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.     

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.     

A comparison of skeletal and dental changesbetween rigid and wire fixation for bilateral sagittal split osteotomy

For two years, this multisite prospective clinical trial examined longitudinalskeletal and dental changes after bilateral sagittal split osteotomy for mandibular advancement in which either rigid or wire fixation was used. Subjects in the rigid fixation group (n = 78) received 2-mm bicortical position screws, while the subjects in the wire fixation group (n = 49) received inferior border wires. Skeletal and dental changes were measured from cephalometric films taken immediately before surgery, one week after surgery, and at eight weeks, six months, one year, and two years after surgery. In both groups, the overbite and overjet increase with time, but were not different from each other. The B-point in the wire group progressively moved posteriorly, and at two years, it had relapsed 28%. In the rigid fixation group, there was a transient anterior movement of the B-point during the first six months and by two years after surgery, the B-point was unchanged from immediate post surgery. Dental changes occurred in both groups. These changes, however, were not able to accommodate the skeletal changes, resulting in similar increases in both overbite and overjet in both groups of patients. These results have implications for the orthodontists in management of the postmandibular advancement occlusion.     

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.     

Five-year outcome and predictability of soft tissue profiles when wire or rigid fixation is used in mandibular advancement surgery.

The purpose of this study was to follow the covariation of hard and soft tissue changes in Class II malocclusion subjects who received a bilateral sagittal split osteotomy. The subjects were randomized to receive wire or rigid fixation after the surgery. Subjects in the rigid group (n = 78) received 2-mm bicortical position screws, and those in the wire group (n = 49) received inferior border wires and 6 weeks of skeletal intermaxillary fixation with 24-gauge wires. Additionally, some subjects received genioplasty in both the rigid (n = 35) and the wire groups (n = 24). Soft and hard tissue profile changes were obtained from cephalometric films immediately before surgery and at various times up to 5 years postsurgery. Soft and hard tissue profile changes were referenced to a cranial-base X-Y coordinate system. Horizontal changes in mandibular incisor, lower lip, B-point, soft tissue B-point, pogonion, and soft tissue pogonion were calculated at each time. There was considerable skeletal relapse in the wire fixation group. Bivariate correlations and ratios between the hard and soft tissue changes were calculated for each time period. Hard to soft tissue correlations were the highest at the earlier times, although the ratios varied among the 4 groups. These results provide a solid basis for both short-term and long-term prediction.     

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 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.     

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.     

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%.     

Mandibular range of motion after bilateral sagittal split ramus osteotomy with wire osteosynthesis or rigid fixation

OBJECTIVES: An analysis was conducted to compare mandibular range of motion among Class II patients treated with wire osteosynthesis or rigid internal fixation after surgical mandibular advancement.Study Design: Patients randomly received wire osteosynthesis and 8 weeks of maxillomandibular fixation (n = 49) or rigid internal fixation (n = 78). Mandibular range of motion was measured 2 weeks before surgery and 8 weeks, 6 months, and 1, 2, and 5 years after surgery. RESULTS: Both groups showed decreased mobility in all movement dimensions that progressively recovered to near presurgical levels over the 5-year follow-up period. The difference in range of motion between treatment groups was not statistically significant. Changes in proximal and distal segment position could not explain decreased mobility. CONCLUSIONS: Similar decreases in mandibular mobility occurred with wire and rigid fixation of a bilateral sagittal split ramus osteotomy after surgery. Long-term changes were statistically, but not clinically, significant.     

Intraoral maxillary quadrangular Le Fort II osteotomy: a long-term follow-up study.

PURPOSE: This study evaluated the clinical outcome and skeletal stability of the intraoral maxillary quadrangular Le Fort II osteotomy (IQLO) with wire or rigid internal fixation following horizontal maxillary advancement. PATIENTS AND METHODS: All 21 patients who had undergone the IQLO were analyzed for operation time, blood loss, length of hospitalization, intraoperative and postoperative complications, and radiographic abnormalities. Lateral cephalometric radiographs were taken preoperatively (T1), postoperatively (T2) and late postoperatively (T3) to analyze skeletal movement. Two maxillary landmarks (posterior nasal spine [PNS] and A point) and 2 dental landmarks (the distobuccal cusp tip of the maxillary left second molar [2M] and the maxillary incisal tip [CI]) were used to determine horizontal and vertical changes for each time period. Student t test was used to evaluate early postoperative changes and late postoperative stability. In addition, 21 patients completed a questionnaire at the most recent follow-up visit regarding personal intentions, perceived outcome, and overall satisfaction. RESULTS: Twenty-one patients (9 females, 12 males) with an average age of 20.3 years diagnosed with horizontal maxillary-zygomatic deficiency underwent IQLO by 1 surgeon with an average follow-up of 6.3 years. Nine patients received mini-plate osseous segment fixation and 12 patients received wire osseous segment fixation. The mean time from surgery to the first postoperative radiograph (T2) was 4.4 weeks (range 1.0 to 6.7 weeks) and the mean time from surgery to the late postoperative radiograph (T3) was 6.2 years (range, 7.9 to 176.3 months). Statistical analysis of cephalometric landmarks revealed the following significant late postsurgical movements (T3-T2) for wire fixation: PNS moved 1.0 mm inferiorly (SD, 1.2), and 2M moved 1.5 mm inferiorly (SD, 2.2). The remaining cephalometric landmarks for rigid and wire fixation showed no statistically significant late postsurgical movement. Clinical outcome analysis revealed few complications, low surgical and postsurgical morbidity, and excellent patient satisfaction. CONCLUSION: The IQLO is a predictable procedure that exhibits long-term skeletal stability. Long-term retrospective review revealed low postsurgical morbidity and high patient satisfaction.     

Stability of skeletal Class III malocclusion after combined maxillary and mandibular procedures: titanium versus resorbable plates and screws for maxillary fixation.

PURPOSE: The aim of this study was to evaluate skeletal stability after double jaw surgery for correction of skeletal Class III malocclusion to assess if there were any differences between resorbable plate and screws and titanium rigid fixation of the maxilla. PATIENTS AND METHODS: Twenty-two Class III patients had bilateral sagittal split osteotomy for mandibular setback stabilized with rigid internal fixation. Low level Le Fort I osteotomy for maxillary advancement was stabilized with conventional titanium plate and screws in 12 patients (group 1) and with resorbable plate and screws in 10 patients (group 2). Lateral cephalograms were taken before surgery, immediately postoperatively, 8 weeks after surgery, and 1 year postoperatively. RESULTS: Before surgery both groups were balanced with respect to linear and angular measurements of craniofacial morphology. One year after surgery, maxillary stability was excellent in both groups. In group 1 no significant correlations were found between maxillary advancement and relapse. In group 2, significant correlations were found between maxillary advancement and relapse at A point and posterior nasal spine. No significant differences in postoperative skeletal and dental stability between groups were observed. CONCLUSION: Surgical correction of Class III malocclusion after combined maxillary and mandibular procedures appears to be a fairly stable procedure for maxillary advancements up to 5 mm independently from the type of fixation used to stabilize the maxilla. Resorbable devices should be used with caution for bony movements of greater magnitude until their usefulness is evaluated in studies with large maxillary advancements.     

Positional change of the hyoid bone after bilateral sagittal split osteotomy with rigid and wire fixation.

The purpose of this study was to compare positional changes of the hyoid bone and the amount of postsurgical compensation in mandibular position in patients who received either wire or rigid fixation after surgery. Data were analyzed from 97 patients (25 males and 72 females) who were randomized to receive wire (43) or rigid (54) fixation after mandibular advancement surgery as part of a multicenter clinical trial. Radiographs were digitized before surgery (T2), immediately after surgery (T3), and 8 weeks (T4), 6 months (T5), 1 year (T6), and 2 years (T7) after surgery. The wire group had greater sagittal relapse of the hyoid bone at T6 (P =.007), which persisted at T7 (P =.02). Both groups showed upward movement of the hyoid bone after surgery. There was no relationship between the vertical change in the the hyoid bone position and the vertical position of mandible (B point y coordinate, mandibular plane). However, there was a relationship between the horizontal hyoid bone position and B point during the postsurgical period (rigid, r = 0.450; wire, r = 0.517). The direct distance from the hyoid bone to basion increased (P <.001) in both groups at T3 and then recovered its original length after 8 weeks (P <.001). The rigid group showed no significant change in distance from the hyoid to the genial tubercles, but the wire group showed recovery of the muscle length at T6 (P <.05) and T7 (P <.05).     

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.     

Mandibular range of motion with rigid/nonrigid fixation

Decreased mandibular range of motion that followed orthognathic surgery and that was treated by wire osteosynthesis and 6 weeks of maxillomandibular fixation (MMF) has been previously documented. The present study evaluated maximum interincisal opening (MIO) in 49 subjects undergoing a bilateral sagittal ramus osteotomy (BSRO) with advancement or a BSRO with advancement and a concomitant LeFort I maxillary osteotomy with the patients having either rigid or nonrigid fixation. The group with rigid fixation had early function and mild physiotherapy. The nonrigid group had wire osteosynthesis, MMF that was maintained for 6 weeks, and no postoperative physiotherapy. Patients who underwent a BSRO with rigid fixation experienced a 3.5 mm decrease in MIO (6.9%). Those who had a BSRO and a LeFort I osteotomy with rigid fixation had a 3.3 mm decrease in MIO (6.6%). In contrast, nonrigidly fixed BSRO subjects had a 16.8 mm decrease (29.6%), while those who underwent a combined BSRO and LeFort I osteotomy had a 13.9 mm decrease (26.1%). This study showed that rigid fixation combined with early function and mild physiotherapy resulted in improved MIO postoperatively, as compared to the MIO in a group in which these treatments were not used.     

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.     

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.     

Stability of mandibular advancement after sagittal osteotomy with screw or wire fixation: a comparative study

Stability and clinical results in 70 patients who underwent bilateral sagittal ramus osteotomy for mandibular advancement were studied. The patients were grouped by the method of fixation (screws vs. wire) and matched for the amount of advancement. There were 35 patients in each group, and the age, sex, and presurgical mandibular plane angle distributions were similar for the two groups. Although the pattern of skeletal and dental changes during the first postsurgical year were quite different for the groups, stability, incisal opening, and clinical results were equivalent at 1 year following surgery. In the first 6 weeks postsurgery, the screw fixation group was more stable horizontally and vertically than the wire group, but between 6 weeks and 1 year, the wire group showed recovery, and the mean differences all but disappeared.     

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

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

Short- and long-term skeletal relapse after mandibular advancement surgery

This study analyzes short- and long-term skeletal relapse after mandibular advancement surgery and determines its contributing factors. Thirty-two consecutive patients were treated for skeletal Class II malocclusion during the period between 1986 and 1989. They all had combined orthodontic and surgical treatment with BSSO and rigid fixation excluding other surgery. Of these, 15 patients (47%) were available for a long-term cephalography in 2000. The measurement was performed based on the serial cephalograms taken preoperatively; 1 week, 6 months and 14 months postoperatively; and at the final evaluation after an average of 12 years. Mean mandibular advancement was 4.1 mm at B-point and 4.9 mm at pogonion. Representing surgical mandibular ramus displacement, gonion moved downwards 2 mm immediately after surgery. During the short-term postoperative period, mandibular corpus length decreased only 0.5 mm, indicating that there was no osteotomy slippage. After the first year of observation, skeletal relapse was 1.3 mm at B-point and pogonion. The relapse continued, reaching a total of 2.3 mm after 12 years, corresponding to 50% of the mandibular advancement. Mandibular ramus length continuously decreased 1 mm during the same observation period, indicating progressive condylar resorption. No significant relationship between the amount of initial surgical advancement and skeletal relapse was found. Preoperative high mandibulo-nasal plane (ML-NL) angle appears to be associated with long-term skeletal relapse.