Postoperative stability following bilateral intraoral vertical ramus osteotomy based on amount of setback

Our aim was to evaluate the postoperative stability associated with differing degrees of mandibular setback and their relations after intraoral vertical ramus osteotomy (IVRO). We planned a retrospective cohort study of 94 patients (mean age (range) 23 (18–46) years) selected from a larger group who had been diagnosed with mandibular prognathism with or without facial asymmetry and who had mandibular setback by IVR osteotomy from 2004 to 2009. The preoperative, 7-day, and 12-month postoperative lateral cephalographs were measured to find out the degree of movement, and the vertical and horizontal positions of menton and pogonion were compared at different time points to measure stability. The mean (SD) setback was 10.5 (5.1) mm, with 0.8 (1.1) posterior relapse at 12 months. The mean surgical change of menton vertically was 3.0 (3.0) mm superiorly, with an additional 1.3 (1.05) mm at 12 months. The amount of posterior relapse was less as the amount of setback increased but not significantly so. The amount of setback therefore has minimal effects on anterior relapse, and cannot be considered singly as a variant that affects the degree of stability. The risk of anterior relapse is low even with a substantial degree of mandibular setback, so overcorrection is not necessary with the IVR osteotomy.     

Postoperative changes in mandibular prognathism surgically treated by intraoral vertical ramus osteotomy

This study investigated short- and long-term postoperative skeletal changes following intraoral vertical ramus osteotomy (IVRO) for mandibular prognathism, as determined from lateral cephalograms. The subjects were 20 patients with mandibular prognathism who had undergone surgical orthodontic treatment combined with IVRO. Lateral cephalograms were taken at six time points: 1 month before surgery, and 1 day, 3 months, 6 months, 1 year, and approximately 2 years after surgery. Intermaxillary fixation (IMF) with four monocortical screws was maintained for 1 week in all patients. Mean posterior movement of the menton (Me) was 5.9 mm at surgery. 3 months after surgery, the FMA and FH-CorMe angles had increased 6.3 and 6.2 degrees, respectively, indicating clockwise rotation of the distal segment of the mandible. This rotation was observed in all 20 patients, suggesting that postoperative rotation of the mandible in the postoperative short term is likely to occur after IVRO and could be considered an adaptation of the mastication system newly established by surgery. In the long term after IVRO, Me had moved anteriorly by only 0.9 mm and the relapse ratio was 15.3%. These findings suggest the excellent long-term stability of surgical orthodontic treatment combined with IVRO in patients with mandibular prognathism.     

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.     

Skeletal stability following maxillary impaction and mandibular advancement

The purpose of this study was to retrospectively evaluate the stability of combined Le Fort I maxillary impaction and mandibular advancement performed for the correction of skeletal Class II malocclusion. Twenty-nine patients, mean age 22.6 years, underwent bimaxillary surgery with rigid internal fixation. Standardised cephalometric analyses were performed using serial lateral cephalometric radiographs. The post-surgical follow-up was a minimum of 12 months, with a mean of 25.2 months. The maxilla was impacted by a mean of 4.3 +/- 3.3 mm, and horizontally advanced by a mean of 2.6 +/- 2.3 mm. The results demonstrated that the maxilla tended to move anteriorly and inferiorly but this was not significant in either horizontal or vertical planes (P > 0.05). The mean advancement of the mandible, at menton, was 10.7 +/- 5.6 mm, and in 14 cases (48.2%) menton was advanced greater than 10 mm. In 34.7% of the patients the mandible underwent posterior movement between 2 and 4 mm. In the vertical plane, gonion moved superiorly by a mean of 2.7 +/- 3.6 mm which was significant. Significant mandibular relapse was found to have occurred in five female patients, with high mandibular plane angles who had undergone large advancements of greater than 10 mm. In conclusion, the majority of patients undergoing bimaxillary surgery for the correction of skeletal Class II malocclusions maintained a stable result. However, a small number of patients, exhibiting similar characteristics, suffered significant skeletal relapse in the mandible secondary to condylar remodelling and/or resorption.     

Considerations in correction of mandibular protrusion by intra-oral vertical ramus osteotomy

This case report presents a case that underwent orthognathic treatment with intra-oral vertical ramus osteotomy (IVRO). The patient was a 19-year-old female with mandibular protrusion and severe maxillary anterior crowding. The overbite was +0.5 mm and the overjet −1.5 mm. She had orofacial pain and tenderness of the temporomandibular joints (TMJ) and surrounding muscles. The pre-surgical orthodontic treatment included the extraction of the maxillary right lateral incisor, maxillary right second premolar, maxillary left canine, mandibular left second molar and mandibular right second premolar. After 18 months of pre-surgical orthodontic treatment, the left and right sides of the mandible were set back 8 and 6 mm, respectively, via IVRO to improve mandibular protrusion. The total treatment period was 26 months. The patient showed the backward reaction of the mandible, which occurred after release of the maxillo-mandibular fixation. The usage of the Class II elastics during the post-surgical phase to maintain the overjet made the inclination of the maxillary incisors more lingual.     

Stability of intraoral vertical ramus osteotomies for mandibular setback: a longitudinal study

This study aimed to investigate the postoperative longitudinal skeletal changes and stability following intraoral vertical ramus osteotomies (IVRO) for orthognathic mandibular setback, and the possible risk factors that might affect the stability. A retrospective cohort study was conducted. Lateral cephalograms were analyzed for the predictor (magnitude of setback and adjunctive procedures) and outcome (stability of vertical and horizontal dimensions) variables at six time points. A total of 152 patients (mean age 24.2 years) were included in the study. Following IVRO, the mandible measured at B-point had moved a mean 0.50 mm posteriorly at 1 week after the removal of intermaxillary fixation (7 weeks postoperative); this was followed by progressive small anterior relapse. At 2 years postoperative, the mean relapse of the mandible after IVRO measured at B-point was 0.05 mm (standard deviation 1.14 mm), representing 0.7% of the mean surgical movement. Large setback (>8 mm) showed significantly higher relapse compared to small setback (<4 mm) at 2 years after surgery (P = 0.021). Patients who underwent adjunctive mandibular surgeries other than IVRO showed no significant differences in relapse compared to those who underwent IVRO alone. In conclusion, IVRO for mandibular setback is a stable procedure in the long term, with small relapse of 0.05 mm after 2 years.     

Postoperative stability of two common ramus osteotomy procedures for the correction of mandibular prognathism: A randomized controlled trial

The aim of this randomized controlled trial was to compare the skeletal stability between sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) in the treatment of mandibular prognathism. Patients presenting with mandibular prognathism and scheduled for orthognathic surgery were randomized into either the SSRO group or the IVRO group. Changes at B-point were assessed by serial tracing of lateral cephalograms, which were taken preoperatively, and at 2 weeks, 6 months, 1 year, and 2 years postoperatively. Ninety-eight patients were recruited, with 49 patients in each group. Between 2 weeks and 6 months postoperatively, there was significantly more surgical relapse in the horizontal direction (anterior movement) in the SSRO group when compared with the IVRO group (1.83 mm (SD 2.91 mm) vs 0.49 mm (SD 2.32 mm); p = 0.019). At 2 years, there was more surgical relapse in the horizontal direction in the SSRO group than in the IVRO group (0.27 mm (SD 0.34 mm) vs 0.10 mm (SD 0.29 mm); p = 0.014). There were also more absolute changes (irrespective of direction) at B-point in the SSRO group than in the IVRO group at postoperative 6 months, 1 year, and 2 years (p = 0.016, 0.049, and 0.045, respectively). The amounts of change at B-point as percentages of total mandibular setback were 1.3% and 3.5% in the IVRO group and SSRO group, respectively. There were no differences in vertical changes between the two groups at any time points. In conclusion, the horizontal stability at B-point was shown to be superior in the IVRO group compared with the SSRO group in the correction of mandibular prognathism during the 2-year follow-up. Although the exact clinical importance of this difference is unknown at this time, this possible benefit may be an important key factor when deciding which osteotomy technique to employ for mandibular setback.     

Evaluation of post-surgical relapse after mandibular setback surgery with minimal orthodontic preparation

BackgroundThe aim of this study was to evaluate of the patterns of post-surgical relapse after mandibular setback surgery with minimal orthodontic preparation (MS-MO).Materials and methodsThe subjects consisted of 15 patients with minimal pre-surgical orthodontic preparation (1.37 ± 1.69 months). Lateral cephalograms were taken in pre-surgical (T0), post-surgical 1 month (T1) and immediately after debonding (T2) stages. To evaluate the surgical changes (T1–T0) and the relapse (T2–T1), the linear and angular measurements were analyzed using paired t-test. Pearson's correlation coefficients of the horizontal and vertical relapses of Pog and Me to other measurements were calculated. Pog or Me in T1 were displaced rotationally on Ar-Pog or Ar-Me lines in T2 to evaluate the remaining surgical relapse except the rotational relapse from total relapse.ResultsThe mandible relapsed anteriorly 3.53 mm (Pog) and 4.00 mm (Me) and superiorly 2.72 mm (Pog) and 2.44 mm (Me). FH to Ar-Pog and FH to Ar-Me decreased by about 2°. Pure surgical relapses at Pog and Me, except rotational relapses, were about 0.5 mm anteriorly and inferiorly 0.8 mm.ConclusionThe vertical relapse might induce mandibular rotation with the horizontal relapse. For an accurate prediction after MS-MO, the rotational relapse might be considered.     

Postsurgical changes of mandible based on vertical dimension increase in Skeletal Class III deformities

The aim of this study was to evaluate the postsurgical mandibular changes after surgery based on vertical dimension increase in skeletal Class III deformities.Patients who underwent mandibular setback surgery for skeletal Class III malocclusion correction with surgery-first orthognathic treatment were enrolled in the study. Lateral cephalograms were obtained at initial visit, immediately after surgery, 6 months after surgery, and at post-treatment. Postsurgical change of the mandible based on the vertical dimension increase was estimated using a diagrammatic method before surgery and this amount was compared with the actual amount of mandibular forward movement at 6 months after the surgery, using a paired t-test and Bland–Altman plot.Thirty patients (16 men and 14 women; mean age, 22.6 years) with skeletal Class III deformities had undergone mandibular setback surgery with the surgery-first orthognathic treatment. Immediately after surgery, the mandible setback was 9.4 ± 3.7 mm at pogonion. Six months after surgery, the mandible moved forward at an average of 2.3 ± 1.5 mm which corresponded to the estimated value of 2.2 ± 0.9 mm. The estimated amount of postsurgical movement did not show a statistically significant difference from the actual value on paired t-test (p = 0.349). The Bland–Altman analysis showed that the difference between the two values was within the limits of agreement.The postsurgical changes based on vertical dimension increase in surgery-first orthognathic treatment might be predicted by using a diagrammatic method.     

Mandibular remodeling after bilateral sagittal split osteotomy for prognathism of the mandible.

PURPOSE: To describe the postoperative remodeling changes in the mandible after bilateral sagittal split osteotomy to correct mandibular prognathism. PATIENTS AND METHODS: Twenty patients who underwent bilateral sagittal split osteotomy for the correction of mandibular prognathism were studied for postoperative remodeling changes within the mandible. The 6-week, 1-year, and long-term postoperative cephalometric mandibular tracings of 12 patients were superimposed using the fixation wires as the stable reference points to demonstrate the specific locations of the intrabony remodeling. RESULTS: There was a general direction of remodeling at the condylion and gonion anteriorly and superiorly, while the B point and pogonion did not show much change in remodeling. At the condylion, 60% and 40% of the cases showed significant horizontal and vertical remodeling, respectively. At the gonion, 50% and 55% of the cases showed significant horizontal and vertical remodeling, respectively. No correlation was found between the remodeling changes at condylion and gonion and the surgical movement or relapse at B point and pogonion. There was a significant correlation between the observed horizontal relapse at gonion and the horizontal remodeling changes at this point showing that the postoperative displacement of this point is a result of both positional translocation and remodeling changes. CONCLUSION: The results of this study show that there are intrabony remodeling changes that occur in the mandible after sagittal split osteotomy and that these continue for a long period of time in some patients. This remodeling occurred more in the condylar and gonial areas, while the chin remained relatively stable.     

Bilateral sagittal split osteotomy for correction of mandibular prognathism: long-term results.

PURPOSE: To identify the long-term maxillomandibular changes after surgical correction of mandibular prognathism using bilateral sagittal split osteotomy (BSSO). PATIENTS AND METHODS: Twenty patients who underwent BSSO to setback the mandible and had cephalometric radiographs taken preoperatively and postoperatively at 6 weeks, 1 year, and long-term follow-up (mean, 28 months). The cephalograms were traced and measured to determine the operative and postoperative changes. Correlation analyses were performed to see the relationship between the magnitude of setback and the amount of long-term postsurgical change at B point and pogonion. RESULTS: The mean surgical setback was 8.2 mm at B point and 8.8 mm at pogonion. The mean long-term horizontal relapse was 2.3 mm (28.0%) at B point and 3.0 mm (34.1%) at pogonion. Out of 20 patients, 12 (60.0%) relapsed horizontally greater than 2 mm at B point and 13 (65.0%) at pogonion. The mean vertical surgical changes showed downward displacement of B point (2.3 mm) and pogonion (2.0 mm). The mean long-term vertical relapse was 1.6 mm (69.6%) at B point and 1.7 mm (85.0%) at pogonion. CONCLUSION: There was no correlation between the magnitude of setback and the amount of relapse at B point and pogonion. However, there was significant correlation between the magnitude of vertical, downward surgical displacement and the amount of vertical relapse at B point and pogonion. The majority of the maxillofacial changes occurred within 1 year postoperatively.     

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.     

Postoperative stability of bimaxillary surgery in Class III patients with mandibular protrusion and mandibular deviation: a frontal cephalometric study

The aims of this study into bimaxillary surgery were to investigate and compare the postoperative stability of deviated side (lengthened side) and non-deviated side (shortened side), the effect of the type of surgery performed in the mandible, and the changes in signs and symptoms of temporomandibular joint (TMJ) disorders before and after surgery. The sample consisted of 31 Class III patients in whom imbalance between the maxilla and the mandible were corrected by Le Fort I osteotomy combined with bilateral intraoral vertical ramus osteotomy (BIVRO group, n=9), bilateral sagittal split ramus osteotomy (BSSRO group, n=10), or IVRO and SSRO (IVRO+SSRO group, n=12). IVRO+SSRO and BIVRO are more effective in improving TMJ signs and symptoms. There was no significant post-surgical difference between deviated and non-deviated sides in any group. BIVRO and BSSRO showed excellent post-surgical stability on both sides; less was found in the IVRO+SSRO group. The IVRO+SSRO group showed greater transverse displacement in menton point than the BIVRO group. In conclusion, after bimaxillary surgery and in asymmetric patients there were no differences between deviated and non-deviated sides, BIVRO and BSSRO appear to be more stable than IVRO+SSRO.     

Neurosensory alterations and function of the temporomandibular joint after high oblique sagittal split osteotomy: an alternative technique in orthognathic surgery

The current most common technique for repositioning of the mandible, bilateral sagittal split osteotomy (BSSO), was first described by Obwegeser and Dal Pont in the early1960s, and has since been modified several times. However, there is always a risk of damaging the inferior alveolar nerve. We have studied 50 consecutive patients who had high oblique sagittal split osteotomy (HSSO) as an alternative to avoid damage to the nerve. The patients were evaluated for sensory alterations and function of the temporomandibular joint (TMJ). Healing of both wound and bone were complete and uneventful in all 50 patients. Mean (SD) sagittal movement of the mandible was 6.6 (2.9) mm and length of the osteotomy line was 11.0 (3.1) mm. No patient had either temporary or permanent alteration in sensitivity. Pinprick tests showed no significant changes between the preoperative and postoperative readings (p > 0.16) or in the chronological results (p > 0.23). No disorders of the TMJ developed. Mean (SD) mouth opening 6 months postoperatively was 41.6 (8.6) mm. The lateral excursion increased postoperatively by 1.86 mm to the left and by 0.76 mm to the right. Protrusion increased by 0.66 mm. HSSO is therefore a suitable alternative to BSSO as it avoids injury to the inferior alveolar nerve without compromising the TMJ. Ossification was uneventful though bony attachment was less than with the classic BSSO.     

Skeletal stability after simultaneous mandibular angle resection and sagittal split ramus osteotomy for correction of mandible prognathism.

PURPOSE: Simultaneous mandibular angle resection with bilateral sagittal split ramus osteotomy (BSSRO) is a useful modification of conventional BSSRO in patients with prominent mandibular angles. The purpose of this study is to prove whether simultaneous mandibular angle resection and BSSRO can influence the tendency of postoperative skeletal instability by means of shortening the pterygomasseteric sling. PATIENTS AND METHODS: This study was based on 26 cases of mandible prognathism. The experimental group consisted of 12 patients (average age, 24.6 +/- 3.9) who underwent BSSRO and mandibular angle resection simultaneously. Fourteen patients (average age, 21.4 +/- 3.4) served as a control group where only BSSRO was carried out. In lateral cephalometric tracings, horizontal and vertical changes of B point, pogonion, and menton were measured to determine the amount of postoperative instability. The amount of skeletal instability was compared between 2 groups. RESULTS: In the experimental group, point B and pogonion moved posteriorly 1.86 mm and 1.21 mm, respectively. In the control group they moved anteriorly 1.04 mm and 0.96 mm, respectively. CONCLUSIONS: Simultaneous mandibular angle resection and BSSRO proved to be a useful modification of the conventional BSSRO to reduce the tension in the pterygomasseteric muscle sling and to obtain more esthetic results clinically.     

3D mandibular positioning after rapid maxillary expansion in Class II malocclusion

This study investigated, using cone beam computed tomography (CBCT), the spatial mandibular positioning after rapid maxillary expansion (RME) in Class II Division 1 malocclusion. This prospective study evaluated 17 children (mean initial age 10.36 years old) presenting Class II, Division 1 malocclusion and skeletal maxillary constriction that underwent to RME Haas' protocol. CBCT was performed before treatment (T1), immediately after the stabilization of expander screw (T2) and after the retention period of 6 months (T3). The scans were managed in Dolphin Imaging? 11.0 software, where landmarks (right and left condylion, right and left gonion, and menton) were positioned and measured in relation to sagittal, coronal and axial plane to verify, respectively, transverse, anteroposterior and vertical displacement of the mandible. Paired Student's t-test was used to identify significant differences (p<0.05) between T1 and T2, T2 and T3, and T1 and T3. After RME, right and left gonion moved downward (1.11 mm and 0.89 mm) and menton displaced downward (1.90 mm) and backward (1.50 mm). During the retention period, only anteroposterior displacement was significant, with the right and left gonion (0.97 mm and 1.26 mm) and the menton (2.29 mm) moving forward. Three-dimensional assessment of the mandible in Class II Division 1 patients subjected to RME showed a transitory backward and downward mandibular positioning, without any lateral displacement. The 6-month retention period allowed the mandible shifting significantly forward, exhibiting a more anterior position compared with the initial condition, even remaining in a more downward direction.     

The correlation of maxillomandibular advancement and airway volume change in obstructive sleep apnea using cone beam computed tomography

The purpose of this retrospective study was to evaluate the correlation of maxillomandibular advancement (MMA) and airway volume changes in patients with obstructive sleep apnea (OSA), and to determine the surgical skeletal movements necessary to achieve an increase in total airway volume (TAV) of ≥70%. Thirty patients with OSA treated by MMA were evaluated. Pre- and postoperative cone beam computed tomography images were used to determine the horizontal distance and angular changes in surgical parameters and linear, area, and volumetric airway parameters. Postoperatively, the horizontal distance of surgical parameters (A-point, UI, B-point, pogonion, and menton) and craniofacial angulation (SNA and SNB) increased significantly, similar to total surface area, TAV, and minimum cross-sectional area of the airway (p < 0.0001). The total airway length decreased significantly (p < 0.0001). The mean increase in TAV was 67.2%. There were positive correlations between linear surgical changes and the percentage change in TAV. All surgical parameters were predictive of a change in TAV ≥70%. The optimal surgical change was 6 mm for A-point, 7.9 mm for UI, 7.6 mm for B-point, 11.2 mm for pogonion, and 10 mm for menton. In conclusion, maxillary advancement of less than 10 mm was adequate in this study to obtain an increase in the TAV of at least 70%.     

Factors contributing to relapse in rigidly fixed mandibular setbacks

The incidence of, and factors accounting for, relapse in 25 subjects who underwent mandibular setbacks via a bilateral sagittal split osteotomy with rigid fixation were studied. Fourteen had single-jaw operations, and the remaining 11 had concomitant maxillary procedures. Cephalometric radiographs were reviewed preoperatively, immediately postoperatively, and 6 months to 3 years after surgery. Relapse was defined as forward movement of pogonion during the postoperative period. No difference in the movement of the mandible in one- or two-jaw cases was noted. Even with excellent occlusal results, there was a tendency for the mandible (chin point) to rotate forward. In the one-jaw cases 43.7% relapse was noted, whereas 53.4% was seen in the two-jaw cases. A regression analysis showed that the magnitude of setback was the single factor that significantly predicted relapse in one-jaw cases, whereas alteration of the proximal segment accounted for relapse in two-jaw procedures. These results seem interrelated when considering alterations in the spatial arrangement of the muscular tissues and their attachments.     

Changes after surgically-assisted maxillary expansion (SARME) to the dentoalveolar, palatal and nasal structures by using tooth-borne distraction devices

Different devices are available to aid surgically-assisted maxillary expansion. In this study we have evaluated the changes to the anchoring teeth, the hard palate, and the lower nasal passage made by tooth-borne distraction devices. Thirty-one patients (mean (SD) age 28 (2) years) with deficiencies in the transverse width of the maxilla were examined by computed tomography and cone beam scans before and after operation. The data were analysed with the help of Wilcoxon's signed rank test and Spearman's r correlation. The mean (SD) distraction width was 6.5 (2.3) mm. All anchorage teeth were tilted (p < 0.01). The axes changed by a mean (SD) of 4.8 (0.9)° in the first premolar and 3.1 (0.8)° in the first molar. The nasal isthmus increased by a mean (SD) of 2.5 (0.3) mm. The hard palate adjacent to the anchoring teeth increased anteriorly by a mean (SD) of 2.8 (0.4) mm and posteriorly by 2.7 (0.4) mm. The hard palate was lowered by 1.2 (0.8) mm. There was a significant correlation in the distraction width, with changes in the intercoronal and interapical distances of the anchoring premolars (p < 0.05) and with the interapical distance of the anchoring molars (p < 0.01). There was also a correlation between the distraction width and the overall gain in width of the lower nasal passage (p < 0.05). The results suggested that surgically-assisted maxillary expansion with tooth-borne devices has significant effects on the anchoring teeth, the nasal floor, and the hard palate. Both tilting of the teeth and an evenly distributed movement of the segments were seen.     

Postoperative mandibular stability after orthognathic surgery in patients with mandibular protrusion and mandibular deviation

Skeletal stability and temporomandibular joint (TMJ) signs and symptoms were analyzed in 23 patients in whom mandibular protrusion and mandibular deviation had been corrected using bilateral sagittal split ramus osteotomy (BSSRO group, n = 10) and unilateral SSRO and intraoral vertical ramus osteotomy (USSRO+IVRO group, n = 13). Miniplate fixation was used in SSRO but no fixation was used in IVRO. The ratio of condylar bony change was 30.4% (7/23) and all condylar bony changes were seen on the deviated side. All preoperative signs and symptoms of TMJ disorders (4/13 patients in the USSRO+IVRO group and 2/10 patients in the BSSRO group) disappeared after surgery. Comparing the USSRO+IVRO group and the BSSRO group, in patients without condylar bony change, the mandible in both groups was stable anteriorly and horizontally after surgery, even though there was a larger horizontal mandibular movement in the USSRO+IVRO group during surgery. Comparing patients with condylar bony change versus no condylar bony change in the USSRO+IVRO group, postoperative horizontal mandibular displacement was significantly larger in the condylar bony change group than in the no condylar bony change group. These results support the idea that USSRO+IVRO can be useful in correcting mandibular deviation as well as improving signs and symptoms of TMJ disorders. However, it also seems important to be aware of the possibility of horizontal mandibular relapse in patients with condylar bony change.