Changes in the duration of the chewing cycle in patients with skeletal class III with and without asymmetry before and after orthognathic surgery.

PURPOSE: The purpose of this study was to examine the changes in the chewing rhythm before and after mandibular ramus osteotomy in patients with prognathism with and without asymmetry. PATIENTS AND METHODS: We divided 12 men and 22 women with mandibular prognathism into groups on the basis of symmetry and osteotomy procedure. The duration of the chewing cycle was recorded preoperatively and postoperatively. The duration of the chewing cycle and coefficient of variation were compared between groups, and the differences were analyzed statistically. RESULTS: No significant differences in each of 3 phases of the chewing cycle and total duration were found between groups on the basis of symmetry or osteotomy procedure. However, there were significant differences between the preoperative and postoperative coefficients of variation for the undeviated side in the asymmetry group (P = .0037) and in the group undergoing sagittal split ramus osteotomy (P = .0166). CONCLUSION: This study suggests that surgical orthodontic treatment does not significantly change the duration of the chewing cycle.

Assessment of pterygomaxillary separation in Le Fort I Osteotomy in class III patients.

PURPOSE: To examine the separation of the pterygomaxillary region at the posterior nasal spine level after Le Fort I osteotomy in Class III patients. PATIENTS AND METHODS: The study group consisted of 37 Japanese patients with mandibular prognathism and asymmetry, with maxillary retrognathism or asymmetry. A total of 74 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. Postoperative computed tomography (CT) was analyzed for all patients. The separation of the pterygomaxillary region and the location of the descending palatine artery were assessed. RESULTS: Although acceptable separation between the maxilla and pterygoid plates was achieved in all patients, an exact separation of the pterygomaxillary junction at the posterior nasal spine level was found in only 18 of 74 sides (24%). In 29 of 74 sides (39.2%), the separation occurred anterior to the descending palatine artery. In 29 of 74 sides (39.2%), complete separation between the maxilla and lateral and/or medial pterygoid plate was not achieved, but lower level separation of the maxilla and pterygoid plate was always complete. The maxillary segments could be moved to the postoperative ideal position in all cases. CONCLUSION: Le Fort I osteotomy without an osteotome does not always induce an exact separation at the pterygomaxillary junction at the posterior nasal spine level, but the ultrasonic bone curette can remove the interference between maxillary segment and pterygoid plates more safely.

Evaluation of bone formation after sagittal split ramus osteotomy with bent plate fixation using computed tomography.

PURPOSE: To evaluate bone formation between the proximal and distal segments after a sagittal split ramus osteotomy (SSRO) with bent plate fixation. PATIENTS AND METHODS: The subjects were 23 patients (46 sides) who underwent bilateral SSRO setback surgery. They were divided into titanium and absorbable plate groups. A 3 to 7-mm gap was made between the proximal and distal segments and a bent plate was fixed with 4 screws in each side of the mandible. The square of ramus (RmS), the anteroposterior length (RmA-RmP), and the mediolateral width (RmM-RmL) of the ramus at the horizontal plane under the mandibular foramen were assessed preoperatively, immediately after surgery, and 1 year postoperatively by computed tomography (CT). RESULTS: There were no significant differences between the titanium and absorbable plate groups over time. RmS after 1 year was larger than preoperatively in both groups (P < .0001). RmA-RmP significantly increased immediately after surgery and significantly decreased after 1 year in both groups (P < .0001). RmA-RmP after 1 year was significantly larger than the preoperative value in both groups (P < .0001). RmM-RmL showed a similar tendency to the anteroposterior length, but was not significant. CONCLUSIONS: The gap between the proximal and distal segments can fill with new bone after SSRO with both titanium and absorbable plates, even with few bony contacts between segments.

The evaluation of surgical factors related to recovery period of upper lip hypoaesthesia after Le Fort I osteotomy.

PURPOSE: It is unclear whether surgical factors can affect the upper lip sensitivity. The aim of this study was to assess the factors that can affect the recovery period of hypoaesthesia of the upper lip after Le Fort I osteotomy, using trigeminal somatosensory evoked potential (TSEP) objectively. PATIENTS AND METHODS: Twenty-nine patients with mandibular prognathism underwent Le Fort I osteotomy with and without artificial pterygoid plate fracture. Trigeminal nerve hypoaesthesia at the region of the upper lip was assessed bilaterally by the TSEP method. The distance between the infraorbital foramen and the osteotomy line (IO) or the nearest plate/screw position (IP) was measured on three-dimensional computed tomography (CT). The relationship between the recovery period in upper lip hypoaesthesia and surgical factors (these distances, movement amount, pterygoid plate fracture) were analysed statistically. RESULTS: The recovery period in upper lip hypoaesthesia did not significantly correlate with IO, IP and movement amount. There was no significant difference between pterygoid plate fracture group and non-fracture group. CONCLUSION: Temporary hypoaesthesia of upper lip after Le Fort I osteotomy could not be avoided, however, osteotomy line, plate/screw position and pterygoid plate fracture in Le Fort I osteotomy did not affect the recovery period of upper lip hypoaesthesia with TSEP.

Assessment of the relationship between the recovery of maximum mandibular opening and the maxillomandibular fixation period after orthognathic surgery.

PURPOSE: The purpose of this study was to evaluate the differences in the recovery of maximum mandibular opening (MMO), and the relationship between MMO and the maxillomandibular fixation (MMF) period after sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), with and without Le Fort I osteotomy. PATIENTS AND METHODS: Sixty-eight patients with diagnosed mandibular prognathism with or without asymmetry were divided into 4 groups (SSRO, IVRO, SSRO with Le Fort I osteotomy, and IVRO with Le Fort I osteotomy). MMO and the MMF period were measured preoperatively and at 1, 3, 6, 12, and 18 months after surgery. The differences among surgical procedures and the relationship between MMO and the MMF period were examined statistically. RESULTS: In relation to time-dependent changes in MMO, there were no significant differences among the groups. There were significant positive correlations between MMO and the MMF period from 1 month to 6 months after surgery. However, there were no significant correlations at 12 and 18 months after surgery. CONCLUSION: This study suggests that there were no significant differences between single-jaw surgery and double-jaw surgery in terms of postoperative time-dependent changes in the recovery of MMO. However, the MMF period was associated with the recovery of MMO.

Skeletal stability after mandibular setback surgery: bicortical fixation using a 2.0-mm locking plate system versus monocortical fixation using a nonlocking plate system.

PURPOSE: This study was conducted to compare the time-course changes in condylar long-axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with bicortical plate fixation versus monocortical plate fixation. PATIENTS AND METHODS: Of a group of 40 Japanese patients diagnosed with mandibular prognathism, 20 underwent SSRO with bicortical plate fixation using a locking plate system and the other 20 underwent SSRO with monocortical plate fixation using a conventional plate system. The time-course changes in condylar long-axis and skeletal stability were assessed through axial, frontal, and lateral cephalograms. RESULTS: Significant differences were found between the 2 groups in changes of the left condylar angle between the initial and 1-month measurements (P = .0454) and in ANB between the 1- and 3-month measurements (P = .0206); however, no significant differences were found between the 2 groups in the other measurements in each time interval. CONCLUSIONS: Our findings suggest no significant differences in postoperative time-course changes between bicortical plate fixation using a locking plate system and monocortical plate fixation using a conventional plate system.

Inhibition of invasion and metastasis in oral cancer by targeting urokinase-type plasminogen activator receptor.

There have been reports of strong correlations between poor prognosis in various cancers and concomitant expression of urokinase-type plasminogen activator (uPA) and its surface receptor (uPAR). We and others have previously shown that the uPA system plays a significant role in a subset of head and neck squamous cell carcinoma. In the present study, we found that uPAR is required for invasion and metastasis of highly malignant oral cancer cells (OSC-19). Treating OSC-19 cells with antisense oligonucleotides (AS) targeting uPAR resulted in a dramatic decrease of uPAR mRNA expression. Furthermore, pretreatment with AS or siRNA targeting uPAR inhibited progression of OSC-19 cells in experimental models. These results suggest that overexpression of uPAR increases the invasiveness and metastasis of OSC-19 cells, and that uPAR is a promising therapeutic target for regulation of progression of oral cancer.

Determining the anatomy of the descending palatine artery and pterygoid plates with computed tomography in Class III patients.

PURPOSE: Understanding the anatomy of the pterygomaxillary junction region helps prevent blood loss in Le Fort I osteotomy. Here, we determined the location of the descending palatine artery and the structure of the pterygomaxillary region. PATIENTS AND METHODS: The study group consisted of 82 Japanese patients with mandibular prognathism and asymmetry, with and without maxillary retrognathism or asymmetry. A total of 164 sides were measured and divided into right versus left, men versus women, and bimaxillary osteotomy (B) versus mandibular osteotomy (S). Lateral and frontal cephalograms and computed tomography (CT) were analysed for all patients. The relationship between the cephalometric measurements and the measurements of the descending palatine artery and pterygoid plate (PP) were assessed. RESULTS: There were no significant correlations between measurements of cephalograms and those of the descending palatine artery and PPs. There were significant differences between right and left in lateral plate length (p=0.0014) and thickness of PP (p=0.0047). There were significant differences between men and women in right width of PP (p=0.0034), right thickness of PP (p=0.0063), left posterior length (p=0.0196), and left thickness of PP (p=0.0279). The B group had a shorter anterior length than the S group (right: p<0.0001, left: p=0.0027). CONCLUSION: These results suggest that the location of the descending palatine artery and the morphology of the PPs were not significantly associated with any cephalometric measurements. CT examination is necessary to recognize the anatomy of pterygomaxillary region and the exact positions of descending palatine artery before Le Fort I osteotomy.

Statin-induced bone morphogenetic protein (BMP) 2 expression during bone regeneration: an immunohistochemical study.

OBJECTIVES: The purpose of this study was to investigate bone morphogenetic protein (BMP) 2 expression after implantation of a statin and recombinant human BMP-2 (rhBMP-2) and to compare the bone regeneration capability of these substances in the rabbit nasal bone using immunohistologic methods. STUDY DESIGN: Twelve adult male Japanese white rabbits (n = 12; age 12-16 weeks, weight 2.5-3.0 kg) were divided into 3 experimental groups and 1 control group. A total of 48 bone defects, 4 per rabbit, were created in the nasal bone while preserving the nasal membrane. In the experimental groups, 1 group was implanted with 10 mg of a statin dissolved in 0.2 mL water with an atelocollagen sponge (ACS); the second group was implanted with 5 microg rhBMP-2 with an ACS; and in the third group only the ACS was implanted. No material was implanted in the control group. Animals were killed at 1, 2, and 4 weeks after surgery. The parts that had been operated on were removed and prepared for histologic assessment. The expression of BMP-2 was evaluated using immunohistochemistry, and double-immunostaining for BMP-2 and Ki-67 was observed by fluorescent microscopy. RESULTS: No significant differences were observed between the statin/ACS group and rhBMP-2/ACS group at 1, 2, and 4 weeks after surgery. The number of cells which stained positively for BMP-2 increased significantly in both of the implanted groups compared with the control group (P < .0001). The positive fluorescent double-immunostaining for BMP-2 and Ki-67 was similar in both implanted groups. CONCLUSION: This study suggests that statin/ACS implants show BMP-2 expression and osteoinductive activity that is similar to those of rhBMP-2/ACS implants.

Assessment of ramus, condyle, masseter muscle, and occlusal force before and after sagittal split ramus osteotomy in patients with mandibular prognathism.

PURPOSE: The purpose of this study was to examine the relationship between the morphologies of the masseter muscle and the ramus and occlusal force before and after sagittal split ramus osteotomy (SSRO) in patients with mandibular prognathism. PATIENTS AND METHODS: The study group consisted of 26 patients with mandibular prognathism. All patients underwent bilateral SSRO as well as 3-dimensional computed tomography on which the masseter muscle, ramus, and condyle were measured preoperatively and at 1 year postoperation. Occlusal force and contact area were also recorded with pressure-sensitive sheets. RESULTS: In the cross-sectional area of the masseter muscle, there were no significant differences between the pre- and postoperative status. However, postoperative ramus width and area were significantly larger than preoperative values (P < .0001). Postoperative right condylar area was significantly larger than the preoperative value (P = .0120). Occlusal force and contact area 1 year after surgery were significantly larger than the preoperative values (P = .0016, P = .0190). CONCLUSION: This study suggested that the masseter muscle area did not significantly differ from preoperative status 1 year after SSRO, although occlusal force, contact area, and ramus area and width increased significantly 1 year after SSRO.

A comparative CT evaluation of pharyngeal airway changes in class III patients receiving bimaxillary surgery or mandibular setback surgery.

OBJECTIVE: The purpose of this study was to compare the morphologic changes of the upper airway space in Class III patients who underwent mandibular setback or bimaxillary surgery (maxillary advancement and mandibular setback) by computed tomography at 2 levels: soft palate and base of tongue. METHODS: The sample consisted of 47 subjects in 2 groups who had been diagnosed as having Class III skeletal deformities and had been treated by mandibular setback or bimaxillary surgery (maxillary advancement and mandibular setback). Anteroposterior, lateral, and cross-sectional area dimensions of the airway at the level of soft palate and base of tongue were measured pre- and postoperatively on computed tomography images. RESULTS: Anteroposterior dimensions of the airway decreased in both groups (P < .0001); however, the reduction was significantly less in cases treated with bimaxillary surgery (P < .05). In the mandibular setback surgery group, the cross-sectional area of the airway decreased significantly (P < .001). Although the cross-sectional area of the airway decreased in the bimaxillary surgery group, the reduction was not statistically significant (P > .05). CONCLUSIONS: This study suggests that bimaxillary surgery can prevent narrowing of the upper airway in the correction of Class III deformities in comparison with mandibular setback surgery used as the sole treatment. Computed tomography was valuable in determining the effects of surgical treatment on pharyngeal airway dimensions.

Horizontal changes in the condylar head after sagittal split ramus osteotomy with bent plate fixation.

OBJECTIVE: The purpose of this study was to evaluate the horizontal changes in the condylar head with bent plate fixation after sagittal split ramus osteotomy (SSRO) with and without a Le Fort I osteotomy. STUDY DESIGN: Of 47 Japanese patients with mandibular prognathism, 24 underwent SSRO and 23 underwent SSRO in combination with a Le Fort I osteotomy. A 3-5-mm gap was made between the proximal and distal segments, and a bent plate was fixed with 4 screws in each side of the mandible. The angle of the condylar long axis, as well as the anteroposterior and mediolateral displacement of the condylar head were assessed preoperatively and postoperatively by computerized tomography (CT). RESULTS: There was no significant difference in reduction in mandibular length between SSRO alone and SSRO with Le Fort I on the axial view of a 3-dimensional CT. There were no significant differences between pre- and postoperative horizontal changes in the condylar long axis or in the anteroposterior and mediolateral displacement of the condylar head, although the length of the proximal segment in SSRO with Le Fort I osteotomy was significantly shorter than in SSRO alone (P < .05). CONCLUSION: These results suggest that the use of a bent plate for SSRO does not change preoperative angle or position significantly in setback surgery, regardless of the addition of Le Fort I osteotomy.

Relationship between recovery period of lower lip hypoesthesia and sagittal split area or plate screw position after sagittal split ramus osteotomy.

OBJECTIVE: The purpose of this study was to objectively evaluate the relationship between recovery of hypoesthesia of the lower lip after sagittal split ramus osteotomy (SSRO) with trigeminal somatosensory evoked potential (TSEP) and sagittal split area or plate screw position, using postoperative computerized tomography (CT). STUDY DESIGN: The subjects consisted of 58 patients (116 sides) with mandibular prognathism who underwent SSRO. The patients were divided into 2 groups. The Ob group, consisting of 62 sides, underwent the Obwegeser method. The OD group, consisting of 54 sides, underwent the Obwegeser-Dal Pont method. Trigeminal nerve hypoesthesia at the region of the lower lip was assessed bilaterally by the TSEP method. An electroencephalograph recording system (Neuropack Sigma; Nihon Koden, Tokyo, Japan) was used to analyze the potentials. Each patient was evaluated preoperatively and then postoperatively at 1 week, 2 weeks, 1 month, 3 months, 6 months and 1 year. Postoperative CT was performed in all cases to measure the sagittal split area (SSA) as well as the distance between the plate (the most medial point of screw) and the mental foramen (PM). Then comparisons between the 2 groups in recovery period of the lower lip, SSA, and PM were performed. Furthermore, the relationships between recovery period of hypoesthesia of the lower lip and SSA or PM were evaluated statistically. RESULTS: The average measurable period and standard deviation of TSEP of the lower lip was 3.4 +/- 5.5 weeks in the Ob group and 11.3 +/- 13.7 weeks in the OD group. There were significant differences between the Ob group and the OD group (P < .0001). The OD group showed significantly greater SSA and PM than the Ob group (P < 0.0001). CONCLUSION: This study suggested that recovery period of hypoesthesia of the lower lip after SSRO was strongly associated with SSA and PM.

Condylar and disc positions after sagittal split ramus osteotomy with and without Le Fort I osteotomy.

PURPOSE: The purpose of this study is to examine the changes in temporomandibular joint (TMJ) morphology and clinical symptoms after sagittal split ramus osteotomy (SSRO) with and without a Le Fort I osteotomy. SUBJECTS AND METHODS: Of 45 Japanese patients with mandibular prognathism, 23 underwent SSRO and 22 underwent SSRO in combination with a Le Fort I osteotomy. The TMJ symptoms and joint morphology, including disc tissue, were assessed preoperatively and postoperatively by magnetic resonance imaging (MRI) and axial cephalography. RESULTS: There were significant differences between pre- and postoperative horizontal changes in the condylar long axis on the right side in the group undergoing SSRO (sagittal split ramus osteotomy) alone. However, there were no other significant differences in pre- and postoperative measurements in this group as compared with the group receiving SSRO plus Le Fort I osteotomy, and the preoperative disc position could not be changed in either group. CONCLUSION: These results suggest that SSRO, either with or without Le Fort I osteotomy, could not change the preoperative disc position or correct anterior disc displacement, although these procedures did improve the symptoms associated with TMJ dysfunction.

Evaluation of upper lip hypoesthesia with a trigeminal somatosensory-evoked potential following Le Fort I osteotomy in combination with mandibular osteotomy.

PURPOSE: The purpose of this study was to objectively evaluate hypoesthesia of the upper lip following Le Fort I osteotomy in combination with mandibular osteotomy with trigeminal somatosensory evoked potential (TSEP). SUBJECTS AND METHODS: The subjects consisted of 25 patients with mandibular prognathism with maxillary retrognathism mandibular prognathism with or without asymmetry, who underwent Le Fort I osteotomy in combination with sagittal split ramus osteotomy (SSRO) or intraoral vertical ramus osteotomy (IVRO). Trigeminal nerve hypoesthesia at the region of the upper lip was assessed bilaterally by the TSEP method. The electrodes were placed exactly above the highest point of the vermilion border and on the mucosa of the upper lip. An electroencephalograph recording system (Neuropack Sigma; Nihon Koden Corp., Tokyo, Japan) was used to analyze the potentials. Each patient was evaluated preoperatively and then postoperatively at 1 week, 2 weeks, 1 month, 3 months, 6 months, and 1 year. RESULTS: The average measurable period and standard deviation of TSEP of the upper lip was 7.8 +/- 10.7 weeks following Le Fort I osteotomy, TSEP of the lower lip was 4.6 +/- 9.2 weeks in the patients who underwent SSRO with Le Fort I osteotomy, and 1.2 +/- 0.4 weeks in the patients who underwent IVRO with Le Fort I osteotomy. CONCLUSION: This study objectively proved that hypoesthesia could appear in the upper lips following Le Fort I osteotomy with TSEP. The measurable period for the upper lip following Le Fort I osteotomy tended to be longer than that for the lower lip in the patients who underwent SSRO and IVRO with Le Fort I osteotomy.

A comparison of lower lip hypoesthesia measured by trigeminal somatosensory-evoked potential between different types of mandibular osteotomies and fixation.

PURPOSE: The purpose of this study was to compare objectively, the recovery of hypoestheia of the lower lip following orthognathic surgery using different procedures (sagittal split ramus osteotomy [SSRO]) and intra-oral vertical ramus osteotomy (IVRO)) and fixation methods (monocortical plate fixation and bi-cortical plate fixation). Hypoesthesia was evaluated using the trigeminal somatosensory-evoked potential (TSEP). PATIENTS AND METHODS: The subjects consisted of 174 patients (348 sides) with mandibular prognathism with or without asymmetry, who underwent mandibular ramus osteotomies using different fixation types. The patients were divided into 4 groups. The OAM group consisted of 128 sides who had SSRO using the Obwegeser method with mono-cortical absorbable plate fixation, the ODTM group consisted of 84 sides who had the Obwegeser-Dal Pont method with mono-cortical titanium plate fixation, the OTB group consisted of 32 sides who had the Obwegeser method with bi-cortical titanium plate fixation and the VO group consisted of 104 sides who underwent IVRO according to the Bell method without fixation. Trigeminal nerve hypoestheia at the region of the lower lip was assessed bilaterally by the TSEP method. An electroencephalograph recording system (Neuropack Sigma; Nion Koden Corp., Tokyo, Japan) was used to analyze the potentials. Each patient was evaluated pre-operatively and then post-operatively at 1 and 2 weeks, 1, 3, and 6 months, and 1 year. RESULTS: The mean measurable period and standard deviation of TSEP of the lower lip in the OAM group was 5.2 +/- 9.9 weeks, 10.9 +/- 13.1 weeks in the ODTM group, 7.8 +/- 4.5 weeks in the OTB group, and 2.5 +/- 6.3 weeks in the VO group. There were significant differences between the OAM and ODTM groups (P < .0001), the ODTM and OTB groups (P = .0001), the OTB and VO groups (P = .0221), the OAM and VO groups (P < .0001), and the ODTM and VO groups (P < .0001). CONCLUSION: This study proved using objective measurements that the recovery period from hypoesthesia of the lower lip following orthognathic surgery was dependent on the surgical procedure. Recovery in lower lip hypoesthesia after IVRO was significantly earlier than SSRO.

Comparison of maxillary stability after Le Fort I osteotomy for occlusal cant correction surgery and maxillary advanced surgery.

OBJECTIVE: To compare postoperative maxillary stability following Le Fort I osteotomy for the correction of occlusal cant as compared with conventional Le Fort I osteotomy for maxillary advancement. STUDY DESIGN: The subjects were 40 Japanese adults with jaw deformities. Of these, 20 underwent a Le Fort I osteotomy and intraoral vertical ramus osteotomy (IVRO) to correct asymmetric skeletal morphology and inclined occlusal cant. The other 20 patients underwent a Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO) to advance the maxilla. Lateral and posteroanterior cephalograms were taken postoperatively and assessed statistically. Thereafter, the 2 groups were followed for time-course changes. RESULTS: There was no significant difference between the 2 groups with regard to time-course changes during the immediate postoperative period. CONCLUSION: This suggests that maxillary stability after Le Fort I osteotomy for cant correction does not differ from that after Le Fort I osteotomy for maxillary advancement.