Sphenoid Sinus Foreign Body After Le Fort I Osteotomy.

This report describes a rare case of a foreign body in the sphenoid sinus from the tip of an osteotome, which was lodged during the Le Fort I osteotomy. After surgery, a 2-mm-diameter round-shaped foreign body was seen as an opaque image in the right sphenoid sinus on computed tomography. The tip of the broken osteotome (Bauer) was confirmed after the intraoperative instruments were investigated. The foreign body was removed using an interventional endoscope and navigation computed tomography, and a good prognosis was obtained.

Evaluation of tongue pressure and lip closing force in bimaxillary orthognathic surgery: A retrospective study.

The purpose of this study was to quantitatively compare changes in tongue pressure and lip closing force among skeletal Class II and Class III patients, who had undergone orthognathic surgery, and a control group. Maximum tongue pressure and lip closing forces were measured preoperatively and at 6 and 12 months postoperatively. Time-course changes were analyzed and compared among the groups. The control group involved 40 skeletal Class I occlusion volunteers (20 male and 20 female), the Class II group involved 20 female patients, and the skeletal Class III group involved 40 patients, who were subdivided by sex into two groups comprising 20 males and 20 females, respectively. Time-course changes in tongue pressure were not significantly different between and within groups. However, postoperative lip closing forces became gradually higher in the Class III group female and male subjects compared with the control group, although this was not observed in the Class II group. There were significant correlations between tongue pressure and lip closing force before and after surgery (p = 0.001), and these correlations increased over time. Although there was no significant increase in maximum tongue pressure after orthognathic surgery, there was an associated increase in perioral muscle strength. This suggests that an increase in perioral muscle strength may contribute more to the stability of postoperative jaw morphology.

Assessment of lateral pterygoid muscle and temporomandibular joint disc after Le Fort I osteotomy with and without intentional pterygoid plate fracture and sagittal split ramus osteotomy in class II and class III patients.

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.

An unusual case of bone regeneration of a necrotic mandible with pathologic fracture in an elderly hemodialysis patient with medication-related osteonecrosis of the jaw: a case report and review of the literature.

BACKGROUND: Bisphosphonates are frequently used for osteoporosis. Medication-related osteonecrosis of the jaw, a complication of bone-modifying agents, including bisphosphonates or angiogenic inhibitors, can be challenging to treat in elderly patients with numerous preexisting conditions. Achieving good treatment outcomes is especially difficult in patients with pathological fractures accompanied with extraoral fistulae. CASE PRESENTATION: We report an unusual case of prominent bone regeneration following palliative surgical treatment in a 72-year-old Japanese female patient undergoing hemodialysis. She previously had severe osteoporosis due to renal osteodystrophy and was receiving antiresorptive intravenous bisphosphonate. Computed tomography revealed a discontinuous left lower mandibular margin with a pathologic fracture and extensive, morphologically irregular sequestrum formation (80 × 35 × 20 mm). The patient was diagnosed with stage III medication-related osteonecrosis of the jaw and pathologic mandibular fracture. Immediately before the surgery, the anticoagulant used for dialysis was changed from heparin to nafamostat mesylate to reduce the risk of intraoperative bleeding. Sequestrectomy was performed under general anesthesia. Postoperative infection was not observed, the intraoral and submandibular fistula disappeared, and, surprisingly, prominent spontaneous bone regeneration was observed postoperatively at 6 months. Despite the severe systemic condition of the patient, the conservative surgical approach with sequestrectomy has yielded desirable results for more than 6 years since the surgery. CONCLUSIONS: This rare report of spontaneous bone regeneration in a patient of advanced age and poor general condition is the oldest case of mandibular regeneration ever reported.

Computed tomography assessment of mandibular morphologic changes and the inferior mandibular border defect after sagittal split ramus osteotomy.

OBJECTIVE: This study aimed to assess mandibular morphologic changes to the condyle, ramus, mandibular body, and inferior mandibular border defect after sagittal split ramus osteotomy in class II and III patients. STUDY DESIGN: The relationships among the condyle, ramus, and mandibular body measured by computed tomography preoperatively and postoperatively were assessed and factors related to the reduction of the condylar square and mandibular inferior border defect were examined. RESULTS: Patients included 72 female patients with jaw deformity (36 skeletal class II cases, 36 skeletal class III cases). Postoperative reduction of the condylar square was significantly correlated with preoperative condylar height in patients with class II (P = .0297) vs preoperative condylar height and preoperative mandibular height in patients with class III (P < .0001). A mandibular inferior border defect was found in 18 of 72 class II sides (25.0%) and was significantly related to the position of the osteotomy line and attachment side of the inferior border cortex (P < .0001). CONCLUSIONS: This study's findings suggest that the postoperative reduction of the condyle could be associated with preoperative condylar height. However, the mandibular inferior border defect in class II advancement surgery could be independently associated with technical factors in sagittal split ramus osteotomy.

Association between the point-rating system used for oral health and the prevalence of Gram-negative bacilli in hematological inpatients: A retrospective cohort study.

ABSTRACT: Gram-negative bacteremia is a major cause of death among hematology inpatients who require heavy-dose chemotherapy and hematopoietic stem cell transplantation. Gram-negative bacillus (GNB) is more likely to be detected when the oral health is poor. However, there is a dearth of studies on the relationship between oral assessment and prevalence of GNB in hematology inpatients.This retrospective study aimed to evaluate the relationship between the original point-rating system for oral health examinations (point-oral exam) and the prevalence of GNB in hematology inpatients at the hematology ward of the Yamanashi University Hospital. GNB was detected by cultivating samples from the sputum and blood of each patient.A total of 129 subjects underwent a medical checkup and point-oral exam. The sputum and blood culture results of 55 patients were included in this study. The total points of patients positive for GNB (n = 25, 45.5%) were significantly higher than those who were negative for GNB (total score: median, 25th, 75th, percentile; 6 [4, 7] vs 2 [1, 4]; P = .00016). Based on the receiver operating characteristic analysis, a cutoff score of 5 proved to be most useful to detect GNB.An oral evaluation with a cutoff value of 5 or higher in the point-oral exam might indicate the need for a more thorough oral management to prevent the development of systemic infections from GNB.

Evaluation of condylar surface CT values related to condylar height reduction after orthognathic surgery.

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.

Evaluation of recovery period in lower lip hypoesthesia after bilateral sagittal split osteotomy using trigeminal somatosensory evoked potential.

BACKGROUND: Bilateral sagittal split osteotomy (BSSO) is one of the most frequently used treatments for jaw deformity worldwide. However, lower lip hypoesthesia is a postoperative complication of BSSO. Trigeminal somatosensory evoked potential can be used to evaluate neural pathway abnormalities by measuring latency. The purposes of this study were to measure latency before and after BSSO and to examine the relationship between latency and the duration of hypoesthesia recovery. STUDY DESIGN AND METHODS: This observational retrospective case-control study analyzed data recorded from 2013 to 2018. We divided the patient data into 5 groups according to recovery time. Using the latency obtained in trigeminal somatosensory evoked potential as the main outcome, we examined the relationship between hypoesthesia recovery time and latency. RESULTS: The group with unresolved postoperative hypoesthesia 6 months after surgery had significantly greater latency values extension than the group without postoperative hypoesthesia. CONCLUSION: By measuring the degree of prolongation of latency before and after surgery, it is possible not only to indicate the presence of hypoesthesia but also to predict the hypoesthesia recovery period.

Evaluation of intravenous prophylaxis antibiotics for third molar extraction under general anesthesia.

Prophylactic antibiotic administration aims to maintain the postoperative wound environment. It is difficult to select appropriate prophylactic antibiotics to minimize the development of antibiotic resistant bacteria and the occurrence of complications. The purpose of this study was to compare the prophylactic effect of narrow spectrum antibiotics (cefazolin) with that of wide spectrum antibiotics (piperacillin) in preventing infection following third molar extraction. In addition, the effect of postoperative cefazolin administration was examined. This retrospective study included 350 patients who underwent third molar removal under general anesthesia. The patients were divided into three subgroups: preoperative cefazolin (N = 122), pre- and postoperative cefazolin (N = 101), and pre- and postoperative piperacillin (N = 127). The patients in the piperacillin group were administered the antibiotic preoperatively and postoperatively for 3 days. The patients in the preoperative cefazolin group were administered cefazolin preoperatively only. The patients in the pre- and postoperative cefazolin group were administered cefazolin preoperatively and postoperatively for 1 day. Surgical site infections (SSIs) were identified based on the Clavien-Dindo 30-day postoperative classification. There was a significant difference among the three groups of patients who had third molars classified as position C using the Pell and Gregory classification, according to the degree of impaction of the impacted third molar (P = 0.015). Our analysis showed that the number of SSI did not significantly differ between the three antibiotic treatment groups (P = 0.671). These results suggest that preoperative administration of cefazolin is as effective as postoperative administration of broad-spectrum antibiotics such as piperacillin.

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.

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.

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 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.

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.

Changes in computed tomography values of mandibular condyle and temporomandibular joint disc position after sagittal split ramus osteotomy.

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 < 0.05). 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.

Comparison of skeletal stability after sagittal split ramus osteotomy with and without extraction of the third molar in patients with mandibular prognathism.

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.

Evaluation of bone formation after sagittal split ramus osteotomy using different fixation materials.

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.

Evaluation of factors affecting recovery period in lower lip hypoesthesia after sagittal split ramus osteotomy in mandibular prognathism patients.

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.