Stability of skeletal class III malocclusion after combined maxillary and mandibular procedures: rigid internal fixation versus wire osteosynthesis of the mandible.

PURPOSE: The aim of this study was to evaluate skeletal stability after double-jaw surgery for correction of skeletal Class III malocclusion to assess whether there were any differences between wire and rigid fixation of the mandible. PATIENTS AND METHODS: Thirty-seven Class III patients had Le Fort I osteotomy stabilized with plate and screws for maxillary advancement. Bilateral sagittal split osteotomy for mandibular setback was stabilized with wire osteosynthesis and maxillomandibular fixation for 6 weeks in 20 patients (group 1) and with rigid internal fixation in 17 patients (group 2). Lateral cephalograms were taken before surgery, immediately after surgery, 8 weeks after surgery, and 1 year after surgery. RESULTS: Before surgery, both groups were balanced with respect to linear and angular measurements of craniofacial morphology. One year after surgery, maxillary sagittal stability was excellent in both groups, and bilateral sagittal split osteotomy accounted for most of the total horizontal relapse observed. In group 1, significant correlations were found between maxillary advancement and relapse at the posterior maxilla and between mandibular setback and postoperative counterclockwise rotation of the ramus and mandibular relapse. In group 2, significant correlations were found between mandibular setback and intraoperative clockwise rotation of the ramus and between mandibular setback and postoperative counterclockwise rotation of the ramus and mandibular relapse. No significant differences in postoperative skeletal and dental stability between groups were observed except for maxillary posterior vertical position. CONCLUSIONS: Surgical correction of Class III malocclusion after combined maxillary and mandibular procedures appears to be a fairly stable procedure independent of the type of fixation used to stabilize the mandible.     

骨性Ⅱ类错伴颞下颌关节紊乱矫正后的长期稳定性

目的:研究骨性Ⅱ类错伴颞下颌关节紊乱患者在正颌-正畸联合治疗后面型和咬合的长期稳定性。方法:选择10例在本院正颌-正畸中心治疗结束3年以上、资料齐全的骨性Ⅱ类错患者,男2例,女8例,平均年龄(22.3±2.9)岁,治疗结束平均随访期(2.63±1.36)a。治疗方案为术前正畸、正颌手术、术后正畸,手术根据面型测量数据采用双颌手术或上颌手术+颏成形,术中采用坚强内固定。比较治疗前(T0)、治疗结束(T1)和随访结束(T2)的X线头影测量数据,评价颞下颌关节(TMJ)症状量表和MRI的变化。采用SPSS16.0软件包分别对治疗前、随访结束与治疗结束的测量数据进行配对t检验。结果:覆盖平均增加0.62mm,有显著性差异,其余骨性、牙性复发和软组织改建无统计学意义;随访结束UI-NA距离、覆盖和覆变化>2mm占10%,Go-Co长度变化>2mm占20%,软组织颏前点的变化量>2mm占40%,LI-NB距离和颏唇沟的深度变化均小于2mm;所有患者关节症状无加重,MRI未见髁突吸收加重,盘髁关系未见明显改变。结论:骨性Ⅱ类错伴TMD患者通过正颌-正畸联合治疗,能获得面型美观和正常的咬合关系,远期面型结构及咬合关系未见明显复发趋势,未发现TMJ症状加重趋势。     

Stability of the Le Fort I osteotomy with anterior internal fixation alone: a case series.

PURPOSE: The purpose of this case series was to evaluate the late postsurgical stability of the Le Fort I osteotomy with anterior internal fixation alone and no posterior zygomaticomaxillary buttress internal fixation. PATIENTS AND METHODS: Sixty patients with maxillary vertical hyperplasia and mandibular retrognathia underwent a 1-piece Le Fort I osteotomy of the maxilla with superior repositioning and advancement or setback. A bilateral sagittal split ramus osteotomy for mandibular advancement was also performed in 22 patients. Stabilization of each maxillary osteotomy was achieved using transosseous stainless steel wires and/or 3-hole titanium miniplates in the piriform aperture region bilaterally, with no zygomaticomaxillary buttress internal fixation. (Twelve of the 60 identified patients were available for a late postoperative radiographic evaluation.) Lateral cephalometric radiographs were taken preoperatively (T1), early postoperatively (T2), and late postoperatively (T3) to analyze skeletal movement. RESULTS: These 12 patients (5 male, 7 female) had a mean age of 24.5 years at surgery. Mean time from surgery to T2 was 41.2 days; mean time from surgery to T3 was 14.8 months. One patient received anterior wire osteosynthesis fixation, while 11 patients received both anterior titanium miniplate internal skeletal fixation and anterior wire osteosynthesis fixation. Six patients underwent Le Fort I osteotomy with genioplasty, 1 patient underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy, and 5 patients underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy and genioplasty. These 12 patients all underwent maxillary superior repositioning with either advancement (11 patients) or setback (1 patient). Statistically significant surgical (T2-T1) changes were found in all variables measured. In late postsurgical measurements (T3-T2), all landmarks in the horizontal and vertical plane showed statistically significant skeletal stability. CONCLUSION: This case series suggests that anterior internal fixation alone in cases of 1-piece Le Fort I maxillary superior repositioning with advancement has good late postoperative skeletal stability.     

Long-term hard and soft tissue relapse rate after genioplasty

PURPOSE: The purpose of this study was to assess hard and soft tissue stability 12 months after advancement genioplasty. MATERIAL AND METHODS: This is a retrospective study of 20 patients who underwent either advancement genioplasty alone (n = 11) or in combination with bilateral sagittal split osteotomy for mandibular advancement (n = 9). Lateral cephalometric radiographs were traced and immediate postoperative changes and 12-month postoperative changes were defined. The relapse rate for the pogonion, the soft tissue pogonion, and the soft tissue B point (Bs) were evaluated. The results were compared for combined mandibular advancement plus genioplasty versus genioplasty alone. Relapse rates were also correlated with the amount of advancement. All patients were treated with rigid internal fixation. RESULTS: After 12 months, the pogonion, the soft tissue pogonion, and the soft tissue B point had a mean relapse rate of -0.38 mm, -1.2 mm, and -1.5 mm (negative value indicates a relapse, and a positive value indicates prolapse), respectively, which was not significant at probability values of.45,.069, and.054, respectively. Relapse was not statistically related to the amount of advancement. There was no significant difference between the relapse rate for genioplasty alone versus combined bilateral sagittal split osteotomy and genioplasty, even with different amounts of advancement. CONCLUSIONS: Advancement genioplasty is an important and reliable technique for the esthetic treatment of the lower facial skeleton. The results indicate that there is no significant relapse after genioplasty and bilateral sagittal split osteotomy or genioplasty alone after 12 months when rigid internal fixation is used. The changes were minimal and hard to detect clinically. Genioplasty, with or without mandibular advancement, is a stable surgical procedure when used in conjunction with rigid internal fixation.     

Transverse displacement of the proximal segment after bilateral sagittal split osteotomy advancement and its effect on relapse.

PURPOSE: To evaluate the transverse displacement of the proximal segment and its association with horizontal relapse post-treatment. METHODS: Retrospective study of 25 patients (10 males, 15 females) who underwent bilateral sagittal split osteotomy (BSSO) advancement and Le Fort I osteotomy with rigid internal fixation (RIF) using bicortical lag screws. Posteroanterior and lateral cephalograms obtained preoperatively (T1), early postoperatively (T2), and after orthodontic treatment completion (T3) were used to assess: the angulation of each proximal segment relative to the upper orbital margin line and obtain the sum of both angles (total angle), mandibular intergonial width (IGW), mandibular length (Ar-B), B point position, and condylion position. Paired t tests were used to determine statistically significant (P < .05) changes within the variables between various time points (T2-T1; T3-T2; T3-T1). Correlations between variables were estimated by calculating Pearson's correlation coefficients. RESULTS: T2-T1 findings: all 25 patients showed an increase in IGW with a mean of 6.5 +/- 2.5 mm and the angulations of the proximal segments increased 3.2 +/- 2.6 degrees (total angle change). Ar-B increased 3.8 +/- 3.4 mm. B point moved anteriorly 4.8 +/- 2.9 mm. T3-T2 findings: IGW decreased 1.8 +/- 1.5 mm; angulation of the right and left proximal segments decreased 1.2 +/- 2.8 degrees (total angle change). Condylion moved superiorly 1.5 +/- 2.0. CONCLUSIONS: Statistically significant changes occurred in transverse width and angulation of proximal segments of patients who underwent BSSO advancement with Le Fort I osteotomy. No clinically significant associations were found between transverse displacement of the proximal segments and horizontal relapse.     

Effect of mandibular setback via bilateral sagittal split ramus osteotomy on transverse displacement of the proximal segment.

PURPOSE: The purpose of this study was to evaluate if a correlation exists between: a) transverse changes in the proximal segments because of mandibular setback surgery and b) postsurgical horizontal relapse of the mandible. PATIENTS AND METHODS: A total of 42 patients underwent bilateral sagittal split ramus osteotomy setback with rigid fixation and Le Fort I osteotomy performed by 1 surgeon between 1986 and 2000. The radiographic material for this study consisted of posteroanterior and lateral cephalometric radiographs for each patient taken preoperatively (T1), early postoperatively (T2), and late postoperatively (T3). Twenty-four of the 42 identified patients had T1, T2, and T3 radiographs, while the remainder of the patients had only T1 and T2 radiographs available. The posteroanterior radiographs were used to evaluate the angulation of the proximal segment and the intergonial width. RESULTS: Statistically significant increases in intergonial width and proximal segment angulation occurred from T1 to T2. In fact, all 42 patients had an increased intergonial width from T1 and T2. From T2 to T3, most patients underwent some relapse in their transverse dimension changes (21 of 24 patients had a decrease in their intergonial width). Overall, the intergonial width and the proximal segment angulations were significantly increased from T1 to T3. However, there was no significant correlation between the amount of transverse displacement of the proximal segment and horizontal postsurgical relapse of the mandible. CONCLUSION: The results show that statistically significant changes in the transverse width and angulation between proximal segments occur in patients undergoing bilateral sagittal split ramus osteotomy for mandibular setback with rigid fixation. However, the magnitude of the changes was small, and it is still uncertain as to whether these changes are of any clinical significance.     

Assessment of the stability of mandibular setback procedures with rigid fixation

The postsurgical changes associated with sagittal ramus osteotomy and mandibular setback stabilized with rigid fixation were evaluated. Lateral cephalometric radiographs of 25 individuals (11 males and 14 females) with a mean age of 23.4 years were evaluated presurgery, immediate postsurgery, and after a follow-up period of 7 to 42 months. The mean amount of surgical setback was 5.1 +/- 3.0 mm and the mean amount of postsurgical anterior movement was 0.51 +/- 1.04 mm, representing a 10% relapse of the original surgical correction. The postsurgical relapse of the mandible was not found to be related to the amount of surgical movement. Sixteen of the 18 cases that demonstrated anterior relapse moved forward between 0.5 and 1.5 mm. The amount of relapse was consistent and statistically significant (P less than .05), but small enough that it was not considered to be clinically significant. The findings of this study indicate that mandibular setback with a sagittal ramus osteotomy and its stabilization with rigid fixation appears to be a stable clinical procedure.     

Three-dimensional evaluation of positional change of the condyle after mandibular setback by means of bilateral sagittal split ramus osteotomy

OBJECTIVE: The aim of this study was to evaluate condylar displacement in 3 dimensions by means of computed tomography after mandibular setback by sagittal split ramus osteotomy with rigid fixation and to compare these results with those from patients with mandibular advancement. STUDY DESIGN: Thirty Korean subjects with skeletal class III malocclusion who had undergone mandibular setback by sagittal split ramus osteotomy had computed tomographs taken. Tomographs were taken to evaluate the temporomandibular joint 1 month before and approximately 1 month after surgery. The position and angulation of the condyle were measured on axial or sagittal views. These measurements were analyzed to determine any correlations between the amount of mandibular movement and condylar displacement. RESULTS: The results of this study show that the condyle tends to move inferiorly and rotate inward on the axial view and backward on the sagittal view by a statistically significant amount. CONCLUSION: The positional change of the condyle after sagittal split ramus osteotomy was not correlated with the amount of the setback.     

Stability of skeletal Class II correction with 2 surgical techniques: the sagittal split ramus osteotomy and the total mandibular subapical alveolar osteotomy.

Combined orthodontic and surgical treatment of severe Class II dentoskeletal deformities with the use of the bilateral sagittal split ramus osteotomy is a routine procedure in orthodontic practices. However, an alternative surgical technique, the total mandibular subapical alveolar osteotomy, could be used for the same purpose. The aim of this investigation was to compare the stability of the sagittal split ramus osteotomy with the total mandibular subapical alveolar osteotomy in the correction of dentoskeletal Class II malocclusions. Forty patients that exhibited Class II dentoskeletal relationships were included in the study. Twenty of these patients had mandibular advancement with the sagittal split ramus osteotomy; the remaining 20 patients had advancement of the whole lower alveolar segment with the total mandibular subapical alveolar osteotomy. The cephalograms studied were taken before the surgical procedure (T1 = 4 weeks before operation), immediately after the procedure (T2 = 10 days after surgery), and 1 year later (T3). The statistical analysis used to assess the results between and within the groups over the different time periods was the analysis of variance. The regression analysis was used to test the interdependence of soft tissue response to hard tissue movement. The results of this study show that both procedures are equally stable when correcting Class II malocclusions. This was proved by the stability of the correction of overjet, B point, and incisor-mandibular plane angle. There were no statistically significant differences between or within the groups in the position of these landmarks over time. There was a statistically significant change in the position of pogonion from T1 to T2 (P <.0028) between the groups, although at T3 this difference was not significant (P <.05). There were no significant changes in face height either within or between the groups over time. The hard/soft tissue interactions for the total mandibular subapical alveolar osteotomy were as follows: The lower lip advanced 60% to the incisor movement; soft tissue B' point responded with a 130% advancement in relation to the change in its hard tissue counterpart. Soft tissue pogonion advanced 90% in relation to the hard tissue landmark. The data suggest that the total mandibular alveolar osteotomy is the treatment of choice for the correction of severe dentoalveolar retrusive Class II malocclusion for which alteration of the mentolabial sulcus is desirable.     

Stability of skeletal Class III malocclusion after combined maxillary and mandibular procedures: titanium versus resorbable plates and screws for maxillary fixation.

PURPOSE: The aim of this study was to evaluate skeletal stability after double jaw surgery for correction of skeletal Class III malocclusion to assess if there were any differences between resorbable plate and screws and titanium rigid fixation of the maxilla. PATIENTS AND METHODS: Twenty-two Class III patients had bilateral sagittal split osteotomy for mandibular setback stabilized with rigid internal fixation. Low level Le Fort I osteotomy for maxillary advancement was stabilized with conventional titanium plate and screws in 12 patients (group 1) and with resorbable plate and screws in 10 patients (group 2). Lateral cephalograms were taken before surgery, immediately postoperatively, 8 weeks after surgery, and 1 year postoperatively. RESULTS: Before surgery both groups were balanced with respect to linear and angular measurements of craniofacial morphology. One year after surgery, maxillary stability was excellent in both groups. In group 1 no significant correlations were found between maxillary advancement and relapse. In group 2, significant correlations were found between maxillary advancement and relapse at A point and posterior nasal spine. No significant differences in postoperative skeletal and dental stability between groups were observed. CONCLUSION: Surgical correction of Class III malocclusion after combined maxillary and mandibular procedures appears to be a fairly stable procedure for maxillary advancements up to 5 mm independently from the type of fixation used to stabilize the maxilla. Resorbable devices should be used with caution for bony movements of greater magnitude until their usefulness is evaluated in studies with large maxillary advancements.     

Open bite: stability after bimaxillary surgery--2-year treatment outcomes in 58 patients

Stability after bimaxillary surgery to correct open bite malocclusion and mandibular retrognathism was evaluated on lateral cephalograms before surgery, 8 weeks post-operatively, and after 2 years. The 58 consecutive patients were treated to a normal occlusion and good facial aesthetics. Treatment included the orthodontic alignment of teeth by maxillary and mandibular fixed appliances, Le Fort I osteotomy, and bilateral sagittal split ramus osteotomy. Twenty-six patients also had a genioplasty. Intra-osseous wires or bicortical screws were used for fixation. Twenty-three patients had maxillo-mandibular fixation (MMF) for 8 weeks or more, six for 4-7 weeks, 14 for 1-3 weeks, and 15 had no fixation. At follow-up 2 years later, the maxilla remained unchanged and the mandible had rotated on average 1.4 degrees posteriorly. Seventeen patients had an open bite. Among them, eight patients had undergone segmental osteotomies. The relapse was mainly due to incisor proclination. The most stabile overbite was found in the group with no MMF after surgery.     

双侧下颌升支矢状劈开后退术后骨稳定性评价

目的 探讨影响双侧下颌升支矢状劈开后退术并行坚固内固定后骨稳定性的因素。方法 对进行双侧矢状劈开后退术后的15例患者于术后1周及术后1年摄头影测量侧位片,对其相关角度及线距进行测量,并作统计学处理。结果 下颌矢状劈开后退术1年后的平均复发量为2.5mm,后退量>6mm组与后退量<6mm组两者变化量之间无显著性差异。结论 下颌双侧矢状劈开后退术并行坚固内固定是矫正下颌前突最有效的方法之一。     

Treatment of painful temporomandibular joint dysfunction with the sagittal split ramus osteotomy.

PURPOSE: We describe a new indication for the sagittal split ramus osteotomy with rigid fixation to treat patients with painful dysfunction of the temporomandibular joint. PATIENTS AND METHODS: Ten patients for whom nonsurgical management failed were found to have a mandibular condyle positioned postero-superior within the glenoid fossa with reduced joint space on corrected-axis tomograms. The sagittal split ramus osteotomy was used to reposition the proximal segment and to increase joint space. Preoperative and long-term postoperative (average, 44.7 months) symptoms and tomographic findings were retrospectively compared. RESULTS: Significant pain relief occurred postoperatively in all patients. One patient had a relapse after initial improvement. No patient developed a malocclusion. The long-term radiographic condyle-fossa relationship tended to return to its preoperative position with no relapse of clinical symptoms, except in the 1 patient. CONCLUSION: The sagittal split ramus osteotomy with rigid fixation is another procedure that can be used to treat painful temporomandibular joint dysfunction by changing the position of the mandibular condyle in the glenoid fossa.     

Rigid versus wire fixation for mandibular advancement: Skeletal and dental changes after 5 years

The bilateral sagittal split osteotomy (BSSO) is the most common surgical procedure for the correction of mandibular retrognathism. Commonly, the proximal and distal segments are fixated together with either wire or rigid screws or plates. The purpose of this study was to compare long-term (5 years) skeletal and dental changes between wire and rigid fixation after BSSO. In this multisite, prospective, randomized clinical trial, the rigid fixation group received three 2-mm bicortical position screws, and the wire fixation group received inferior border wires and 6 weeks of skeletal maxillomandibular fixation with 24-gauge wires. Cephalometric films were obtained 2 weeks before surgery and at 1 week, 8 weeks, 6 months, 1 year, 2 years, and 5 years after surgery. Linear cephalometric changes were referenced to a cranial base coordinate system. Before surgery, both groups were comparable with respect to linear and angular measurements of craniofacial morphology. Both groups underwent similar surgical changes. Skeletal and dental movements occurred in both groups throughout the study period. Five years after surgery, the wire group had 2.2 mm (42%) of sagittal skeletal relapse, while the rigid group remained unchanged from immediately postsurgery. Surprisingly, at 5 years, both groups had similar changes in overbite and overjet. This was attributed to dental changes in the maxillary and mandibular incisors. Although rigid fixation is more stable than wire fixation for maintaining the skeletal advancement after a BSSO, the incisor changes made the resultant occlusions of the 2 groups indistinguishable.     

Skeletal and dental stability of segmental distraction of the anterior mandibular alveolar process. A 2-year follow-up

33 patients (27 females; 6 males) were retrospectively analysed for skeletal and dental relapse before distraction osteogenesis (DOG) of the mandibular anterior alveolar process at T1 (17.0 days), after DOG at T2 (mean 6.5 days), at T3 (mean 24.4 days), and at T4 (mean 2.0 years). Lateral cephalograms were traced by hand, digitized, superimposed, and evaluated. Skeletal correction (T3-T1) was mainly achieved through the distraction of the anterior alveolar segment in a rotational manner where the incisors were more proclined. The horizontal backward relapse (T4-T3) measured -0.8mm or 19.0% at point B (p<0.001) and -1.6mm or 25.0% at incision inferior (p<0.001). Age, gender, amount and type (rotational versus translational) of advancement were not correlated with the amount of relapse. High angle patients (NL/ML'; p<0.01) and patients with large gonial angle (p<0.05) showed significantly smaller relapse rates at point B. Overcorrection of the overjet achieved by the distraction was seen in a third of the patients and could be a reason for relapse. Considering the amount of skeletal relapse the DOG could be an alternative to bilateral sagittal split osteotomy for mandibular advancement in selected cases.     

Skeletal stability after mandibular advancement with rigid versus wire fixation.

PURPOSE: This study examined the stability of skeletal changes after mandibular advancement surgery with rigid or wire fixation up to 2 years postoperatively. PATIENTS AND METHODS: Subjects for this multisite, prospective, clinical trial received rigid (n = 78) or wire (n = 49) fixation. The rigid cases were fixed with three 2-mm bicortical position screws and 1 to 2 weeks of skeletal maxillomandibular fixation with elastics, and the wire fixation subjects were fixed with inferior border wires and had 6 weeks of skeletal maxillomandibular fixation with 24-gauge wires. Cephalometric radiographs were obtained before orthodontics, immediately before surgery, and at 1 week, 8 weeks, 6 months, 1 year, and 2 years after surgery. Linear cephalometric changes were referenced to a cranial base coordinate system. RESULTS: Before surgery, both groups were balanced with respect to linear and angular measurements of craniofacial morphology. Mean anterior sagittal advancement of the mandibular symphysis was 4.92 +/3.01 mm in the rigid group and 5.11 +/- 3.09 mm in the wire group, and the inferior vertical displacement was 3.37 +/- 2.44 in the rigid group and 2.85 +/- 1.78 in the wire group. The vertical changes were similar in both groups. Two years postsurgery, the wire group had 30% sagittal relapse of the mandibular symphysis, whereas there was no change in the rigid group (P < .001). Both groups experienced changes in the orientation and configuration of the mandible. CONCLUSIONS: Rigid fixation is a more stable method than wire fixation for maintaining mandibular advancement after sagittal split ramus osteotomy.     

Extraoral vertical ramus osteotomy combined with internal fixation for the treatment of mandibular deformities

Extraoral vertical ramus osteotomy (EVRO) is used in orthognathic surgery for the treatment of mandibular deformities. Originally, EVRO required postoperative intermaxillary fixation (IMF). EVRO has been developed using rigid fixation, omitting postoperative IMF. We examined retrospectively the long-term stability and postoperative complications for patients with mandibular deformities who underwent EVRO with internal rigid fixation. Patients who were treated with EVRO for a mandibular deformity in the period 2008–2017 at the Clinic of Oral and Maxillofacial Surgery, Mölndal, Sweden were included (N = 26). Overjet and overbite were calculated digitally and cephalometric analyses were performed preoperatively, and at three days, six months, and 18 months postoperatively. There was a general setback of the mandible, decreased gonial angle and reduced degree of skeletal opening. Excellent dental and vertical skeletal stabilities were seen up to 18 months postoperatively, although relapse was seen sagitally up to six months postoperatively. Since the overjet did not show any significant change over time, the sagittal skeletal changes have been attributed to dental compensation. There was no permanent damage to the facial nerve and 5.8% neurosensory damage to the inferior alveolar nerve was observed.     

Unilateral sagittal split ramus osteotomy: an alternative for some cases of asymmetric mandibular prognathism

The objective of this study was to propose a treatment protocol for patients with lateral prognathism based on the unilateral sagittal split ramus osteotomy (USSRO). This was a prospective study involving 31 patients with lateral prognathism, who required a bilateral sagittal split ramus osteotomy (BSSRO). Two groups were formed using the proposed protocol, with specific inclusion criteria for each group: BSSRO (n = 17) and USSRO (n = 14). Occlusal parameters (dental midline deviation, overbite, and overjet) were measured preoperatively (T0), at model surgery (T1), 1 month postoperative (T2), and 1 year after surgery (T3) and compared. P-values of <0.05 were considered significant. No significant difference was found between the USSRO and BSSRO groups for all occlusal parameters (T0, T1, T2, and T3). In both groups, there was a significant difference between T0 and T1 and no significant difference between T1 and T2 or T1 and T3 in all of the occlusal parameters; the exception was overbite between T1 and T2 in the BSSRO group, which showed a significant difference. No patient in either group showed signs or symptoms of temporomandibular joint dysfunction at T0 or T3. USSRO was found to be a stable alternative in patients with asymmetric mandibular prognathism. At the same time, it reduced the operating time and morbidity when compared to BSSRO.     

Mandibular advancement surgery in high-angle and low-angle class II patients: different long-term skeletal responses.

The objective of this cephalometric study was to compare skeletal stability and the time course of postoperative changes in high-angle and low-angle Class II patients after mandibular advancement surgery. The subjects were 61 consecutive mandibular retrognathism patients whose treatment included bilateral sagittal split osteotomy and rigid fixation. The patients were divided according to the preoperative mandibular plane angle; the 20 patients with the lowest mandibular plane angle (20.8 degrees +/- 4.9 degrees ) constituted the low-angle group, while the 20 cases with the highest mandibular plane angle (43.0 degrees +/- 4.0 degrees ) represented the high-angle group. Lateral cephalograms were taken on 6 occasions: immediately before surgery, immediately after surgery, 2 and 6 months after surgery, and 1 and 3 years after surgery. Results demonstrated that the high-angle and low-angle groups had different patterns of surgical and postoperative changes. High-angle patients were associated with both a higher frequency and a greater magnitude of horizontal relapse. While 95% of the total relapse took place during the first 2 months after surgery in the low-angle group, high-angle patients demonstrated a more continuous relapse pattern, with a significant proportion (38%) occurring late in the follow-up period. Possible reasons for the different postsurgical response are discussed.     

Surgical-orthodontic correction of mandibular deficiency: five-year follow-up.

Changes in dental and skeletal relationships at 5 years postsurgery were evaluated in a group of 35 patients whose mandibular deficiency had been corrected by the same surgeon, using sagittal split osteotomy of the mandibular ramus. From 1 to 5 years postsurgery, there was a small (0.9-mm) but statistically significant mean decrease in mandibular length (condylion to point B). In six patients, the decrease in mandibular length was 2 to 4 mm, and in two it was more than 4 mm, but only one of these individuals had more than a 2-mm increase in overjet. There was no mean change in overjet, but three patients had a 2 to 4-mm increase. Of these, one had 3.2 mm shortening of the mandible, one had 1.4 mm shortening of the mandible, and one had no change in mandibular length but repositioning of the incisors. Most patients had a deep overbite initially, and there was a tendency for the bite to deepen between the first and fifth years postoperatively, more as a result of extrusion of incisors than of mandibular rotation. Remodeling of the gonial angle area, with vertical and/or horizontal repositioning of gonion, was noted in more than half the subjects. It appears that morphologic changes related to continued skeletal remodeling, often compensated for by small changes in mandibular posture or tooth positions, continue after 1 year postsurgery for many patients.