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This study aimed to evaluate and predict the factors that affect the postoperative maxillary sinus and inferior nasal cavity conditions after Le Fort I osteotomy.The rate of aerated (healthy) sinus area and the inferior nasal airway area were calculated by preoperative computed tomography measurements and at 1 week and 1 year postoperatively. Factors predicting the rate of aerated sinus area and the ratio of the inferior nasal cavity area after 1-week were examined using these variables.The subjects consisted of 112 patients (224 sides) who underwent Le Fort I osteotomy with sagittal split ramus osteotomy. The rate of aerated sinus area after 1 week was significantly correlated with sex, age, and amount of blood loss ( P0.0001). The rate of the inferior nasal cavity area after 1 week was significantly correlated with the anterior impaction amount of the maxilla and the preoperative rate of the inferior nasal airway area ( P= 0.0017).This study suggests that attention should be paid to females, older patients, and the amount of blood loss to prevent sinusitis, and larger maxillary impaction at the anterior site should be carefully planned to prevent severe nasal obstruction immediately after Le Fort I osteotomy.

The purpose of this study was to investigate whether differences in the pattern of the lingual plate split in sagittal split ramus osteotomy (SSRO) affect the remodelling of the split site. Sixty-one patients with mandibular prognathism (122 sides) underwent SSRO. Computed tomography (CT) was performed at 1 week and 1 year after SSRO. Bone splits were classified according to the lingual split scale (LSS) and the lateral bone cut end (LBCE) by evaluating CT images at 1 week. The remodelling at the split sites was evaluated by superimposing the CT images obtained at 1 week and 1 year. Regarding the LSS pattern, significant differences were observed in the distance between anteroposterior ramus points (P = 0.033) and the ramus area in the axial image (P = 0.011). The LBCE pattern also showed a significant difference in the distance between anteroposterior ramus points (P = 0.043). In conclusion, the differences in the lingual plate split and ramus cut end of the SSRO influence the postoperative remodelling in the anteroposterior region of the split site.

The purpose of this study was to compare bone healing after Le Fort I osteotomy with sagittal split ramus osteotomy (SSRO) in class II and class III patients.The subjects consisted of 46 Japanese class II and III patients. Le Fort I osteotomy was performed in combination with SSRO. They were divided into two groups (23 class II cases and 23 class III cases). Four absorbable plates (uncalcined and unsintered hydroxyapatite and poly-l-lactic acid - uHA/PLLA) and screws were used to fix the maxillary segment in all patients, in the same manner. Postoperative computed tomography (CT) was analyzed for all patients at 1 week and 1 year postoperatively. The anterior and lateral areas between the maxillary segments were measured using two-dimensional frontal and lateral views from the three-dimensional images reconstructed over a constant CT value.There were no significant differences in the area of bone defect healing between classes II and III at 1 year postoperatively, although there were significant differences between the two groups at 1 week postoperatively (p 0.05). Furthermore, there were no significant differences in the areas of bone defect between 1 week and 1 year postoperatively, in both groups.Using measurements based on CT value threshold within 1 year after Le Fort I osteotomy, this study suggests that the areas of bony defect in the region of the anterior and lateral walls of the maxilla do not always decrease in both classes II and III.

Purpose This study was performed to evaluate changes in nasal airflow, nasal airway resistance, nasal cross-sectional area, pharyngeal horizontal area, nasopharyngeal and oropharyngeal volume following Le Fort I osteotomy (L1) impaction with sagittal split ramus osteotomy (SSRO) in classes II and III. Materials and methods The subjects consisted of 35 patients (6 males and 29 females, 70 sides) 17 of which were diagnosed as class II and 18 as class III who underwent L1 and SSRO. Nasal airflow and resistance were measured using the rhinomanometry system (GM NR-6 EXECUTIVE) before and at 1 and 6 months after surgery. Nasal, cross-sectional area, and volume were measured using a 3-dimensional computed tomography respectively, before and 1-year after surgery. Results Although a significant decrease was found in nasal volume after surgery (P = 0.0042), there was no difference between before and after surgery in the nasal airway resistance in class II.A significant decrease in nasal volume was found after surgery (P = 0.0005) and there were no postoperative changes in both nasal airflow and resistance in class III. Conclusion The study suggested that L1 impaction with SSRO did not worsen nasal function such as nasal airflow and nasal airway resistance, although nasal volume significantly decreased in both groups.

The aim of the study was to examine lateral pterygoid muscle (LPM) and temporomandibular joint (TMJ) disc before and after Le Fort I osteotomy with and without intentional pterygoid plate fracture and sagittal split ramus osteotomy (SSRO) in class II and class III patients. Le Fort I osteotomy and SSRO were performed in class II and class III patients. LPM measurements using oblique sagittal computed tomography (CT) images and TMJ disc position using magnetic resonance imaging (MRI) were examined. Statistical comparisons were performed for the LPM and TMJ between class II and class III patients and between those with and without intentional pterygoid plate fracture in Le Fort I osteotomy. The subjects comprised 60 female patients (120 sides), with 30 diagnosed as class II and 30 as class III. Preoperatively, the width of the condylar attachment, width at eminence, length of the LPM, angle of the LPM, and square of the LPM were significantly smaller in the class II group than in the class III group (p 0.05). After 1 year, the width of the condylar attachment, width at eminence, and angle of the LPM remained significantly smaller in the class II group than in the class III group (p 0.0001). TMJ disc position was significantly related to the width of the condylar attachment of the LPM, both pre- and postoperatively (p 0.0001). However, postoperative disc position did not change in all patients. Next, the class II patients (60 sides) were divided into two groups who underwent Le Fort I osteotomy with or without intentional pterygoid plate fracture. Changes in all measurements of the LPM showed no significant differences between these two groups. Our study suggested that TMJ disc position classification could be associated with the width of condylar attachment of the LPM before and after surgery, while the surgical procedure, including Le Fort I osteotomy with intentional pterygoid plate fracture, might not affect postoperative LMP or disc position in class II patients.

Resorbable materials are used to fix bony fragments after sagittal split ramus osteotomy (SSRO), but to our knowledge, there is no clear regimen for antibiotic prophylaxis when such materials are used. The purpose of this study therefore was to compare inpatient single-agent and extended dual-agent antibiotic prophylaxis for the prevention of surgical site infections (SSI) in patients after SSRO. This prospective study included 100 patients who underwent SSRO for deformities of the jaw. Cephalometric analysis was performed preoperatively, and at one month and one year postoperatively. Patients were divided into two groups of 50 each. Group A was given cefazolin sodium 1g preoperatively and every eight hours for 48 hours postoperatively. Group B was given cefazolin sodium 1g preoperatively and every eight hours for 48 hours postoperatively, after which they were provided with oral amoxicillin for three days. Both groups were assessed for SSIs for one year postoperatively using the Clavien-Dindo classification. SSIs were documented in seven patients in Group A and six in Group B, with no significant difference between the groups. The two regimens had no significant association with SSI. In conclusion, our results suggest that the inpatient, single-agent, postoperative antibiotic regimen is sufficient to prevent SSI in patients who have SSRO with resorbable plate and screw fixation.

This study was performed to evaluate the relationship between condylar height reduction and changes in condylar surface computed tomography (CT) values in jaw deformity patients following orthognathic surgery. Mandibular advancement by sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy was performed in class II patients, and mandibular setback by SSRO with Le Fort I osteotomy was performed in class III patients. The maximum CT values (pixel values) at five points on the condylar surface and the condylar height, ramus height, condylar square, ramus angle, and gonial angle in the sagittal plane were measured preoperatively and 1 year postoperatively. Disc position was classified as anterior disc displacement (ADD) or other types by using magnetic resonance imaging (MRI). Ninety-two condyles of 46 female patients were prepared for this study. Their temporomandibular joints (TMJs) were divided into two groups based on class (46 joints in class II and 46 joints in class III) and two groups based on the findings (25 joints with ADD and 67 joints with other findings). ADD with and without reduction was observed in two joints in the class III group and in 23 joints in the class II group. The distribution of ADD incidence had not changed 1 year after surgery. Condylar height decreased 1 year after surgery in both class II patients (mandibular advancement) (p < 0.0001) and class III patients (mandibular setback) (p = 0.0306). Similarly, condylar height decreased 1 year after surgery both in patients who showed ADD (p = 0.0087) and those with other types (p = 0.0023). Significant postoperative increases at all angle sites on the condylar surface were found in the class II (p < 0.05) and ADD (p < 0.05) groups. This study showed that an enhanced condylar surface CT value might be one sign of condylar height reduction related to sequential condylar resorption, in combination with ADD.

Purpose The purpose of this study was to examine the effect of injecting basic fibroblast growth factor following surgical induced anterior disc displacement in temporomandibular joints (TMJ). Materials and methods Adult male Japanese white rabbits (n = 16; 2.0–2.5 kg; 10 weeks old) were assigned to experimental and control groups. In the experimental group, anterior disc displacement was induced in the bilateral TMJ. Recombinant human basic fibroblast growth factor (rh bFGF) 0.1 μg/1 μL aqueous solution was injected into the left retro-discal connective tissue close to the disc (ADL group), and saline alone was injected into the same site on the right (ADR group). In the control group, a sham operation without disc position change was performed in the bilateral TMJ (CR group and CL group). Four animals from the experimental (ADR and ADL) and control (CR and CL) groups were sacrificed at 1 and 12 weeks postoperatively to evaluate the mandibular morphology and computed tomographic (CT) value of the condylar head, using 3 dimensional computed tomography. Furthermore, cartilage layers and disc tissue were examined histologically. Results Regarding CT value at the 0° site of the condylar surface, ADR showed the lowest value after 1 week (P = 0.0325). However, there were no significant differences among the 4 groups regarding CT values at the other degree sites after 1 and 12 weeks. Regarding mandibular length, ADR showed the lowest value after 12 weeks (P = 0.0079). In condylar width, ADR showed the lowest value after 1 week (P = 0.0097). Conclusion This study suggested that surgically induced anterior disc displacement could affect condylar morphology in the early stage, and could decrease mandibular length in the late stage. However, bFGF injection into the TMJ might prevent the degenerative change derived from anterior disc displacement and inhibition of sequential mandibular growth.

Purpose The purpose of this study was to examine the relationship between occlusal force and condylar morphology in class II and III after sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy. Materials and methods The subjects were 42 female patients who underwent bi-maxillary surgery, and were divided into 2 groups (21 class II and 21 class III cases). They were selected randomly from among patients that underwent surgery from 2012 to 2017. Condylar height, ramus height, ramus inclination and condylar square were assessed by computed tomography (CT), preoperatively and 1 year postoperatively. Occlusal contact area and occlusal force were measured pre- and 1, 3, 6 and 12 months post-operative. Results Condylar height and ramus height of the class II advancement cases decrease more significantly than those of class III. There were no significant differences in time-course changes of occlusal force and area between the class II and III. In the class II cases, occlusal force at 1 and 3 months was significantly lower than the preoperative value (P = 0.0009, P = 0.0002). On the other hand, in class III, occlusal force at 1, 3 and 6 months (P = 0.0038, P = 0.0031, P = 0.0283) was significantly lower than the preoperative value. Conclusion This study suggested that occlusal force of the class II advancement cases reached the pre-operative level earlier than that of the class III setback cases, even though condylar height decreased after surgery in the class II cases. However, a correlation between occlusal force change and condylar height reduction after surgery could not be found.

The purpose of this study was to compare mandibular bone healing after advancement or setback surgery using sagittal split ramus osteotomy (SSRO).and Methods. The subjects were 50 patients (100 sides) who underwent bi-maxillary surgery, and were divided into 2 groups (25 class II advancement cases and 25 class III setback cases). They were selected randomly from the patients who underwent surgery between 2012 and 2017. Ramus square, ramus length and ramus width were measured in the horizontal plane image of computed tomography (CT), before and immediately after the operation, and at 1 year after the operation.Ramus square in the class III cases significantly increased in 1 year after the operation (P 0.0001), meanwhile there was no change after 1 year in the class II cases. Before the operation, there were no significant differences in the all measurements between classes II and III. However, for ramus width, class III was significantly larger than class II immediately after (P = 0.0014) and at 1 year after the operation (P = 0.0003).This study suggested that post-operative change in ramus morphology was different between class II advancement surgery and class III setback surgery.

The purpose of this study was to examine changes in lateral pterygoid muscle and temporomandibular joint (TMJ) disc position in classes II and III patients, before and after bi-maxillary surgery. The subjects were comprised of 48 patients (96 sides), 23 of whom were diagnosed as class II and 25 as class III patients who underwent Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO). The cross-sectional measurements of the lateral pterygoid muscles were measured at two levels of horizontal plane images (condyle and mandibular notch levels) by computed tomography (CT), before and 1 year after the operation. The relationship between these measurements regarding lateral pterygoid muscle and disc position by magnetic resonance image (MRI) was also examined statistically. Preoperatively, class II was significantly larger than class III in condylar angle at the upper level and in long diameter, square, condylar angle, and muscle angle at the lower level (P

The purpose of this study was to examine the changes in the mandibular border movement between class II and class III jaw deformity patients before and after orthognathic surgery, by using the same device.and Methods: Eighty one patients (28 in class II and 53 in class III) who underwent sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy using absorbable plate fixation and 27 controls with normal occlusion were enrolled. Mandibular border movement (observed using a kinesiograph) was recorded with a mandibular movement measure system (K7) before surgery, and at 6 months and 1 year after surgery. Time-course changes of 5 components of the mandibular border movement (MVO: Maximum vertical opening, CO to MAP: Maximum antero-posterior movement from centric occlusion, MLDL: maximum lateral deviation left, MLDR: maximum lateral deviation right, CO to MO: centric occlusion to maximum opening) were compared between classes II, III and controls statistically. The relationship between lateral cephalometric measurements and the components of mandibular border movement was also examined.There was a significant difference in CO to MAP (P = 0.0025) and CO to MO (P 0.0001) between class II and class III in the time-course change. In class III, mean and standard deviation of MVO were 44.5 ± 6.7 mm before surgery and 39.8 ± 6.8 mm after 1 year. Mean and standard deviation of CO to MAP were 25.2 ± 6.8 mm before surgery and 21.5 ± 7.9 mm after 1 year. Mean and standard deviation of CO to MO were 53.4 ± 9.0 mm before surgery and 47.3 ± 8.4 mm after 1 year. In class II, mean and standard deviation of MVO were 38.8 ± 5.8 mm before surgery and 36.2 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MAP were 18.0 ± 6.3 mm before surgery and 17.8 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MO were 43.1 ± 7.5 mm before surgery and 39.6 ± 10.5 mm after 1 year. In MVO, CO to MAP and CO to MO, the values after 1 year did not significantly reach the pre-operative values in class III (P = 0.0001, P = 0.0007 and P 0.0001), although there was no significant difference between pre-operation and after 1 year in class II. In CO to MO, class II (mean and standard deviation 39.6 ± 10.5 mm) and class III (mean and standard deviation 47.3 ± 8.4 mm) still remained smaller values than control (mean and standard deviation 52.7 ± 9.2 mm) after 1 year (P 0.0001 and P = 0.0095).This study suggests that bi-maxillary surgery can have more influence on the reduction in the range of mandibular border movement including vertical or antero-posterior motion than lateral deviation motion, in both groups. The difference in the time-course change in the mandibular border movement between the groups might depend more on the mandibular length than on the movement direction of the mandible by surgery such as advancement or setback.

Purpose The purpose of this study was to compare the stability of the chin between absorbable plate and screws with a template device and titanium plate after advancement genioplasty in class II patients. Patients and methods The subjects consisted of 22 Japanese class II patients who underwent genioplasty advancement in combination with bi-maxillary surgery. After genioplasty horizontal osteotomy, the template plate and screws were fixed at the central region of the chin temporarily. Then, two absorbable bi-cortical screws (uncalcined and unsintered hydroxyapatite and poly- l -lactic acid: uHA/PLLA) were used and fixed bilaterally. After removal of the template plate and screws, one absorbable plate and screws were added to fix the segment in the advancement genioplasty (n = 14). The remaining 8 patients underwent genioplasty advancement surgery with the conventional titanium plate. For all patients, lateral cephalograms were obtained pre- and immediately after surgery and at 1 year after surgery. Change in the Pogonion (Pog) and Menton (Me) points and the corresponding soft tissue points (PogS and MeS) were evaluated. Results Although there were no significant differences in the change from before to immediately after surgery between the absorbable and titanium groups, there were significant differences in the Pog (Y) (P = 0.0379) and PogS (Y) (P = 0.0379) from immediately after surgery to after 1 year between both groups. Conclusion This study shows that predicted advancement of the chin in the absorbable group could be achieved by using a template and screws, and likewise in the titanium group. However, this study suggested that vertical relapse to the inferior site or resorption at the antero-superior edge of the segment could occur in the absorbable group.

The purpose of this study was to evaluate the relationship between computed tomography (CT) values of the condylar surface and temporomandibular joint (TMJ) disc position in the sagittal plane before and after sagittal split ramus osteotomy (SSRO) setback surgery, retrospectively. The subjects were 75 patients (150 condyles) who underwent bilateral SSRO setback surgery. They were divided into two groups (42 symmetric patients and 33 asymmetric patients). Maximum CT values (pixel values) of five points of the condylar surface and condylar height, length, fossa height, fossa length, and ramus angle in the sagittal plane were measured preoperatively and 1 year postoperatively. Disc position was classified as anterior disc displacement, anterior type, fully covered type, and posterior type, both pre- and postoperatively, using magnetic resonance imaging (MRI). Postoperative value was significantly higher than preoperative one in CT value of 135° (P = 0.0199) and 180° (0.0363), in the non-deviation side in the asymmetry group. The anterior disc displacement group was significantly larger than those of some other areas pre- and postoperatively in the CT value of 0° point (P

The purpose of this study was to compare computed tomography (CT) Hounsfield unit values of bone fragment gaps after sagittal split ramus osteotomy (SSRO) in patients with and without asymmetry, and to evaluate differences between the deviated and non-deviated sides in asymmetric patients. Thirty-two patients who underwent a bilateral SSRO were included in this retrospective study. Patients were divided into symmetric and asymmetric groups by cephalometric analysis. CT values of the bone fragment gap were measured at 1 week and at 1 year after surgery. There were significant differences between CT values obtained at 1 week and at 1 year after surgery for all measurement points. However, there were no significant differences in CT values between symmetric and asymmetric patients at either 1 week or 1 year after surgery. Among asymmetric patients, there were no significant differences between the deviated and non-deviated sides at 1 week or 1 year after surgery. This study showed ossification of the bone fragments and adaptation to change the mandible form in patients with and without asymmetry following SSRO.

The purpose of this study was to compare bone regenerative capability following use of polytetrafluoroethylene (ePTFE) membrane against that when various densities of pore titanium meshes are used with and without low intensity pulsed ultrasound (LIPUS).Adult male white rabbits were divided into 8 groups. In 4 groups, after incising along the nasal bone, four 3 × 8 mm bone defects were made in both sides and covered by an ePTFE membrane (group E: n = 15), a high density pore titanium mesh (group H: n = 15), a low density pore titanium mesh (group L: n = 15), and no mesh (control) (group C: n = 15). Furthermore, LIPUS was irradiated after surgery in 4 groups (groups EL, HL, LL and CL, in each n = 15). The rabbits were sacrificed at 1, 2 and 8 weeks postoperative, and formalin-fixed specimens were embedded in acrylic resin. The specimens were stained with hematoxylin and eosin. For immunohistochemical analysis, the specimens were treated with bone morphogenetic protein (BMP)-2 antibody.Group H had significantly higher values than groups L, E, and C regarding bone area ratio and labeling index of BMP-2 positive cells (P 0.05). Furthermore, Group HL also had significantly higher values than the other groups regarding bone area ratio and labeling index of BMP-2 positive cells at 1, 2 and 8 weeks postoperative (P 0.05).The results suggested that high density pore titanium mesh could induce new bone regeneration more than low density pore titanium mesh and ePTFE membrane. New bone formation may increase following LIPUS application.

The purpose of this study was to examine changes in masseter and medial pterygoid muscles, ramus, condyle and occlusal force after bi-maxillary surgery in class II and III patients.The subjects were 42 patients (84 sides) who underwent sagittal split ramus osteotomy with Le Fort I osteotomy (21 class II cases: mandibular advancement and 21 class III cases: mandibular setback). The cross-sectional measurements of the masseter and medial pterygoid muscles, ramus and condyle were measured in horizontal plane images by computed tomography (CT), before and 1 year after the operation. Occlusal force and contact area were also recorded before and 1 year after the operation.Preoperatively, class II was significantly larger than class III in masseter width (P = 0.0068), masseter area (P 0.0001) and medial pterygoid length (P 0.0001). However, class II was significantly smaller than class III in medial pterygoid width (P 0.0001). After 1 year, class II was significantly smaller than class III in masseter length (P = 0.0017). Class II was still larger than class III in medial pterygoid area after 1 year (P = 0.0343). Class II was significantly larger than class III in condylar angle pre-operatively (P 0.0001) and after 1 year (P = 0.0006). After 1 year, class II decreased significantly more than class III in condylar thickness (P = 0.0020), condylar width (P 0.0001) and condylar area (P 0.0001).This study suggested that changes in the cross-sectional measurements of masseter and medial pterygoid muscles and the condyle differed between class II and class III patients, although occlusal force did not significantly change 1 year after surgery in both groups.

The purpose of this study was to examine the influence between the magnitude of setback in sagittal split ramus osteotomy (SSRO) and occlusal contact area and bite force without relapse after surgery.Sixty female patients with a diagnosis of mandibular prognathism were divided into 3 groups according to the magnitude of setback: group 1 (≤5 mm), group 2 (5 mm but10 mm), and group 3 (≥10 mm). All patients underwent skeletal analysis by lateral and frontal cephalogrammetry and measured the occlusal contact area and bite force by the pressure-sensitive system (Dental Prescale, Dental Occlusion Pressuregraph FDP-705; Fuji Photo Film Co., Tokyo, Japan) preoperatively and postoperatively at 1 month, 3 months, 6 months, and 1 year.There were no significant differences in occlusal contact area and bite force between the 3 groups. Only group 3 showed a significant difference in occlusal contact area and bite force between the preoperative and 1-year measurements.The results indicate that the magnitude of setback did not influence the bite force or occlusal contact area in SSRO.

The purpose of this retrospective study was to evaluate the changes in computed tomography (CT) values of ramus bone and screws after sagittal split ramus osteotomy (SSRO) setback surgery. The subjects were 64 patients (128 sides) who underwent bilateral SSRO setback surgery. They were divided into six groups according to the fixation plate type used and the use or not of self-setting α-tricalcium phosphate (Biopex): group 1: titanium plate and screws; group 2: titanium plate and screws with Biopex; group 3: poly-l-lactic acid (PLLA) plate and screws; group 4: PLLA plate and screws with Biopex; group 5: uncalcined and unsintered hydroxyapatite particles and poly-l-lactic acid (uHA/PLLA) plate and screws; group 6: PLLA/uHA plate and screws with Biopex. CT values (pixel values) of the lateral cortex, medial cortex, osteotomy site, and screws were measured preoperatively, immediately after surgery, and 1 year postoperatively using horizontal CT images at the mandibular foramen taken parallel to the Frankfort horizontal plane. There were significant differences in the time-course change of pixel values for the lateral cortex (P

Purpose The purpose of this study was to evaluate change in computed tomography (CT) value of condyle and temporomandibular joint (TMJ) disc position after sagittal split ramus osteotomy (SSRO) setback surgery, retrospectively. Subjects and methods The subjects were 76 patients (152 condyles) who underwent bilateral SSRO setback surgery. They were divided into 2 groups (43 symmetric patients and 33 asymmetric patients). CT values (pixel values) of 5 sites of the condyle and condylar width, length, horizontal angle were measured pre-operatively and 1 year post-operatively. Disc position was classified as anterior disc displacement, anterior type, fully covered type and posterior type, preoperatively and postoperatively using magnetic resonance imaging (MRI). Results In maximum CT value at the center of the condyle, post-operative value was significantly lower than pre-operative value bilaterally (Deviation side: P = 0.0003, Non-deviation side: P = 0.0003) in asymmetry group. In minimum CT value at the center of the condyle, the post-operative value was significantly lower than the pre-operative value bilaterally (Deviation side: P = 0.0309, Non-deviation side: P = 0.0004) in the symmetry group. With regard to maximum CT value at the lateral site of the condyle in the deviation side, the value for the anterior disc displacement group was significantly larger than that of the posterior type pre-operatively (P = 0.0123). CT value of the anterior disc displacement group was significantly larger than those of some other areas pre- and post-operatively (P Conclusion This study suggested that CT value of condylar bone changes after 1 year in SSRO and anterior disc displacement may partially affect the CT value of the condyle in the TMJ in mandibular prognathism patients.

Purpose The purpose of this study was to evaluate bony change between the proximal and distal segments after sagittal split ramus osteotomy (SSRO) using different fixation materials. Subjects and methods The subjects consisted of 74 patients (21 male and 53 female; 148 sides) who underwent SSRO with and without Le Fort I osteotomy. They were divided into five groups: (1) an MT group, mono-cortical titanium plate fixation (26 sides); (2) an MA group, mono-cortical absorbable plate fixation (48 sides); (3) a BA group, bi-cortical absorbable plate fixation (22 sides); (4) an MAα group, mono-cortical plate absorbable fixation with α-tricalcium phosphate (36 sides); and (5) a BAα group, bi-cortical plate absorbable fixation with α-tricalcium phosphate (16 sides). Ramus square (RmS), ramus width (RmM-RmL) and ramus length (RmA-RmP) at the horizontal plane under the mandibular foramen were assessed pre-operatively, immediately after surgery, and at 1 year after surgery by computed tomography (CT). Results There were significant differences among the groups regarding change over time in RmS ( p = 0.0126) and RmM-RmL ( p = 0.0001). However, there was no significant difference among the groups regarding change over time in RmA-RmP. Conclusion These results suggest that the use of different fixation materials leads to significant differences in the bone healing process after SSRO.

Purpose The purpose of this study was to compare time-course changes in temporomandibular joint (TMJ) space between mandibular advancement surgery and setback surgery after sagittal split ramus osteotomy (SSRO) and Le Fort I osteotomy. Subjects and Methods The subjects were 46 patients (92 joints) who underwent bi-maxillary surgery. The TMJ disc position was assessed by magnetic resonance imaging (MRI) and the anterior, superior, posterior, medial and lateral joint spaces were assessed by computed tomography (CT), preoperatively and at 1 week and 1 year postoperative. The 92 joints were divided into 2 groups, namely class II (n = 46 joints), and class III (n = 46 joints) (an advanced group vs a setback group). Next, the 92 joints were divided into 2 groups comprising 36 joints with anterior disc displacement joint (ADD group) and 56 joints without (non-ADD group). Time-course changes in the measurements were compared statistically between the advanced and setback groups, and between the ADD and non-ADD groups. Results There were no significant differences between the advance group and setback group regarding time-course change in all the joint spaces. However, there were significant differences between the ADD group and non-ADD group regarding time-course change in the medial, anterior, superior and posterior joint spaces (P Conclusion This study suggested that ADD could affect the time-course change in TMJ space and condylar position after bi-maxillary osteotomy.

The purpose of this study was to compare changes in temporomandibular joint (TMJ) and ramus morphology between class II and III cases before and after sagittal split ramus osteotomy (SSRO) and Le Fort I osteotomy.The subjects were 39 patients (78 sides) who underwent bi-maxillary surgery. They consisted of 2 groups (18 class II cases and 21 class III cases), and were selected randomly from among patients who underwent surgery between 2012 and 2016. The TMJ disc tissue and joint effusion were assessed by magnetic resonance imaging (MRI) and the TMJ space, condylar height, ramus height, ramus inclination and condylar square were assessed by computed tomography (CT), pre- and post-operatively.The number of joints with anterior disc displacement in class II was significantly higher than that in class III (p 0.0001). However, there were no significant differences between the two classes regarding ratio of joint symptoms and ratio of joint effusion pre- and post-operatively. Class II was significantly better than class III regarding reduction ratio of condylar height (p 0.0001) and square (p = 0.0005).The study findings suggest that condylar morphology could change in both class II and III after bi-maxillary surgery. The findings of the numerical analysis also demonstrated that reduction of condylar volume occurred frequently in class II, although TMJ disc position classification did not change significantly, as previously reported.

This study evaluated bone regeneration by periosteal elevation using conventional orthodontic wire and an unsintered hydroxyapatite (u-HA)/poly-L-lactic acid (PLLA) mesh in rabbit frontal bone. Thirty two rabbits (12-16 weeks: 2.5-3.0 kg) were used in this study. In the experimental group, 1 week after the mesh was inserted under the periosteal membrane, it was elevated by traction using the mesh connected with wire and two anchor screws. In the control group, the mesh was kept inserted under the periosteal membrane. Four animals were killed in each period in both groups, at 2, 3, 5 and 9 weeks postoperatively. Operated parts in the frontal bone were removed and prepared for radiological and histological assessment. The distance between the mesh and pristine bone (elevation length), the bone area and the expression of BMP-2 were evaluated. The value in the experimental group was significantly higher when compared to the control group (length P0.0001, bone area P0.0010, BMP-2 P = 0.0015). The BMP-2 labelling index after 3 weeks tended to be the largest in both groups. This study suggests that bone regeneration can be induced by periosteal elevation using a conventional orthodontic wire and an uHA/PLLA mesh.

Purpose The purpose of this study was to evaluate the relationship between lip closing force, occlusal contact area and occlusal force after orthognathic surgery in skeletal Class III patients. Subjects and methods The subjects consisted of 54 patients (28 female and 26 male) diagnosed with mandibular prognathism who underwent sagittal split ramus osteotomy with and without Le Fort I osteotomy. Maximum and minimum lip closing forces, occlusal contact area and occlusal force were measured pre-operatively, 6 months and 1 year post-operative. Results Maximum and minimum lip closing forces, occlusal contact area and occlusal force increased with time after surgery, however a significant increase was not found in the occlusal contact area in women. In increased ratio (6 months/pre-operative and 1 year/pre-operative), the maximum lip closing force was significantly correlated with the occlusal contact area ( P Conclusions This study suggested that orthognathic surgery could improve the occlusal force, contact area and lip closing force, and an increase ratio in maximum lip closing force was associated with an increased ratio in occlusal contact area.

Purpose The purpose of this study was to investigate the effects of alar base cinch suture in Le Fort I osteotomy in mandibular prognathism with and without asymmetry. Material and methods Forty patients who underwent Le Fort I osteotomy were divided into an asymmetry group and a symmetry group ( n = 20 each). Computed tomography (CT) was taken in all patients before and 1 year after surgery. The CT-3D volume rendering data with Aquarius Net (TeraRecon, Foster City, CA, USA) was reconstructed and the soft tissue was measured as follows, the distance between the bilateral alar base (Alar base width), the distance between the bilateral alar (Alar width), the angles between the FH plane and the line between the bilateral alar base (Alar base angle), the angle between the FH plane and the line between the bilateral alar (Alar angle), the angle between the FH plane and the line between the bilateral corners of the mouth (Lip angle), and the angle between the perpendicular line to the FH plane and the Philtrum (Philtrum angle). Results Significant differences were observed in the Alar width ( P = 0.0448), the Alar angle ( P = 0.0044), the Lip angle ( P P = 0.0057) between before and after surgery in the asymmetry group. Conclusions This study suggested that the alar base cinch suture could prevent increases in the alar base width in both groups and help to improve the angle of soft tissue in the asymmetry group, although alar width significantly increases after surgery.

Objectives The purpose of this study was to examine the changes with time in lip pressure after orthognathic surgery for skeletal Class III patients. Study design The subjects consisted of 63 patients (32 female and 31 male) diagnosed with mandibular prognathism who underwent sagittal split ramus osteotomy with and without Le Fort I osteotomy. Maximum and minimum lip closing forces were measured with Lip De Cum ® . The changes with time were compared statistically. Results The maximum and minimum lip closing force increased time-dependently in men and women after surgery and there were significant differences between men and women with changes with time in the maximum lip closing force ( p = 0.0086) and the minimum lip closing force ( p = 0.0302). After 1 year, the Class III group maximum lip closing force was significantly smaller than the control group in both men ( p p Conclusions This study suggests that there was significant difference in over time in the lip closing force between men and women in Class III patients. Although the maximum lip closing force increased with time, it did not reach the level of the control group after 1 year.

The purpose of this study was to compare retrospectively postoperative differences in maxillary stability after Le Fort I osteotomy and fixation with an unsintered hydroxyapatite (u-HA)/poly-l-lactic acid (PLLA) plate with or without self-setting α-tricalcium phosphate (Biopex ®) as interpositional material. Subjects comprised 45 patients diagnosed with mandibular prognathism with maxillary retrognathism and mandibular prognathism with bimaxillary asymmetry. All patients underwent Le Fort I osteotomy and bilateral sagittal split ramus osteotomy with fixation by uHA/PLLA plates. Patients were divided into 4 groups consisting of 9 maxillary impaction cases with Biopex ® (group 1) to fill the gap between the bone segments, 14 maxillary advancement cases with Biopex ® (group 2), 8 maxillary impaction cases without Biopex ® (group 3) and 14 maxillary advancement cases without Biopex ® (group 4). Changes in cepahalometric parameters at time intervals (1, 3 and 12 months) between the groups were compared. Results showed that stability did not depend on the use or otherwise of Biopex ®. © 2012 International Association of Oral and Maxillofacial Surgeons.

The purpose of this study was to examine the skeletal stability of mandibular advancement after sagittal split ramus osteotomy (SSRO) with modified hybrid fixation using absorbable plates and screws.A total of 54 Japanese patients were enrolled in this study. Of them, 23 who were diagnosed with mandibular prognathism underwent setback surgery with bi-cortical plate fixation using absorbable plates and screws (setback group). Another 23 who were diagnosed with mandibular retrognathism underwent advancement surgery with modified hybrid fixation using absorbable plates (advance group), and 8 who were diagnosed with mandibular retrognathism underwent advancement surgery with titanium plates (titanium group). Skeletal stability and horizontal condylar angle were analyzed by axial, frontal, and lateral cephalograms preoperatively and at 1 month, 3 months and 1 year post-operatively. The findings were compared statistically.The advance group showed no significant difference compared with the titanium group. There were significant differences between the setback and advance groups regarding SNB, ANB, gonial angle, ramus inclination, occlusal plane, convexity and Me-Ag right in T1 naturally (P 0.05). However, in T2, there were no significant differences between the groups for the other measurements, although there were significant differences in ANB, interincisal angle, occlusal plane and Me-Ag right (P 0.05). In T3, a significant difference was seen only in Me-Ag right (P = 0.0145).This study suggested that the use of an absorbable plate and screw was useful and reliable for mandibular advancement surgery as well as mandibular setback surgery, when the fixation method was devised successfully.

Purpose The purpose of this study was to examine lip closing force in Class II and III patients before and after orthognathic surgery. Subject and methods The subjects were 45 patients (15 Class II women, 15 Class III men and 15 Class III women) diagnosed with jaw deformity who underwent sagittal split ramus osteotomy with Le Fort I osteotomy and 30 controls with normal skeleton and occlusion (15 men, 15 women). Maximum and minimum lip closing forces were measured using Lip De Cum® before and after surgery, and compared statistically. Results In the Class II women, maximum and minimum lip closing forces did not change after surgery. However, maximum and minimum lip pressure increased significantly in the Class III men (P = 0.0116, P = 0.0295) and maximum lip closing force increased significantly in the Class III women (P = 0.0082). After 6 months, maximum lip closing force was significantly lower in both Classes II and III women than in the control women (P = 0.0002, P = 0.0045). Conclusions This study suggested that maximum postoperative lip pressure did not improve in the Class II women, although maximum lip closing force increased in the Class III men and women after sagittal split ramus osteotomy with Le Fort I osteotomy.

The purpose of this study was to evaluate maxillary sinus and predict the factors affecting the postoperative sinus condition after Le Fort I osteotomy using various fixation materials.The study subjects consisted of 71 patients (21 male and 50 female, 142 sides) who underwent Le Fort I osteotomy with sagittal split ramus osteotomy. The maxillary sinus bony area and the inside air area were measured in the coronal plane across the mesial aspect of the first molar perpendicular to the Frankfurt horizontal plane of a computed tomography (CT) image preoperatively and at 1 week and 1 year after surgery. The rate of intact sinus area (the inside air area/the maxillary sinus bony area) was calculated. Subjects were divided into groups according to gender, preoperative diagnosis (Angle class II and III with and without asymmetry), plate fixation material (PLLA and uHA/PLLA), and use or non-use of bone alternative material (α-tricalcium phosphate). Statistic comparisons between groups were performed in each division. Furthermore, age, operation time, amount of blood loss, and direction and amount of movement were examined as the continuous variables to statistically predict the rate of intact sinus area after 1 week and 1 year.The rate of intact sinus area after 1 week was significantly correlated with age, amount of anterio-posterior movement, and preoperative rate of the intact sinus area (p 0.0001). Rate of intact sinus area after 1 year was significantly low in the group that used the bone alternative material compared to the group that did not (p 0.0282).The study suggests that the bone alternative material might be a cause of inflammation in the sinus after 1 year. Moreover, attention needs to be paid to older age, backward movement of the maxillary segment, and preoperative sinusitis including hypertrophy of sinus membrane in Le Fort I osteotomy.

Purpose The purpose of this study was to examine skeletal stability and plate breakage after sagittal split ramus osteotomy (SSRO) with the mono-cortical plate fixation, bi-cortical plate fixation, and hybrid fixation techniques using absorbable plates and screws. Materials and methods A total of 76 Japanese patients diagnosed with mandibular prognathism with and without maxillary deformity were divided into 3 groups randomly. A total of 28 patients underwent SSRO with mono-cortical plate fixation, 23 underwent SSRO with bi-cortical plate fixation, and 25 underwent SSRO with hybrid fixation. Skeletal stability and horizontal condylar angle were analyzed by axial, frontal, and lateral cephalograms from before the operation to 1 year postoperatively. Breakage of the plate and screws was observed by 3-dimensional computed tomography (3DCT) immediately after surgery and after 1 year. Results Although there was a significant difference between the mono-cortical plate fixation group and hybrid fixation group regarding right Me Ag in T1 (P = 0.0488) and occlusal plane in T1 (P = 0.0346), there were no significant differences between the groups for the other measurements in each time interval. In 2 cases, namely, 6 sides in the mono-cortical plate fixation group, breakage of the absorbable plate was found by 3DCT. However, there was no breakage in the bi-cortical plate fixation group and hybrid fixation group. Conclusion This study results suggested that there were no significant differences in the postoperative skeletal stability among the 3 groups, and bi-cortical fixation as well as hybrid fixation was a reliable and useful method to prevent plate breakage even if an absorbable material was used.

Purpose The purpose of this study was to evaluate the effect of bone regeneration enhancement by ultra-violet (UV) treatment of an unsintered hydroxyapatite (u-HA)/poly- l -lactic acid (PLLA) mesh in rabbitnasal bone. Materials and methods Thirty adult male Japanese white rabbits (12–16 weeks, 2.5–3.0 kg) were used in this study. After incising along the nasal bone, 6 × 6 × depth 1 mm two bone defects were made on both sides. In the UV group (n = 30), the defects were covered with uHA/PLLA mesh, treated by UV (wavelength 172 nm, tube wall illumination 13 mW/cm 2 , period 8 min, intensity 6.26 J/cm 2 ) and screwed. In the control group (n = 30), untreated uHA/PLLA was applied in a similar manner. The rabbits were sacrificed at 1, 2, 3, 4 and 6 weeks postoperatively, and formalin-fixed specimens were frozen. The specimens were stained with haematoxylin and eosin. For immunohistochemical analysis, the specimens were treated with anti-alkaline phosphatase (ALP). Finally, bone ratio and ALP expression were evaluated microscopically. Results The UV group had a significantly higher number of ALP stained cells than the control group after 1, 2, and 3 weeks (P Conclusion This study suggests that bone regeneration can be enhanced by UV treatment using an uHA/PLLA mesh.

The purpose of this study was to compare postoperative changes in maxillary stability after Le Fort I osteotomy in three groups: with an unsintered hydroxyapatite (u-HA)/poly-l-lactic acid (PLLA) plate; a PLLA plate; and a titanium plate. Subjects comprised 60 Japanese patients diagnosed with mandibular prognathism. All patients underwent Le Fort I osteotomy and bilateral sagittal split ramus osteotomy. All patients were randomized in groups of 20 to a u-HA/PLLA group, a PLLA plate group and a titanium plate group. Changes in postoperative time intervals between the plate groups were compared using lateral and posteroanterior cephalography. The uHA/PLLA group had significantly larger values than the PLLA group regarding change of mx1-S perpendicular to SN between 3 and 12 months (T3) (P = 0.0269). The uHA/PLLA group had a significantly larger value than the PLLA group regarding change of S-A perpendicular to SN between baseline and 1 month (T1) (P = 0.0257). There was no significant difference in the other measurements. This study suggests that maxillary stability with satisfactory results could be obtained in the u-HA/PLLA, PLLA plate and titanium plate groups, although there was a slight difference between the u-HA/PLLA and PLLA plate systems in Le Fort I osteotomy. © 2012 International Association of Oral and Maxillofacial Surgeons.

Aims: The aim of this study was to evaluate hypoaesthesia of the lower lip and bone formation using self-setting α-tricalcium phosphate (Biopex®) between the proximal and distal segments following sagittal split ramus osteotomy (SSRO) with bent absorbable plate fixation. Subjects and methods: The subjects were 40 patients (80 sides) who underwent bilateral SSRO setback surgery. They were divided into a Biopex® group (40 sides) and a control group (40 sides). The Biopex® was inserted into the anterior part of the gap between the segments in the Biopex® group. Trigeminal nerve hypoaesthesia in the region of the lower lip was assessed bilaterally using the trigeminal somatosensory-evoked potential (TSEP) method. Ramus square, ramus length, and ramus width, the square of the Biopex® at the horizontal plane under the mandibular foramen were assessed preoperatively, immediately after surgery, and 1 year postoperatively by computed tomography (CT). Results: The mean measurable period and standard deviation were 9.3 ± 15.7 weeks in the control group, 5.3 ± 8.3 weeks in the Biopex® group, and there was no significant difference. Ramus square after 1 year was significantly larger than that prior to surgery and new bone formation was found between the segments in both groups (P < 0.05). In the Biopex® group, the square of the Biopex® after 1 year was significantly smaller than that immediately after surgery (P < 0.05). Conclusion: This study suggested that inserting Biopex® in the gap between the proximal and distal segments was useful for new bone formation and it did not prevent the recovery of lower lip hypoaesthesia after SSRO with bent absorbable plate fixation. © 2011 European Association for Cranio-Maxillo-Facial Surgery.

金沢大学医薬保健研究域医学系, Purpose: The purpose of this study was to examine bone healing after Le Fort I osteotomy in Class III patients. Patients and methods: The study group consisted of 18 Japanese patients with mandibular prognathism with and without asymmetry, maxillary retrognathism or open bite. A total of 36 sides were examined. Le Fort I osteotomy was performed without a pterygoid osteotome, with an ultrasonic curette used to remove interference at the pterygomaxillary region. Titanium plates (Universal Mid-face fixation module, Stryker, Freiburg, German) were used for four patients, absorbable plates (poly-l-lactic acid (PLLA): NEOFIX®, Gunze, kyoto, Japan) were used for four patients and other absorbable plates (uncalcined and unsintered hydroxyapatite and poly-L-lactic acid (uHA/PLLA): super FIXSORB®MX, Takiron Co. Ltd, Osaka, Japan) were used for 10 patients, in the same manner. Postoperative computed tomography (CT) was analyzed for all patients pre-operatively and 1 year postoperative. The anterior and lateral areas between the maxillary segments were measured with 3-dimensional (3D) CT. Bone healing at the pterygomaxillary region was also assessed. Results: There were no significant differences in the area of bone defect healing among the plate types. The areas of bone defect after 1 year were significantly smaller than that immediately after surgery on the right side (p = 0.0145) and left side (p = 0.0010) in the frontal view and right side in the lateral view (p = 0.0118). Bone healing at the pterygomaxillary junction was found in all cases without artificial pterygoid plate fracture. Fourteen of 22 sides with artificial pterygoid plate fracture by an ultrasonic curette showed bone continuity between the pterygoid plate and posterior part of maxilla. Conclusion: This study suggested that bony healing could occur in spaces between the segments of maxilla and pterygomaxillary regions as well as the region of the anterior and lateral walls in the maxilla, but it is not always complete within 1 year after Le Fort I osteotomy. © 2010 European Association for Cranio-Maxillo-Facial Surgery.

金沢大学医薬保健研究域医学系, Purpose: The purpose of this study is to compare the time-course changes in condylar long-axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with an unsintered hydroxyapatite (u-HA)/poly-L-lactic acid (PLLA) plate, PLLA plate, or titanium plate. Patients and Methods: Of 60 Japanese patients diagnosed with mandibular prognathism, 20 underwent SSRO with a u-HA/PLLA plate system, 20 underwent SSRO with a PLLA plate system, and 20 underwent SSRO with a conventional titanium plate system. The time-course changes in condylar long-axis and skeletal stability were assessed by use of axial, frontal, and lateral cephalograms. Results: Compared with the u-HA/PLLA group, the titanium group showed a significantly greater change in the right condyle angle between initially and 1 month (P = .0105) and intercondylar axes angle between 1 and 3 months (P = .0013). The PLLA group showed a significantly greater change than the titanium group (P = .0043) and u-HA/PLLA group (P = .0002) in terms of ramus inclination between 1 and 3 months; however, there were no significant differences among the 3 groups in the other measurements for each time interval. Conclusion: This study suggests that there are no significant differences in postoperative time-course changes among a u-HA/PLLA plate system, PLLA plate system, and conventional titanium plate system. © 2010 American Association of Oral and Maxillofacial Surgeons.

金沢大学医薬保健研究域医学系

The purpose of this study was to evaluate the effects of Le Fort I osteotomy on nasal septum deviation and differences in left and right airway sizes, and to determine whether the nasal septum was affected by differences in the direction of movement. Forty patients underwent conventional Le Fort I osteotomy, and computed tomography (CT) was performed preoperatively, and 1 week and 1 year postoperatively. The nasal septum angle and airway area were measured at the anterior, middle, and posterior positions on the CT images Patients were divided into 2 groups depending on each difference in movement (impaction ≥5 mm or other; anterior movement or other; and impaction asymmetry or other). There were no significant differences in the nasal septum angle and the airway of all patients. Among the patient groups, there were no significant differences in the nasal septum angle and airway. We concluded that conventional LI osteotomy did not influence the nasal septum deviation or the left and right airway asymmetry. Differences in the method of moving the maxilla have not been shown to affect changes in the nasal septum.

Purpose The purpose of this study was to evaluate changes in mandibular body height at the site of a fixation plate in the advance (lengthening) and setback (shortening) sides after sagittal split ramus osteotomy (SSRO). Subjects and methods The subjects were 49 patients (98 sides) who underwent bilateral SSRO surgery. The subjects were divided into 4 groups as follows, setback (shortening) sides in mandibular prognathism (Prog S group; n = 42), advancement (lengthening) sides in mandibular retrognathism (Retro L group; n = 24), setback (shortening) sides in mandibular asymmetry (Asym S group; n = 16) and advancement (lengthening) sides in mandibular asymmetry (Asym L group; n = 16). Postoperative computed tomography (CT) was analyzed for all patients pre-operatively, and at 1 week and 1 year postoperative. Mandibular body height at the site of the fixation plate, mandibular upper height above the plate and mandibular lower height under the plate were measured by 3-dimensional (3D) CT. Results There were no significant differences in mandibular height between the lengthening and shortening sides in mandibular prognathism, retrognathism and asymmetry in the time-course change. Upper mandibular height at the mid-point of the fixation plate after 1 year was significantly smaller than that after 1 week in all sides (P Conclusion This study suggested that slight bone resorption could occur at the upper site of a fixation plate after set back and advancement SSRO.

Purpose The purpose of this study was to evaluate, through cephalometric analysis, the skeletal stability following BSSRO performed with and without extraction of the third molar, and to examine the healing of the extraction sockets through computed tomography (CT). Patients and methods Sixty Japanese patients (male: 14, female: 46) diagnosed with mandibular prognathism were included in this study. While 30 patients underwent BSSRO along with extraction of the third molar (extraction group), the other 30 patients underwent BSSRO alone (non-extraction group). Skeletal stability was assessed using axial, frontal, and lateral cephalograms. CT scans were obtained 1 week after surgery and at the 1-year follow-up for all the patients. CT value was measured at the point of the extraction socket on the horizontal plane parallel to the Frankfurt plane using computer software (SimPlant 2011; Materialise Dental, Leuven, Belgium). The region of interest (ROI) was approximately 4 mm 2 and the mean value was recorded. Healing of the extraction sockets was examined through CT 1 year postoperatively. Results There were no significant differences between the groups for any of the parameters at any observation interval. In the extraction group, there were significant differences between the values of CT obtained 1 week postoperatively and 1 year postoperatively in the extraction socket (P = 0.0003). Conclusion The results of this study indicate that there is no significant difference in the skeletal stability between BSSRO performed with and without third molar extraction.

Purpose The purpose of this study was to evaluate the factors affecting the recovery period of lower lip hypoesthesia after sagittal split ramus osteotomy (SSRO) in mandibular prognathism patients using multivariate analysis, retrospectively. Subjects and methods The subjects were 222 patients (444 sides) who underwent bilateral SSRO setback surgery with and without Le Fort I osteotomy. Trigeminal nerve hypoesthesia at the region of the lower lip was assessed bilaterally by the trigeminal somatosensory-evoked potential (TSEP) method pre- and post-operatively. Recovery period was determined as the time when TSEP was first measurable post-operatively. Age, sex, presence or absence of third molars, setback amount and osteotomy type and fixation method were selected as covariates in the multivariate analysis. The factor affecting the recovery period in lower lip hypoesthesia was examined with Cox's proportional hazard regression. Results Sex and osteotomy fixation method affected the recovery period in lower lip hypoesthesia significantly ( P = 0.0132 and P = 0.0394). However, the other factors did not affect the recovery period. Conclusion This study suggested that sex and osteotomy type and fixation method may affect the recovery period in lower lip hypoesthesia after SSRO setback surgery.

Purpose The purpose of this study was to compare the recovery period of lower lip hypoesthesia between hybrid fixation and conventional fixation using absorbable plates and screw systems following sagittal split ramus osteotomy (SSRO). Subjects and methods The subjects were 66 patients (132 sides) who underwent bilateral SSRO setback surgery. They were divided into a hybrid fixation group (66 sides, 1 u-HA/PLLA plate and 4 mono-cortical screws and a bi-cortical screw in each side) and a conventional fixation group (66 sides, 1 u-HA/PLLA plate and 4 mono-cortical screws in each side). Trigeminal nerve hypoesthesia at the region of the lower lip was assessed bilaterally by the trigeminal somatosensory-evoked potential (TSEP) method. Results The mean measurable periods were 8.1 ± 10.4 weeks in the hybrid fixation group, 5.1 ± 11.5 weeks in the conventional group with no significant difference. However, the maximum in the hybrid fixation group was 27 sides at 4 weeks postoperative and in the conventional fixation group was 37 sides at 1 week postoperative, and there was significant difference in the distribution of the measurable period ( P Conclusion This study suggested that additional bi-cortical screws could affect the recovery of lower lip hypoesthesia after SSRO with bent absorbable plate fixation.

This study aimed to evaluate the postoperative changes in masticatory function in patients with jaw deformities with or without asymmetry treated by orthognathic surgery. Thirty female patients who underwent a Le Fort I osteotomy with sagittal split ramus osteotomy (SSRO) were enrolled. The patients were divided into symmetry and asymmetry groups. The bite force, occlusal contact area, and bite force balance were measured before and at 1, 3, and 6 months and 1 year after surgery; these measurements were compared statistically within and between the two groups. In the symmetry group, there was a significant difference in the preoperative bite force and the 1 month postoperative bite force (P=0.0033). In the asymmetry group, the bite force before surgery was significantly different from that at 1 month (P=0.0375) and at 1 year (P=0.0353) after surgery. Significant differences in the bite force were also observed between the following time points: 1 month and 1 year (P=0.0003), 3 months and 1 year (P=0.0034), and 1 month and 6 months (P=0.0486). The occlusal contact area, bite force, and occlusal balance tended to change after Le Fort I osteotomy with SSRO, with a significantly improved bite force in patients with asymmetry before surgery.

The purpose of this study was to evaluate bony change in an overlapped cortical bone area at the anterior site of the proximal segment after modified plate fixation with a bent plate in sagittal split ramus osteotomy (SSRO).The subjects were 66 patients (132 sides) who underwent bilateral SSRO setback surgery. After the surgery in SSRO, an overlapped area of cortical bone at the anterior site of the proximal segment was not removed to keep the contact area between the proximal and distal segments intact, and was fixed with a bent plate and 4 screws in each side of the mandible. At the posterior site, a 3-7 mm gap was maintained between the proximal and distal segments to prevent inward-rotation of the condylar long axis. Ramus width, lateral cortex width and lateral cortex step angle were assessed in a coronal image immediately after the surgery, and 1-year postoperative by computed tomography (CT).Ramus width after 1-year was significantly larger than that before surgery and smaller than that immediately after surgery in both sides (P 0.0001). Lateral cortex width after 1-year was significantly larger than the preoperative value and smaller than that immediately after surgery in both sides (P 0.0001). Lateral cortex angle after 1-year was significantly larger than the preoperative value in both sides (P 0.0001).The above findings suggested that the overlapped cortical bone decreased thickness and the cortical bone step disappeared following favourable bone remodelling after 1-year, even though the cortical bone was not removed at the anterior site of the proximal segment.