Functional therapy and adenotonsillectomy clinical trial for class II malocclusion (FACT-II): protocol for a randomised controlled trial.

INTRODUCTION: Class II malocclusion with mandibular retrognathia is a common complication of paediatric obstructive sleep apnoea (OSA), often accompanied by transverse maxillary deficiency. In early orthodontic treatment, a twin block (TB) is a regular functional appliance for correcting this malocclusion. For paediatric OSA, the most common risk factor is adenotonsillar hypertrophy (AHT). Untreated AHT may lead to the persistence and worsening of obstructive sleep-disordered breathing traits, including habitual mouth breathing. Additionally, the clockwise mandibular rotation associated with AHT-induced pharyngeal crowding can undermine the effectiveness and stability of TB treatment. Adenotonsillectomy (T&A) is currently the first-line treatment for paediatric OSA. This proposed trial will investigate the impact of T&A surgery timing on the efficacy and stability of TB functional treatment in children with class II mandibular retrognathia and ATH. METHODS AND ANALYSIS: This will be a single-centre, parallel-group, superiority randomised controlled trial with participants randomised to intervention (T&A followed by TB treatment) or control arms (TB treatment followed by T&A) in a 1:1 ratio. A total of 40 patients aged 8-14 years, diagnosed with class II mandibular retrognathia and co-existing ATH-induced OSA, and indicated for both T&A surgery and TB treatment, will be recruited at the School and Hospital of Stomatology, Wuhan University. The primary outcomes will be the changes in the apnoea-hypopnoea index and the point A-nasion-point B angle from baseline to postorthodontic treatment between the two groups. Secondary outcomes will include other dental, skeletal, upper airway and soft tissue changes, as well as subjective sleep-related and oral-related quality of life. Outcome changes within each group and between groups will be analysed. ETHICS AND DISSEMINATION: This study is approved by the Ethics Committee of the School and Hospital of Stomatology, Wuhan University (no. 2022-D07). The research findings will be faithfully disseminated through scientific conferences or published articles. TRIAL REGISTRATION NUMBER: ChiCTR2200061703 (https://www.chictr.org.cn).

Incidence of inferior alveolar nerve sensory deficit and intra-operative nerve encounters after advancement of retrognathic mandible - A cross-sectional survey study.

Aims and Objectives: The aim of the current cross-sectional study was to conduct a survey among the oral and maxillofacial surgeons of South India regarding their experiences of incidence of inferior alveolar nerve (IAN) neurosensory deficit after bilateral sagittal split osteotomy (BSSO) for correction of mandibular retrognathism and to assess the intra-operative nerve encounters and its effect on the inferior alveolar neurosensory deficit (NSD), 6 months post-operatively. Materials and Methods: A self-administered questionnaire (SAQ) was prepared using Google Forms (Google Inc.) and sent to the prospective participants through various social media outlets such as Facebook, WhatsApp groups etc., of the maxillofacial surgery specialty for a period of 3 months. SAQ from surgeons with more than 5 years of experience in orthognathic surgery were included. Results: The incidence of NSD post-BSSO advancement surgery from 859 cases after 6 months was 15.1% (130). After splitting the mandible, the IAN was seen in the proximal fragment in 472 sites and needed dissection. The nerve was transected and neurorrhaphy was carried out in 26 sites. A Chi-square test was used to analyse the qualitative variables. The IAN was not visible post-osteotomy in 140 sites and in the distal fragment in 1080 sites. These groups had decreased incidence of NSD. The NSD was significantly higher in cases where the nerve was transected and sutured, P value <0.001 as compared with the other nerve status, followed by the nerve in the proximal fragment needing dissection. Conclusion: The IAN status intra-operatively can be assumed to have a significant role in persisting NSD.

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.

Bilateral temporomandibular joint reconstructions with stock alloplastic prostheses on a distracted mandible - A case report.

Background: The management of patients with a triad of temporomandibular joint (TMJ) ankylosis, retrognathia, and obstructive sleep apnea (OSA) has long been a matter of debate. Even though consensus favors distraction osteogenesis (DO) in the 1st phase of treatment to relieve the OSA, various treatment approaches for TMJ reconstruction after ankylosis release have been put forth. Most of the reconstructive modality has been focused on autogenous materials or customized TMJ prostheses after mandibular distraction.Case Presentation: The authors present a case of a patient with the triad of TMJ ankylosis, retrognathia, and OSA who underwent DO for correction of his OSA. This was followed by bilateral TMJ reconstruction with stock alloplastic prostheses on the distracted mandible, along with genioplasty to correct retrogenia.Conclusion: In this case, stock TMJ total joint prostheses were used successfully to treat bilateral TMJ ankylosis following previous surgery for mandibular distraction.

[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.

A cirurgia ortognática no tratamento da DTM em pacientes classe II / The orthognatic surgery in treatment of TMJ in class II patients

Introdução: A má oclusão Classe II pode influenciar negativamente na qualidade de vida dos pacientes, tanto na aparência facial, quanto função oral ou até ambas. Atualmente, o tratamento ortodôntico-cirúrgico é comumente utilizado em pacientes com discrepâncias esqueléticas graves. Objetivo: Este estudo tem como objetivo analisar os resultados da cirurgia ortognática associada ao tratamento ortodôntico nos pacientes que possuem DTM e má oclusão de Classe II por retrognatismo mandibular. Metodologia: Foi realizada uma pesquisa bibliográfica nas plataformas de buscas científicas Google Acadêmico, CAPES/MEC, PubMed/Medline, Scielo, Elsevier, e nas revistas AJO-DO (American Journal of Orthodontics and Dentofacial Orthopedics) e The Angle Orthodontist (An International Journal of Orthodontics and Dentofacial Orthopedics), utilizando as seguintes palavras chave: retrognatismo, cirurgia ortognática e transtornos da ATM. Conclusão: A maioria dos pacientes que apresentam sinais e sintomas de DTM pré-operatórios melhoram a disfunção e diminuem os níveis de dor com o tratamento ortognático. Além disso, o tratamento ortodôntico é de suma importância para se obter o sucesso do procedimento cirúrgico, assim como na estabilidade pós-cirúrgica.(AU)

Introduction: Class II malocclusion can negatively influence patients in quality of life, in the facial and oral appearance or both. Currently, orthodontic-surgical treatment is commonly used in patients with severe skeletal discrepancies. Objective: The objective of this study was to analyze the results of orthognathic surgery associated with orthodontic treatment in patients who have TMD and Class II malocclusion due to mandibular retrognathism. Methodology: A bibliographic search was performed in the scientific search platforms Google Scholar, CAPES/MEC, PubMed/Medline, Scielo, Elsevier, AJO-DO (American Journal of Orthodontics and Dentofacial Orthopedics) and in The Angle Orthodontist (An International Journal of Orthodontics and Dentofacial Orthopedics), using the keywords: retrognathism, orthognathic surgery and TMJ disorders. Conclusion: With orthognathic treatment, most patients who had preoperative DTM signs and symptoms showed an improvement and a decrease in pain levels. In addition, orthodontic treatment is important for the success of the surgical procedure, as well as for post-surgical stability.(AU)

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.

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.

The efficacy of different treatment approaches for pediatric OSAHS patients with mandibular retrognathia: study protocol for a multicenter randomized controlled trial.

BACKGROUND: Pediatric obstructive sleep apnea/hypopnea syndrome (OSAHS) is a multifactorial syndrome caused by many risk factors, such as craniofacial anomalies, adenotonsillar hypertrophy, obesity, and airway inflammation. Although new treatment patterns have recently been proposed, treatment methods for children remain particularly challenging and controversial. This randomized controlled trial was designed to investigate the efficacy of adenotonsillectomy and/or orthodontic treatment for children who have mild OSAHS with mandibular retrognathia. METHODS: A sample of 352 children with mild OSAHS and mandibular retrognathia, who are aged between 7 and 10 years, will be enrolled in the study. They will be randomized into four groups: the drug treatment group, the surgical treatment group, the orthodontic treatment group, or the surgery and postoperative orthodontic group. After randomization the children will receive treatments within 4 weeks. Outcome assessment will take place at the following points: (1) baseline, (2) 7 months after the treatment starting point, (3) 12 months after the treatment starting point, and (4) 24 months after the treatment starting point. The primary endpoint of the trial is the mean change in obstructive apnea/hypopnea index. Other endpoints will consist of the lowest oxygen saturation, apnea index, and hypopnea index assessed by polysomnography, subjective symptoms (assessed by the OSA-20 questionnaire), cephalometric measurements, and morphologic analysis of the upper airway. DISCUSSION: The results of this study will provide valuable evidence for the merits and long-term efficacy of different treatment approaches and contribute to facilitating the multidisciplinary treatment of pediatric OSAHS. TRIAL REGISTRATION: ClinicalTrials.gov : NCT03451318. Registered on 2 March 2018 (last update posted 19 April 2018).

Cirurgia ortognática no tratamento da Síndrome da Apneia Obstrutiva do Sono / Orthognathic Surgery in the Treatment of Obstructive Sleep Apnea Syndrome

Introdução: A síndrome da apneia obstrutiva do sono (SAOS) é considerada um problema de saúde pública associada a diversas comorbidades que afetam a qualidade e a expectativa de vida. Atualmente, o uso de dispositivos que controlam a pressão do ar durante o sono é considerado uma das melhores terapias para diminuir os sintomas da apneia, entretanto, apresentam difícil adesão dos pacientes. Assim, o tratamento cirúrgico para este distúrbio, cuja cirurgia ortognática se destaca, apresenta alta previsibilidade e bons resultados. Relato de caso: O presente trabalho tem como objetivo relatar o caso clínico de uma paciente do sexo feminino de 40 anos, portadora da SAOS severa e com alto índice de apneia-hipopneia (IAH). Ao exame físico foi observada respiração bucal, deformidade dentofacial do tipo classe II, plano oclusal acentuado e disfunção bilateral da articulação temporomandibular. O tratamento utilizado foi avanço maxilomandibular com rotação anti-horária do plano oclusal associado à mentoplastia. O acompanhamento foi realizado por um período de dois anos, no qual observou uma diminuição no IAH após oito meses da cirurgia e um aumento significativo no volume axial das vias aéreas superiores. Considerações finais: A cirurgia ortognática proposta para este caso demonstrou ser o tratamento adequado, apresentando ótimos resultados e eficácia a longo prazo... (AU)

Introduction: Obstructive sleep apnea syndrome (OSAS) is considered a public health problem associated with several comorbidities that affect quality and life expectancy. Currently, the use of devices that control air pressure during sleep is considered to be one of the best therapies to reduce apnea symptoms, however, it is difficult for patients to adhere. Thus, surgical treatment for this disorder, whose orthognathic surgery stands out, has high predictability and good results. Case report: The present study aims to report the clinical case of a 40-year-old female patient with severe OSAS and a high rate of apnea-hypopnea (AHI). On physical examination, mouth breathing, class II type dental-facial deformity, accentuated occlusal plane and bilateral temporomandibular joint dysfunction were observed. The treatment used was maxillomandibular advancement with counterclockwise rotation of the occlusal plane associated with chin repair. Follow-up was carried out for a period of two years, in which were observed a decrease in AHI eight months after surgery and a significant increase in the axial volume of the upper airways. Final considerations: The orthognathic surgery proposed for this case proved to be the appropriate treatment, presenting excellent results and long-term efficacy... (AU)

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 .

Impact of orthognathic surgery on velopharyngeal function by evaluating speech and cephalometric radiographs.

BACKGROUND: Maxillary retrognathia is a well-known consequence of abnormal facial growth in patients with cleft lip and palate. Orthognathic surgery improves facial appearance and occlusion but may induce velopharyngeal insufficiency. The aim of this study was to evaluate the effect of orthognathic surgery on velopharyngeal function by using speech analysis and lateral cephalometric radiographs. PATIENTS AND METHODS: We conducted a retrospective study of 47 patients who underwent maxillary advancement ±â€¯mandibular setback between 2006 and 2016. Preoperative and 1 year postoperative audio recordings were blinded for scoring by three trained speech therapists. Preoperative and 1 year postoperative lateral cephalometric radiographs were used to obtain information about skeletal movement and its relationship with the velopharyngeal area. Correlations between speech outcomes and cephalometric radiographs were determined. RESULTS: Hyponasality improved significantly after surgery (p < 0.05), whereas hypernasality deteriorated significantly only in patients who underwent maxillary advancement alone (p < 0.05). No difference in speech parameters was found between patients with hypernasality or patients who had a pharyngoplasty preoperatively and the rest of the group. No correlation was found between the amount of maxillary advancement and hypernasality. A significant correlation (r < -0.49, p < 0.05) was found between the preoperative velar length and hypernasality postoperatively. CONCLUSIONS: Maxillary advancement has a negative impact on velopharyngeal function, whereas bimaxillary surgery seems to protect from deterioration. No difference was found in the amount of maxillary advancement or in velopharyngeal measurements between the Le Fort I group and the bimaxillary group. A short soft palate is a predictor of hypernasality after orthognathic surgery.

Three-dimensional volumetric analysis of condylar head and glenoid cavity after mandibular advancement.

The aim of this study was to assess condylar resorption, spatial change in glenoid cavity, and its risk factors after mandibular advancement by three-dimensional volumetric analysis. Subjects consisted of 30 condyles of 15 patients diagnosed with mandibular retrognathism who underwent Le Fort I and bilateral sagittal split ramus osteotomy advancement. CBCT images were taken before surgery (T0), immediately after surgery (T1), and postoperatively at 6 months (T2) and 1 year (T3). Condylar resorption was observed in 21 condyles. The posterior was the most affected region, while the anterior was the least affected. The volume of the glenoid cavity was significantly increased after surgery regardless of the presence or absence of resorption. However, the cavity recovered close to its original volume over time. At 1 year after surgery, the volume was not significantly different from the preoperative volume. Counterclockwise rotation of the proximal segment was found to be a risk factor affecting resorption based on correlation analysis. Mandibular advancement appeared to generate excessive mechanical stress on the posterior condyle, and might be responsible for the resorption. Counterclockwise rotation might have added stress to the region. Articular spatial change was transient and did not appear to be related to condyle resorption.

Release of syngnathia by anticlockwise rotation and mandibular advancement using bilateral alloplastic temporomandibular joint prostheses: a new approach.

We describe a new approach to the planning of treatment and subsequent operation on a patient with syngnathia and severe mandibular retrognathism. To facilitate a large mandibular advancement we applied alloplastic temporomandibular joint (TMJ) prostheses to the coronoid processes after anticlockwise rotation of the mandible. To the best of our knowledge this is the first documented case of its kind.

Mandibular bone healing after advancement or setback surgery using sagittal split ramus osteotomy.

PURPOSE: The purpose of this study was to compare mandibular bone healing after advancement or setback surgery using sagittal split ramus osteotomy (SSRO). SUBJECTS: and Methods. The subjects were 50 patients (100 sides) who underwent bi-maxillary surgery, and were divided into 2 groups (25 class II advancement cases and 25 class III setback cases). They were selected randomly from the patients who underwent surgery between 2012 and 2017. Ramus square, ramus length and ramus width were measured in the horizontal plane image of computed tomography (CT), before and immediately after the operation, and at 1 year after the operation. RESULTS: Ramus square in the class III cases significantly increased in 1 year after the operation (P < 0.0001), meanwhile there was no change after 1 year in the class II cases. Before the operation, there were no significant differences in the all measurements between classes II and III. However, for ramus width, class III was significantly larger than class II immediately after (P = 0.0014) and at 1 year after the operation (P = 0.0003). CONCLUSION: This study suggested that post-operative change in ramus morphology was different between class II advancement surgery and class III setback surgery.

[Mandibular repositioning in adult patients. An alternative to surgery in some patients? A two-year follow-up]. / Le repositionnement mandibulaire : une alternative à la chirurgie chez des patients adultes ? Un suivi sur deux ans.

INTRODUCTION: A number of adult patients with skeletal discrepancies refuse surgical intervention. AIMS: The aim was to assess the reaction to mandibular repositioning in simulating a skeletal correction in such patients. MATERIALS AND METHODS: 32 consecutive patients without any signs of temporo-mandibular dysfunction (TMD) were offered mandibular repositioning, as a non-invasive alternative and it was explained to them that the approach was based on the results described in case reports. Before initiating any treatment initial records, headfilms, study casts and photos were taken (T0) and the mandible was repositioned to camouflage the skeletal discrepancy by means of an occlusal built-up in Triad® Gel. RESULTS: Three months later (T1) 23 patients had adapted to the new occlusion reflected in absence of functional problems and lack of fracture of the built-up. In these patients the mandibular position was maintained by orthodontics adjusting the occlusion to the built-up position (T1). The skeletal changes occurring during repositioning were assessed on sagittal and frontal head films while intra-articular changes occurring during a 2-year follow-up period (T2) were evaluated on images constructed from CBCT images. No significant changes, neither in the direction of a relapse nor in the direction of further normalization of the condylar positioning, were observed during the 2-year observation period. CONCLUSIONS: Repositioning is a non-invasive intervention and may be considered a valid alternative to surgery in some patients. Morphological variables from the radiographs taken at T0 and the results of the initial clinical evaluation of dysfunction yielded only vague and insignificant indications regarding the predictability of adaptation to the repositioning.

Long-term stability of mandibular advancement with bilateral sagittal split osteotomy.

INTRODUCTION: Aim of this study was 1) to evaluate long-term dental/skeletal stability in patients with mandibular retrognathia corrected by BSSO, and 2) to examine factors associated with relapse. MATERIALS AND METHODS: Seventy-seven of initial 151 study cohort subjects who had undergone orthognathic surgery in 2007-2011 agreed to participate. Present paper presents data on dental/skeletal stability in 46 patients; 31 patients were excluded because of missing calibration indicator in one of the patients' pre-operative cephalometric radiographs, or because of pregnancy. Pre-operative (T1), post-operative (T2) and long-term follow-up (T3) radiographs and patient's files were used in the study. RESULTS: Based on overjet measurements, mean mandibular advancement was 5.7 mm and mean relapse 0.1 mm. Mean pre-operative overbite was 5.4 mm, reduction at surgery 3.4 mm and mean relapse 1.1 mm, a statistically significant change. Mean mandibular advancement measured from condyle tognathion (Co-Gn) was 6.5 mm. Relapse in Co-Gn was 1.6 mm on average, i.e., about 25% of the advancement. Amount of advancement, fixation method, patient's age or gender or orthodontist/surgeon experience did not have influence on relapse. CONCLUSIONS: Mandibular advancement with BSSO in healthy Class II patients is considered a stable procedure. 25% skeletal relapse was found with clinically non-significant dental changes.

Study of condylar positional changes after sagittal split osteotomy for mandibular advancement: A prospective cohort study.

PURPOSE: To analyse the possible morphologic and positional changes of the mandibular condyles after orthognathic surgery. MATERIAL AND METHODS: A prospective cohort study was performed. Patients with mandibular retrognathism were surgically treated to advance the mandible. The study group included seventeen patients (34 condyles) treated with sagittal split osteotomies alone (4 patients) or in combination with maxillary osteotomies (13 patients). Only condyles located on the mandibular side that advance during surgery were studied, therefore only 25 condyles entered this prospective study. Beside it, a group of 6 patients undergoing maxillary surgery as only procedure, maxillary group, was also studied to determinate the influence of maxillary surgery on condylar displacement. Computed tomographies and lateral cephalometric radiographs were performed two weeks before surgery and one year after the surgical procedures. Different variables which analyse the position and morphology of the mandible were studied. The data obtained were analysed statistically by computing R2 values. RESULTS: In the maxillary group they were small displacements in magnitude and not significant. In the study group, 8 condyles showed morphological changes with alteration on reference points. In the remainder 17 condyles different displacements were noted after surgery. Several of these positional changes were predictable and did not affect postoperative mandibular stability. CONCLUSIONS: condylar displacements that occur after sagittal split osteotomies for mandibular advancement show significant correlation with the degree of mandibular advancement and can be defined by mathematical formulae. Maxillary osteotomies do not seem to influence condylar position when bimaxillary procedures take place.

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.