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

Surgical Treatment of Dentofacial Deformities Caused by Juvenile Idiopathic Arthritis

The purpose of our retrospective study was to evaluate the results of orthognathic treatment, distraction osteogenesis, and/or prosthetic reconstruction of the temporomandibular joints in patients with juvenile idiopathic arthritis (JIA).Twelve patients with severely affected temporomandibular joints (TMJs) and reduced ramus height were treated with mandibular advancement with orthognathic surgery (11) and additional bilateral or unilateral mandibular ramus distraction (3) or additional bilateral or unilateral prosthetic reconstruction of the TMJ (3). One patient was treated surgically with bilateral TMJ prosthetic reconstruction only. The patients were followed up clinically and radiologically with emphasis on healing, TMJ function, stability of the occlusion, skeletal stability, and facial appearance for an average of 2.3 years after the final surgery. The mean mandibular advancement was 10.1 mm. The mean relapse at pogonion was 2.1 mm, which represents 20.8% of the surgical advancement. The occlusion was stable in 11/12 patients. The TMJ function was good and the facial esthetics improved in all patients. Orthognathic treatment and mandibular ramus distraction osteogenesis provide beneficial lengthening of the mandibular body in JIA patients with asymptomatic and stabile condyles. In adult patients with relapse of the disease or postoperative condylar relapse prosthetic total joint replacement is a reliable and safe alternative.

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.

Changes in posterior airway space and hyoid bone position after surgical mandibular advancement

OBJECTIVE

To evaluate cephalometric changes in posterior airway space (PAS) and in hyoid bone distance to mandibular plane (MP) 1-3 years after bilateral sagittal split osteotomy (BSSO).

MATERIAL AND METHODS

The sample consisted of 36 females and 16 males who underwent mandibular advancement by BSSO. To observe sagittal changes in PAS and in hyoid bone distance to MP both pre- and postoperative cephalograms were analyzed using WinCeph^® 8.0 software. For the statistical analyses paired T-test and multivariate logistic regression models were used.

RESULTS

By the surgical-orthognathic treatment the sagittal dimension of PAS showed variable changes but it mainly diminished when the mandibular advancement exceeded 6 mm. In most cases the hyoid bone moved superiorly by BSSO. Logistic regression models showed that males, patients with narrow PAS at the baseline, and those with counterclockwise rotation of the mandible by the treatment gained more increase in PAS. However, an increase in sagittal PAS dimension tended to relapse over time. Concerning the movement of the hyoid it was found that the more PAS increased the less hyoid moved superiorly. In males the change in hyoid position was more obvious than in females.

CONCLUSION

Males, patients with narrow PAS at the baseline, and those whose mandible moved in the counterclockwise direction with moderate advancement gained more retrolingual airway patency by BSSO.

Distraction osteogenesis as a treatment of obstructive sleep apnea syndrome: A systematic review

BACKGROUND

To conduct a systematic review to answer the clinical question "What are the effectiveness of mandibular distraction osteogenesis (MDO) and its complications to treat patients with obstructive sleep apnea syndrome (OSAS)?".

METHODS

A systematic search including a computer search with specific keywords, reference list search, and manual search were done. Relevant articles on MDO were assessed and selected in 3 rounds for final review based on 5 predefined inclusion criteria and followed by a round of critical appraisal. Different types of distraction and their treatment outcomes of OSAS were recorded with standardized form and analyzed.

RESULTS

Twelve articles were included in the final review. A total of 256 patients aged 7 days to 60 years were treated with either external or internal MDO, with a mean follow-up period of 6 to 37 months. The average distraction distance of 12 to 29 mm was achieved with various distraction protocols. The success rate for adult patients was 100%, and cure rates were ranged from 82% to 100%. The definition of success or cure for OSAS in children or infants was not defined. Therefore, there were no clearly reported success or cure rates for children/infants in the included studies. However, all studies reported that these patients showed significant improvement in OSAS, with many of them who avoided tracheostomy or had the tracheostomy decannulated. The complication rates were ranged from 0% to 21.4%, with most being from local wound infections or neurosensory disturbances.

CONCLUSION

This systematic review showed that MDO was effective in resolving OSAS in adults with retrognathic mandible. MDO also showed promising results in infants or children with OSAS. From the results of this systematic review, we recommend to define the criteria of success or cure for OSAS surgery in children and infants. We also recommend setting up randomized controlled trials to compare MDO with traditional maxillomandibular advancement surgery for OSAS patients and to provide a better evidence on the success and complication rates of the techniques.

“Converting a bi-jaw surgery to a single-jaw surgery:” Posterior maxillary dentoalveolar intrusion with microimplants to avoid the need of a maxillary surgery in the surgical management of skeletal Class III vertical malocclusion

The management of a vertical skeletal Class III malocclusion with mandibular prognathism revolves around the protocol of bi-jaw surgery (maxillary LeFort I impaction and mandibular bilateral sagittal split osteotomy with setback). The maxillary surgery not only provides increased stability to the ultimate surgical outcome but also increases the amount by which the mandibular set back can be done, therefore aiding in greater profile improvement. With the need of maxillary surgery almost inevitable in treating such situations, the complexity and the increased discomfort associated with such surgery can never be ignored. Is it at all possible to convert a bi-jaw surgery into a single-jaw surgery with the aid of microimplants? With increasing number of patients being treated with microimplants for anterior openbite and gummy smiles, our idea was to incorporate this novel protocol in treating Class III vertical situations and therefore avoid the need of a maxillary surgery in treating such a situation, together with achieving optimum treatment outcome.

Surgical treatment of class II dento-facial deformity during adolescence: Long-term follow-up

PURPOSE

The purpose of this study is to evaluate the long-term stability of patients operated during adolescence on the base of clinical measurements and cephalometric analysis. Although, the potential benefits of early orthognathic surgery are known to be a reduction in treatment times and a greater healing potential leading to a better adaptation and stability of the occlusion, muscles, bones and joints, no consensus can be found in literature on the minimum age for surgical correction.

MATERIALS AND METHODS

In this study, thirty patients (age ≤ 15) with a class II dento-skeletal malocclusion were selected, of which 11 having a hyperdivergent (II,1) and 19 a hypodivergent (II,2) growth pattern, representing 2 distinct groups with a different treatment plan and long-term behavior.

RESULTS AND CONCLUSION

Observing the performance of all parameters over-time, it is seen that subjects belonging to division II,2 have a modification of the growth vectors maintaining the harmonious development between the jaws and the facial aesthetics. Less predictable is the trend in hyperdivergent patients, which are more prone to relapse in the long-term. Early surgery in these patients should be considered in the light of the degree of deformity and its influence felt by the patient on his development of self-image and interpersonal relationship.

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.

Satisfaction with orthognathic surgery of skeletal Class III patients

INTRODUCTION

Class III relationships can be corrected with single-jaw or bimaxillary surgery. The purpose of this research was to assess patient satisfaction after bimaxillary surgery, compared with setback surgery alone, for Class III corrections. Identifying patients' relative levels of satisfaction will provide guidance for the selection of surgical options.

METHODS

The cephalometric outcomes for 25 patients who underwent 2-jaw surgery were compared with the outcomes in 40 patients who had mandibular setback. Soft and hard tissue changes were evaluated using initial and postsurgical lateral cephalograms. The patients were asked to complete self-administered questionnaires after orthognathic treatment. Correlations between cephalometric improvement and patient satisfaction were evaluated.

RESULTS

The patients in the 2-jaw group reported significantly higher satisfaction in the appearance of the mouth (P <0.05), smile (P <0.05), and treatment outcome (P <0.001). These item scores and the changes in ANB, ANS-M, and nasolabial angle showed strong correlations in the 2-jaw group and moderate correlations in the 1-jaw group.

CONCLUSIONS

ANS-M and nasolabial angle should be considered in the conventional diagnosis of skeletal Class III orthognathic surgery to obtain adequate correction of facial esthetics and patient satisfaction. Esthetic needs contribute to surgical decisions when treating patients with skeletal Class III malocclusions and dentofacial deformities such as maxillary deficiency and long facial height that causes a turned-up upper lip.

Evaluation of three-dimensional position change of the condylar head after orthognathic surgery using computer-aided design/computer-aided manufacturing-made condyle positioning jig

This study was performed to evaluate the efficacy of computer-aided design/computer-aided manufacturing (CAM/CAD)-made condyle positioning jig in orthognathic surgery. The sample consisted of 40 mandibular condyles of 20 patients with class III malocclusion who underwent bilateral sagittal split ramus osteotomy with semirigid fixation (6 men and 14 women; mean age, 25 y; mean amount of mandibular setback, 5.8 mm). Exclusion criteria were patients who needed surgical correction of the frontal ramal inclination and had signs and symptoms of the temporomandibular disorder before surgery. Three-dimensional computed tomograms were taken 1 month before the surgery (T1) and 1 day after the surgery (T2). The condylar position was evaluated at the T1 and T2 stages on the axial, frontal, and sagittal aspects in the three-dimensional coordinates. The linear change of the posterior border of the proximal segment of the ramus between T1 and T2 was also evaluated in 30 condyles (15 patients), with the exception of 10 condyles of 5 patients who received mandibular angle reduction surgery. There was no significant difference in the condylar position in the frontal and sagittal aspects (P > 0.05). Although there was a significant difference in the condylar position in the axial aspect (P < 0.01), the amount of difference was less than 1 mm and 1 degree; it can be considered clinically nonsignificant. In the linear change of the posterior border of the proximal segment of the ramus, the mean change was 1.4 mm and 60% of the samples showed a minimal change of less than 1 mm. The results of this study suggest that CAD/CAM-made condyle positioning jig is easy to install and reliable to use in orthognathic surgery.

Do the changes in muscle mass, muscle direction, and rotations of the condyles that occur after sagittal split advancement osteotomies play a role in the aetiology of progressive condylar resorption?

Changes in cross-sectional area (CSA), volume (indicating muscle strength), and direction of the masseter and medial pterygoid muscles after surgical mandibular advancement were measured, along with the rotation of the condyles after bilateral sagittal split osteotomies (BSSOs) to advance the mandible. Measurements were done on magnetic resonance images obtained before and 2 years after surgery. CSA and volume were measured in five short-face and seven long-face patients (five males, seven females). Muscle direction was calculated in eight short-face and eight long-face patients (eight males, eight females). Short-face patients underwent BSSO only; long-face patients underwent combined BSSO and Le Fort I osteotomies. The CSA and volume decreased significantly (mean 18%) in all patients after surgery. The postoperative muscle direction was significantly more vertical (9°) in long-face patients. Rotations of the proximal segments (condyles) were minimal after 2 years. The results of this study showed that, after BSSO advancement surgery, changes in the masseter and medial pterygoid muscles are not likely to cause increased pressure on the condyles and nor are the minimal rotations of the condyles. It is concluded that neither increased muscle traction nor condylar rotations can be held responsible for progressive condylar resorption after advancement BSSO.

Mandibular surgery: technologic and technical improvements

The ability of surgeons to use advanced techniques can significantly improve both surgical outcome and patient satisfaction. Surgical evolution in mandibular orthognathic surgery is no exception, because advancements have aided both surgical planning and technique. It is important for clinicians to be aware of the historical progression of improvements in this technique and appreciate the technologic advancements as they are happening. Computer-driven surgical planning is becoming increasingly popular, providing surgeons and patients with the ability to adjust to intraoperative and postoperative variations. By using these capabilities, clinicians are now able to give patients the best possible outcomes.

Skeletal relapse following sagittal split ramus osteotomy advancement

BACKGROUND

Sagittal split ramus osteotomy (SSRO) is an accepted and standard procedure to address mandibular corpus deficiency. The relapse following the mandibular advancement has a negative impact both on clinician and patient.

PURPOSE

To analyse the hard tissue changes and to investigate relapse following SSRO advancement procedure.

MATERIALS AND METHODS

A retrospective review of 21 patients treated by bilateral SSRO advancement at our institute was conducted. Lateral cephalograms obtained at pre-treatment (T1), pre-surgery (T2), 2 months (T3) and 2 years post-surgery (T4) were evaluated by an independent investigator. The data T2-T3 revealed immediate postoperative changes, and T3-T4 revealed skeletal relapse following surgery after 2 years.

RESULTS

Twelve females and nine males with age ranging from 16 to 24 years underwent mandibular advancement. The mean follow-up period was 2 years 7 months ± 4 months. The mean mandibular advancement at pogonion was 5.1 ± 1.25 mm with significant improvement in SNB, ANB, CoGn, maxillo-mandibular differential and SN:GoPg ratio following surgery. Comparison of the outcomes following surgery revealed that the mean relapse at pogonion was 0.2 ± 0.44 mm. B point, mandibular corpus length, anterior and posterior facial height remained stable with no significant relapse following mandibular advancement.

CONCLUSION

Sagittal split ramus osteotomy within the range of mandibular advancement is a stable procedure.

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.

Comparative Study of Skeletal Stability between Postoperative Skeletal Intermaxillary Fixation and No Skeletal Fixation after Bilateral Sagittal Split Ramus Osteotomy: an 18 Months Retrospective Study

Objectives

The purpose of the present study was to evaluate skeletal stability after mandibular advancement with bilateral sagittal split osteotomy.

Material and Methods

Twenty-six patients underwent single-jaw bilateral sagittal split osteotomy (BSSO) to correct skeletal Class II malocclusion. One group (n = 13) were treated postoperatively with skeletal elastic intermaxillary fixation (IMF) while the other group (n = 13) where threated without skeletal elastic IMF.

Results

The mean advancement at B-point and Pog in the skeletal elastic IMF group was 6.44 mm and 7.22 mm, respectively. Relapse at follow-up at B-point was -0.74 mm and -0.29 mm at Pog. The mean advancement at B-point and Pog in the no skeletal elastic IMF group was 6.30 mm and 6.45 mm, respectively. Relapse at follow-up at B-point was -0.97 mm and -0.86 mm at Pog. There was no statistical significant (P > 0.05) difference between the skeletal IMF group and the no skeletal group regarding advancement nor relapse at B-point or Pog.

Conclusions

Bilateral sagittal split osteotomy is characterized as a stable treatment to correct Class II malocclusion. This study demonstrated no difference of relapse between the skeletal intermaxillary fixation group and the no skeletal intermaxillary fixation group. Because of selection-bias and the reduced number of patients it still remains inconclusive whether to recommend skeletal intermaxillary fixation or not in the prevention of relapse after mandibular advancement.

Segmental stability in orthognathic surgery: hydroxyapatite/Poly-l-lactide osteoconductive composite versus titanium miniplate osteosyntheses

Hydroxyapatite was included into F-u-HA/PLLA (unsintered hydroxyapatite - Poly l-lactide) composite osteosynthesis material for its documented osteoconductive capacity. This study investigates segmental retention capacities and outcome stability using F-u-HA/PLLA composite osteosyntheses in orthognathic surgery. Of fifty patients in total, 25 patients were osteofixated with F-u-HA/PLLA osteoconductive bioabsorbable osteosyntheses and compared to a group of 25 patients treated with titanium miniplates. The F-u-HA/PLLA group included 14 maxillary advancements, 4 setbacks, 13 impactions, 5 elongations at A-point; the titanium group included 20 maxillary advancements, 2 setbacks, 11 impactions and 11 elongations. In the mandible the F-u-HA/PLLA group included 13 advancements at B-point, 11 setbacks, 16 clockwise rotations and 8 counterclockwise rotations at the Gonial angle (Ar-Go-Gn); the titanium group included 9 mandibular advancements, 5 setbacks, 8 clockwise rotations and 6 counterclockwise rotations at Ar-Go-Gn. Segmental stability and relapse were assessed comparing preoperative, postoperative and follow-up roentgen cephalometrics at 22 ± 11 months on average in F-u-HA/PLLA cases, 24 ± 22 months on average in the titanium group. All absolute operative movements were nonsignificant in the F-u-HA/PLLA cases compared to the titanium osteosynthesis cases. Relapses were nonsignificant but there was greater vertical relapse in maxillary impactions with titanium osteosyntheses. Throughout this study, F-u-HA/PLLA composite osteosyntheses appeared as stable as titanium miniplates. It can therefore be concluded, although from a limited number of patients, that the investigated osteoconductive osteosynthesis can be used in a similar way to titanium miniplates in orthognathic surgery. Compared to earlier studies using other bioabsorbable polymers in the literature, F-u-HA/PLLA proved to be more stable in segmental retention.

Effect of intended manual condylar positioning on skeletal and dental changes in Skeletal Class III deformities: CBCT-generated half-cephalograms

INTRODUCTION

To investigate the effect of intended manual condylar positioning on skeletal changes from preoperative stage to posttreatment stage.

MATERIALS AND METHODS

The sample comprised 23 patients divided into two groups according to surgery type: mandible-only setback surgery (group I) versus 2-jaw surgery (group II). CBCT-generated Half-Cephalograms were fabricated to evaluate the skeletal, dental, and condylar positioning changes for each subject at three time points (preoperatively (T0), immediate-postoperatively (T1), and posttreatment (T2)).

RESULTS

The angle of the proximal segment in group II was reduced immediate-postoperatively. In both groups, the result showed a negative mean value for the horizontal mandibular position (B point to N-perpendicular plane at T2-T1 stage). In group II, the vertical mandibular position (B point to FH plane at T2-T1 stage) also had a negative mean value. In group I, the change of the B point to N-perpendicular plane (T2-T1) had statistically significant correlations with the change of the Cd to Po-perpendicular plane (T2-T1). In group II, the change of the B point to the N-perpendicular plane (T2-T1) had statistically significant correlations with the change of the <Cd-Cp-FH plane angle (T2-T1) and the Cp to FH plane (T1-T0).

CONCLUSIONS

In this study, the change from the T1 to T2 stage, though not statistically significant, showed a negative short-term relapse. Intended manual condylar positioning may suppress the short-term skeletal relapse.

Skeletal stability after mandibular advancement in bilateral sagittal split osteotomies during adolescence

Bilateral sagittal split osteotomy (BSSO) is the most frequently performed surgery for correcting mandibular retrognathia. Few studies have reported the use of BSSO in young patients, as growth may cause relapse. The aim of the present study was to determine the amount of relapse after performing BSSO in patients aged less than 18 years. Patients who had a mandibular advancement by BSSO surgery between January 2003 and June 2008 were evaluated. Eighteen patients were treated before the age of 18 years and compared with patients treated at 20-24 years of age. Cephalometric radiographs were used to determine the amount of relapse. For patients aged less than 18 years, the mean horizontal relapse after 1 year was 0.5 mm, (10.9% of perioperative advancement). For patients aged 20-24 years, the mean relapse was 0.9 mm, (16.4% of perioperative advancement). There were no significant differences between the age groups (p > 0.05). In conclusion, the BSSO procedure is a relatively stable procedure, even during adolescence.

Closure of anterior open bites with mandibular surgery: advantages and disadvantages of this approach

INTRODUCTION

While closure of an anterior open bite with a mandibular procedure may predispose a surgical case to instability, there are instances where this type of treatment planning is indicated.

METHODS AND MATERIALS

In this paper, the authors review the advantages and disadvantages of this approach and present three cases with varying degrees of success. Additionally, treatment strategies are presented for managing large advancements of the maxilla and mandible.

RESULTS AND SUMMARY

Counterclockwise rotation of the mandible is a valuable tool that can be used in the treatment of patients with dentofacial deformities.

Segmental stability of resorbable P(L/DL)LA-TMC osteosynthesis versus titanium miniplates in orthognatic surgery

After two decades of the use of resorbable miniplates, new polymer compositions for resorbable osteosynthesis are still being developed to make the handling and outcome of operations even more predictable and give higher stability to the repositioned segments. This study investigates a new resorbable osteosynthesis system in orthognathic patients. 50 patients were treated with P(L/DL)LA-TMC resorbable osteosynthesis and compared to a group of 50 patients treated with titanium miniplates. Segmental stability and relapse were measured comparing preoperative, postoperative and follow-up lateral cephalograms. Throughout this study, resorbables appeared to be as stable as titanium miniplates except in maxillary elongation and mandibular setback. Here, the titanium miniplates showed significantly higher stability than resorbable plates. P(L/DL)LA-TMC osteosynthesis seem to have less strength against compressive forces after maxillary elongation and they are less resistant to the forces the tongue exerts, pressing against the mandible after setback. It can therefore be concluded that the resorbable osteosynthesis can be used in the same situations as titanium miniplates except in maxillary elongation and mandibular setback.

Positional changes of the masseter and medial pterygoid muscles after surgical mandibular advancement procedures: an MRI study

This study evaluated whether surgical mandibular advancement procedures induced a change in the direction and the moment arms of the masseter (MAS) and medial pterygoid (MPM) muscles. Sixteen adults participated in this study. The sample was divided in two groups: Group I (n=8) with a mandibular plane angle (mpa) <39° and Group II (n=8) with an mpa >39°. Group I patients were treated with a bilateral sagittal split osteotomy (BSSO). Those in Group II were treated with a BSSO combined with a Le Fort I osteotomy. Pre- and postoperative direction and moment arms of MAS and MPM were compared in these groups. Postsurgically, MAS and MPM in Group II showed a significantly more vertical direction in the sagittal plane. Changes of direction in the frontal plane and changes of moment arms were insignificant in both groups. This study demonstrated that bimaxillary surgery in patients with an mpa >39° leads to a significant change of direction of MAS and MPM in the sagittal plane.

Cephalometric evaluation of airways after maxillary anterior advancement by distraction osteogenesis in cleft lip and palate patients: a systematic review

OBJECTIVE

This study was conducted to review the changes in airways after maxillary anterior advancement by distraction osteogenesis in patients with cleft lip and palate.

MATERIALS AND METHODS

Several electronic databases were searched. The selection criteria were set to include clinical trials and at least 1 year of postsurgical data. The original articles were then retrieved and evaluated by two investigators to ensure that they met the selection criteria. The references were also hand searched for possible missing articles.

RESULTS

Forty-three abstracts were found in the electronic searches. After the first set of selection criteria was applied to these abstracts, 14 articles were retrieved. After the final selection criteria, only four articles were finally selected. However, sample sizes of the selected articles were small, and the methodological quality of the studies was inadequate. All selected articles were consistent in that upper airway sizes increased and nasal resistance was reduced after distraction osteogenesis.

CONCLUSIONS

Despite the consistency of increasing the upper airway size and reducing nasal resistance in the only four found articles, limitations of the studies merit caution in interpreting these findings. We conclude that there are insufficient prospective randomized controlled clinical trials to confirm these results.

Dental or skeletal relapse after sagittal split osteotomy advancement surgery? Long-term follow-up

PURPOSE

To evaluate the short- and long-term stability of mandibular advancement surgery with sagittal split osteotomy (SSO), and to investigate when relapse occurs and identify variables contributing to relapse.

PATIENTS AND METHODS

Thirty-six patients with Class II anomalies were included; the mean age at surgery was 33.0 years. All underwent SSO surgery and clinical and radiologic follow-up at 8 weeks, 1 year, and 13 years. Model analysis, cephalometric analysis, and clinical examinations were performed at each control.

RESULTS

Mean overjet relapse from 8 weeks to 13 years was 2.3 mm (range, 0 to 7.0 mm). Between 8 weeks and 1 year, mean overjet relapse was 0.6 mm (range, -1.0 to 4.0 mm), and it was 1.7 mm (range, -1.0 to 6.0 mm) between 1 year and 13 years. Overjet relapse greater than 4 mm was found in 13.9% of the patients. Mean overjet 1 year after surgery was 2.6 mm and was significantly increased compared with 8 weeks (P = .006). Mean overjet 13 years after surgery was 4.3 mm and was significantly increased compared with 1 year (P < .001). Inferior incisor line to nasion-B-point was 29.0° at 8 weeks after surgery and 25.4° at 13 years (P = .001). Insignificant changes in the other cephalometric variables were found at follow-up.

CONCLUSION

SSO advancement surgery is a relatively stable technique over time. Mean overjet relapse was found to be 2.3 mm after 13 years, following a continuous pattern over time. The cephalometric variables showed insignificant changes during follow-up, indicating that relapses are mainly of dental and not skeletal origin.

Three-year follow-up of bimaxillary surgery to correct skeletal Class III malocclusion: stability and risk factors for relapse

INTRODUCTION

The purpose of this study was to evaluate long-term skeletal and occlusal stability after bimaxillary surgery to correct skeletal Class III malocclusion.

METHODS

The sample comprised 81 consecutively treated patients. All subjects had received a combined 1-piece LeFort I and bilateral sagittal split ostotomies with rigid fixation between 1990 and 2003 and were followed for 3 years. Lateral cephalograms were obtained before surgery and at 5 occasions after surgery.

RESULTS

The mean setback was 6.9 mm in the mandible, and the maxilla was moved forward 3.7 mm. In most patients, the posterior maxilla was impacted. Relapse of maxillary advancement was insignificant (0.1 mm), whereas relapse at B-point was on average 1.7 mm (P <0.010). After 3 years, mean overjet and overbite amounts were 2.0 and 1.9 mm, respectively. Skeletal relapse of the mandible increased significantly with the surgical setback (P <0.001) and the change in the vertical position of the posterior maxilla (P = 0.010) (multivariate regression analysis).

CONCLUSIONS

Bimaxillary surgery resulted in good occlusal stability. Maxillary advancement was stable, whereas relapse of the mandibular setback varied. Risk factors for horizontal relapse of the mandible were large setback and inferior repositioning of the posterior maxilla.

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.

Long-term stability of adolescent versus adult surgery for treatment of mandibular deficiency

In mandibular deficient patients, mandibular growth is not expected after the adolescent growth spurt, so mandibular advancement surgery is often carried out at 13 years. To test if the long-term stability for younger patients is similar to that for adult patients, the authors compared cephalometric changes from 1-year postsurgery (when changes due to the surgery should be completed) to 5-year follow up. 32 patients who had early mandibular advancement with or without simultaneous maxillary surgery (aged up to 16 for girls and 18 for boys), and 52 patients with similar surgery at older ages were studied. Beyond 1-year postsurgery, the younger patients showed significantly greater change in the horizontal and vertical position of points B and pogonion, the horizontal (but not vertical) position of gonion, and mandibular plane angle. 50% of younger patients had 2-4mm backward movement of Pg and another 25% had >4mm. 15% of older patients had 2-4mm change and none had >4mm. Long-term changes in younger patients who had two-jaw surgery were greater than for mandibular advancement only. Changes in younger groups were greater than for adult groups. Satisfaction with treatment and perception of problems were similar for both groups.

Mandibular hypoplasia with curvilinear distraction

Mandibular distraction with intraoral curvilinear distractor is an effective procedure for lengthening the mandibular corpus and ramus dimensions. Mandibular distractor is valuable for the treatment of hypoplastic mandible. The aim of this article was to describe the treatment of a patient with hypoplastic and severely retrognathic mandible resulting from isolated Pierre Robin sequence, by means of curvilinear distraction osteogenesis followed by fixed orthodontic treatment. As a result, the curvilinear path of distraction can form a new mandibular angle and bring the mandible significantly forward. Attention should be given for the stability of the treatment results.