Surgery-first in interdisciplinary class II cases.

OBJECTIVES: To present an interdisciplinary case treated with a surgery-first orthognathic approach, followed by orthodontic and prosthodontic treatment. CLINICAL CONSIDERATIONS: After an accurate pre-operative virtual planning, a young patient with skeletal class II, retrognathia, and an anterior open bite was treated with bimaxillary orthognathic surgery without pre-surgical orthodontic decompensation. Orthodontic treatment was carried out post-operatively. The treatment was completed with a prosthodontic phase to improve the final esthetic outcome of the smile. CONCLUSIONS: A surgery-first approach allowed to achieve esthetic and functional results in a reduced treatment duration that remained stable over the course of 1 year. The outcomes were consistent with prior research in terms of advantages brought by following an accurately planned surgery-first protocol. Nevertheless, longer-term follow-up was required to evaluate the treatment stability. CLINICAL SIGNIFICANCE: An accurately planned surgery-first approach significantly helped in shortening the duration of the treatment, while providing a stable, functional, and esthetic solution to the patient's problems.

Long-term three-dimensional condylar remodeling during presurgical orthodontics and after orthognathic surgery of mandibular retrognathia with high mandibular plane angle.

OBJECTIVES: Patients with high mandibular plane facial morphology are the most dominant facial type who experience TMJ abnormalities with resultant condylar resorption, affecting the orthodontic and orthognathic treatment outcomes. The study aimed to quantitatively assess the three-dimensional condylar remodeling during the presurgical orthodontics and after orthognathic surgery of the retrognathic mandible with a high mandibular plane angle. The study also investigated the correlation between the resultant remodeling based on the hypothesis that condylar resorption following orthognathic surgery is a part of a progressive presurgical resorption process. MATERIALS AND METHODS: The study included adults with mandibular retrognathism and high mandibular plane angle who have computed tomography scans (CT) obtained before any treatment (T0), after completion of presurgical treatment before surgery (T1), and at long-term follow-up after surgery (T2). DICOM of CT scan was gathered and processed using ITK-SNAP and 3D Slicer software. The interval between T0 and T1 was represented as a presurgical phase, while between T1 and T2 was defined as a postsurgical phase (T1-T2). RESULTS: Twenty-five patients (50 condyles) were included with a mean age of 23 ± 3.2 years. The mean of the follow-up during the presurgical phase was 19.8 ± 7.1 months and 15.5 ± 5.5 months during the postsurgical phase. The condylar volume during the presurgical phase (T0-T1) was relatively stable (- 3.3 ± 37.2mm3). However, during the postsurgical phase (T1-T2), the volume was significantly reduced - 113.8 ± 98.3mm3 (P < 0.001). Localized condylar surface resorption during the postsurgical phase was significantly higher than during the presurgical phase (P < 0.05). No correlation was found between the localized condylar surface remodeling during the presurgical and postsurgical phases. However, a negative statistically significant correlation existed between the overall condylar volume changes during the presurgical and postsurgical phases (r = 0.502, P < 0.001). CONCLUSION: Significant condylar resorption following orthognathic surgery of the retrognathic mandible with a high mandibular plane angle might occur regardless of the presurgical status of the condyle. CLINICAL RELEVANCE: The study provided an evidence to be discussed with the patients and considered throughout the treatment of mandibular retrognathia with high mandibular plane angle.

[Orthodontic treatment of adult patients with mandibular retrognathia]. / Ortodonticheskoe lechenie vzroslykh patsientov s nizhnei retrognatiei.

This article describes a case report of the patient with mandibular retrognathia, class II malocclusion, constriction and deformation of dental arches and bimaxillary protrusion. Due to the patient's refuse to undergo the orthognathic surgery, after diagnostic, it was decided to carry out the orthodontic dentoalveolar compensation. The combined use of the functional fixed telescopic appliance (FFTA), bracket system and orthodontic miniscrews made it possible to effectively normalize the mandibular position, achieve orthognathic occlusion, eliminate bimaxillary protrusion and improve the face profile. This method significantly reduced invasiveness and time of orthodontic treatment.

Management of Severe Midface Retrusion With Distraction Osteogenesis in Patients With Cleft Lip and Alveolus.

A cleft lip, palate, and alveolus is one of the most common birth defects. Depending on the type of cleft, multiple surgeries may be required throughout the growth stage. Traditionally, an orthodontic-surgical approach has been adopted to treat maxillary retrusion. Osteodistraction it is the surgical choice in patients with severe midface retrusion that require maxillary advancement. Our objective is to present our experience using this orthodontic and surgical approach.

Novel Approach of Mandibular Distraction to Avoid Tracheostomy in KAT6B-related Gene Disorders.

Previously, severe upper airway obstruction in patients with retrognathia and glossoptosis has been managed with tracheostomy. However, tracheostomy is associated with significant morbidity. In recent years, mandibular distraction has become an alternative management strategy in infants, but these applications have been limited to patient populations with retrognathia and glossoptosis. The authors present 2 unique cases of patients with KAT6B-related gene disorders, who present with a paradox of tongue-based airway obstruction in the absence of retrognathia. In both cases mandibular distraction osteogenesis with an obliquely oriented vector was successfully performed and both children avoided the need for tracheostomy.

Quality of life several years after orthodontic-surgical treatment with bilateral sagittal split osteotomy.

Objective: To analyse oral health related quality of life (OHRQoL) several years after orthognathic treatment in patients who had Class II malocclusion with retrognathic mandible.Material and methods: The initial study cohort comprised 151 patients with orthognathic treatment in 2007-2011. Of them, 77 patients (Group 1, mean age 41 years, range 19-71 years, 71% women) were clinically examined 6 years (range 4-8 years) after bilateral sagittal split osteotomy (BSSO). Group 2 included 24 former patients (mean 48 years, range 25-79 years, 50% women) who were willing to participate in a structured telephone interview. Group 3 consisted of 22 prospective patients (mean 35 years, range 18-56 years, 86% women) with a recent orthognathic treatment plan and awaiting treatment. QoL was assessed using two questionnaires, OHIP-14 and OQLQ.Results: Based on responses, patients who had received orthognathic treatment (Groups 1 and 2) had better QoL than those awaiting treatment (Group 3).Conclusion: Conventional orthognathic treatment, including mandibular advancement with BSSO, seems to have a positive long-term effect on patients' QoL. More long-term follow-up studies are needed to assess the real impact of treatment on patients' lives in the long run.

Effects of Hat-Shaped Mortised Genioplasty with Genioglossus Muscle Advancement on Retrogenia and Snoring: Assessment of Esthetic, Functional, and Psychosocial Results.

BACKGROUND: An increasing number of patients undergo genioplasty for esthetic purposes to correct micrognathism or retrognathism. However, these conditions are considered an important risk factor for snoring. The purpose of this study was to evaluate both esthetic improvement and functional changes of snoring symptoms in patients who underwent hat-shaped mortised advancing genioplasty with genioglossus muscle advancement. MATERIALS AND METHODS: This retrospective study enrolled 25 patients. We evaluated scores for subjective snoring classification (Stanford scale) and questionnaire findings for esthetic results. RESULTS: Most people (96%) were satisfied with the esthetic improvement after surgery. The grade of subjective snoring classification (Stanford scale) improved from 8.68 (range 0-10) to 4.08 (range 0-10) after surgery. Twenty-four patients had an improved snoring grade. All patients reported a positive impact on their daily activity and self-confidence, and they were willing to recommend the same operation to someone with the same clinical problems. CONCLUSION: We conclude that hat-shaped mortised advancing genioplasty with genioglossus muscle advancement can relieve the symptoms of snoring for patients with hypoplastic chin or retrogenia. Patients were satisfied with the functional and esthetic results. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Custom-Made Titanium Miniplates Associated With Ultrahigh-Molecular-Weight Polyethylene Graft in Orthognathic Surgery: An Adjunct to Maxillary Advancement.

Patients with considerable maxillomandibular anteroposterior discrepancies and maxillary hypoplasia require corrective treatment through orthognathic surgery. However, in the treatment of severe maxillary retrognathism, it is necessary to reconstruct areas of bone deficiency through grafting techniques in addition to maxillary advancement using only the Le Fort I osteotomy. Treatment in these patients is more challenging and requires high surgical predictability. Alloplastic materials often have been used for the reconstruction of poor bone contours. Ultrahigh-molecular-weight polyethylene (UHMWPE) is currently an excellent filler material for poor bone regions and is a good substitute for autografts and other alloplastic materials for its unique properties, including high biocompatibility. Insertion of this material in the fixation system customized for virtually planned orthognathic surgeries is an innovative technique. This report describes the insertion of UHMWPE into custom-made titanium miniplates manufactured by computer-aided design and computer-aided manufacturing technology for orthognathic surgery consisting of maxillary advancement and mandibular retrusion to treat a patient with Crouzon syndrome, Class III malocclusion, and severe maxillary retrognathism.

Determining the Patient-Specific Optimum Osteotomy Line for Severe Mandibular Retrognathia Patients.

PURPOSE: The purpose of this study is to suggest a patient-specific osteotomy line to optimize the distractor position and thus to minimize the disadvantages of conventional mandibular distraction osteogenesis (MDO) protocols. In addition, this study also aims to compare the conventional MDO protocols with the new MDO protocol proposed in this study in terms of both orthodontic outcomes and mechanical effects of osteotomy level on callus stabilization by means of the finite element method. METHODS: A preoperative patient-specific 3-dimensional bone model was created and segmented by using computed tomography images of an individual patient. Virtual orthodontic set-up was applied to the segmented model prior to the virtual surgery. In order to compare the proposed osteotomy line with the conventional lines used in clinical applications, virtual surgery simulations were performed and callus tissues were modelled for each scenario. The comparison of the success of each osteotomy line was carried out based on the occlusion of the teeth. RESULTS: The osteotomy line determined using the method proposed in this study has resulted in far less malocclusion than the conventional method. Namely, any angular deviation from the optimum osteotomy line determined in this study might result in deep-bite or open-bite. On the other hand, the finite element analysis results have indicated that this deviation also negatively affects the callus stability. CONCLUSION: In order to achieve a better MDO treatment in terms of occlusion of the teeth and the callus stability, the location of the osteotomy line and the distractor position can be computationally determined. The results suggest that MDO protocol developed in this study might be used in clinic to achieve a better outcome from the MDO treatment.

Three-Dimensional Reconstruction of Post-Traumatic Deficient Anterior Maxilla.

PURPOSE: Maxillary retrognathism appears in 14.3% of patients exhibiting malocclusion after trauma treatment. This report describes the application of alveolar distraction osteogenesis (ADO) for treating the severely deficient anterior maxilla after trauma injuries in the vertical and anteroposterior planes. MATERIALS AND METHODS: This is a retrospective study of patients exhibiting severe vertical and anteroposterior maxillary bone deficiency after trauma injuries and treated by ADO as a first stage with additional Le Fort I advancement when required. Predictor variables included ADO for alveolar augmentation and Le Fort I advancement for anteroposterior discrepancy after ADO. Outcome variables included dental implant failure and anteroposterior maxillary relations. RESULTS: Twelve patients with severe atrophic anterior maxilla secondary to trauma injuries were included and treated using ADO. In accordance to the size of the horizontal deficiency, 1 or 2 distractors were used. Vertical alveolar distraction was performed and the transported segments were elongated at a rate of 0.5 mm/day to a mean total of 13.9 mm (12 to 15 mm). In 4 of 12 cases, there was a severe anteroposterior discrepancy larger than 8 mm that could not be fully corrected using an anterior inclination during the vertical elongation. Therefore, a second stage of conventional Le Fort I advancement was performed. Thirty-eight dental implants were inserted, with a survival rate of 97.37% (median follow-up, 6.2 yr). CONCLUSIONS: This report describes treatment of the deficient anterior maxilla after trauma injuries in the vertical and anteroposterior planes, including implant-based dental rehabilitation. The main advantages include simultaneous bone and mucosa augmentation, no donor site morbidity, considerably higher vertical augmentation compared with other methods, and minimal relapse. Using an additional Le Fort I advancement in severe cases permits a useful method for proper repositioning of the maxilla, thus resulting in superior intermaxillary relations.

Patient With Cleft Maxillary Hypoplasia Who Underwent Distraction Osteogenesis and Conservative Therapies to Postoperative Velopharyngeal Insufficiency.

The authors performed distraction osteogenesis using The Maxillary Distractor System (SYNTHES) to maxillary hypoplasia patient with cleft lip palate, and consequently improved the aesthetic complexion of the patient. Velopharyngeal insufficiency developed after bone elongation; the authors improved the insufficiency with conservative therapies such as articulatory training using the bulb attached palatal lift prosthesis. The authors were successful and accepted postoperative speech outcome.

Cephalometric Improvement of Severe Microretrognathia With an Anterior Open Bite Using Curvilinear Mandibular Distraction Osteogenesis.

Curvilinear mandibular distraction osteogenesis (MDO) provides for multidimensional augmentation and rotation in mandibles with complex, abnormal morphology. This study aims to demonstrate cephalometric changes after curvilinear MDO.A prospectively maintained craniofacial database was queried for patients undergoing curvilinear MDO from 2009 to 2015. Demographic and operative data were collected. Cephalometric measurements were obtained from preoperative and postdistraction imaging, including sella-nasion-B point angle (SNB), mandibular plane angle (MPA), occlusal plane angle (OPA), and gonial angle (GA). Measurements were compared using a paired t test.Nine patients exhibiting microretrognathia and an anterior open-bite deformity had a mean age of 8.4 ±â€Š6.0 years and a mean follow-up of 23.2 ±â€Š25.3 months. Mean distance distracted was 32.6 ±â€Š7.2 mm, with augmentation in length and height, and rotatory closure of anterior open bites. Preoperative SNB versus postdistraction was 66.9 ±â€Š4.2 versus 78 ±â€Š9.1° (P = 0.0029). MPA, OPA, and GA all decreased (61.0 ±â€Š10.7 vs. 45.7 ±â€Š11.1°, P = 0.0066, 37.3 ±â€Š8.9 vs. 25.7 ±â€Š6.0°, P = 0.0025, 140.3 ±â€Š16.1 vs. 127.3 ±â€Š13.2°, P = 0.0019, MPA, OPA, and GA, respectively), trending toward normalization. Airway diameter increased by 7.1 ±â€Š2.8 mm. Anterior bite improved by 7.2 ±â€Š1.9 mm. Complications arose in 2 subjects including device malfunction and wound infection.Curvilinear MDO results in dramatic cephalometric improvement in patients with severe microretrognathia and anterior open-bite. The procedure is associated with a high rate of complications, and long-term stability of movement has yet to be documented.

Early, Computer-Aided Design/Computer-Aided Modeling Planned, Le Fort I Advancement With Internal Distractors to Treat Severe Maxillary Hypoplasia in Cleft Lip and Palate.

Traditionally, maxillary hypoplasia in the setting of cleft lip and palate is treated via orthognathic surgery at skeletal maturity, which condemns these patients to abnormal facial proportions during adolescence. The authors sought to determine the safety profile of computer-aided design/computer-aided modeling (CAD/CAM) planned, Le Fort I distraction osteogenesis with internal distractors in select patients presenting at a young age with severe maxillary retrusion. The authors retrospectively reviewed our "early" Le Fort I distraction osteogenesis experience-patients performed for severe maxillary retrusion (≥12 mm underjet), after canine eruption but prior to skeletal maturity-at a single institution. Patient demographics, cleft characteristics, CAD/CAM operative plans, surgical complications, postoperative imaging, and outcomes were analyzed. Four patients were reviewed, with a median age of 12.8 years at surgery (range 8.6-16.1 years). Overall mean advancement was 17.95 + 2.9 mm (range 13.7-19.9 mm) with mean SNA improved 18.4° to 87.4 ±â€Š5.7°. Similarly, ANB improved 17.7° to a postoperative mean of 2.4 ±â€Š3.1°. Mean follow-up was 100.7 weeks, with 3 of 4 patients in a Class I occlusion with moderate-term follow-up; 1 of 4 will need an additional maxillary advancement due to pseudo-relapse. In conclusion, Le Fort I distraction osteogenesis with internal distractors is a safe procedure to treat severe maxillary hypoplasia after canine eruption but before skeletal maturity. Short-term follow-up demonstrates safety of the procedure and relative stability of the advancement. Pseudo-relapse is a risk of the procedure that must be discussed at length with patients and families.

Split-Overlapping Genioplasty: Surgical Technique, Morphological and Radiological Long-Term Outcomes.

BACKGROUND: The overlapping bone flap genioplasty, described by Tessier, was developed to treat major retrognathia or long and retruded chins. For 15 years, we have used a modified version of this technique to avoid its drawbacks. The aim of this article is to describe our modification and evaluate the long-term morphologic and radiologic outcomes. PATIENTS AND METHOD: The authors included every split-overlapping genioplasty performed in our department between 2004 and 2014. Demographics, surgical data, and complications were recorded. Radiologic bone resorption was evaluated comparing preoperative, day-1 postoperative, and year-1 postoperative cephalometric x-rays. Morphologic outcomes were evaluated on standardized pre- and postoperative views using an analogic Likert scale. SURGICAL TECHNIQUE: The main modification of the procedure consists in separating the posterior cortex of the transplant using a reciprocating saw. After overlapping the reduced transplant onto the mandible, the posterior cortex is used as an apposition graft to soften the labiomental crease. RESULTS: Forty-seven patients were analyzed during this period. In 44 patients, the procedure was combined with mandibular and/or maxillary osteotomy. The average reduction of symphysis height was 5 mm, and the average pogonion advancement was 4.3 mm. After 1 year, we recorded 7% average bone resorption. No major complications (nerve injury, hematoma, among others) were reported. Morphologic outcomes were deemed satisfactory or very satisfactory in the vast majority of cases. CONCLUSION: Split-overlapping genioplasty is a safe and reliable procedure with stable, long-lasting outcomes. This versatile technique is particularly useful for the correction of a massive symphysis or high and retruded chins.

A Morphological Classification Scheme for the Mandibular Hypoplasia in Treacher Collins Syndrome.

BACKGROUND: Mandibular hypoplasia is a hallmark of Treacher Collins syndrome (TCS), and its severity accounts for significant functional morbidity. The purpose of this study is to develop a mandibular classification scheme. METHODS: A classification scheme was designed based on three-dimensional computed tomography (3D-CT) scans to assess 3 characteristic features: degree of condylar hypoplasia, mandibular plane angle (condylion-gonion-menton), and degree of retrognathia (sella-nasion-B point angle). Each category was graded from I to IV and a composite mandible classification was determined by the median value among the 3 component grades. RESULTS: Twenty patients with TCS, aged 1 month to 20 years, with at least one 3D-CT prior to mandibular surgery were studied. Overall, 33 3D-CTs were evaluated and ordered from least to most severe phenotype with 10 (30%) Grade 1 (least severe), 14 (42%) Grade 2, 7 (21%) Grade 3, and 2 (7%) Grade 4 (most severe). Seven patients had at least 2 longitudinal scans encompassing an average 5.7 (range 5-11) years of growth. Despite increasing age, mandibular classification (both components and composite) remained stable in those patients over time (P = 0.2182). CONCLUSION: The authors present a classification scheme for the TCS mandible based on degree of condylar hypoplasia, mandibular plane angle (Co-Go-Me angle), and retrognathia (SNB angle). While there is a natural progression of the mandibular morphology with age, patients followed longitudinally demonstrate consistency in their classification. Further work is needed to determine the classification scheme's validity, generalizability, and overall utility.

Differences in attractiveness comparing female profile modifications of Class II Division 1 malocclusion.

INTRODUCTION: Our objective was to study the perceptions of laypeople for digital alterations and the amount of nasolabial angle increase that is tolerable and how much chin-neck length increase is needed to achieve a desirable profile in Class II Division 1 women with mandibular retrognathia. METHODS: The profile image of a white woman with a Class II Division 1 mandibular rethrognatic profile was digitally modified to create 6 images: 3 with stepwise increased nasolabial angles of 113°, 121°, and 129°, and 3 with stepwise increased chin-neck distances of 51, 54, and 57 mm. These images were assessed and ranked by 155 white laypeople. RESULTS: The baseline profile was judged significantly as the least attractive. A nasolabial angle of 129° was judged as unattractive as the baseline profile. Profiles with a chin-neck length of 54 and 57 mm were equally judged as most attractive. CONCLUSIONS: The untreated (baseline) profile was found to be least esthetic, as well as the profile with the largest nasolabial angle. Nasolabial angle increases up to 121° seem to be acceptable. Profiles simulating a chin-neck length increase as produced by surgery seem to be most favored.

Timing of Surgical Removal of Odontoma in a Growing Orthodontic Patient: A Case Report.

In patients with skeletal malocclusion and odontoma, the prioritization of treatment is ofgreat importance. Ifsurgical removal of odontoma is postponed, the probability of adjacent teeth impaction increases. In this case, skeletal treatment was performed before odontoma rgery due to concerns about facial appearance and the patient's fear of surgery, and therefore adjacent tooth failed to erupt.

Anatomical position of the mandibular canal in relation to the buccal cortical bone in Chinese patients with different dentofacial relationships.

BACKGROUND/PURPOSE: The purpose of this study was to determine the position of the mandibular canal in relation to the buccal cortical bone in Chinese patients with three dentofacial relationships: normal dentition, retrognathism, and prognathism. METHODS: Cone-beam computed tomography and lateral cephalograms of patients with normal dentation, retrognathism, and prognathism (n = 32 each group) were reviewed. Measurements of the shortest distance from the outer/buccal edge of the mandibular canal to the inner surface of the buccal cortex, and the distance from the lingula of the ramus to the dorsal root of the first molar were recorded. RESULTS: No significant difference was observed between the three groups in the distribution of contact or fusion of the mandibular canal, or in the course of the mandibular canal on the right or left side. When the shortest distance at the lingula on the left side was >2.1 mm, no instances of contact or fusion were observed. On the right side, 100% of the patients had no contact or fusion when the shortest distance was >2.7 mm at the lingula. CONCLUSION: The shortest distance from the outer/buccal edge of the mandibular canal to the inner surface of the buccal cortex measured at the lingula can predict contact or fusion. During sagittal split ramus osteotomy, great care should be observed at the point halfway between the lingula and the anterior ramus border where the inferior alveolar nerve is the closest to the cortical bone.

Long-term surgical-orthodontic management of hemimandibular hyperplasia.

BACKGROUND: Hemimandibular hyperplasia (HH), also known as hemimandibular hypertrophy, is characterised by excessive unilateral three-dimensional growth of the mandible after birth. Vertical unilateral elongation of the mandible becomes clinically evident as a rare form of vertical facial asymmetry. Aberrant growth of the facial skeleton affects the developing dentition and the dental compensatory mechanism is usually unable to maintain optimal occlusal relationships. The resulting malocclusion is effectively managed by combined surgical-orthodontic care to address the facial, skeletal and dental problems that confront clinicians. Orthodontists are advised to assess patients with HH during the post-treatment retention stage for continuing mandibular growth and assess the stability of treatment outcomes with long-term follow-up and records as required. AIM: To present a case of hemimandibular hyperplasia treated successfully by combined surgical-orthodontic care and evaluated for stability over a seven-year follow-up period. METHODS: Surgical-orthodontic management was accomplished in four stages: 1) pre-surgical orthodontic; 21 surgical; 3) post-surgical orthodontic; and 4) post-treatment orthodontic retention. Complete orthodontic records, including extra- and intra-oral photographs, study models, and cephalograms plus panoramic radiographs were taken at the pretreatment, post-treatment, and seven-year orthodontic retention time-points. RESULTS: Facial, skeletal and dental goals were achieved in the three planes of space and the long-term stability of the treatment results was shown during a post-treatment orthodontic retention period of seven years. CONCLUSION: Hemimandibular hyperplasia is a true growth anomaly which may be managed effectively. Clinicians may expect successful long-term correction and stability by utilising a comprehensive surgical-orthodontic treatment approach.

Bilateral Sagittal Split Ramus Osteotomy Versus Distraction Osteogenesis for Advancement of the Retrognathic Mandible.

PURPOSE: The aim of the present study was to identify significant differences in skeletal stability and neurosensory disturbance (NSD) of the inferior alveolar nerve (IAN) between bilateral sagittal split ramus osteotomy (BSSO) and distraction osteogenesis (DO) for mandibular advancement surgery. MATERIALS AND METHODS: We performed a systematic and electronic search of several databases using specific keywords, a reference search, and a manual search through November 2014. The inclusion criteria were clinical human studies, including randomized controlled trials (RCTs), controlled clinical trials (CCTs), and retrospective studies, with the aim of comparing BSSO and DO (predictor variables) after mandibular advancement surgery with regard to skeletal stability and NSD of the IAN (outcome variables). Both linear and angular measurements of the horizontal and vertical positions of the mandible were analyzed. For binary outcomes, we calculated a standard estimation of the risk ratio using the random-effects model if heterogeneity was detected; otherwise, a fixed effects model, with a 95% confidence interval (CI), was used. Weighted mean differences or standard mean differences were used to construct forest plots of continuous data. In addition, the number needed to treat, with the 95% CIs, was calculated for NSD of the IAN. RESULTS: Our initial PubMed search identified 215 studies, of which 9 met our inclusion criteria-3 RCTs, 1 CCT, and 5 retrospective studies. No statistically significant difference was found between the 2 groups regarding skeletal stability in either the vertical (P = .34) or horizontal (P = .88) direction. A statistically significant difference was found between BSSO and DO with regard to NSD of IAN function (P = .004). CONCLUSION: The results of the present meta-analysis have shown that DO significantly reduced the incidence of NSD of the IAN after lengthening of the retrognathic mandible compared with the BBSO.