Maintenance of soft tissue changes after rigid versus wire fixation for mandibular advancement, with and without genioplasty

OBJECTIVE: This multisite prospective randomized clinical trial examined 2-year longitudinal soft tissue profile changes after bilateral sagittal split osteotomy for mandibular advancement by using rigid or wire fixation, with and without genioplasty. STUDY DESIGN: The study sample consisted of 127 subjects. The rigid-fixation group (n = 78) received 2-mm bicortical position screws, whereas the wire-fixation group (n = 49) received inferior border wires. In the rigid-fixation group, 35 subjects underwent genioplasty, whereas 24 subjects underwent genioplasty in the wire-fixation group. Soft tissue profile changes of labrale inferius, B-point, and pogonion were obtained from digitized cephalometric films taken immediately before surgery and up to 2 years after surgery. RESULTS: Regardless of fixation technique, subjects who had genioplasty in conjunction with the mandibular advancement had the largest surgical movement and the largest postsurgical change (P <.05). When all variables were constant, fixation technique was associated with maintenance of soft tissue change. Subjects who underwent rigid fixation maintained more soft tissue change than patients who underwent wire fixation. CONCLUSIONS: These findings suggest that subjects undergoing rigid fixation and genioplasty maintained the most soft tissue advancement.     

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 correction of skeletal Class III malocclusion. 2. Maxillary advancement.

Nearly half the patients with skeletal Class III malocclusion have maxillary deficiency as the major component of their problem, and modern surgical techniques allow maxillary osteotomy to correct the deformity. Changes at surgery and postsurgically were studied in 49 patients who underwent isolated surgical maxillary advancement. Thirty-one had wire osteosynthesis and maxillomandibular fixation, and 18 had rigid fixation with bone plates. In nearly half the patients, the maxilla was moved down as well as forward, indicating that the patient had both vertical and anteroposterior deficiency. In the anteroposterior plane, 80% of the patients had excellent stability at 1 year, while 20% had 2 to 4 mm of posterior movement of anterior maxillary landmarks. There was no difference in anteroposterior stability between wire/maxillomandibular fixation and rigid internal fixation groups. When the maxilla was moved down as well as forward, there was a strong tendency for relapse upward in both fixation groups. As a result, the chin frequently became more prominent from immediate postsurgery to 1-year followup, as upward movement of the maxilla allowed the mandible to rotate upward and forward.     

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.     

A comparison of synovial fluid pressure after immediate versus gradual mandibular advancement in the miniature pig.

PURPOSE: Mandibular advancement is a commonly performed surgical procedure for the treatment of mandibular hypoplasia. With the increased use of rigid fixation, there has been a decrease in the amount of relapse but an increase in the amount of force transmitted to the condyles. Gradual advancement of the mandible by distraction osteogenesis slowly overcomes the soft-tissue envelope and may decrease the amount of force exerted on the condyles. The purpose of this study was to develop an animal model to measure the magnitude of pressure associated with immediate versus gradual mandibular advancement. MATERIALS AND METHODS: A 2.0-mm pressure transducer was placed in the superior joint space in 2 miniature pigs. In the first animal, immediate advancement of the mandible with rigid fixation was performed. The synovial fluid hydrostatic pressures were measured prior to surgery and postoperatively. A second animal underwent gradual advancement with distraction osteogenesis. The synovial fluid hydrostatic pressures were measured prior to and after each activation of the distraction device. The condyles were examined radiographically and microscopically. RESULTS: The superior joint space fluid pressures increased and remained elevated over a 5-week period after immediate advancement. In the gradually advanced mandible, the pressures were elevated but returned to near baseline prior to the activation the following day. CONCLUSION: This animal model is useful to directly measure the pressure that is exerted on the condyle. This will allow further studies to compare methods for mandibular advancement. It is likely that gradual advancement of the mandible by distraction osteogenesis produces less force and causes less condylar resorption than large mandibular advancement stabilized with rigid fixation.     

Skeletal stability following mandibular advancement and rigid fixation

Twenty non-growing subjects underwent sagittal ramus osteotomies and rigid fixation. Cephalograms were analyzed before surgery, immediately after surgery and at least six months following surgery to evaluate skeletal stability. A mean horizontal relapse of 0.42 mm (8%) and a mean vertical increase in lower face height of 0.2 mm were found six months after surgery. Both were statistically insignificant. The mean backward rotation of the mandible of 0.55 degrees found six months after surgery was statistically significant (P less than 0.015), but was considered to be clinically insignificant. The results of this study show that surgical mandibular advancement with rigid fixation is a very reliable and stable procedure.     

Stability of the mandible following advancement: a comparison of three postsurgical fixation techniques

This study examines short-term stability of the mandible following mandibular advancement surgery by means of three standard techniques of postsurgical fixation. Twenty-two adult female rhesus monkeys (Macaca mulatta) underwent sagittal ramus advancement osteotomy of approximately 4 to 6 mm. Six animals had dental maxillomandibular fixation alone. Six animals had dental plus skeletal maxillomandibular fixation with circummandibular wires connected to pyriform aperture wires. Ten animals had rigid internal fixation with bicortical bone screws between the proximal and distal segments without maxillomandibular fixation. Radiographic cephalograms with the aid of tantalum bone markers and dental amalgams were analyzed during the first 6 postoperative weeks to evaluate skeletal and dental stability. Rigid internal fixation and the use of dental plus skeletal maxillomandibular fixation were both equally effective in the prevention of postsurgical relapse. However, in the animals in which only dental maxillomandibular fixation was used, statistically significant changes (relapse) occurred when compared with either of the other groups.     

A 3-year evaluation of skeletal stability of mandibular advancement with rigid fixation

The postsurgical changes associated with mandibular advancements using the sagittal ramus osteotomy and rigid fixation were evaluated. This retrospective study was based on examination of lateral cephalometric radiographs of 19 individuals (16 females and 3 males) with a mean age of 26.6 years. These radiographs were evaluated presurgically, immediately postsurgery, and 3 years postsurgically (2 years, 9 months to 4 years, 5 months). The mean amount of sagittal surgical advancement was 6.7 +/- 2.3 mm, and the mean amount of postsurgical relapse was 1.3 +/- 2.0 mm, representing a 14% relapse of the original surgical advancement. However, individual variation in the amount and direction of movement of the mandible was found during the follow-up period. Postsurgical relapse was found to be related to the amount of surgical advancement. Linear-regression analysis between these two variables resulted in an R2 value of 0.448. Fourteen of the subjects relapsed in the posterior direction, with 2 relapsing more than 50% of the surgical advancement. Five of the subjects moved further anteriorly, with 1 advancing as much as 50% more than the original advancement. The findings of this study suggest that mandibular advancement with the sagittal ramus osteotomy and rigid fixation does not provide consistently stable postsurgical results. However, when compared with previously reported relapse studies using nonrigid fixation techniques, rigid fixation yielded superior results.     

Stability of simultaneous maxillary intrusion and mandibular advancement: A comparison of rigid and nonrigid fixation techniques

This study examines the short-term stability of bimaxillary surgery following Le Fort I impaction with simultaneous bilateral sagittal split osteotomies and mandibular advancement using two standard techniques of postsurgical fixation. Fifteen adults had skeletal plus dental maxillomandibular fixation, and fifteen adults had rigid internal fixation using bone plates in the maxilla and bicortical bone screws between the proximal and distal segments in the mandible. The group with rigid internal fixation did not undergo maxillomandibular fixation. Radiographic cephalograms were analyzed during the postsurgical period to evaluate skeletal and dental stability. There was no statistical difference in postsurgical stability with rigid internal fixation or skeletal plus dental maxillomandibular fixation other than the vertical position of the maxillary molar; the skeletal plus dental maxillomandibular fixation group had a significant amount of postsurgical intrusion of the maxillary molar when compared with the rigid internal fixation group. Although the other measures showed no statistically significant difference between the experimental groups, the amount of variability in postsurgical stability in the group with skeletal plus dental maxillomandibular fixation was greater than that found in the group with rigid internal fixation.     

Stability of simultaneous maxillary and mandibular osteotomy for treatment of class III malocclusion: an analysis of three-dimensional cephalograms.

PURPOSE: The current investigation was undertaken to study the three-dimensional (3-D) stability of simultaneous maxillary advancement and mandibular setback using rigid fixation. The study also aimed to analyse the factors involved in postsurgical relapse by evaluation of changes in various parameters. PATIENTS: Twenty-five cases were evaluated of simultaneous Le Fort I maxillary advancement and mandibular setback using rigid fixation. METHODS: Preoperative, immediate and 6-month postoperative skeletal and dental changes were analysed using 3-D cephalograms obtained from biplanar stereoradiography. Maxillary fixation screws were used as landmarks to evaluate postoperative stability. RESULTS: The mean maxillary advancement was 3.7 mm. Relapse in the sagittal, vertical, and transverse planes was not detectable in the maxilla (p > 0.05). However, for an average mandibular setback of 5.7 mm, mean mandibular relapse was 1.1 mm or 19.3% anteriorly (p < 0.05). Surgical or postsurgical skeletal changes in the maxilla had no detectable influence on mandibular relapse (p > 0.05). Vertical alterations of the facial skeleton achieved surgically predicted the mandibular relapse (R2 = 0.27, p < 0.05). CONCLUSION: Maxillary advancement and vertical changes of +/- 2 mm did not influence the postoperative stability of the mandible. Relapse of the mandible seems to be influenced mainly by the amount and direction of the surgical alteration of mandibular position.     

The stability of facial osteotomies. 2. Mandibular advancement with bicortical screw fixation

Surgical repositioning of the dento-skeletal components of the lower third of face, combined with appropriate orthodontic treatment, can be used to improve function and aesthetics. However, the attainment of three-dimensional stability following corrective jaw surgery continues to be a major problem in the post-surgical period.
This paper examines the short-term (6 week postoperative) and long-term (12 months postoperative) horizontal skeletal stability of bilateral sagittal split mandibular advancement in 15 patients. The mean horizontal advancement of the mandible was 6.1 mm. Six weeks later, a mean continued forward movement of 0.16 mm was identified. The mean relapse at long-term follow-up was 0.46 mm (7.5%). Results indicate that rigid bicortical screw fixation of bilateral sagittal split osteotomies undertaken to correct horizontal lower dentofacial deficiency is both statistically and surgically predictable and stable when reviewed up to twelve months after surgery.     

Superior repositioning of the maxilla combined with mandibular advancement: mandibular RIF improves stability.

Postsurgical changes in 24 patients who had rigid internal fixation (RIF) of the mandible with screws after combined superior repositioning of the maxilla and mandibular advancement were compared with 53 patients who underwent the same surgery but who had intraosseous wire fixation, skeletal suspension wires, and 8 weeks of maxillomandibular fixation (MMF). During the first 8 weeks after surgery, the mean posterior relapse of the mandible was greater in the MMF group than in the RIF group (for example, -1.1 mm versus 0.15 mm at B point), and the percentage of patients with clinically significant vertical and horizontal changes was greater in the MMF group. By 1 year, there had been slight additional mean relapse in the MMF group (-1.5 mm net relapse at B point, with 42% of the patients showing 2 mm or more relapse). In the RIF group, the mandible was more likely to be repositioned forward than posteriorly (net mean change at B point, 0.7 mm forward; 33% had 2 mm or more forward movement). In the RIF group, all but one of the patients (96%) were judged to have an excellent clinical result; in the MMF group, the corresponding figure was 60%.     

A comparative study of stability after mandibular advancement surgery

The postsurgical stability of two groups of patients treated with different fixation techniques after mandibular advancement was evaluated retrospectively. Sixteen patients (group 1) underwent rigid osseous fixation, and another group of 16 patients (group 2) underwent intraosseous wiring fixation. Our findings suggested that skeletal and dental changes occurred in both groups as a result of adaptation to the altered functional equilibrium. Relapse resulting in a percentage loss of the initial advancement occurred primarily 6 to 8 weeks postsurgically. No statistically significant difference was found to exist in the short-term and long-term rates between the two groups. For the population studied, relative stability after mandibular advancement surgery was affected more by individual variability than by the fixation technique.     

The skeletal stability of one-piece Le Fort 1 osteotomy to advance the maxilla; Part 1. Stability resulting from non-bone grafted rigid fixation

During the past decade, we have increasingly preferred to do a one-piece Le Fort 1 osteotomy to advance the maxilla, sometimes in isolation to treat patients with maxillary retrusive skeletal Class III patients or combined with mandibular advancement to treat bimaxillary retrusive skeletal Class II. Clinical impressions of rigid fixation techniques have indicated that there is improved stability when compared with wire fixation. There are few studies in the literature that have addressed relapse following one-piece Le Fort 1 osteotomy to advance the maxilla. Such surgery involves one single spatial movement and thereby eliminates other possible surgical variables, which may impact on the degree of stability achievable postoperatively. We studied 45 patients who had undergone a uniform one-piece maxillary advancement with elimination of controllable variables, apart from 15 patients who had simultaneous mandibular advancement. Rigid fixation was adopted throughout the study. The mean surgical change documented was 7.42 mm. The mean stability calculated at 12 months revealed a relapse of 0.72 mm (10%). This was not significant (P = 0.3). We conclude that the Le Fort 1 advancement osteotomy is a stable and surgically predictable procedure that gives only slight relapse at 12 months.     

Anterior open-bite malocclusion: stability of maxillary repositioning using rigid internal fixation

A retrospective cephalometric study was performed to investigate the stability of 37 non-growing anterior open-bite cases using mini-plate rigid fixation. The sample was divided into two groups: Group A: maxillary repositioning alone (17 cases) and Group B: bimaxillary surgery (20 cases). Tracings were performed pre-operatively (T1), immediately post-operatively (T2) and at a minimum of one year follow-up (T3) (12-90 months). In Group A, the maxilla was advanced (3.8 +/- 2.8 mm, p < 0.01) and superiorly repositioned at PNS (2.8 +/- 2.3 mm, p < 0.001). In Group B, the maxilla was advanced (3.5 +/- 3.0 mm, p < 0.01) and superiorly repositioned at PNS (3.7 +/- 1.8 mm, p < 0.001); and the mandible (11.7 +/- 3.8 mm, p < 0.001), with no significant change in the vertical plane (p > 0.05). Late relapse due to condylar remodelling or resorption was found as a cause of large horizontal relapse (8.0 < x < 14.0 mm) in three cases (15%), the amount being associated with the amount of operative advancement (r = 0.7, r-sq = 40%, p < 0.01). It was concluded that the correction of anterior open bite by posterior repositioning of the maxilla using rigid fixation is a stable procedure during the follow-up period, and that in bimaxillary cases, post-operative stability depends largely on the stability of the mandibular advancement, which in turn relates to the amounts of advancement, the pre-operative anterior open bite and the mandibular plane angle.     

Stability of the hard and soft tissue profile after mandibular advancement in sagittal split osteotomies: a longitudinal and long-term follow-up study

The aim of the study was to conduct a long-term follow-up investigation of the stability of hard and soft tissues after bilateral sagittal split osteotomy (BSSO) with rigid internal (RIF) fixation to advance the mandible. Sixteen consecutive patients (12 females and 4 males, mean age 21.4 years) were available for re-examination 12.7 years (T5) after surgery. The preceding follow-ups were before (T1), and 5 days (T2), 7.3 months (T3), and 13.9 months (T4) after surgery. Lateral cephalograms were traced by hand, digitized, and evaluated with the Dentofacial Planner program. The x-axis for the system of co-ordinates ran through sella (point zero) and the line NSL -7 degrees. Thus, the program determined the x- and y-values of each variable and the usual angles and distances. Statistical analysis was carried out using Wilcoxon's matched-pair signed-ranks test with Bonferroni adjustments. The relationships between the examined variables were analysed by Spearman rank correlation coefficients. The backward relapse at point B (T5) was 2.42 mm, or 50 per cent, and at pogonion 3.21 mm, or 60 per cent of the initial advancement. The mean net effect at T5 on the labial fold (soft tissue point B) was 94 per cent of the advancement at point B. For the soft tissue chin (soft tissue pogonion), it was 119 per cent of the advancement at pogonion. The net effect on the lower lip (labrale inferior) was 55 per cent of the advancement at incision inferior. The amount of the surgical advancement of the mandible was correlated with the long-term relapse in point B. Among possible reasons for this relapse are the initial soft tissue profile, the initial growth direction, and the remodelling processes of the hard tissue.     

Long-term skeletal stability after surgical correction in Class III open-bite patients: a retrospective study on 40 patients treated with mono- or bimaxillary surgery

Many reports have paid attention to skeletal stability after orthognathic surgery, but only few focalize attention on patients with III class III malocclusion and open bite. In this article, long-term stability (2 yr) of the maxilla and the mandible after orthognathic surgery in 40 patients with class III malocclusion and anterior open bite is evaluated. The sample has been obtained from those 420 patients with class III malocclusion treated with Le Fort I osteotomy isolated (group A, 20 patients) or in association with bilateral sagittal split osteotomy (group B, 20 patients) from 1985 to 2003. On the basis of cephalometric analysis obtained in the immediate postoperative period and 2 years after surgery, in class III patients with anterior open bite treated with mono- or bimaxillary surgery and stabilization with rigid internal fixation, the maxilla was demonstrated to remain in the postsurgical position, whereas a moderate rate of mandibular relapse dependent on the amount of surgical alteration of the mandibular position was present.     

The stability of facial osteotomies. 4. Maxillary and mandibular (with or without chin) advancement with rigid internal fixation

The short-term (6 weeks postoperative) and long-term (12 months postoperative) horizontal skeletal stability of combined maxillary and mandibular advancement was evaluated by cephalometric analysis of 15 patients.
The mean horizontal advancement of the maxilla was 5.84 mm. Six weeks later a mean horizontal relapse of 0.03 mm (0.05%) was identified. The mean horizontal relapse at long-term follow-up was 0.59 mm (10.1%).
The mean horizontal advancement of the mandible was 12.35 mm at menton and 12.65 mm at pogonion. At 6 weeks, mean horizontal relapse, respectively at the above landmarks, was 0.11 mm and 0.21 mm (1.3%). The mean horizontal relapse at long-term follow-up was 2.19 mm and 1.98 mm (16.6%) respectively for the same landmarks.
Subjectively and objectively, improvements were seen in facial aesthetics and dental occlusion. The results indicate that rigid fixation of osteotomies undertaken to correct 'horizontal facial deficiency' is a surgically predictable and relatively stable procedure when reviewed up to 12 months after surgery.     

A comparison of stimulated bite force after mandibular advancement using rigid and nonrigid fixation

This study evaluated maximum stimulated molar bite force following advancement of the mandible in 17 adult Macaca mulatta using rigid and nonrigid fixation techniques. Cephalometric analysis was also performed to determine the amount of proximal segment rotation. Analysis of the bite force showed the animals whose mandibles were advanced using rigid fixation to have significantly greater bite force at six weeks postsurgery when compared to those animals who underwent mandibular advancement and six weeks of maxillomandibular fixation. By the ninth postoperative week, there was no longer any significant difference between the two groups, indicating a rapid recovery of muscle function in the animals whose mandibles were immobilized following advancement. Both groups, however, had significant decreases in bite force at 12 weeks postsurgery when compared to preoperative values. Neither group had a significant amount of proximal segment rotation from the surgery.     

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.