Mandibular advancement surgery in high-angle and low-angle class II patients: different long-term skeletal responses

Bilateral sagittal split osteotomies and mandibular distraction osteogenesis: a randomized controlled trial comparing skeletal stability

OBJECTIVE

To conduct a randomized controlled trial comparing the skeletal stability of bilateral sagittal split osteotomy (BSSO) and mandibular distraction ostoegenesis (MDO) for moderate mandibular advancement.

STUDY DESIGN

Fourteen class II mandibular hypoplasia patients requiring mandibular advancement between 6 and 10 mm were randomized into 2 groups for either BSSO or MDO. Serial lateral cephalographs were taken 2 weeks, 6 weeks, 12 weeks, 6 months, and 12 months after surgery for the assessment of skeletal stability. The Student t test was used to analyze stability with statistical significance set at P < .05.

RESULTS

There was no significant difference (P > .05) in horizontal and vertical skeletal relapse between the 2 groups at every postoperative time period.

CONCLUSIONS

Although the MDO group reported less horizontal and vertical skeletal relapse for mandibular advancements between 6 and 10 mm at 1 year, no statistically significance was found between the groups. Other patient-related factors need to be considered when choosing one technique over the other.

Orthodontic Treatment Combined with Mandibular Distraction Osteogenesis and Changes in Stomatognathic Function

We performed an orthodontic treatment combined with mandibular distraction osteogenesis in a 15-year-old patient who wanted a correction of a chin deficiency and a protruding upper lip. The patient had an Angle Class II division 1 malocclusion with mandibular retrusion, a low mandibular plane angle, and scissors bite. First, a quad-helix appliance was applied to the mandibular dentition to correct the scissors bite in the bilateral premolar region. Later, a preadjusted edgewise appliance was applied to the maxillary and mandibular teeth. After 3 days, a mandibular distraction osteogenesis was performed. During and after the distraction, the open bite between the upper and lower dental arches was corrected using up and down elastics. The total treatment time with the edgewise appliance was 14 months. A skeletal Class I apical base relationship, good facial profile, and optimum intercuspation of the teeth were achieved with the treatment. The jaw-movement pattern on the frontal view did not change during gum chewing. However, the maximum gap without pain increased. The electromyographic (EMG) activity of the masseter and anterior temporalis muscles, and maximum occlusal force increased. The present case report suggests that an orthodontic treatment combined with mandibular distraction osteogenesis in a patient with mandibular retrusion in the late growth period might be effective for improving stomatognathic function.

Stability of orthognathic surgery and distraction osteogenesis: options and alternatives

Relapse in orthognathic surgery is multifactorial and can be attributed to posttreatment growth, condylar changes, lack of rigid fixation, and muscle pull and function. Consideration of these factors can aide the surgeon in the decision-making process with regards to treatment options and alternatives. This article reviews the stability of various orthognathic movements using traditional osteotomies and fixation, and compares them to what is currently in the literature regarding distraction osteogenesis.

Soft-tissue changes in association with anterior maxillary osteotomy: a pilot study

INTRODUCTION

The purpose of this study was to investigate and predict soft-tissue changes in the forehead, nose, lips, and chin in association with anterior maxillary osteotomy.

MATERIALS AND METHODS

The sample consisted of 20 adult patients (seven men and 13 women, 29.1 years of age immediately before surgery). Both hard- and soft-tissue changes were evaluated using a set of lateral cephalograms taken immediately before and at 7 months after surgery. Pearson correlation coefficients were computed to examine the relationship between hard- and soft-tissue changes. A prediction model was developed using a multiple regression equation.

RESULTS AND DISCUSSION

The findings were as follows: (1) Hard-tissue changes were only observed in the maxillary region. Soft-tissue changes included backward displacement of the subnasale and the upper and lower lips. (2) The highest correlation coefficient was obtained between hard- and soft-tissue changes in the upper lip region. (3) The horizontal soft-tissue change in the upper lip region was predicted using a multiple regression equation. These results suggest that anterior maxillary osteotomy influences hard- and soft-tissue changes in the upper lip region and that the response in the horizontal dimension in association with surgery can be predicted.

Segment Stability in Bimaxillary Orthognathic Surgery After Resorbable Poly(L-lactide-co-glycolide) versus Titanium Osteosyntheses

This study compared segment stability after bimaxillary orthognathic surgery, comparing poly(L-lactide-co-glycolide) with titanium osteofixation at 12 months follow up. Fifteen patients were osteofixated with poly(L-lactide-co-glycolide) copolymer, 30 with 2.0-mm titanium miniplates. Preoperative, postoperative, and 1-year follow-up lateral cephalograms were analyzed. Maxillary average advancement in resorbable plate osteosyntheses (+/- standard deviation) was (case numbers/titanium controls) 2.5 (+/- 1.0) mm; n = 7/5.4 (+/- 3.5)mm; n = 21, setback 2.2 (+/- 2.4) mm; n = 7/1.9 (+/- 1.8) mm; n = 8, elongation 6.5 (+/- 3.4) mm; n = 9/3.7 (+/- 5.2) mm; n = 14, intrusion 1.0 (+/- 0.7) mm; n = 5/3.3 (+/- 2.7)mm; n = 13, mandibular average advancement was 5.5 (+/- 3.7) mm; n = 4/6.3 (+/- 8.8) mm; n = 18, setback 11.2 (+/- 7.7) mm; n = 7/7.2 (+/- 3.2) mm; n = 12, mandibular angle enlargement 7.9 (+/- 2.4) degrees ; n = 9/7.9 (+/- 6.6) degrees ; n = 21, reduction 6.9 (+/- 2.6) degrees ; n = 4/6.3 (+/- 6.6) degrees ; n = 9. Changes in landmark position within the study and control groups differed significantly in paired t testing (P =.01); operative movements were comparable in between study and control groups (P = 0.5, two-sided t test), only maxillary advancement was significantly smaller (P = 0.04) within study cases. Absolute instability at advanced A-point was (study group/controls) 1.2 (+/- 0.8)/2.4 (+/- 2) mm; setback 1.8 (+/- 1.9) mm/2.5 (+/- 1.7) mm; elongation at anterior nasal spine (ANS) 2.0 (+/- 1.4) mm/3.1 (+/- 3.6) mm, intrusion 1.1 (+/- 1.1) mm/2.2 (+/- 1.5) mm; advancement instability at B-point was 2.6 (+/- 2.7) mm/5.1 (+/- 8.2) mm, setback 2.7 (+/- 2.6) mm/1.7 (+/- 2) mm; mandibular angle enlargement instability 2.4 (+/- 2.7) degrees /8.2 (+/- 9.6) degrees , angle narrowing 7.0 (+/- 5.4) degrees /4.2 (+/- 5.9) degrees . Absolute postoperative instability was not significantly different in between study and control groups (P = 0.3). Tested resorbable poly(L-lactide-co-glycolide) osteofixation proved to be as reliable in segment fixation as titanium; however, study and control groups were not matched; the study group was small and therefore the results (especially advancement) have to be interpreted as preliminary until larger prospective cohorts become evaluated.

Alteration of the mandibular plane during sagittal split advancement: Short- and long-term stability

OBJECTIVES

We investigated predictors of long- and short-term stability of surgical mandibular advancements with bilateral sagittal split osteotomy (BSSO).

STUDY DESIGN

Class II patients (n = 127) received mandibular advancement through BSSO with either rigid internal fixation or wire osteosynthesis. We used multiple linear regression analysis to assess the association of predictor variables with post-treatment horizontal and vertical B-point movement through 2 years.

RESULTS

Counterclockwise rotation of the mandibular plane angulation (MPA) was associated with greater horizontal and vertical relapse at all time periods except 8 weeks. Wire osteosynthesis, larger advancements, younger age, and genioplasty were significantly associated with relapse.

CONCLUSIONS

Surgically closing the MPA is associated with late horizontal and vertical relapse, whereas fixation type is related to early B-point movement. Large advancements with forward and upward repositioning of the mandible, genioplasty, and young age also play a role in relapse after BSSO.

Distraction osteogenesis versus bilateral sagittal split osteotomy for advancement of the retrognathic mandible: a review of the literature

Bilateral sagittal split osteotomy (BSSO) and distraction osteogenesis (DO) are the most common techniques currently applied to surgically correct mandibular retrognathia. It is the responsibility of the maxillofacial surgeon to determine the optimal treatment option in each individual case. The aim of this study was to review the literature on BSSO and mandibular DO with emphasis on the influence of age and post-surgical growth, damage to the inferior alveolar nerve, and post-surgical stability and relapse. Although randomized clinical trials are lacking, some support was found in the literature for DO having advantages over BSSO in the surgical treatment of low and normal mandibular plane angle patients needing greater advancement (>7 mm). In all other mandibular retrognathia patients the treatment outcomes of DO and BSSO seemed to be comparable. DO is accompanied by greater patient discomfort than BSSO during and shortly after treatment, but it is unclear whether this has any consequences in the long term. There is a need for randomized clinical trials comparing the two techniques in all types of mandibular retrognathia, in order to provide evidence-based guidelines for selecting which retrognathia cases are preferably treated by BSSO or DO, both from the surgeon's and the patient's perspective.

Skeletal Stability in Bimaxillary Orthognathic Surgery: P(L/DL)LA-Resorbable versus Titanium Osteofixation

BACKGROUND

One-year skeletal stability following bimaxillary orthognathic surgery was assessed by comparing poly(L-lactide-co-DL-lactide) to titanium osteofixation.

METHODS

Thirty patients underwent osteofixation with poly(L-lactide-co-DL-lactide) copolymer and 30 had 2.0-mm titanium-miniplate osteosyntheses. Lateral cephalograms were analyzed preoperatively, postoperatively, and at 1-year follow-up. Average +/- SD values were as follows in resorbable plate-osteosyntheses (number of cases/titanium controls): for maxillary advancement, 3.5 +/- 4.1 mm (n = 19)/5.4 +/- 3.5 mm (n = 21); setback, 2.8 +/- 3.7 mm (n = 9)/1.9 +/- 1.8 mm (n = 8); elongation, 4.2 +/- 3.6 mm (n = 18)/3.7 +/- 5.2 mm (n = 14); and intrusion, 1.9 +/- 1.7 mm (n = 12)/3.3 +/- 2.7 mm (n = 13); for mandibular advancement, 4.6 +/- 3.6 mm (n = 10)/6.3 +/- 8.8 mm (n = 18); setback, 7.5 +/- 8.3 mm (n = 20)/7.2 +/- 3.2 mm (n = 12); enlargement of the mandibular angle, 11.8 +/- 9.9 degrees (n = 19)/7.9 +/- 6.6 degrees (n = 21); and reduction, 4.5 +/- 3.2 degrees (n = 9)/6.3 +/- 6.6 degrees (n = 9).

RESULTS

Preoperative to postoperative landmark positions within the study and control groups differed highly significantly (p = 0.008, paired t test), yet the amount of operative movement was comparable between the study and control groups (p = 0.5, two-sided t test). Absolute instability at the advanced A-point was (study group/controls) 2.3 +/- 1.8/2.4 +/- 2 mm, setback was 2.3 +/- 1.9 mm/2.5 +/- 1.7 mm, elongation at the anterior nasal spine was 3.8 +/- 3.1 mm/3.1 +/- 3.6 mm, intrusion was 2.1 +/- 1.9 mm/2.2 +/- 1.5 mm, advancement instability at the B-point was 4.9 +/- 4.3 mm/5.1 +/- 8.2 mm, setback was 3.0 +/- 2 mm/1.7 +/- 2 mm, mandibular angle enlargement instability was 6.7 +/- 8.9 degrees/8.2 +/- 9.6 degrees, and angle narrowing was 6.8 +/- 5.2 degrees/4.2 +/- 5.9 degrees. Absolute postoperative instability did not differ significantly between the study and control groups (p = 0.6).

CONCLUSIONS

Resorbable osteofixation as tested proved to be as reliable as titanium, but as the study and control groups were not matched, the results have to be interpreted as preliminary. Resorbable materials permitted clinically faster occlusal and condylar settling than standard titanium osteosyntheses, as bone segments showed slight clinical mobility up to 6 weeks postoperatively.

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.

Mandibular setback by sagittal split ramus osteotomy: a 12-year follow-up

Short- and long-term skeletal changes after mandibular setback were analyzed using bilateral sagittal split ramus osteotomy. Twelve patients who had undergone mandibular setback surgery between 1986 and 1990 were available for long-term cephalography on average 12 years after primary surgery. The mean amount of surgical setback had been 6.4 mm. After the first postoperative year, there was skeletal relapse of 1 mm at the B-point and pogonion (Pg), amounting to 14% of the initial skeletal setback. In contrast to condylar displacement and proximal segment rotation, osteotomy slippage was associated with positional changes at the B-point and Pg. From 1 to 12 years postoperatively, the B-point and Pg remained stable. Mandibular ramus and corpus length decreased 2.1 mm and 1.3 mm, respectively, indicating remodeling at the osteotomy sites and probably condylar resorption.

Mandibular advancement using a retrocondylar cartilage graft: a 20-year prospective study

We examined the outcome after a mean of 46 months (range 18-204) of 73 patients with severe mandibular retrusion who had surgical advancement of the mandible by a post-condylar cartilage graft. The extent of the mandibular advance and the change in position of the condyle were measured by a previously described cephalometric method. Tomograms of the temporomandibular joint (TMJ) were taken at defined intervals and any changes in the articulation recorded. The mandible was advanced by a mean (S.D.) of 9.8 (3.4) mm. The mean postoperative change recorded on the final cephalometric radiograph was 0.4 (4.7) mm forward (95% CI -0.70 to+1.50). The mandibular condyle was advanced horizontally by a mean 7.2 (2.1) mm and depressed vertically by a mean of 5.9 (2.6) mm. postoperatively the condyle relapsed horizontally by a mean of 1.5mm and moved vertically downward by a mean of 0.2mm. Eleven patients had substantial skeletal relapse. Eight patients were regarded as clinical failures. Skeletal relapse did not always lead to clinical failure because of compensatory mandibular growth. Changes in the condylar region, which contributed to relapse, included condylar absorption and remodelling (n=7) and absorption of the cartilage graft (n=6). There were no postoperative functional problems with the TMJ. We conclude that the post-condylar cartilage graft is a useful technique for the treatment of certain cases of mandibular retrusion. The postoperative morbidity was less than that reported after other techniques of mandibular advancement including distraction. Skeletal relapse was found in more cases than clinical results had suggested.

Long-term changes of hyoid bone and pharyngeal airway size following advancement of the mandible

OBJECTIVE

To determine long-term changes in hyoid bone position and pharyngeal airway size after mandibular advancement, including evaluation of the relationship between length of suprahyoidal musculature and skeletal relapse.

STUDY DESIGN

A cephalometric follow-up study (12 years) of 15 patients who underwent mandibular advancement surgery.

RESULTS

The final position of the hyoid bone was more posterior than it had been preoperatively. Suprahyoidal musculature continuously lengthened from preoperatively to 12 years postoperatively. Total skeletal relapse at B-point and pogonion correlated significantly with postoperative stretch of suprahyoidal musculature. The upper and middle pharyngeal airways were narrower than their preoperative values.

CONCLUSIONS

Mandibular changes influence hyoid bone position during the entire postoperative period, whereas stretching of suprahyoidal musculature seems to contribute to skeletal relapse. Mandibular advancement surgery alone possibly does not achieve a stable increase of pharyngeal airway size over a long-term period of 12 years.

Skeletal relapse after mandibular advancement and setback in single-jaw surgery

PURPOSE

The aim of this study was to identify contributing factors to skeletal relapse by analyzing cephalometric changes after bilateral sagittal split ramus osteotomy.

PATIENTS AND METHODS

This study included 60 consecutive patients who underwent either mandibular advancement (30 patients) or setback surgery (30 patients). There were 36 women and 24 men (mean age, 23 years). The radiographs of these patients taken immediately before operation, at 1 week, and 14 months postoperatively were studied. To analyze the influence of hyper- and hypodivergent facial patterns on the surgical outcome, the patients were divided into 3 groups according to the mandibulo-nasal plane angle. The position of the maxilla was also taken into account.

RESULTS

Measured at B-point, skeletal relapse was 1.3 mm (30%) after mean advancement of 4.4 mm and 0.8 mm (12%) after setback of 6.0 mm. The magnitude of the surgical movement correlated with skeletal relapse. However, the correlation was not linear. Advancement of greater than 7 mm is associated with an increased tendency to relapse (r=0.52), but setback of more than 12 mm with a decreased tendency (r=-0.95). The retrognathic patients with a high mandibulo-nasal plane angle (hyperdivergence) had 30% higher relapse rate. Patients with hypodivergent facial patterns had less relapse in both advancement and setback surgery.

CONCLUSION

Skeletal relapse was affected by magnitude of surgical movement and different facial patterns according to the mandibulo-nasal plane angle; however, influences of both factors were different between mandibular advancement and setback.

Stabilisation of sagittal split advancement osteotomies with miniplates: a prospective, multicentre study with two-year follow-up. Part II. Radiographic parameters

This prospective study implied a two-year follow-up on a group of patients that underwent a Bilateral Sagittal Split Osteotomy (BSSO) for advancement (n=222) of the mandible that were treated in seven institutions following the same treatment protocol. The aim of Part II of this study was to correlate the clinical findings on stability and relapse as reported in Part I (clinical parameters) of this series of articles with the cephalometric findings. The mean skeletal relapse at pogonion of the whole group after two years was 0.9 mm. The clinically stable group, however, had only 0.4 mm relapse, whereas the clinical relapse group showed a mean relapse of 3.3 mm. The findings underline a relationship between the amount of advancement and relapse. The tendency for both, horizontal and vertical movement is the same, i.e., the larger the surgery effect, the larger the relapse. The angle post plane/mandibular plane showed the highest explained variance 9%. Patients with a high mandibular plane angle may be more prone to relapse. The explained variance of all considered prognostic factors together, however, is small (13%). The findings of this study express that patients with a clinical stable occlusion after a BSSO advancement, stabilised with miniplates, have a minimal to no skeletal relapse as measured on the cephalometric radiograms. The clinically non-stable group, however, appeared to have considerable skeletal relapse.

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.

Mandibular osteotomies in patients with juvenile rheumatoid arthritic disease

OBJECTIVE

This retrospective study evaluates the results after orthognathic surgery in a group of patients with juvenile rheumatoid arthritis.

METHODS

The material comprised sixteen patients where genioplasty with or without bilateral sagittal split (BSSO) had been performed during a 10-year period between 1991 and 2000. The patients were recalled for follow-up examination and the clinical records and radiographs of the patients were analysed.

RESULTS

All patients reported an improved facial esthetics. Sixty-two% reported altered neurosensory dysfunction in the inferior alveolar nerve, but no patients reported altered feelings to interfere with function. Two patients reported reduction in pain in the TMJ from a score 10 and 7 in the VAS-scale preoperatively, to 0 after the orthognathic surgery. Eight of the patients reported this to be less uncomfortable compared to other surgical procedures because of their JRA. Ninety-four% noted a positive social change after the operation.

CONCLUSION

Orthognathic surgical treatment of the JRA patient improves the facial profile. The described procedures are safe and serious complications were not seen in our study.

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.