Retraction notice to "Effect of low-intensity pulsed ultrasound on injured temporomandibular joints with or without articular disc removal in a rabbit model "[Journal of Dental Sciences Volume 16, Issue 1, January 2021, Pages 287-295].

[This retracts the article DOI: 10.1016/j.jds.2020.04.002.].

Evaluation of Nasal Function and Upper Airway Morphology After Bi-Maxillary Surgery Using Rhinomanometry and Computed Tomography.

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.

Effect of low-intensity pulsed ultrasound on injured temporomandibular joints with or without articular disc removal in a rabbit model.

BACKGROUND/PURPOSE: Dynamic stimulation can induce bone and cartilage growth. The purpose of this study was to examine the effect of low-intensity pulsed ultrasound (LIPUS) on injured temporomandibular joints (TMJs) in a rabbit model. MATERIALS AND METHODS: Twenty-four female Japanese white rabbits (age: 12-16 weeks, weight: 2.0-2.5 kg) were equally divided into 4 groups. In two groups, discectomy was performed with (the LD group) and without (the D group) subsequent LIPUS treatment. In the other groups, a sham operation was performed with (the LC group) and without (the C group) subsequent LIPUS treatment. Two animals in each group were sacrificed at each time point (2, 4, and 8 weeks postoperatively). Mandibular measurements were made using three-dimensional computed tomography. We performed histological and immunohistochemical examination of the articular disc, and the cartilage layer and bone at the 30- and 60-degree sites in each condyle. RESULTS: There were no statistically significant differences among the groups in terms of thickness of the disc or the fibrous articular zone, or the number of BMP-2 positive cells. In terms of mandibular length, there were differences among the groups after 4 (P = 0.0498) and 8 weeks (P = 0.0260). Specifically, there was a difference between the LC group and the C group after 4 weeks (P = 0.014) and 8 weeks (P = 0.029). CONCLUSIONS: This study suggests that LIPUS has little effect on cartilage after TMJ injury. It may promote bone growth in a normal TMJ, although discectomy seems to reduce this effect.

Evaluation of border movement of the mandible before and after orthognathic surgery using a kinesiograph.

PURPOSE: 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. SUBJECTS: 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. RESULTS: 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). CONCLUSION: 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.

Changes in cross-sectional measurements of masseter, medial pterygoid muscles, ramus, condyle and occlusal force after bi-maxillary surgery.

PURPOSE: 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. SUBJECTS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Adaptive change in temporomandibular joint tissue and mandibular morphology following surgically induced anterior disc displacement by bFGF injection in a rabbit model.

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.

Relationship between occlusal force and condylar morphology in class II and III after bi-maxillary osteotomy.

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.

Mandibular bone healing after advancement or setback surgery using sagittal split ramus osteotomy.

PURPOSE: The purpose of this study was to compare mandibular bone healing after advancement or setback surgery using sagittal split ramus osteotomy (SSRO). SUBJECTS: 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. RESULTS: 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). CONCLUSION: This study suggested that post-operative change in ramus morphology was different between class II advancement surgery and class III setback surgery.

Time-course change in temporomandibular joint space after advancement and setback mandibular osteotomy with Le Fort I osteotomy.

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 < 0.05). CONCLUSION: This study suggested that ADD could affect the time-course change in TMJ space and condylar position after bi-maxillary osteotomy.

Comparison of temporomandibular joint and ramus morphology between class II and class III cases before and after bi-maxillary osteotomy.

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Modified hybrid fixation using absorbable plate and screw for mandibular advancement surgery.

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Change in lip closing force in Classes II and III malocclusion before and after sagittal split ramus osteotomy with Le Fort I osteotomy.

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.

Condylar surface CT value in sagittal plane before and after sagittal split ramus osteotomy.

PURPOSE: 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. MATERIALS AND METHODS: 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). RESULTS: 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 < 0.05). CONCLUSIONS: This study suggested that CT value of the posterior site of the condylar surface could change in the non-deviation side in the asymmetry group after 1 year SSRO, and the condyle with anterior displacement showed high CT value at the anterior site of the condyle before and after surgery.

Bone regeneration enhancement by ultra-violet (UV) treatment for uHA/PLLA absorbable mesh.

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/cm2, period 8 min, intensity 6.26 J/cm2) 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 < 0.05). The bone ratio was also significantly higher in the UV group than in the control group after 1, 2, 3, and 4 weeks (P < 0.05). CONCLUSION: This study suggests that bone regeneration can be enhanced by UV treatment using an uHA/PLLA mesh.

Evaluation of maxillary sinus after Le Fort I osteotomy using various fixation materials.

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Comparison of skeletal stability after sagittal split ramus osteotomy among mono-cortical plate fixation, bi-cortical plate fixation, and hybrid fixation using absorbable plates and screws.

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 MeAg 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.

Comparison between various densities of pore titanium meshes and e-polytetrafluoroethylene (ePTFE) membrane regarding bone regeneration induced by low intensity pulsed ultrasound (LIPUS) in rabbit nasal bone.

PURPOSE: 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). MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Assessment of nasal septum after Le Fort I osteotomy with computer tomography.

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.

Change in mandibular body height at the site of a fixation plate in the advance (lengthening) and setback (shortening) sides after sagittal split ramus osteotomy.

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 < 0.05). CONCLUSION: This study suggested that slight bone resorption could occur at the upper site of a fixation plate after set back and advancement SSRO.

The amount of mandibular setback influence on occlusal force following sagittal split ramus osteotomy.

PURPOSE: 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. PATIENTS AND METHODS: 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 but <10 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. RESULTS: 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. CONCLUSION: The results indicate that the magnitude of setback did not influence the bite force or occlusal contact area in SSRO.