Stability of skeletal Class III malocclusion after combined maxillary and mandibular procedures

The aim of this study was to evaluate the skeletal stability and time course of postoperative changes after surgical correction of skeletal Class III malocclusion. Combined maxillary and mandibular procedures were performed in 40 consecutive patients. Bilateral sagittal split osteotomy stabilized with wire osteosynthesis for mandibular setback and low-level Le Fort I osteotomy stabilized with plates and screws for maxillary advancement were performed. Maxillomandibular fixation (MMF) was in place for 6 weeks. Lateral cephalograms were taken before surgery, immediately postoperatively, 8 weeks after surgery, and 1 year postoperatively. Patients were divided into 2 groups according to vertical maxillary movement at surgery: a maxilla-up group with upward movement of the posterior nasal spine of 2 mm or more (group 1, n = 22), and a minimal vertical change group with less than 2 mm of vertical repositioning (group 2, n = 18). The results indicate that surgical correction of Class III malocclusion with combined maxillary and mandibular osteotomies appears to be fairly stable. One year postsurgery, maxillary stability was excellent, with a mean horizontal relapse at point A that represented 10.7% of maxillary advancement in group 1 and 13.4% in group 2. In the vertical plane, maxillary stability was also excellent, with a mean of 0.18 mm of superior repositioning at point A for group 1 and 1.19 mm for group 2. The mandible relapsed a mean of 2.97 mm horizontally at pogonion in group 1 (62% of mandibular setback) and 3.41 mm (49.7% of setback) in group 2. Bilateral sagittal split osteotomy with wire osteosynthesis and MMF was not as stable as maxillary advancement and accounted for most of the total horizontal relapse (almost 85%) observed. A trend to relapse was observed for maxillary advancement greater than 6 mm, while the single variable accounting for mandibular relapse in group 1 was the amount of surgical setback. Clockwise rotation of the ascending ramus at surgery was not correlated with mandibular relapse in relation to the type of fixation performed and therefore does not seem to be responsible for relapse.     

Soft tissue changes after a mandibular osteotomy for symmetric skeletal class III malocclusion

The soft tissue profile is crucial to esthetics after orthognathic surgery. The aim of this study was to assess the soft tissue changes of the subnasal and submental regions more than 1 year after a sagittal split ramus osteotomy (SSRO) in patients with skeletal class III malocclusion. A total of 22 patients with mandibular prognathism were included in this study. Patients had lateral cephalograms before and more than 1 year after they underwent an isolated SSRO. Soft and hard tissue changes were assessed using the lateral cephalograms. The lower lip, labiomenton, and soft tissue menton moved posteriorly by 85, 89, and 88% compared with the corresponding hard tissue, and the movement of the soft tissue B point and the top of the chin nearly reflected the displacement of the hard tissues, at 96 and 99%, respectively. The labiomenton, stomions, and naso-labial angles were changed after the mandibular set-back and the changes in these angles correlated with either the width of the soft tissue or skeletal displacement. The naso-labial angle could be altered even if an isolated mandibular osteotomy is performed. Changes to the stomions and naso-labial angles were affected by hard tissue movement, while changes to the labiomental angle were affected by the width of the soft tissue after the mandibular osteotomy. It is important to create an accurate preoperative prediction of the esthetic outcomes after a mandibular osteotomy by considering the interrelations between the hard and soft tissues.     

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.     

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.     

Stability after surgical-orthodontic corrective of skeletal Class III malocclusion. 3. Combined maxillary and mandibular procedures

Stability after combined Le Fort I and bilateral sagittal split osteotomies was reviewed in 51 patients with skeletal Class III malocclusion. Because vertical changes in the position of the maxilla affect both the vertical and anteroposterior positions of the mandible, the sample was subdivided by the direction of vertical movement of the maxilla at surgery. Excellent postsurgical stability was observed in the long-face Class III patients in whom upward and forward movement of the maxilla was combined with ramus osteotomy to prevent excessive forward rotation of the mandible. When the maxilla was moved forward and the mandible set back with minimal vertical change, moderate relapse tendencies were observed in both jaws, but most of the correction was maintained at 1 year. When the maxilla was moved down and forward while the mandible was set back, moderate vertical relapse of the maxilla and anteroposterior relapse of the mandible followed. Stability of the downward movement of the maxilla was, on average, better than that resulting from maxillary surgery alone.     

The orthopedic treatment of skeletal class III malocclusion with maxillary protraction therapy]

OBJECTIVE: The aim of this study was to investigate the changes of skeletal anterior crossbite in early-stage after maxillary expansion and protraction therapy. METHODS: 40 chinese children with skeletal anterior crossbite were divided into two groups: the control group received no orthodontic treatment and the experimental group received maxillary expansion and protraction. The cephalometric analysis was used to evaluate the changes in both groups. RESULTS: In the experimental group, A point moved forward 3.5 mm (-1.75 mm in the control group). SNB, SNPg decreased and ANB, NP-PA increased. Protraction therapy to treat skeletal anterior crossbite in the middle and late stage of mixed dentition could influence craniofacial growth and development, such as accelerating forward growth of the maxilla, making mandible downward growth. CONCLUSIONS: Protraction therapy can achieve successful result in treatment of skeletal anterior crossbite in middle and late mixed dentition.     

Orthognathic treatment with maxillary and mandibular anterior segmental osteotomy

This case report presents a case that underwent orthognathic treatment with anterior segmental osteotomies on both jaws. The patient was a 26-year-old female with maxillary protrusion, lip incompetence with an everted vermilion border. The overbite was +1.0 mm, overjet +1.0 mm. The pre-surgical orthodontic treatment included the extraction of the four first premolars and a multi-bracket treatment was started. After 12 months of pre-surgical orthodontic treatment, both the anterior maxillary and the anterior mandibular segments were retracted surgically by 5.5 mm. The total treatment period was 18 months. An anterior segmental osteotomy can induce the remarkable structural changes for bimaxillary lip protrusion patients.     

Orthodontic-surgical treatment of Class III malocclusion with mandibular asymmetry

Class III skeletal malocclusion may present several etiologies, among which maxillary deficiency is the most frequent. Bone discrepancy may have an unfavorable impact on esthetics, which is frequently aggravated by the presence of accentuated facial asymmetries. This type of malocclusion is usually treated with association of Orthodontics and orthognathic surgery for correction of occlusion and facial esthetics. This report presents the treatment of a patient aged 15 years and 1 month with Class III skeletal malocclusion, having narrow maxilla, posterior open bite on the left side, anterior crossbite and unilateral posterior crossbite, accentuated negative dentoalveolar discrepancy in the maxillary arch, and maxillary and mandibular midline shift. Clinical examination also revealed maxillary hypoplasia, increased lower one third of the face, concave bone and facial profiles and facial asymmetry with mandibular deviation to the left side. The treatment was performed in three phases: presurgical orthodontic preparation, orthognathic surgery and orthodontic finishing. In reviewing the patient's final records, the major goals set at the beginning of treatment were successfully achieved, providing the patient with adequate masticatory function and pleasant facial esthetics.     

Stability of maxillary advancement for correction of skeletal Class III malocclusion after combined maxillary and mandibular procedures: preliminary results of an active control equivalence trial for semirigid and rigid fixation of the maxilla

In this paper preliminary results are presented of a prospective study designed to examine the effect of maxillary fixation methods on postoperative stability. The purpose of this study was to evaluate the stability of Le Fort I osteotomy stabilized with semirigid fixation of the maxilla (SRMF) or rigid fixation of the maxilla (RMF). All patients had skeletal Class III malocclusion and underwent bimaxillary surgery (Le Fort I maxillary advancement with or without superior repositioning and bilateral sagittal split osteotomies of the mandible). Standardized cephalometric analysis was performed on serial radiographs of 42 patients immediately before surgery, 1 week after surgery, after release of fixation, and 1 year postoperatively. The patients were randomized into 2 treatment groups: 23 patients received RMF (group A), and 19 patients received SRMF (group B). Within the groups, patients showed good stability with regard to their baseline characteristics. To show the therapeutic equivalence of the 2 treatments, analysis of the recorded data followed the approach for an equivalence trial. The mean surgical advancement was 5.34 +/- 1.50 mm for group A and 4.51 +/- 1.37 mm for group B. The mean amount of postsurgical relapse was 0.98 +/- 1.27 mm for group A and 0.30 +/- 1.04 mm for group B. Group A patients experienced 93% of their relapse (0.92 mm) during fixation, while group B patients experienced 96% of their relapse (0.29 mm) after release of fixation. RMF provided better stability than SRMF for all maxillary landmarks in the vertical plane. All considered points both in horizontal and vertical plane exhibited full equivalence for 95% confidence intervals, which seems to indicate equivalent stability between the surgical procedures.     

Management of a hyperdivergent class III malocclusion, maxillary midline diastema, and infected mandibular incisors in a young adult

This is a case report of a 20-year-old woman with a hyperdivergent Class III malocclusion, infected mandibular incisors, maxillary midline diastema, and a mild tongue thrust. Extraction of the infected incisors and orthodontic treatment involving partial mesial movement of the remaining mandibular teeth produced a well-intercuspated Class III occlusion. After successful orthodontic treatment, a 4-unit bridge with pontics for the mandibular central incisors completed the rehabilitation and met the functional, esthetic, and occlusal treatment goals. Occlusal stability of the treatment result has been excellent in the 3-year follow-up.     

Stability after rigid fixation of simultaneous maxillary impaction and mandibular advancement osteotomies

The purpose of this study was to investigate the short- and long-term stability of bimaxillary surgery following LeFort I (LF-1) impaction with simultaneous bilateral sagittal split ramus osteotomy (BSSO) and mandibular advancement using the technique of rigid internal fixation (RIF). In order to assess the postoperative maxillary and mandibular movement pattern in 26 patients with vertical maxillary excess and mandibular deficiency, cephalograms were taken immediately preoperatively, and 1 week, 2 months, and 1 year after surgery. With paired t-test showing no statistically significant postoperative change for the point A of the maxilla from immediate postsurgery to longest follow-up (P> 0.05), the used technique of "RIF LF-I impaction and RIF BSSO advancement" tended to render excellent postsurgical stability in the horizontal (0.1+/-0.8mm mean posterior movement) and vertical (0.1+/-0.5mm mean inferior movement) direction. There was no instance of maxillary relapse of >2mm. Regarding mandibular BSSO advancement, the point B showed a significant vertical upward movement (1.6+/-1.2mm) (P< 0.001) and a slight horizontal forward movement (0.3+/-2.0mm) (P> 0.05) at 1-year follow-up. The incidence of posterior relapse of >2mm accounted for 11.5%. The data confirm the concept that the bimaxillary approach of "LF-I impaction and BSSO advancement" using the described technique of RIF is a stable procedure in the treatment of open bite patients classified as vertical maxillary excess in combination with mandibular deficiency.     

Variables associated with stability after Le Fort I osteotomy for skeletal class III malocclusion

The purpose of this study was to assess skeletal stability and predictors of relapse in patients undergoing an isolated Le Fort I osteotomy. A retrospective cohort study of 92 subjects undergoing Le Fort I osteotomy for Class III malocclusion was implemented. Predictor variables were demographic and perioperative factors. The primary outcome variable was postoperative skeletal position with relapse defined as >2 mm sagittal and/or vertical change at A-point on serial lateral cephalograms at immediate postoperative, 1 year, and latest follow-up time points. Mean advancement at A-point was 6.28 ± 2.63 mm and mean lengthening was 0.92 ± 1.76 mm. Eight subjects (8.70%) had relapse (>2 mm) in the sagittal plane, and two subjects (2.17%) in the vertical plane. No subjects required reoperation for relapse as overbite and overjet remained in an acceptable range due to dental compensation. In regression analysis, magnitude of maxillary advancement was an independent predictor of relapse in the sagittal plane (P = 0.008). There were no significant predictors of relapse in the vertical plane. This study suggests that isolated Le Fort I osteotomy for correction of skeletal Class III malocclusion is a stable procedure and that greater advancement is an independent risk factor for sagittal relapse.     

Surgical-orthodontic approach to skeletal class III malocclusion. Analysis of 45 cases with evaluation of curved oblique osteotomy and sliding osteotomy.

A curved oblique osteotomy in which the ascending ramus was cut obliquely on a curved line from its anterior border to the angle was used for the treatment of 29 patients with skeletal Class III malocclusion, and 16 other patients were corrected by either an ordinary body ostectomy or a sliding osteotomy in the first premolar region. Both curved oblique osteotomy and sliding osteotomy could easily be performed with a Stryker's reciprocating saw, and osseous healing at the sites of surgery was rapid as a large area of intimate bony contact between the segments was obtained. The resulting profile and skeletal changes studied by cephalograms were excellent, with no significant relapse, and recovery of a stable occlusion was attained. The combined approach with orthodontists which included thorough analysis of each patient, preoperative alignment of the dental arches and postoperative care was essential for obtaining the best results.     

安氏II类骨性下颌后缩患者Twin－Block矫治前后下颌骨变化的三维测量研究鄢

目的：观察安氏Ⅱ类下颌后缩病例Twin－Block矫治器治疗前后下颌骨的三维变化,探讨Twin－Block对下颌骨生长发育的影响。方法：替牙晚期、恒牙列早期安氏Ⅱ类骨性下颌后缩病例10例,采用Twin－Block矫治器矫治,矫治前、后拍摄CBCT,应用Mimics 17．0软件进行下颌骨三维重建后定点测量,SPSS 13．0软件进行统计分析。结果：矫治后下颌骨综合长度、下颌体、下颌升支长度增长明显,有统计学差异,但是髁突宽度及喙突长度无明显变化。结论：Twin－Block功能矫治可以促进安氏Ⅱ类骨性下颌后缩患者下颌骨长度及升支高度的增长。     

The stability of bilateral sagittal ramus osteotomy and vertical ramus osteotomy after bimaxillary correction of class III malocclusion

Introduction

The purpose of this retrospective cephalometric study was to compare the stability of bilateral sagittal split osteotomy (BSSO) with extra-oral vertical ramus osteotomy (VRO) after correction of class III malocclusion by means of bimaxillary orthognathic surgery.

Methods

The sample comprised 51 consecutively treated patients, 38 females and 13 males, with a mean age of 19.1 years. All had a one-piece Le Fort I osteotomy with maxillary advancement and mandibular setback. VRO was performed in 30 cases, and BSSO was performed in 21 cases. Lateral cephalograms were obtained before surgery, within 1 week of surgery and 1 year after surgery.

Results

The mean forward movement of the maxilla was 5.6 mm in both groups (p < 0.001). The mean horizontal surgical change in the VRO group was 4.4 mm (p < 0.001), and in the BSSO group it was 5.4 mm (p < 0.001). In the VRO group, the horizontal relapse was 1.2 mm (p < 0.001), and in the BSSO group, it was 1.4 mm (p < 0.001).

Conclusion

There was no difference in the stability between the BSSO and VRO groups. The average relapse in the whole sample was 26% of the surgical movement.