnea: A randomized clinical trial

PurposeTo compare mandibular distraction osteogenesis (MDO) to sagittal split ramus osteotomy (SSRO) to treat moderate-to-severe obstructive sleep apnea (OSA), and their surgical morbidities and skeletal stability. Materials and methodsA randomized clinical trial was conducted on non-syndromic adult patients with apnea-hypopnea index (AHI) 15 or above to receive MDO or SSRO as part or whole skeletal advancement surgery. Post-operative 1 year OSA cure rate (AHI < 5/hour) and treatment success rate (50% reduction of AHI and AHI< 20/hour) were compared. Polysomnography were conducted pre-operatively and post-operatively up to 2 years. Surgical morbidities and skeletal stability were analyzed. ResultsEighteen patients (9 in each group) were recruited. Patient recruitment was terminated after two major complications in the MDO group. The OSA cure rate and treatment success rate showed no statistical difference between MDO group or SSRO group at post-operative 1 year. Major complication rate was 44.4% in the MDO group and 0 in the SSRO group. No statistical difference was found in skeletal stability between the two groups. ConclusionBoth MDO and SSRO were highly effective to treat moderate-to-severe OSA. MDO had a high major complication rate and was not superior than SSRO in airway function improvement and skeletal stability.

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.

Stability of pre-orthodontic orthognathic surgery depending on mandibular surgical techniques: SSRO vs IVRO.

The aim of this retrospective cohort study was to evaluate the postoperative stability of sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) in pre-orthodontic orthognathic surgery (POGS) for skeletal Class III malocclusion. Thirty-seven patients (SSRO, n=18; IVRO, n=19) who underwent bimaxillary surgery were divided into two groups according to the type of surgery. During the postoperative period, there were no significant differences in anterior and superior movements of the mandible at point B between the two groups, but occlusal plane angle of the SSRO group significantly decreased more than that of the IVRO group (P=0.003). Only the SSRO group showed a linear relationship between the amount of postoperative horizontal and vertical movements of the mandible (R(2)=0.254; P=0.033), indicating that the amount of postoperative upward movement of the mandible increased as the amount of postoperative forward movement increased (r=-0.504; P=0.033). The mandible after SSRO in POGS rotated counterclockwise due to rigid fixation between two segments, whereas the mandible after IVRO without rigid fixation in POGS moved mainly in a superior direction. These differences must be considered before surgery to ensure postsurgical stability for patients with mandibular prognathism.

Transverse and sagittal angulations of proximal segment after sagittal split and vertical ramus osteotomies and their influence on the stability of distal segment

This study aimed at comparing the transverse and sagittal angulations of proximal segment after sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), and examining their influences on the stability of distal segment. Patients who received SSRO (n = 21) or IVRO (n = 11) for mandibular setback were included. Lateral and posteroanterior cephalograms taken within 1 month before surgery (T1), within 1 week after surgery (T2), and at least 6 months after surgery (T3) were analyzed. The angulation of each proximal segment relative to the upper orbital margin line was measured on posteroanterior cephalogram and the sum of both angles (total ramus angle, TRA) was obtained. On lateral radiograph, ramus inclination angle (RIA) relative to a horizontal reference line 7° to the sella-nasion was assessed and B-point position was measured. From T1 to T2, more increases in TRA and RIA were noted after IVRO than after SSRO. From T2 to T3, TRA and RIA significantly decreased in IVRO group but remained relatively stable in SSRO group. ΔTRA(T1-T2) positively related to upward rotation of distal segment for SSRO and downward rotation for IVRO from T2 to T3. For SSRO only, ΔRIA(T1-T2) significantly related to forward movement of distal segment during remodeling. TRA and RIA increase significantly after IVRO and then regress, whereas they increase mildly after SSRO and remain stable. Increase in TRA significantly relates to distal segment rotation during remodeling for both surgeries, but increase in RIA relates to forward relapse of the distal segment only for SSRO. The reasons underlying the correlations are not certain and deserve future investigations.

Soft and hard tissue changes after bimaxillary surgery in Japanese class III asymmetric patients

Objectives:To assess the effects of bimaxillary surgery on Class III subjects with mandibular asymmetry, and to compare the effects of the type of surgery performed in the mandible on the facial profile especially in the presence of facial asymmetry.Materials and Methods:Thirty-six 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=14), or a combination of intraoral vertical ramus osteotomy (IVRO) and sagittal split ramus osteotomy (SSRO) (IVRO + SSRO group, n=13). Cephalograms were taken before surgery (T1), and 1 year after surgery (T2). Hard and soft-tissue changes were compared.Results:The postsurgical findings showed that greater mandibular backward displacement and greater upper lip forward movement were more pronounced among BIVRO group when compared with BSSRO group. Upper lip relation to E-line showed greater improvement in BIVRO group than BSSRO and IVRO + SSRO groups. The ratios of corresponding mandibular soft to hard tissue movements were higher than that of maxillary movements and were more pronounced in IVRO + SSRO and BSSRO groups when compared with BIVRO group.Conclusion:IVRO surgical technique appears to be more effective in positioning the mandible more posteriorly and improving upper and lower lips position and competence.

Changes in the pharyngeal airway space and hyoid bone position after mandibular setback surgery for skeletal Class III jaw deformity in Japanese women

The purpose of the study was to examine the changes in stability of pharyngeal airway space (PAS) and hyoid bone position after 2 types of mandibular osteotomies in comparison with a control group. The subjects included 46 Japanese women with skeletal Class III malocclusion. Twenty-five patients with mandibular prognathism underwent single-jaw surgery with bilateral sagittal split ramus osteotomy (SSRO), and 21 patients underwent bilateral intraoral vertical ramus osteotomy (IVRO). The control subjects included 30 volunteer women with normal occlusion. The treated subjects were assessed at the beginning of treatment, immediately after surgery, and after postsurgical treatment. The Class III subjects had a significantly wider PAS than did the control subjects. Significant decreases in the lower PAS were observed after orthognathic surgery. The hyoid bone showed upward and forward movement with upward movement of the lower border of the PAS during the postsurgical stage in the SSRO group. In contrast, the anterior border of the PAS and the hyoid bone showed considerable backward movement in the IVRO group. The posttreatment morphology of the PAS in both Class III groups approached that of the control group. The IVRO group showed a reduction in the airway dimensions, especially during the postsurgical period, which occurred during surgery in the SSRO group.

Editor's Comment and Q&A: Changes in pharyngeal airway space and hyoid bone position after mandibular setback surgery for skeletal Class III jaw deformity in Japanese women

Introduction The purpose of the study was to examine the changes in stability of pharyngeal airway space (PAS) and hyoid bone position after 2 types of mandibular osteotomies in comparison with a control group. Methods The subjects included 46 Japanese women with skeletal Class III malocclusion. Twenty-five patients with mandibular prognathism underwent single-jaw surgery with bilateral sagittal split ramus osteotomy (SSRO), and 21 patients underwent bilateral intraoral vertical ramus osteotomy (IVRO). The control subjects included 30 volunteer women with normal occlusion. The treated subjects were assessed at the beginning of treatment, immediately after surgery, and after postsurgical treatment. Results The Class III subjects had a significantly wider PAS than did the control subjects. Significant decreases in the lower PAS were observed after orthognathic surgery. The hyoid bone showed upward and forward movement with upward movement of the lower border of the PAS during the postsurgical stage in the SSRO group. In contrast, the anterior border of the PAS and the hyoid bone showed considerable backward movement in the IVRO group. Conclusions The posttreatment morphology of the PAS in both Class III groups approached that of the control group. The IVRO group showed a reduction in the airway dimensions, especially during the postsurgical period, which occurred during surgery in the SSRO group.

骨格性下顎前突症に対する下顎枝矢状分割術（ＳＳＲＯ）と下顎枝垂直骨切り術（ＩＶＲＯ）の比較検討について

The most frequently used techniques for correcting skeletal Class III deformity are sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO). The purpose of this study was to compare the clinical outcome including skeletal stability after SSRO with semirigid fixation and IVRO. The subjects of this study were 23 patients who underwent SSRO for mandibular setback with semirigid fixation by titanium miniplate and 20 patients who underwent IVRO for mandibular setback without interosseous fixation. The mean period of maxillo-mandibular fixation was 5.1 days in the SSRO group and 7.3 days in the IVRO group. The evaluation items were skeletal changes, operation time, blood loss, sensory disturbance, temporomandibular joint (TMJ) sound and mandibular range of motion (ROM). Compared with the SSRO group, the B-point and pogonion moved significantly posteriorly in the IVRO at more than 6 months after surgery. Operation time, blood loss and occurrence of sensory disturbance were also less than those in the SSRO group. There were no significant differences in TMJ sound and ROM. The results of this study showed that both methods had minimal relapse and no significant difference in comparison by measurement of B-point and pogonion. In conclusion, both methods are effective for correcting skeletal Class III malocclusion, and the surgical method should be selected in consideration of each clinical distinction.

Hard and Soft Tissue Stability of Orthognathic Surgery

To test the hypothesis that there is no difference in the stability of the hard and soft tissue changes following a surgical mandibular setback using a sagittal split ramus osteotomy or an intraoral vertical ramus osteotomy. The samples consisted of 45 female patients with mandibular prognathism, who were divided into two groups. Twenty-three underwent a sagittal split ramus osteotomy (SSRO) with rigid fixation by titanium mini-screws and maxillomandibular fixation (MMF) for 14.0 +/- 0.7 days. Twenty-two underwent intraoral vertical ramus osteotomy (IVRO) without rigid fixation, and MMF was released 21.5 +/- 3.3 days after surgery. Data were collected from standardized cephalometric radiographs taken at the start of preoperative orthodontic treatment (T1), immediately after surgery (MMF, T2), and the completion of postoperative treatment (T3). Angular measurements were compared on each of T1, T2, and T3. There were no significant differences in the pretreatment hard and soft tissue morphology between the SSRO and IVRO. However, when fixation was released, the mandible was posteriorly positioned in the IVRO group. In the soft tissue profile, the mental region was located backward in the IVRO group at postoperative stage (T3). The hypothesis is rejected. The soft tissue profile of the IVRO group especially showed a retromandibular position after postoperative treatment in comparison with the SSRO group. This tendency of the IVRO group would contribute to the database for treatment planning and prediction.

Vertical Ramus Versus Sagittal Split Osteotomies: Comparison of Stability After Mandibular Setback

Intraoral vertical ramus osteotomy (IVRO) offers some advantages over sagittal split ramus osteotomy (SSRO) for treatment of the prognathic patient. The purpose of this study was to compare the postoperative changes of proximal and distal segments after IVRO and SSRO with semirigid internal fixation. Thirty Japanese adults with a diagnosis of prognathic mandible were randomized to undergo either IVRO (n = 15) or SSRO (n = 15) according to an adaptive random assignment procedure. The postoperative changes of the proximal and distal segments were assessed with posteroanterior and lateral cephalograms. Compared with the SSRO group, the B-point and pogonion moved significantly posteriorly and inferiorly in the IVRO group from 1 month to 3 months after surgery. At 1 year after surgery, there was no significant difference between the 2 groups in the horizontal and vertical stability of the B-point and the pogonion. In the IVRO group, the gonion deviated significantly laterally from 1 week until 1 month after surgery as compared with that of the SSRO group. There was a significant correlation between the amount of setback and the amount of lateral gonial deviation in the IVRO group from 1 week to 1 year after surgery. Although in IVRO cases, distal segments moved posteriorly and inferiorly immediately after the release of maxillomandibular fixation, the stability after IVRO is equal to that after SSRO with semirigid internal fixation.

P.281 Metastasizing atypical cutaneous malignant histiocytoma in head and neck

The purpose of this study was to examine the cause of joint effusion (JE) appearing postoperatively in the temporomandibular joint (TMJ) of patients with mandibular prognathism on T2-weighted magnetic resonance (MR) images.MR imaging was performed before and after surgery in 30 TMJs of 15 subjects with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) and in 20 TMJs of 10 subjects with mandibular prognathism who underwent sagittal split ramus osteotomy (SSRO). The preoperative MR imaging was performed 1 month before surgery, and postoperative MR imaging was performed during maxillomandibular fixation.Preoperatively, none of SSRO and IVRO groups had JE. Postoperatively, 12 TMJs (40%) of the IVRO group and only 1 TMJ (5%) of the SSRO group had JE. As for the TMJs in the IVRO group, on MR imaging, the degree of downward movement of the condyle after surgery was larger in TMJs with JE (3.8 ± 2.3 mm) than in TMJs without JE (1.8 ± 1.6 mm). JE diminished within about 4 months after removal of the maxillomandibular fixation.JE appearing postoperatively in the TMJ of patients with mandibular prognathism might be relation to the degree of downward movement of the condyle.

Condylar head remodeling following mandibular setback osteotomy for prognathism: A comparative study of different imaging modalities

Condylar remodeling, which develops after mandibular setback osteotomy, was evaluated and compared in CT, plain film radiographs, and MR images acquired postoperatively. Thirty-nine patients treated with sagittal split ramus osteotomy (SSRO) and 46 patients treated with intraoral vertical ramus osteotomy (IVRO) were studied. Remodeling as seen in the images and the diagnostic agreement between imaging modalities was evaluated. A newly formed bone layer in the posterior part of the condylar head was identified as a sign suggestive of remodeling. This sign was seen predominantly at periods over 6 months postoperatively. IVRO subjects had a higher incidence of remodeling than did the SSRO group. The diagnostic agreement between the 3 imaging modalities was substantial. There was a positive correlation between postoperative condylar displacement and the incidence of remodeling. The incidence of postoperative condylar head remodeling may be predictable. High-dose postoperative imaging studies to assess the TMJ should be restricted to those cases having a clear need for such studies.

Change in Condylar Long Axis and Skeletal Stability Following Sagittal Split Ramus Osteotomy and Intraoral Vertical Ramus Osteotomy for Mandibular Prognathia

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). 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. 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). 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 Pharyngeal Airway Space and Hyoid Bone Positions After Body Ostectomies and Sagittal Split Ramus Osteotomies

Although mandibular setback might lead to possible pharyngeal narrowing, the development of obstructive sleep-related breathing disorders may occur because of multiple factors. In this study, the changes in the pharyngeal airway space (PAS) and the hyoid bone position have been evaluated before and after surgery in patients who underwent body ostectomy (BO) and sagittal split ramus osteotomy (SSRO). In addition, the effects of the BO on PAS and on hyoid bone position have been compared with the effects of the SSRO. Thirty patients with mandibular prognathism underwent mandibular setback osteotomy. The patients were divided into two groups: BO group, 15 patients (5 men, 10 women) who underwent BO; and SSRO group, 15 patients (11 men, 4 women) who underwent SSRO. Changes in PAS and hyoid bone position were analyzed throughout the preoperative and early and long-term postoperative periods via lateral cephalometric radiographs. A decrease has been observed in the PAS area and the anteroposterior dimension of the PAS detected in all patients in the long-term period. Hyoid bone revealed backward and downward movement during the early postoperative period; however, it showed a tendency to return to its original anatomic position during the long-term postoperative period. None of the patients had disturbances in respiration. After BO and SSRO, a decrease in PAS area was observed, and this decrease also continued in the long-term period. Our results revealed a decrease in PAS area after BO, but the decrease was less than that in cases having SSRO.

Transitional joint effusion in the mandibular prognathic surgery patient: intraoral vertical ramus osteotomy versus sagittal split ramus osteotomy

Purpose The purpose of this study was to examine the cause of joint effusion (JE) appearing postoperatively in the temporomandibular joint (TMJ) of patients with mandibular prognathism on T2-weighted magnetic resonance (MR) images. Patients and methods MR imaging was performed before and after surgery in 30 TMJs of 15 subjects with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) and in 20 TMJs of 10 subjects with mandibular prognathism who underwent sagittal split ramus osteotomy (SSRO). The preoperative MR imaging was performed 1 month before surgery, and postoperative MR imaging was performed during maxillomandibular fixation. Results Preoperatively, none of SSRO and IVRO groups had JE. Postoperatively, 12 TMJs (40%) of the IVRO group and only 1 TMJ (5%) of the SSRO group had JE. As for the TMJs in the IVRO group, on MR imaging, the degree of downward movement of the condyle after surgery was larger in TMJs with JE (3.8 ± 2.3 mm) than in TMJs without JE (1.8 ± 1.6 mm). JE diminished within about 4 months after removal of the maxillomandibular fixation. Conclusion JE appearing postoperatively in the TMJ of patients with mandibular prognathism might be relation to the degree of downward movement of the condyle.

Effects of mandibular setback on the temporomandibular joint: A comparison of oblique and sagittal split ramus osteotomy

Purpose: This investigation studied the changes in temporomandibular joint function and condylar position after mandibular setback using different ramus osteotomies. Patients and methods: The sample consisted of 50 Chinese adults with mandibular prognathism. Twenty-eight of the patients underwent intraoral oblique ramus osteotomy (TORO), and 22 received sagittal split ramus osteotomy (SSRO) with rigid internal fixation (RIF). TMJ symptoms and radiographic findings were evaluated preoperatively and postoperatively. Results:After surgery in the TORO group, the TMJ radiographs showed a significant anterior-inferior displacement of the condyle. Seventy-five percent of the preoperatively symptomatic patients reported fewer or no TMJ symptoms and no preoperatively asymptomatic patients developed new TMJ symptoms. In the SSRO group, the TMJ radiographs showed a posterior displacement of the condyle. Sixty percent of the preoperatively symptomatic patients had no improved TMJ function and 8% of asymptomatic patients developed TMJ symptoms afer surgery. Conclusion: The results of this study show that TORO with MMF appears to be more favorable to the TMJ than the SSRO with RIF; TORO is particularly good in orthognathic surgery patients with preoperative TMJ symptoms.