Stability Of Orthognathic Surgery Research Articles

Assessment of Masseter Volume and Postoperative Stability After Orthognathic Surgery in Patients With Skeletal Class III Malocclusion With Facial Asymmetry.

This study aimed to evaluate the effect of orthognathic surgery on masseter volume in patients with skeletal Class III malocclusion with facial asymmetry and the effect of masseter volume on stability in orthognathic surgery. This research studied 16 patients with Class III malocclusion with facial asymmetry who received combined orthodontic-orthognathic treatment and underwent craniofacial computed tomography (CT) before (T0), 2 weeks after (T1), and 6 months after (T2) surgery. Three-dimensional (3D) CT images were retrospectively analyzed, using 3D volume reconstruction to obtain the masseter volume and examine the impact of the masseter volume on stability in orthognathic surgery. A statistically significant difference ( P < 0.05) in the volume of the masseter was found up to 6 months after orthognathic surgery compared with the preoperative period, and the reduction in the masticatory muscle volume on the lengthened side is greater than on the shortened side ( P < 0.05). The volume of both masseters differed according to facial asymmetry, and the difference was significantly reduced after orthognathic surgery ( P < 0.05). During the period time (T1-T2), cephalometric maxillary marker points were not significantly different ( P > 0.05), and mandibular marker points were significantly anteriorly shifted ( P < 0.05). There was an association between the masseter volume and anterior shift of point B (R > 0.5, P < 0.05), the upward and anterior shifts of the gonion point differed between the lengthened and shortened sides ( P < 0.05). The size of the masseter becomes smaller 6 months after orthognathic surgery, and orthognathic surgery improves both bone and soft tissue symmetry. A larger sagittal relapse of mandibular setback occurred in patients with greater masseter volume. Considering these alterations may be helpful in planning orthognathic surgery.

特別講演：Advantages and Disadvantages of 3D simulation in Orthognathic Surgery and Postoperative Stability in Orthognathic Surgery

特別講演：Advantages and Disadvantages of 3D simulation in Orthognathic Surgery and Postoperative Stability in Orthognathic Surgery

In Vivo Accuracy of a New Digital Planning System in Terms of Jaw Relation, Extent of Surgical Movements and the Hierarchy of Stability in Orthognathic Surgery.

This retrospective cohort study compares the virtual planned and postoperative jaw positions in patients undergoing orthognathic surgery. Surgery was virtually planned with the Digital Münster Model Surgery system (DMMS). Primary outcome: Spatial difference in the maxillo-mandibulo relation between virtual planning and postoperative result. Secondary outcome: Possible relationship between the measured differences and surgical movements as well as the postoperative stability according to Proffit. Ninety female and sixty-one male patients were included in the study. The average translation errors were 0.54 ± 0.50 mm (anteroposterior), 0.37 ± 0.33 mm (mediolateral), and 0.33 ± 0.28 mm (superoinferior). Orientation errors were 0.86 ± 0.79 degrees (yaw), 0.54 ± 0.48 degrees (roll), and 0.90 ± 0.72 degrees (pitch). The surgical procedures do not differ with respect to their error sizes. Maxilla forward and class II maxilla up with mandible forward are the most precise procedures. Most significant differences were found in the anteroposterior direction, whereby the extent of the surgical movement has no effect on the magnitude of the error. The process of planning with the DMMS followed by surgery is highly accurate and shows error values well below the clinically accepted limit of two millimeters in translation and four degrees in rotation.

Residents' journal review

Residents' journal review

Mechanical stability of 2-plate versus 4-plate osteosynthesis in advancement Le Fort I osteotomy. An in vitro study.

Stability in orthognathic surgery is nowadays considered as efficient and adequate. The objective of this study was to determine and to compare the mechanical resistance to vertical load of a Le Fort I advancement osteotomy stabilized by mean of two different osteosynthesis techniques, one using two 10-hole pre-bent T-shaped plates, the other using four manually bent 4-hole L- and J-shaped plates. Standardized Le Fort I advancement osteotomies have been made on polyurethane models. The maxillary advancement was 5mm. Two groups of five models each were created. Group 1 was stabilized by mean of two 10-hole pre-bent T-shaped plates fixed by monocortical screws in the paranasal region. Group 2 was stabilized by mean of manually bent four 4-hole L-shaped plates fixed monocortical screws in the zygomatic and paranasal regions. A testing machine was used to load vertically the models at the range of 1mm/min linear displacement until peak load and system failure. Statistical analysis was realized using ANOVA and t-test, considering P as significant if <0.005. The maximal tolerated load was 15N in group 1and 42.71N in group 2 (P=0.003). The use of two T-shaped 10-holes pre-bent plates allows for less resistance in vertical loading than the use of four 4-holes manually bent L-shaped plates.

The stability of occlusal plane rotation during orthognathic surgery

Abstract Background Considered rotation of the occlusal plane and the maxillomandibular complex during orthognathic surgery is an approach that enables optimisation of the functional and aesthetic outcomes of surgical-orthodontic treatment for the correction of a variety of dentofacial deformities. Objectives The objectives of this study are to: (1) retrospectively evaluate the stability of clockwise and anti-clockwise rotation of the occlusal plane during orthognathic surgery, and (2) compare the findings with the stability of orthognathic surgery in which no significant occlusal plane rotation occurs. Aims and methods Data were collected from a sample of 31 adult patients (22 females and nine males) treated by one orthodontist in private practice and at the University of Western Australia from 1992–2008. Patients received a Le Fort I osteotomy and BSSO to reposition the maxilla and mandible, respectively. The patients were separated into three groups defined by no occlusal plane rotation; clockwise occlusal plane rotation; or anti-clockwise occlusal plane rotation. Lateral cephalograms were taken at four time periods during treatment: T1 (pre-surgery), T2 (immediately post-surgery), T3 (six weeks post-surgery), and T4 (longest follow-up). The cephalograms were digitised and analysed using a customised cephalometric analysis (QuickCeph Studio, CA, USA) and landmarks were transferred via cranial base and maxillary superimpositions for each patient from T1 sequentially to T4. Results Clockwise rotation of the occlusal plane was highly stable one year following surgery and showed comparable results with cases treated without occlusal plane rotation. Anti-clockwise rotation of the occlusal plane was less stable and showed significant relapse of the occlusal plane angle towards the pre-surgical value during the post-surgical observation period. Conclusion Clockwise rotation of the occlusal plane during orthognathic surgery appears highly stable. Anti-clockwise occlusal plane rotation during orthognathic surgery appears less stable. Further studies are needed to evaluate the longer-term stability of clockwise and anti-clockwise rotation of the occlusal plane during surgical-orthodontic treatment.

Evaluation of different modalities of intraorally harvested bone graft in oral and maxillofacial reconstructive surgery

Objectives: Although the iliac crest is most often used in major jaw reconstruction for dental implants and other maxillofacial reconstructive surgeries it has the disadvantages of higher costs, alteration of ambulation, and the need for hospitalization and general anesthesia. , bone grafts harvested from the maxilla and mandible offer several benefits. This study was conducted to the quality and the quantity of intraorally harvested bone graft from different sites, and assessing the suitability of each donor site for the selected recipient site.&#x0D; Material and Methods: Twenty-two patients (27 bone graft donor sites) (5 of them with bilateral alveolar reconstruction), of both sexes (9 males and 17 females), were operated on by harvesting intraoral bone grafts from different sites used in different reconstructive surgeries. Specific intraoral donor sites were used for specific type of surgery according to the feasibility and need. Preoperative and intraoperative evaluation of the recipient defect size and selecting proper intraoral donor sites was the paramount parameter in our study.&#x0D; Results: The success rate was 96.2% in a follow-up period of 6-18 months, the patients were evaluated for bone graft stability, ability to insert the dental implant, stability of the implant, stability in orthognathic surgery, and the satisfactory aesthetic and functional results, all the patient had satisfactory results and only one case of particulates cortical bone had developed fibrous union ,&#x0D; Conclusion: Intraoral bone graft can successfully be used for treating small and selected facial and alveolar defect with minimal complications in the donor sites, patients report minimal discomfort and morbidity and all complications were temporary. Types of fixation, prompt graft adaptation were the most important factors for success. Symphysis of the mandible has the advantage of easy access and visibility and can easily be done under local anesthesia. However, for reconstruction of a bigger bony defect, an extraoral bone.

Skeletal Stability of Orthognathic Surgery: A Comparison of Patients Over and Under 40 Years of Age

Orthognathic surgery is the treatment of choice for correction of dentofacial deformities secondary to jaw size discrepancies and asymmetries. Although patients have been typically in the second or third decade of life, there has been a noted increase in patients$40 years of age undergoing orthognathic surgery. 2 In general, these older patients seek treatment to manage severe malocclusion or obstructive sleep apnea.Skeletal stability and other surgical outcomes are not well documented in this group. The purpose of this study is to compare skeletal stability following maxillary and mandibular advancement procedures in patients over and under 40 years of age. This was a retrospective cohort study of all patients who underwent maxillary or mandibular advancement procedures at Massachusetts General Hospital from 2004-2012. Subjects were included if preoperative, postoperative and 1 year (+/2 months) postoperative lateral cephalograms were available. Subjects were excluded if they underwent a setback or non-conventional orthognathic surgery procedures (eg, osteotomies for distraction osteogenesis, condylar reconstruction) or had a diagnosis of hemifacial microsomia, craniofacial microsomia, or other craniofacial syndromes or incomplete records. Demographic variables including age and gender, and type(s) of procedures performed were documented. The predictor variable was age over or under 40 years. The outcome variable was skeletal stability measured via standard linear and angular cephalometric measurements taken preoperatively (T0), immediately postoperatively (T1), and at 1 year follow-up (T2). Skeletal and dental movements were also quantified in the vertical and horizontal planes by assessing changes in position of A point, B point, U1 tip, and L1 tip. Statistical comparisons were performed using Student’s t-test. During the study period a total of 139 subjects (25 subjects $ 40) had adequate radiographic records and were included. Procedures included: One piece Le Fort 1 osteotomy (53 subjects, 7 subjects $40), bilateral sagittal

Skeletal stability in orthognathic surgery: evaluation of methods of rigid internal fixation after counterclockwise rotation in patients with class II deformities

Our aim was to assess the influence of internal fixation in skeletal stability on patients who had had counterclockwise rotation of the maxillomandibular complex and mandibular advancement procedures. We studied 60 records of 20 patients (14 female, 6 male), mean (range) age at operation 29 (16-50) years. The mean (range) postoperative follow-up was 15 (8-24) months. Sixty standard lateral cephalometric radiographs were randomly traced and digitised by one senior radiologist to estimate surgical and postoperative changes. Patients were divided into two groups, the first group (n=10) of which had fixation with only 2.0 system plates (2 plates with monocortical screws alone) and the second (n=10) of which had hybrid fixation (1 plate with monocortical screws and 2 or 3 bicortical bone screws). During operation the change in the mean occlusal plane with counterclockwise rotation was 9.4° (range -17.3 to -2.5mm). The maxilla moved forward and upward. All the anterior mandibular measurements had advanced horizontally, the mean (range) being 17 (6.4 to 9.9) mm for the pogonion, and 17.6 (6.0 to 30.7) mm for the menton. At the longest follow-up period, there were significant long-term changes, but these were clinically acceptable (<2mm). There was no significant difference between the two groups in postoperative stability or in the magnitude of the advancement and stability.

Alteration of Masticatory Electromyographic Activity and Stability of Orthognathic Surgery in Patients With Skeletal Class III Malocclusion

The purposes of this study were to 1) investigate longitudinal changes in electromyographic masticatory activity subsequent to orthognathic surgery (OGS) in patients with skeletal Class III malocclusion, and 2) compare masticatory muscle activity and skeletal factors in patients with stable versus relapsed mandibular positions after OGS. A consecutive series of patients with skeletal Class III malocclusion who underwent 2-jaw OGS (35 patients, 17 men and 18 women; age, 24.5 ± 5.0 yr) were included. Lateral cephalometric films were obtained preoperatively (T1), 1 month after OGS (T2), and at completion of orthodontic treatment (T3). Serial cephalometric tracings and analyses were obtained. Surface electromyograms of the anterior temporalis and masseter muscles were recorded at T1, T2, and T3 (6 mo after OGS). Resting tonus, maximum voluntary clench with habitual intercuspation and on cotton pads, and maximum muscle firing were evaluated. Percentage of overlapping coefficient and torque coefficient were calculated. Patients were categorized further into stable and relapse groups according to the sagittal relapse rate of mandibular setback. These surface electromyographic variables were compared between the 2 groups. On average, the mandible showed a significant setback of 10.19 mm and a relapse of 1.12 mm (10.99%). Surgical relapse did not correlate with gender or genioplasty. Serial surface electromyographic data indicated a significant decrease from T1 to T2 that then recovered from T2 to T3. No significant difference between T1 and T3 was noted. Percentage of overlapping coefficient was significantly decreased after OGS. The torque coefficient did not differ significantly from T1 to T3. The relapse group (relapse, >11%; n = 15) had a greater resting tonus of the anterior temporalis muscle at T3, a larger percentage of overlapping coefficient at T1, and a greater maximum voluntary clench of the masseter muscles at all times than in the stable group (n = 20). The relapse group exhibited a greater decrease in facial height (2.18 mm) from T2 to T3 than did the stable group (0.5 mm). A larger sagittal relapse of mandibular setback occurred in patients with greater masticatory muscle activity. Modifications in surgical design and overcorrection should be considered in patients with greater masticatory muscle activity before OGS.

Stability of Orthognathic Surgery in Class III Patients: Effect of Active Condylar Hyperplasia and High Condylectomy

Stability of Orthognathic Surgery in Class III Patients: Effect of Active Condylar Hyperplasia and High Condylectomy

Long term stability in orthognathic surgery

Long term stability in orthognathic surgery

The skeletal stability of one-piece Le Fort 1 osteotomy to advance the maxillaPart 2. The influence of uncontrollable clinical variables

<h2>Abstract</h2> The stability of orthognathic surgery has been the subject of numerous publications over the last 20 years. It is now apparent that studies must pay attention to the homogeneity of the patients investigated and in particular, surgical techniques. In Part 2 of our study of 45 patients who had a uniform one-piece maxillary advancement with rigid fixation to advance the maxilla, we found that uncontrollable variables, including patients age, sex, the degree of advancement, and simultaneous mandibular advancement, had no effect on post-operative skeletal stability.

The skeletal stability of one-piece Le Fort 1 osteotomy to advance the maxilla: Part 2. The influence of uncontrollable clinical variables

The stability of orthognathic surgery has been the subject of numerous publications over the last 20 years. It is now apparent that studies must pay attention to the homogeneity of the patients investigated and in particular, surgical techniques. In Part 2 of our study of 45 patients who had a uniform one-piece maxillary advancement with rigid fixation to advance the maxilla, we found that uncontrollable variables, including patients age, sex, the degree of advancement, and simultaneous mandibular advancement, had no effect on post-operative skeletal stability.