Skeletal stability following maxillary impaction and mandibular advancement

Stability of vertical dimension following total arch intrusion

BACKGROUND

The purpose of this study is to evaluate stability of vertical dimension following total arch intrusion using miniscrews by measuring the change during treatment and relapse amount after more than one year of retention.

METHODS

Thirty patients (6 men, 24 women) were included in this study. Lateral cephalographs were taken with conventional radiography at the start of treatment (T0), after treatment (T1), and at least one year after treatment (T2). The evaluation was performed by measuring changes of selected parameters during treatment and the extent of relapse after more than one year.

RESULTS

During total arch intrusion treatment (T1-T0), anterior and posterior teeth intruded significantly. The mean vertical distance between the maxillary posterior teeth and palatal plane was reduced by 2.30 mm (P < 0.001). The mean vertical distance between the maxillary anterior teeth and palatal plane was reduced by 2.04 mm (P < 0.001). The anterior facial height was also reduced by 2.70 mm (P < 0.001). During retention period (T2-T1), the vertical distance between the maxillary anterior teeth and the palatal plane significantly increased by 0.92 mm (P < 0.001). The anterior facial height increased by 0.81 mm (P < 0.01).

CONCLUSIONS

Anterior facial height significantly decreases after treatment. During retention period, relapse of AFH and maxillary anterior teeth observed. There was no correlation between initial amount of AFH, mandibular plane angle, or SNPog and posttreatment AFH relapse. However, there was a significant correlation between the amount of intrusion of anterior and posterior teeth achieved by the treatment and the extent of relapse.

Relapse in class II orthognathic surgery: a systematic review

OBJECTIVES

Relapse after orthognathic surgery seems to depend on diverse factors. Proffit et al. postulated in 2007 a "hierarchy of stability" (Head Face Med 6:66, 2007), ranking posttreatment stability after various orthognathic procedures, but no systematically reviewed evidence was provided. Therefore, the aim of this review was to investigate the extent of class II relapse in orthognathic surgery of Angle class II patients depending on the surgical procedure used.

MATERIALS AND METHODS

Seven databases were searched for randomized and controlled clinical trials to compare relapse in surgical procedures for Angle class II patients. After duplicate study selection, data extraction and risk of bias assessment were performed with the ROBINS-I tool as well as data synthesis by frequency distribution, followed by assessment of the quality of evidence with GRADE.

RESULTS

Four non-randomized cohort-studies with a total of 132 patients were included. Bimaxillary procedures as well mandibular advancement procedures proved to be highly stable. Single jaw interventions at the maxilla achieved mostly stable results at sagittal dimension and problematic stability in the vertical dimension. However, there were only limited data available with low quality of evidence.

CONCLUSIONS

Limited existing evidence of low quality partly support the postulated hierarchy of stability of Proffit et al. (Head Face Med 6:66, 2007) and indicates that a surgical correction of class II dysgnathia with bimaxillary procedures and mandibular advancement seems to be highly stable. However, additional studies are needed to address the relation between relapse and surgical orthognathic intervention. Trial registration PROSPERO 2019 CRD42019144873.

One-year stability of the mandibular advancement and counterclockwise rotation for correction of the skeletal class II malocclusion and high mandibular plane angle: Dental and skeletal aspect

Background

The purpose of this study was to evaluate the stability on dental and skeletal aspect after surgical advancement and counterclockwise rotation for the correction of the mandibular deficiency in patients with high mandibular plane angle (MPA).

Methods

We analyzed the records of patients who had undergone surgical treatment for dentofacial deformities with mandibular deficiency and high MPA. Clinical and radiological data were taken 1 month before surgery (T0), 6 weeks after surgery (T1) and 1 year after surgery (T2). Cephalometric values of the MPA were recorded and compared. The cephalometric changes in the different time periods were defined as follows: A: postsurgical changes (T0–T1), B: one-year changes (T1–T2), and C: short term changes (T0–T2).

Results

Twenty-seven patients had prominent mandibular deficiency with an MPA of over 35° (high angle). The mean age of patients at surgery was 29.7 years. Seven patients had a single jaw procedure, 20 patients had bilateral sagittal split osteotomy (BSSO) combined with a Le Fort I osteotomy, and 14 patients had additional genioplasty. MPA values differed significantly between the time periods (p < 0.05) with an observed relapse of the angle. However, satisfactory clinical improvement was achieved in the dental and skeletal presentation. The overjet improvement was evident from 8.815 ± 2.085 mm (T0) to 3.426 ± 1.253 mm (T2).

Conclusion

Counterclockwise surgical advancement of the mandible to correct mandibular deficiency in patients with a high mandibular plane angle showed an overall acceptable stability during one-year follow-up.

Bimaxillary surgery to correct high-angle class II malocclusion: does a simultaneous genioplasty affect long-term stability?

BACKGROUND AND OBJECTIVES

High-angle skeletal Class II malocclusion is one of the most challenging dentofacial deviations to treat and, in adults, a combination of orthodontic treatment and bimaxillary orthognathic surgery is often indicated. This study examines the rate of clinically significant relapse and whether a genioplasty affects the treatment outcome of high-angle Class II malocclusions.

MATERIAL AND METHODS

Cephalometric tracings of 36 consecutively treated high-angle Class II patients were evaluated from pre-surgery to 3 years post-surgery. All patients had undergone bimaxillary surgery (Le Fort I and BSSO), 13 of them had in addition a genioplasty.

RESULTS

The maxilla remained stable, whereas relapse (greater than or equal to 2 mm) of the mandibular advancement was seen in 40 per cent of the patients. Advancement greater than 10 mm increased the risk for horizontal relapse. The overjet was normalized and remained stable despite mandibular relapse. Half of the patients had an anterior open bite 3 years post-surgery. A supplemental genioplasty did not affect the relapse rate.

CONCLUSIONS AND IMPLICATIONS

Overjet was normalized and remained stable long term; there was an open bite in half of the patients. Combined orthodontic and bimaxillary surgical treatment of high-angle Class II patients showed skeletal relapse (greater than or equal to 2 mm) of the mandible in 40 per cent of patients. Mandibular advancement greater than 10 mm increased the risk for relapse. There was no increased risk for dental or skeletal instability associated with a genioplasty in combination with maxillary and mandibular surgery in the treatment of high-angle skeletal Class II malocclusion.

One-year postoperative skeletal stability of 3D planned bimaxillary osteotomies: maxilla-first versus mandible-first surgery

Orthognathic surgery is carried out to correct jaw deformities and to improve facial aesthetics. However, controversy surrounds whether the maxilla- or mandible-first surgery approach leads to better surgical outcomes. In our previous study, we have shown that in most instances, the maxilla-first surgical approach yielded closer concordance with the 3D virtual treatment plan than a mandibular-first procedure. However, the post-operative stability of each approach has not been investigated. Therefore, this one-year follow-up study was set-up and investigated the postoperative skeletal stability of the 3D planned translations and rotations after either the maxilla- or mandible-first surgery. In total, 106 patients who underwent bimaxillary surgery and had an individualized 3D virtual operation plans, received either maxilla-first (n = 53) or mandible-first (n = 53) surgery. 3D printed interocclusal splints were used during surgery to position the jaws. One year postoperatively a cone-beam computed tomography (CBCT) scan was made to assess the effects using the OrthoGnathicAnalyser. The mean sagittal, vertical and transverse relapse was less than 1.8 mm and no significant differences were found in relapse between the maxilla-first or the mandibular-first surgical procedure. Overall, this study shows that 3D virtual planning in combination with an optimised sequencing of osteotomies provides predictable long-term results in bimaxillary surgery.

Skeletal stability following mandibular advancement: is it influenced by the magnitude of advancement or changes of the mandibular plane angle?

Objectives

The aim of this study was to investigate the effects of advancement magnitude and changes in mandibular plane angle on the stability of mandibular advancement.

Materials and Methods

This retrospective cohort study evaluated the postoperative stability of mandibular advancement in class II skeletal subjects who underwent bilateral sagittal split osteotomy. Radiographs taken preoperatively, immediately postoperatively and 1 year postoperatively were traced and analyzed using linear and angular measurements. To determine horizontal and vertical relapse, an X-Y coordinate system was established in which the X-axis was constructed by rotating S-N downward by 7° (approximation of the Frankfort horizontal plane) and the Y-axis was defined as a line perpendicular to the X-axis and passing through the point Sella. For certain reference points including point A, point B, pogonion and menton, the perpendicular distance between each point and both axes was determined and cephalometric variables were recorded as X and Y coordinates.

Results

Twenty-five subjects were studied. A significant correlation between the amount of mandibular advancement and relapse in the B point (vertical and horizontal) and the pogonion point was observed (vertical and horizontal, P<0.001). Evaluation of data demonstrated a positive correlation between the mandibular plane angle (SN/ML) change and vertical relapse in the B point (P<0.05). A simple regression model demonstrated that 74% of horizontal relapse and 42.3% of vertical relapse in the B point was related to the amount of mandibular advancement. The receiver operating characteristic test showed that 8.5 mm mandibular advancement is related to a relapse rate of 1 mm or more in the pogonion, vertically or horizontally.

Conclusion

The magnitude of mandibular advancement is a stronger surgical predictor for horizontal rather than vertical relapse at the B point. Changes in mandibular plane angle (SN/ML) during surgery affect vertical, but not horizontal relapse at the B point.

Stability of Le Fort I Osteotomy With Propeller Graft for Canting Correction in Facial Asymmetry

The aim of this study was to evaluate the maxillary stability in patients who had undergone Le Fort I osteotomy with propeller graft and mandibular sagittal split ramus osteotomy for correction of maxillary asymmetry. This was a retrospective study on 15 facial asymmetry patients (7 men, 8 women: 22.2 years) requiring surgical correction at the preoperative (T0), immediately postoperative (T1) and 6 months after surgery (T2) stages. To evaluate the skeletal stability, computed tomography (CT) superimposition was used, and skeletal landmarks were measured and compared from the superimposed images according to an x, y, z coordinate system. The skeletal changes at each stage (ΔT1-T0 and ΔT2-T1) were compared by paired t-test (P<0.05). The obtained data on the skeletal changes immediately postoperatively to 6-month follow-up (ΔT2-T1) showed that the Le Fort I osteotomy with propeller graft had effected stable maxillary skeletal stability at the maxillary measurement points (posterior nasal spine (PNS ), nasopalatine canal, U3 crown tip, U3 root apex, and U6 furcation). These results suggested that in cases of facial asymmetry where the upper tooth exposure is proper and anterior-posterior movement of the maxilla is not much required, Le Fort I osteotomy with propeller graft is an effective method for stable canting correction.

Skeletal Stability after Large Mandibular Advancement (> 10 mm) with Bilateral Sagittal Split Osteotomy and Skeletal Elastic Intermaxillary Fixation

OBJECTIVES

The aim of the present study was to assess the skeletal stability after large mandibular advancement (> 10 mm) with bilateral sagittal split osteotomy and skeletal elastic intermaxillary fixation and to correlate the skeletal stability with the vertical facial type.

MATERIAL AND METHODS

A total of 33 consecutive patients underwent bimaxillary surgery to correct skeletal Class II malocclusion with a mandibular advancement (> 10 mm) measured at B-point and postoperative skeletal elastic intermaxillary fixation for 16 weeks. Skeletal stability was evaluated using lateral cephalometric radiographs obtained preoperative (T1), 8 weeks postoperatively (T2), and 18 month postoperatively (T3). B-point and pogonion (Pog) was used to measure the skeletal relapse and the mandibular plane angle (MP-angle) was used to determine the vertical facial type.

RESULTS

The mean advancement from T1 to T2 were 11.6 mm and 13.5 mm at B-point and Pog, respectively. The mean skeletal relapse from T2 to T3 was -1.3 mm at B-point and -1.6 mm at Pog. The nineteen patients characterized as long facial types, showed the highest amount of skeletal relapse (-1.5 mm at B-point and -1.9 mm at Pog).

CONCLUSIONS

The present study showed a limited amount of skeletal relapse in large mandibular advancement (> 10 mm) with bilateral sagittal split osteotomy and skeletal elastic intermaxillary fixation. Bilateral sagittal split osteotomy in combination with skeletal intermaxillary fixation can therefore be an alternative to distraction osteogenesis in large mandibular advancements.

TMJ response to mandibular advancement surgery: an overview of risk factors

Objective

In order to understand the conflicting information on temporomandibular joint (TMJ) pathophysiologic responses after mandibular advancement surgery, an overview of the literature was proposed with a focus on certain risk factors.

Methods

A literature search was carried out in the Cochrane, PubMed, Scopus and Web of Science databases in the period from January 1980 through March 2013. Various combinations of keywords related to TMJ changes [disc displacement, arthralgia, condylar resorption (CR)] and aspects of surgical intervention (fixation technique, amount of advancement) were used. A hand search of these papers was also carried out to identify additional articles.

Results

A total of 148 articles were considered for this overview and, although methodological troubles were common, this review identified relevant findings which the practitioner can take into consideration during treatment planning: 1- Surgery was unable to influence TMJ with preexisting displaced disc and crepitus; 2- Clicking and arthralgia were not predictable after surgery, although there was greater likelihood of improvement rather than deterioration; 3- The amount of mandibular advancement and counterclockwise rotation, and the rigidity of the fixation technique seemed to influence TMJ position and health; 4- The risk of CR increased, especially in identified high-risk cases.

Conclusions

Young adult females with mandibular retrognathism and increased mandibular plane angle are susceptible to painful TMJ, and are subject to less improvement after surgery and prone to CR. Furthermore, thorough evidenced-based studies are required to understand the response of the TMJ after mandibular advancement surgery.

Evaluation of relapse after orthodontic therapy combined with orthognathic surgery in the treatment of skeletal class III

INTRODUCTION

Multidisciplinary treatment of skeletal malocclusion by orthognathic surgery in addition to orthodontics is a routine strategy believed to offer good functional and esthetic outcomes. Postoperative relapse is, however, a problem. The present study was conducted to analyze the stability of outcomes achieved by surgical treatment of skeletal class III patients in terms of the rate and extent of relapses.

PATIENTS AND METHODS

A total of 30 patients who had undergone orthodontic treatment combined with orthognathic surgery were included. The primary inclusion criterion was a skeletal class III treated by mandibular setback (Obwegeser/Dal Pont) surgery alone or combined with maxillary advancement (Le Fort I) surgery. Analysis was based on one preoperative and two postoperative cephalograms per patient.

RESULTS

We observed relapse (defined, in accordance with Proffit, as changes >2 mm or 2°) at a rate of 24% after bimaxillary procedures, compared to a lower rate of 21% after mandibular setback procedures only. The relapse rate was 21% among patients who had undergone upper-jaw surgery versus 27% among those who had undergone lower-jaw surgery, which was statistically significant.

CONCLUSION

The majority of patients exhibited stable treatment outcomes. Maxillary advancement procedures were found to be less susceptible to relapse-resulting in more stable outcomes-and mandibular setback distances correlated positively with the degree of the relapse. No statistically significant differences were observed between the procedures conducted in both jaws versus in the lower jaw only, or in the extent of upper-jaw repositioning.

Surgical treatment modality for facial esthetics in an obstructive sleep apnea patient with protrusive upper lip and acute nasolabial angle

For patients with severe obstructive sleep apnea syndrome (OSAS), maxillomandibular advancement (MMA) offers a good treatment option by physically expanding the skeletal framework. However, facial esthetics can be aggravated by MMA in patients with OSAS who have a normally positioned maxilla, a protrusive upper lip, and an acute nasolabial angle. Therefore, surgical treatment planning should be customized according to diverse skeletodental and soft-tissue patterns to produce a favorable change in facial esthetics and sleep function in patients with OSAS. In this case report, good treatment results were achieved in a young female patient with OSAS and skeletal Class II, a normally positioned maxilla, a protrusive upper lip, and acute nasolabial angle by impaction of the maxilla, autorotation/advancement of the mandible, and advancement of the chin. A customized flowchart for surgical treatment planning in OSAS that considers facial esthetics was suggested.

A novel design of a computer-generated splint for vertical repositioning of the maxilla after Le Fort I osteotomy

OBJECTIVE

The objective of this study was to evaluate the efficacy of a novel tooth/bony-supported virtual splint design to control the maxillary vertical, rotational, and anteroposterior intraoperative movements.

STUDY DESIGN

A tooth/bone-borne splint was designed to position the osteotomized maxilla intraoperatively. Lateral cephalometric radiographs were obtained 1 week before the operation and 1 week after to compare the planned and actual movements of the maxilla.

RESULTS

The paired t test showed no significant difference between the planned and actual movements in both the vertical and horizontal measurements (P ≤ .05). The difference between the planned and actual horizontal movements in 4 (66.7%) of the 6 patients was 1 mm or less. For the vertical movements, 5 (83.3%) of the 6 patients showed a difference equal to or less than 1 mm.

CONCLUSIONS

The 2-piece surgical stent showed accurate control on the osteotomized maxilla and succeeded its repositioning to the preplanned positions.

The impact of functional jaw orthopedics in subjects with unfavorable Class II skeletal patterns

OBJECTIVE

To evaluate the outcomes of functional jaw orthopedics (FJO) followed by fixed appliances in Class II patients showing cephalometric signs predictive of unfavorable responsiveness to orthopedic treatment.

MATERIALS AND METHODS

A total of 48 treated subjects (20 males, 28 females) with unfavorable Class II malocclusions were treated with FJO at the adolescent growth spurt, followed by fixed appliances. Treatment outcomes were compared with the growth changes in a matched control group of untreated subjects with "unfavorable" Class II malocclusions.

RESULTS

A significant prevalence rate of successful outcome was recorded within the treated group (64.5%). When compared with the untreated controls, both the overall treated group and the successful treated subgroup revealed a significant reduction in maxillary growth and sagittal position, along with a significant enhancement in mandibular length, sagittal advancement of the mandible, and significant improvements in the maxillo-mandibular relationships. Both overjet and molar relation showed significant favorable changes in the treated group.

CONCLUSIONS

FJO at the pubertal spurt followed by fixed appliances is a viable therapeutical option in patients with "unfavorable" Class II malocclusions, although skeletal changes are of minor entity.

Changing skeletal pattern by means of osteogenesis distraction: a new therapeutic approach to patients with dysmorphism

The correction of class II high-angle open-bite in patients is difficult to achieve by traditional and conventional techniques in occlusal stability and function. The authors propose a new approach to a patient with dysmorphism (class II, short ramus, and open bite) using distraction osteogenesis to change the skeletal pattern of patients with high-angle class II to low-angle class III before undergoing traditional orthognathic surgery. This new approach is based on osteogenesis distraction, emphasizing planning and surgical procedures.

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.

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.

The effects of guided tissue regeneration (GTR) on modified Le Fort I osteotomy healing in rabbits

Osteogenesis following surgery depends on the osteoblasts at the wound site. Fibrous nonunions may be the result of differential and rapid migration of fibroblasts compared to osteoblasts into the wound. The present study was designed to test this hypothesis through the use of guided tissue regeneration (GTR) in a rabbit model. Bilateral, Le Fort I osteotomies (n=20) were produced in the maxillae of 10 New Zealand White rabbits. The segments were advanced 6mm and rigidly fixed using microplates and screws. One side was covered with a resorbable collagen membrane or left uncovered. Rabbits were followed for four weeks with radiographs and the maxillae were harvested for histology. Cephalometry revealed that membrane-covered defects had significantly (P<0.01) reduced defect area (by approximately 70%) compared to uncovered defects. Histologically, membrane-covered defects showed more organized osteogenesis and less fibrous tissue than uncovered defects. Histomorphometry revealed that membrane covered defects had significantly (P<0.05) reduced defect areas (by approximately 20%) compared to uncovered defects. While findings suggest that GTR can facilitate osseous wound healing in Le Fort I osteotomies, results also caution against relying exclusively on two-dimensional radiography to assess bony wound healing in lieu of three-dimensional imaging and evaluations.