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.     

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.     

Stability of mandibular advancement osteotomy using rigid internal fixation

Forty-three patients who underwent surgical lengthening of the mandible using an inverted L osteotomy, bone grafting, and rigid internal fixation between the mandibular segments were evaluated by retrospective cephalometric analysis for longitudinal skeletal and dental changes. Postoperative response (means = 1 year 9 months) was found to demonstrate a high level of stability with some individual variability. No propensity for relapse was observed in any postoperative time interval. Condylar repositioning postoperatively appeared to be an important factor in those patients who exhibited any relapse tendency. Overall postoperative stability of this surgical/fixation technique appears to be significantly improved compared with previously documented techniques.     

Stability associated with mandibular advancement treated by rigid osseous fixation

Relapse after a mandibular sagittal ramus split osteotomy (SSO) fixed by transosseous wire has been shown to occur. Authors who use rigid screw fixation claim a lesser incidence of such relapse. Nine subjects with horizontal mandibular deficiency treated by an SSO and fixed with bone screws were prospectively studied. Serial cephalometric radiographs were traced and superimposed on the sella-nasion line and anterior cranial base structures. A markedly reduced horizontal movement during the first six weeks at both points B and Pg, followed by a slight advancement at six months, was observed. Concomitantly, the surgically increased facial height was shown to subsequently decrease during both those time intervals. The stability of this procedure warrants further investigation.     

A comparative study of temporomandibular symptoms following mandibular advancement by bilateral sagittal split osteotomies: rigid versus nonrigid fixation

Rigid fixation to attach proximal and distal segments during bony healing of osteotomy sites has become increasingly popular. The effects of rigid fixation on the temporomandibular joints have been questioned. The purpose of this study was to evaluate the effects of rigid fixation after bilateral sagittal split osteotomies on temporomandibular dysfunction symptoms. Forty patients who had mandibular advancement surgery were evaluated for temporomandibular joint dysfunction. Twenty had received rigid fixation, and twenty had received nonrigid fixation. It was determined that there was no statistically significant difference in temporomandibular signs or symptoms between patients who were treated with rigid internal fixation for bilateral sagittal split osteotomies for mandibular advancement and those patients who were treated with nonrigid wire fixation.     

Relapse after rigid fixation of mandibular advancement

In 19 subjects rigid fixation of bilateral sagittal split osteotomies was used for mandibular advancement. Five angles and four linear measurements were determined cephalometrically for two time intervals: before surgery to immediately after surgery (T1-T2), and immediately after surgery to six months to one year after surgery (T2-TL). A multiple regression analysis with a backward stepping procedure was used to determine relationships between relapse, as defined by the position of pogonion at T2-TL (PgT2) and B point during this same time interval (BT2). The only significant predictor of PgT2 was PgT1 (P less than 0.001) (amount of advancement of pogonion during the time interval T1-T2). When BT2 was examined, both the change in position of B point at T1-T2 (P less than 0.001) and the change in anterior facial height at T1-T2 (P less than 0.02) were significant predictors of relapse. There were no other predictors of relapse. Advancements of 6 to 7 mm or greater as measured at B or Pg deserve special attention as they were more predisposed to relapse. Methods for preventing relapse are discussed.     

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 following combined maxillary and mandibular osteotomies treated with rigid internal fixation

Skeletal stability was examined in 16 patients following combined maxillary and mandibular osteotomies using rigid internal fixation. Postoperative changes (T2 to T3) were generally less than 1.0 mm for linear measurements and less than 2.0 degrees for angular measurements. The removal of maxillomandibular fixation (MMF) splints accounted for 85% to 95% of the counterclockwise rotation in the proximal and distal mandibular segments from T2 to T3. Maxillary inferior repositioning and large mandibular advancements exhibited the greatest tendency for relapse; however, the changes were less than with comparable procedures using nonrigid methods for stabilization. Except for large mandibular advancements, relapse was essentially unrelated to the magnitude of the surgical repositioning. Although the use of skeletal, maxillomandibular, and transosseous wire fixation have traditionally provided satisfactory clinical results, the use of rigid internal fixation in combined osteotomy procedures provides better stabilization of dentosseous segments when compared with these nonrigid methods, and may be particularly indicated in complex surgical procedures.     

Histochemical analysis of the masseter and temporalis muscles in macaca mulatta after mandibular advancement using rigid or nonrigid fixation

This study compared the histochemical characteristics of the temporalis and masseter muscles in monkeys who underwent mandibular advancement with and without immobilization of the mandible. The results showed, when compared with controls, that the animals who underwent maxillomandibular fixation (MMF) following advancement of the mandible had significant atrophy in both temporalis and masseter muscles. In contrast, much less myoatrophy was noted in the animals who underwent rigid internal fixation and no MMF following advancement of the mandible.     

Stability of maxillary advancement using rigid fixation and porous-block hydroxyapatite grafting: cleft palate versus non-cleft patients

This study was undertaken to evaluate the stability of maxillary advancement using bone plates for skeletal stabilization and porous block hydroxyapatite (PBHA) as a bone graft substitute for interpositional grafting in cleft and non-cleft patients. The records of 74 patients (41 females, 33 males) who underwent Le Fort I maxillary advancement using rigid fixation and PBHA interpositional grafting were evaluated retrospectively. All patients also underwent simultaneous sagittal split mandibular ramus osteotomies. Patients were divided into 2 groups for study purposes: group 1 consisted of 17 cleft palate patients and group 2 consisted of 57 non-cleft patients. Each group was further subdivided into 2 subgroups based on the concurrent vertical positioning of the maxillary incisors: groups 1a and 2a, where the maxilla underwent 3 mm or more of inferior repositioning, and groups 1b and 2b, where the maxilla underwent minimal vertical change (< or = 1 mm). Presurgery, immediate postsurgery, and longest follow-up lateral cephalometric tracings were superimposed and analyzed to calculate surgical change and long-term stability of results by assessing horizontal and vertical changes at point A, incisor superius, and the mesial cusp tip of maxillary first molar. The average follow-up time in group 1 was 37.9 months (range 12 to 136) and in group 2 was 28.77 months (range 17 to 88). Average maxillary advancement at point A was: group 1a, 5.4 mm; group 1b, 5.25 mm; group 2a, 5.48 mm; group 2b, 5.46 mm. Average relapse at point A was: group 1a, -0.75 mm; group 1b, -1 mm; group 2a, -0.47 mm; group 2b, -0.48 mm. Average horizontal and/or vertical relapse at the central incisors and first molars was 1 mm or less in group 1 and less than 0.5 mm in group 2. Although there was a slightly greater relapse in group 1, no statistically significant difference was observed between the groups. Maxillary advancement with Le Fort 1 osteotomies using rigid fixation and interpositional PBHA grafting during bimaxillary surgery is a stable procedure with good predictability in cleft and non-cleft patients, regardless of the direction of vertical maxillary movement.     

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.     

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.     

Simultaneous maxillary and mandibular orthognathic surgery stabilized by rigid internal fixation

Rigid internal fixation was used successfully in 111 consecutive cases in which both the maxilla and the mandible were mobilized simultaneously. The use of rigid fixation allowed for early mobilization of the mandible, which facilitated resumption of orthodontic therapy after surgery. The favorable short-term results achieved indicate the need to study the long-term stability of the technique.     

Stability of the Le Fort I osteotomy for maxillary advancement using rigid fixation and porous block hydroxyapatite grafting

PURPOSE: The purpose of this study was to evaluate the stability of maxillary advancement using bone plates for skeletal stabilization and porous block hydroxyapatite (PBHA) as a bone graft substitute for interpositional grafting. PATIENTS AND METHODS: The records of 78 patients (55 female, 23 male) with a diagnosis of anteroposterior maxillary hypoplasia were retrospectively evaluated. All patients underwent greater than 5 mm Le Fort I maxillary advancement with rigid fixation and PBHA interpositional grafting. The study sample was divided into 3 groups on the basis of the concurrent superior or inferior positioning of the maxillary incisors. Presurgery (T1), immediately postsurgery (T2), and longest follow-up (T3) lateral cephalometric tracings were superimposed to analyze for horizontal and vertical changes at the following landmarks: (1) point A, (2) incisal edge of the maxillary incisor, and (3) mesial cusp tip of maxillary first molar. RESULTS: The maxilla was inferiorly repositioned in 27 patients, superiorly repositioned in 21 patients, and advanced horizontally without a significant vertical change in 30 patients. All groups showed 0.5 mm or less horizontal and vertical relapse. There was no statistically significant difference between the 3 groups. CONCLUSIONS: Maxillary advancement with Le Fort 1 osteotomies by using rigid fixation and interpositional PBHA grafting is a stable and predictable procedure regardless of the direction of vertical maxillary movement.     

Comparison of postoperative stability of three rigid internal fixation techniques after sagittal split ramus osteotomy for mandibular advancement

IntroductionThe aim of this investigation was to compare the skeletal stability of three different rigid fixation methods after mandibular advancement.Material and methodsFifty-five class II malocclusion patients treated with the use of bilateral sagittal split ramus osteotomy and mandibular advancement were selected for this retrospective study. Group 1 (n = 17) had miniplates with monocortical screws, Group 2 (n = 16) had bicortical screws and Group 3 (n = 22) had the osteotomy fixed by means of the hybrid technique. Cephalograms were taken preoperatively, 1 week within the postoperative care period, and 6 months after the orthognathic surgery. Linear and angular changes of the cephalometric landmarks of the chin region were measured at each period, and the changes at each cephalometric landmark were determined for the time gaps. Postoperative changes in the mandibular shape were analyzed to determine the stability of fixation methods.ResultsThere was minimum difference in the relapse of the mandibular advancement among the three groups. Statistical analysis showed no significant difference in postoperative stability. However, a positive correlation between the amount of advancement and the amount of postoperative relapse was demonstrated by the linear multiple regression test (p < 0.05).ConclusionIt can be concluded that all techniques can be used to obtain stable postoperative results in mandibular advancement after 6 months.     

Electromyography of the suprahyoid musculature following mandibular advancement with and without rigid fixation

The purpose of this investigation was to determine if the activity of the suprahyoid musculature changes following advancement of the mandible and the use of rigid or nonrigid fixation. Ten monkeys underwent mandibular advancement; six underwent 6 weeks of maxillomandibular fixation (MMF), and four had rigid fixation without MMF. Electromyography (EMG) of the suprahyoid musculature was performed preoperatively, and at 3, 7, and 10 weeks postoperatively. The results of this study fail to demonstrate an increase in suprahyoid EMG activity following mandibular advancement. Furthermore, there were no differences between the groups with different types of fixation.     

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.