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 the mandible after advancement and use of dental plus skeletal maxillomandibular fixation: an experimental investigation in Macaca mulatta

This study examined short-term stability of the mandible following advancement surgery and the use of skeletal suspension wires plus dental maxillomandibular fixation. Twenty-four adult female Macaca mulatta underwent bilateral sagittal ramus osteotomy and advancement of approximately 6 mm. All animals had dental maxillomandibular fixation secured by bonding the upper and lower teeth together with an orthodontic composite resin. In half of the animals, the use of circummandibular wires connected to pyriform aperture wires were additionally applied. Tantalum bone markers were placed and cephalograms analyzed during the first six postoperative weeks to evaluate skeletal stability. A statistically significant mean horizontal relapse at the mandibular symphysis occurred in the group without the skeletal wires, whereas no relapse occurred in the group with the skeletal wires. A significant difference in the vertical displacement of the anterior mandible occurred, with an inferior movement of the symphysis in the group without skeletal wires, and a superior movement of the symphysis in the group with skeletal wires. The results of this study indicate that the use of skeletal suspension wires is advantageous in the prevention of horizontal and vertical skeletal relapse.     

Relapse following mandibular advancement with dental plus skeletal maxillomandibular fixation

This study examines the short-term stability of the mandible following mandibular advancement surgery in which skeletal suspension wires were used in addition to dental maxillomandibular fixation. Twenty adults underwent sagittal ramus osteotomies. No concomitant surgical procedures were performed. Maxillomandibular fixation consisted of wiring between the upper and lower orthodontic brackets and circummandibular wires connected to the piriform aperture or anterior nasal spine wires for eight weeks. Cephalograms were analyzed during this period to evaluate skeletal stability. A statistically insignificant mean horizontal relapse of 8.9% was found at pogonion during the period of fixation. Significant vertical intrusion of the anterior mandible occurred, however, with a mean superior movement of pogonion of 0.83 mm (P less than or equal to 0.05). Dental changes noted were uprighting of the maxillary incisors and flaring of the mandibular incisors. In comparison with the results of other studies in which dental maxillomandibular fixation was used alone, the results of this study indicate that the use of skeletal suspension wires is advantageous in the prevention of horizontal skeletal relapse.     

Mobility of the mandible following advancement and maxillomandibular or rigid internal fixation: an experimental investigation in Macaca mulatta

This study examined the postsurgical range of mandibular motion following sagittal advancement osteotomy in Macaca mulatta when either maxillomandibular or rigid osseous fixation were used. Seventeen adult female Macaca mulatta underwent sagittal advancement osteotomy of approximately 4 to 6 mm. Six had 6 weeks of maxillomandibular fixation and eleven had rigid osseous fixation with no maxillomandibular fixation. Mandibular range of motion was measured by the change in the angle of the posterior aspect of the mandibular ramus from a closed-mouth and an open-mouth cephalogram. Parametric tests were used to statistically analyze the results. The results of this investigation showed that the animals who did not undergo maxillomandibular fixation maintained a greater range of motion in the early postsurgical period and obtained preoperative mobility by 12 weeks postsurgery. The animals who underwent six weeks of maxillomandibular fixation showed statistically significant decreases in range of motion when compared to the rigid fixation group at each period of time postsurgery, with significant reductions from preoperative values at 12 weeks postsurgery.     

A comparative study of skeletal and dental stability between rigid and wire fixation for mandibular advancement

This study examined the skeletal and dental stability after mandibular advancement surgery with rigid or wire fixation for up to 2 years after the surgery. Subjects for this multisite, prospective, randomized, clinical trial were assigned to receive rigid (n = 64) or wire (n = 63) fixation. The rigid cases received three 2-mm bicortical position screws bilaterally and elastics; the wire fixation subjects received inferior border wires and 6 weeks of skeletal maxillomandibular fixation with 24-gauge wires. Cephalometric films were obtained before surgery, and at 1 week, 8 weeks, 6 months, 1 year, and 2 years after surgery. Skeletal and dental changes were analyzed using the Johnston's analysis. Before surgery both groups were balanced with respect to linear and angular measurements of craniofacial morphology. Mean anterior advancement of the mandibular symphasis was 5.5 mm (SD, 3.2) in the rigid group and 5.6 mm (SD, 3.0) in the wire group. Two years after surgery, mandibular symphasis was unchanged in the rigid group, whereas the wire group had 26% of sagittal relapse. Dental compensation occurred to maintain the corrected occlusion, with the mandibular incisor moving forward in the wire group and posteriorly in the rigid group. However, at 2 years after surgery, when most subjects were without braces, the overjet and molar discrepancy had relapsed similarly in both groups.     

Mandibular advancement: skeletal and dental changes during fixation.

Skeletal and dental changes that occurred during maxillomandibular fixation after surgical advancement of the mandible were examined in 21 patients. Serial cephalometric monitoring showed skeletal relapse with compensatory dental changes in every case; the pattern of relapse varied. Common hypotheses currently expressed and applied by clinicians for presurgical prediction of such treatment results were objectively assessed for validity on the basis of the patient sample studied. The findings indicate that single variables cannot be isolated as being solely responsible for specific postsurgical changes.     

Stability of extraoral vertical ramus osteotomy: plate fixation versus maxillomandibular/skeletal suspension wire fixation

The objective of this cephalometric study was to evaluate skeletal stability and time course of postoperative changes in 2 groups of mandibular prognathism patients following extraoral oblique vertical ramus osteotomy (VRO). One group (n = 22) received maxillomandibular fixation and skeletal suspension wires (MMF group) for a period of 8 weeks. In the other group (n = 22), the segments were rigidly fixed with plates and the patients were allowed to function immediately after surgery. Lateral cephalograms were taken on 5 occasions: immediately presurgical, immediately postsurgical, 8 weeks postsurgical, 6 months postsurgical, and 1 year postsurgical. During the first 8 weeks after surgery, the MMF group demonstrated posterior movement of the mandible, with an increase in mandibular plane angle, shortening of the rami, and dental compensations. Upon release of MMF and skeletal suspension wiring, a small anterior relapse tendency was observed, but the net setback 1 year after surgery was still greater than the actual surgical setback. In the plate fixation group, postoperative changes were mainly in the form of a small anterior relapse tendency in the range of 10% of the surgical setback. The results indicate that the use of plate fixation with VRO, while eliminating the inconvenience for the patient of several weeks of MMF and preventing the early side effects observed in the MMF group, also resulted in a more predictable surgical procedure, with excellent stability 1 year after surgery.     

Adaptation of the suprahyoid muscle complex to large mandibular advancements

The purpose of this study was to provide quantitative data concerning the changes and adaptations that take place within the suprahyoid complex to larger mandibular advancements. Mandibular advancement of 6.5 mm was performed on 12 adult rhesus monkeys. Six underwent maxillomandibular fixation (MMF) using the dentition, six underwent MMF using the dentition plus skeletal suspension wires. Mandibular position and changes in the length of the various anatomic regions of the suprahyoid complex were evaluated cephalometrically with the aid of radiopaque bone, muscle, and tendon markers implanted preoperatively. Relapse of the mandible in the dental MMF animals was 27% of the advancement, whereas there was none in the dental plus skeletal MMF group. Results of adaptations within the suprahyoid complex showed that 1) the suprahyoid complex was elongated slightly less than the mandible, and 2) the major adaptations (lengthening) occurred at the muscle-bone interface, the muscle-tendon interface, and within the belly of the anterior digastric muscle. On the basis of these results, it was concluded that adaptations within the suprahyoid complex to mandibular lengthening occur first at the connective tissue attachments of the muscle, and then within the muscle belly itself. The methods of dealing with the potentially distracting forces from the stretch within the suprahyoid complex are discussed.     

Maxillomandibular growth 2 years after mandibular advancement surgery with and without suprahyoid myotomy in juvenile Macaca mulatta

There is conflict in the literature on whether continued and harmonious growth occurs after mandibular advancement in growing persons. The studies available are difficult to interpret because of the differing age ranges and the questionable growth potential inherent within the mandibular deficient patient. This study was performed to isolate the major question of interest to clinicians: Does the mandibular advancement surgical procedure inhibit future growth in a normally growing person? Six juvenile male Macaca mulatta monkeys were divided equally into two experimental groups. Group MAA had mandibular advancement surgery of approximately 4 mm. Group MAD had a similar surgical procedure with detachment of the suprahyoid musculature. All underwent 4 to 5 weeks of maxillomandibular fixation. Serial computerized cephalograms with the aid of bone markers were used to analyze the changes during a 2-year follow-up period. The postsurgical changes of the two experimental groups were compared statistically with control growth data on a large sample of normal Macaca mulatta animals available in our laboratory. The results showed the following. (1) There were significant short-term differences in the stability of the mandibular advancement between experimental groups. Group MAA (suprahyoid musculature attached) experienced significant relapse during the period of maxillomandibular fixation. Group MAD (suprahyoid musculature detached) experienced no relapse. (2) During the 2-year follow-up period after fixation, the rate and amount of mandibular growth in both experimental groups were not significantly different from age-matched controls or from each other. (3) At the end of the 2-year experimental period, the advanced mandibles were longer than the mandibles in age-matched controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

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 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.     

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.     

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.     

A comparative study of bicortical screws and suspension wires versus bicortical screws in large mandibular advancements

Relapse with large mandibular advancements treated by bicortical position screws has been documented in the literature. This study compares stability seen with two groups of patients; one treated with bicortical position screws and allowed to function, the second treated with bicortical position screws, skeletal wires, and 1 week of maxillomandibular fixation. Both groups had large advancements. The screw group was advanced an average of 10.9 mm, whereas the screw and wire group was advanced 12.2 mm. The screw group relapsed an average of 2 mm in the first 6 weeks, with further relapse occurring after that point. In contrast, the screw and wire group relapsed an average of 0.6 mm in the first 6 weeks, followed by a small advancement in the long term. Differences between the two groups were significant in the first 6 weeks and from the initial postoperative period to the long-term examination point. While stability was markedly improved with up to 13 mm of advancement in the group with screws and wires, relapse was noted after that amount of advancement. Methods to keep larger advancements stable are reviewed.     

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.     

Osseous healing of the sagittal ramus osteotomy: a histologic comparison of rigid and nonrigid fixation in Macaca mulatta.

Twenty-three adult female rhesus monkeys underwent advancement of the mandible by the sagittal split ramus osteotomy. Twelve had the proximal and distal segments wired together and underwent 6 weeks of maxillomandibular fixation (MMF). Eleven animals had bicortical bone screws placed between the segments and no postsurgical MMF. The animals were killed at 6 and 12 weeks and the osteotomy sites were prepared for histologic examination. Overall, the results showed that the two groups of animals underwent markedly different patterns of osseous healing. The osteotomy sites in the MMF animals were filled with callus, which then formed bone. In contrast, no callus was found in the majority of the rigid fixation osteotomy sites; direct bony deposition was found instead. The results of this investigation show that, like long bones, the sagittal osteotomy can heal by direct or indirect means depending on the rigidity of the fixation.     

Stability two years after mandibular advancement with and without suprahyoid myotomy: an experimental study

Ten adult rhesus monkeys underwent mandibular advancement surgery of 4-6 mm with and without suprahyoid myotomy. Serial lateral cephalograms using radiopaque bone markers were obtained during maxillomandibular fixation and for 96 weeks after release of fixation to determine the effects of suprahyoid myotomy on short-term and long-term adaptations in the advanced mandible. The non-myotomy group exhibited a significant reduction in the length of the advanced mandible (relapse) during the fixation period but showed no significant change in mandibular length after release of fixation. The myotomy group exhibited no relapse during the fixation period and after release of fixation displayed a slight but statistically significant increase in mandibular length. This supports the hypothesis that stretching of the suprahyoid musculature as a result of mandibular advancement surgery is a major factor leading to skeletal relapse.     

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.