Validation of a fully automatic three-dimensional assessment of orthognathic surgery.

The aim of the present study was to propose and validate FAST3D: a fully automatic three-dimensional (3D) assessment of the surgical accuracy and the long-term skeletal stability of orthognathic surgery. To validate FAST3D, the agreement between FAST3D and a validated state-of-the-art semi-automatic method was calculated by intra-class correlation coefficients (ICC) at a 95 % confidence interval. A one-sided hypothesis test was performed to evaluate whether the absolute discrepancy between the measurements produced by the two methods was statistically significantly below a clinically relevant error margin of 0.5 mm. Ten subjects (six male, four female; mean age 24.4 years), class II and III, who underwent a combined three-piece Le Fort I osteotomy, bilateral sagittal split osteotomy and genioplasty, were included in the validation study. The agreement between the two methods was excellent for all measurements, ICC range (0.85-1.00), and fair for the rotational stability of the chin, ICC = 0.54. The absolute discrepancy for all measurements was statistically significantly lower than the clinical relevant error margin (p < 0.008). Within the limitations of the present validation study, FAST3D demonstrated to be reliable and may be adopted whenever appropriate in order to reduce the work load of the medical staff.

Influencing factors for the development of obstructive sleep apnea after orthognathic surgery in skeletal class III patients: A systematic review.

This systematic review aimed to investigate the factors that may contribute to the development of OSA after orthognathic surgery in patients with skeletal class III. Electronic searches of PubMed, Embase, Web of Science, and Cochrane databases were conducted up to December 10, 2022. In total, 277 studies were retrieved and screened according to the inclusion and exclusion criteria, and 14 were finally selected. All studies were of medium quality (moderate risk of bias). The occurrence of OSA after orthognathic surgery in patients with class III skeletal relationships depends on surgical factors and patient self-factors. Surgical factors include surgery type, amount of maxillary and mandibular movement, and the patient's postoperative swelling. Patient self-factors include weight, age, gender, and hypertrophy of the soft palate, tonsils, and tongue. According to information in the 14 selected articles, the incidences of OSA after Le Fort I impaction and BSSO setback, BSSO setback, and Le Fort I advancement and BSSO setback were 19.2%, 8.57%, and 0.7%, respectively, mostly accompanied with greater amounts of mandibular recession. However, no clear evidence exists to confirm that orthognathic surgery is a causative factor for postoperative sleep breathing disorders in patients with mandibular prognathism. The wider upper airway in patients with class III skeletal might be the reason for the rare occurrence of OSA after surgery. In addition, obesity and advanced age may lead to sleep apnea after orthognathic surgery. Obese patients should be advised to lose weight preoperatively.

Efficacy of navigation system-assisted distraction osteogenesis for hemifacial microsomia based on artificial intelligence for 3 to 18 years old: study protocol for a randomized controlled single-blind trial.

BACKGROUND: Mandibular distraction osteogenesis (MDO) is a major part of the treatment for hemifacial microsomia patients. Due to the narrow surgical field of the intraoral approach, osteotomy accuracy is highly dependent on the surgeons' experience. Electromagnetic (EM) tracking systems can achieve satisfying accuracy to provide helpful real-time surgical navigation. Our research team developed an EM navigation system based on artificial intelligence, which has been justified in improving the accuracy of osteotomy in the MDO in animal experiments. This study aims to clarify the effect of the EM navigation system in improving the MDO accuracy for hemifacial microsomia patients. METHODS: This study is designed as a single-centered and randomized controlled trial. Altogether, 22 hemifacial microsomia patients are randomly assigned to the experiment and control groups. All patients receive three-dimensional CT scans and preoperative surgical plans. The EM navigation system will be set up for those in the experiment group, and the control group will undergo traditional surgery. The primary outcome is the surgical precision by comparing the osteotomy position of pre- and postoperative CT scan images through the Geomagic Control software. The secondary outcomes include mandibular symmetry (occlusal plane deviation angle, mandibular ramus height, and body length), pain scale, and complications. Other indications, such as the adverse events of the system and the satisfactory score from patients and their families, will be recorded. DISCUSSION: This small sample randomized controlled trial intends to explore the application of an EM navigation system in MDO for patients, which has been adopted in other surgeries such as orthognathic procedures. Because of the delicate structures of children and the narrow surgical view, accurate osteotomy and protection of nearby tissue from injury are essential for successful treatment. The EM navigation system based on artificial intelligence adopted in this trial is hypothesized to provide precise real-time navigation for surgeons and optimally improve patient outcomes, including function and aesthetic results. The results of this trial will extend the application of new navigation technology in pediatric plastic surgery. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2200061565. Registered on 29 June 2022.

O uso do planejamento virtual na cirurgia ortognática / The use of virtual planning in orthognathic surgery

Introdução: A cirurgia ortognática envolve manipulação da arquitetura óssea facial, através de osteotomias, para restaurar a forma e a função, corrigindo a má oclusão, as desproporções maxilomandibulares e assimetrias faciais. O planejamento virtual em cirurgia ortognática é realizado com ajuda de softwares que utilizam as medidas reais do esqueleto craniofacial e registros da oclusão do paciente, através de uma análise 3D. Método: Foram avaliados 18 pacientes com deformidades dentofaciais, de acordo com a classificação de Angle submetidos a cirurgia ortognática com o uso do planejamento virtual, entre 2018 e 2019. Os critérios de inclusão foram pacientes entre 16 e 60 anos com desproporções maxilo-mandibulares nas quais o tratamento ortodôntico isolado não era suficiente. Os critérios de exclusão foram a presença de lesões císticas ou tumorais nos maxilares e comorbidades clínicas que contraindicavam a cirurgia. O planejamento virtual foi realizado em todos os pacientes, utilizando o software Dolphin® Imaging 11 e os guias cirúrgicos confeccionados em impressora 3D. Resultados: O guia cirúrgico intermediário apresentou adaptação perfeita nas faces oclusais promovendo grande estabilidade para o reposicionamento e fixação da maxila na oclusão intermediária. Os 18 pacientes operados responderam como "totalmente satisfeitos" em relação ao resultado estético-funcional nessa série estudada. Foi encontrada uma semelhança muito grande da posição do esqueleto maxilofacial no planejamento virtual préoperatório e o obtido no pós-operatório, através da avaliação das telerradiografias. Conclusão: O planejamento virtual em cirurgia craniomaxilofacial possui inúmeras vantagens, como diminuição do tempo laboratorial pré-operatório, maior precisão na confecção dos guias cirúrgicos e melhor reprodutibilidade dos resultados simulados.

Introduction: Orthognathic surgery involves the manipulation of facial bone architecture through osteotomies to restore form and function, correcting malocclusion, maxillomandibular disproportions, and facial asymmetries. Virtual planning in orthognathic surgery is carried out with the help of software that uses real measurements of the craniofacial skeleton and records of the patient's occlusion through 3D analysis. Method: 18 patients with dentofacial deformities were evaluated, according to Angle's classification, who underwent orthognathic surgery using virtual planning between 2018 and 2019. The inclusion criteria were patients between 16 and 60 years old with maxylo-mandibular disproportions in which orthodontic treatment alone was not sufficient. Exclusion criteria were the presence of cystic or tumoral lesions in the jaw and clinical comorbidities that contraindicated surgery. Virtual planning was carried out on all patients, using Dolphin® Imaging 11 software and surgical guides made with a 3D printer. Results: The intermediate surgical guide presented perfect adaptation on the occlusal surfaces, promoting great stability for the repositioning and fixation of the maxilla in intermediate occlusion. The 18 operated patients responded as "completely satisfied" in relation to the aesthetic-functional result in this series studied. A very great similarity was found between the position of the maxillofacial skeleton in the preoperative virtual planning and that obtained post-operatively through the evaluation of teleradiography. Conclusion: Virtual planning in craniomaxillofacial surgery has numerous advantages, such as reduced pre-operative laboratory time, greater precision in the creation of surgical guides, and better reproducibility of simulated results.

Changes of the facial soft tissue after mandibular reconstruction using vascularized iliac flap.

OBJECTIVES: To reveal the change patterns of the facial soft tissue after applying mandibular reconstruction. MATERIALS AND METHODS: 16 Patients with mandibular benign tumor were recruited in this retrospective study. For all patients, segmental mandibular osteotomy and concurrent reconstruction using vascularized iliac flap were conducted. The soft tissue thickness of patients' lower face was measured with CT scans before surgery, 1 week, 6 months and 1 year after surgery. The time-dependent changes of tissue thickness were analyzed. RESULTS: The most significant tissue swelling was 28.86%, at 1 week after the surgery. The average increase of tissue thickness was 4.78 ± 5.30 mm across patient. After 1 year of the surgery, tissue thickness decreased to the level before operation or the level of the healthy side. The thickness of the low-density tissue fluctuated mildly, while the thickness of the high-density tissue fluctuated significantly. The disuse atrophy of the masseter occurred 1 week after the surgery, and was reversed after 1 year. The removal of the submandibular gland caused depression in submandibular area, which intensified over time. CONCLUSION: Across patients, soft tissue thickness in the lower face after mandibular osteotomy and reconstruction increased significantly 1 week after the surgery, and decreased over time. After 1 year, tissue thickness went back to the pre-surgery level, where matched up with the healthy side. CLINICAL RELEVANCE: We documented the change patterns of the facial soft tissue after mandibular reconstruction. These results can help improve the planning of virtual surgeries and the timing for aesthetic assessment. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: ChiCTR2100054103.

Osteotomia periférica no tratamento de cisto odontogênico glandular / Peripheral osteotomy in the treatment of glandular odontogenic cyst / Osteotomía periférica en el tratamiento del quiste odontogénico glandular

O objetivo deste artigo é relatar um caso de COG em sínfise mandibular, tratado com enucleação e osteotomia periférica. Relato de Caso: Paciente do sexo feminino, 58 anos de idade, foi encaminhada para avaliação de uma lesão mandibular, apresentando-se assintomática no momento da consulta. Foi observado um leve aumento de volume vestibular na região da sínfise mandibular, sem sensibilidade ao toque. Na tomografia foi observada imagem hipodensa, multiloculada, bem delimitada, na região de sínfise, próxima as raízes dentárias e a basilar mandibular, além de um dente incluso intralesional. Foi realizada biópsia incisional e exame histopatológico, através do qual foi estabelecido o diagnóstico de COG. Como forma de tratamento, o paciente foi submetido a enucleação com curetagem de toda lesão e a osteotomia periférica, além da remoção do dente incluso. Após um ano de acompanhamento, a paciente encontra-se livre de recorrências. Conclusão: Por fim, este caso destaca a importância de um tratamento eficaz de COG com a osteotomia periférica, considerando o tamanho da lesão, suas características e sua localização, a fim de reduzir suas chances de recidiva... (AU)

The aim of this article is to report a case of COG in mandibular symphysis, treated with enucleation and peripheral osteotomy. Case Report: A 58-yearold female patient was referred for evaluation of a mandibular lesion, instrument was asymptomatic at the time of consultation. An increase in vestibular volume was observed in the region of the mandibular symphysis, without sensitivity to touch. The tomography showed a hypodense, multiloculated, well-delimited image in the symphysis region, close to tooth roots and a mandibular basilar, in addition to an intralesional impacted tooth. An incisional biopsy and histopathological examination were performed, through which the diagnosis of COG was established. As a form of treatment, the patient underwent enucleation with curettage of the entire lesion and peripheral osteotomy, in addition to removal of the impacted tooth. After a year of follow-up, the patient is free from recurrences. Conclusion: Finally, this case highlights the importance of an effective treatment of COG with peripheral osteotomy, considering the size of the lesion, its characteristics and its location, in order to reduce its chances of recurrence... (AU)

El objetivo de este artículo es reportar un caso de COG en la sínfisis mandibular, tratado con enucleación y osteotomía periférica. Caso Clínico: Paciente femenino, de 58 años de edad, fue remitida para valoración de lesión mandibular, presentándose asintomática al momento de la consulta. Se observa ligero aumento de volumen vestibular en la región de la sínfisis mandibular, sin sensibilidad al tacto. En la tomografía se observó una imagen hipodensa, multiloculada, bien delimitada en la región de la sínfisis, próxima a las raíces dentarias y la base de la mandíbula, además de un diente intralesional. Se realizó biopsia incisional y examen histopatológico, a través del cual se estableció el diagnóstico de GOC. Como forma de tratamiento, el paciente fue sometido a enucleación con curetaje de toda la lesión y osteotomía periférica, además de extracción del diente impactado. Después de un año de seguimiento, un paciente está libre de recurrencias. Conclusión: Finalmente, este caso destaca la importancia de un tratamiento efectivo de la GOC con osteotomía periférica, considerando el tamaño de la lesión, sus características y su ubicación, para reducir sus posibilidades de recurrencia... (AU)

Mandibular midline osteotomy for correction of bimaxillary transverse discrepancy: a technical note.

Bimaxillary transverse width discrepancies are commonly encountered among patients with dentofacial deformities. Skeletal discrepancies should be diagnosed and managed appropriately with possible surgical corrections. Transverse width deficiencies can present in varieties of combinations involving the maxilla and mandible. We observed that in a significant proportion of cases, the maxilla is normal, and the mandible showed deficiency in the transverse dimension after pre-surgical orthodontics. We designed novel osteotomy techniques to enhance mandibular transverse width correction, as well as simultaneous genioplasty. Chin repositioning along any plane is applicable concomitant with mandibular midline arch widening. When there is a requirement for larger widening, gonial angle reduction may be necessary. This technical note focuses on key points in management of patients with transversely deficient mandible and the factors affecting the outcome and stability. Further research on the maximum amount of stable widening will be conducted. We believe that developing evidence-based additional modifications to existing conventional surgical procedures can aid precise correction of complex dentofacial deformities.

Additional pre-extubation local anaesthetic application to improve the postoperative course in orthognathic surgery: a randomised controlled trial.

A clinical trial was performed to assess the analgesic efficacy of adding ropivacaine pre-extubation for pain management after bimaxillary osteotomy. Forty-eight patients were assigned to receive general anaesthesia followed by either a single pre-incisional infiltration with lidocaine (control group, n = 24) or the same pre-incisional infiltration with lidocaine and an additional second infiltration with ropivacaine before awakening (test group, n = 24). Postoperative pain was assessed subjectively using a visual analogue scale and objectively based on the frequency of postoperative rescue opioid consumption. The dose of opioids (methadone) consumed and frequency of postoperative-nausea-vomiting were also recorded. Patients who received the two infiltrations of local anaesthetic had better results in terms of lesser pain during the first 8 hours postoperative (P<0.001 at 2 and 4 hours; P = 0.028 at 8 h), a lesser need for rescue opioids (P = 0.020) and lower doses of rescue opioids (P = 0.011), and consequently a lesser incidence of postoperative-nausea-vomiting (0-4 hours postoperative, P<0.03). The results obtained suggest that the infiltration of an additional dose of local anaesthetic is a simple strategy for reducing pain perception and opioid use, and for ensuring greater patient comfort after bimaxillary osteotomy.

Evaluation of outcomes after conservative mandibular surgery in patients with oral squamous cell carcinoma.

This study aimed to assess preoperative radiological and clinical examinations for identifying bone status and to evaluate survival outcomes in patients undergoing marginal mandibulectomy for the primary treatment of oral squamous cell carcinoma. The medical records, enhanced computed tomography (CT) scans, and pathological specimens of these patients were reviewed. Disease-free (DFS), local recurrence-free (LRFS), and osteoradionecrosis-free (ORNFS) survival were analysed. The study included 104 patients. The preoperative CT and clinical examinations achieved a sensitivity of 45.8% and specificity of 100% for judging bone condition. LRFS was 79.6% and DFS was 68.8%. Pathological bone invasion in significantly affected DFS (P = 0.597), while DFS was significantly higher for those with a lower clinical tumour stage (1/2 vs 3/4; P = 0.005) and postoperative radiotherapy (P = 0.011). Among 39 patients receiving postoperative radiotherapy, ORNFS was 75.2%. Postoperative chemotherapy significantly decreased ORNFS (P = 0.009). Tumour subsite (P = 0.003) and the resection site (P = 0.035) significantly affected the remaining bone height. The results indicate that CT and clinical examinations cannot precisely identify superficial bone damage, but work well in selecting patients for marginal resection. Adhering to current indications, this resection approach can guarantee safe bone margins in terms of survival outcomes.

Long-term evaluation of the upper airway following mandibular setback surgery in the patients with mandibular prognathism.

OBJECTIVE: The aim of this study was to evaluate the changes in the upper airway following mandibular setback surgery. METHODS: The patients underwent mandibular setback surgery and cone-beam computed tomography scan data obtained at four time points: before surgery, immediately after surgery, short- and long-term follow-up. Upper airway geometries were segmented and extracted at each time point. Time-averaged airflow through the upper airway was evaluated at each time point. The measurements of airway volume and minimum cross-sectional areas were obtained at four time points. RESULTS: The airway volume and cross-sectional areas of airway significantly decreased immediately after surgery (p = 0.013 for airway volume and 0.016 for cross-sectional area). At short-term follow-up, the decreased airway volume and cross-sectional areas still showed statistically significant difference to original dimension (p = 0.017 for airway volume and 0.006 for cross-sectional area). At long-term follow-up, although there were no statistical significances (p = 0.859 for airway volume and 0.721 for cross-sectional area), the airway volume and cross-sectional areas had increased slightly compared to those at short-term follow-up. CONCLUSIONS: Although the airflow and dimensional parameters of the upper airway worsened following mandibular setback surgery, there was a tendency to gradually recover during long-term follow-up.

Craniofacial Fibrous Dysplasia: Surgical Management and Long-Term Outcomes at a Referral Center in Mexico City.

Background Craniofacial fibrous dysplasia (CFD) is an uncommon benign condition in which a bone is replaced by fibrous tissue. An adequate clinical characterization considering the number of affected bones and functional impairment is important to determine the most effective surgical intervention for its management. This study aims to present our institution's experience in the evaluation and management of CFD. Methods This was a retrospective study that included patients with CFD managed at our institution. Data included demographic characteristics, afflicted bones, surgical procedures performed, and recurrence. Results are presented as mean and percentages. Recurrence-free years and association between the type of surgery and recurrence was evaluated. Results Eighteen patients were included (11 females, 61%). The zygomatic, maxillary, and frontal bones were the most commonly affected with eight (18%) cases each. The most common procedure was bone burring, with 36 procedures. Recurrence was more prevalent after burring (58.3%) and occurred earlier than in the bone resection group (13 vs. 15 years, p > 0.05). Conclusion Surgery continues to be the cornerstone of CFD treatment. Bone burring is effective for debulking and contouring but increases the risk for recurrence. An individualized approach should be tailored according to the anatomical location of the disease, type of CFD, behavior of the lesion, and accompanying clinical complaints.

Predictability of the virtual surgical plan for orthognathic surgery with the mandible surgery first sequence.

The aim of this study was to compare the virtually planned position to the postoperative position of the maxilla, having performed the maxilla-first sequence or mandible-first sequence orthognathic surgery. An audit of 64 patients who underwent bimaxillary surgery between 2017 and 2020 was performed. Thirty patients had maxilla-first surgery and 34 had mandible-first surgery. The planned and post-surgical positions were analyzed using specific skeletal landmarks. Differences were calculated and the two-sample t-test was used to compare the groups. Measured differences between the planned and postoperative results differed significantly between the mandible-first and maxillary-first surgery groups (P < 0.001). The maxillary central incisors were under-advanced in the anterior-posterior direction in both groups. Most data points showed deviation from the surgical plan ≤ 2 mm and ≤ 4°. Secondarily, maxillary under-advancement in the mandible-first cohort was evaluated; these patients were subdivided into rigid and non-rigid fixation groups. The non-rigid fixation group showed less accuracy compared to the rigid fixation group, which was statistically significant (P = 0.014). The findings of this study demonstrate that virtual surgical planning can be less accurate in predicting the maxillary incisor position when performing mandible-first surgery, but this inaccuracy is within the acceptable range and can be mitigated by rigid fixation of the mandible.

Redundancy of the Visual Identification of Lingula in the Bilateral Sagittal Split Ramal Osteotomy Procedure of the Mandible.

Introduction: The bilateral sagittal split ramus osteotomy (BSSRO) is the technique in vogue which is used for correction of a range of mandibular corpus deformity involving the dentoalveolar segment. The surgical technique has been subjected to a variety of modifications ever since its inception in the 1950s. One of the operative objectives which has been advocated sacrosanct has been the visual identification of lingula during the exposure of the medial aspect of the ramus. Materials and Method: BSSRO was successfully carried out in 45 cases operated over a period of eight years for correction of different kinds of skeletal mandibular deformity. The medial subperiosteal dissection did not involve a visual identification of the lingula. Conclusion: In our experience, the visual identification of the lingula is not essential to carry out a safe BSSRO procedure.

Outcomes of mandibular reconstruction using three-dimensional custom-made porous titanium prostheses.

BACKGROUND: Our aim was to report the long-term outcomes of mandibular reconstruction using CAD-CAM-designed 3D-printed porous titanium implants in patients not amenable to a free vascularized fibula flap reconstruction. METHODS: The implants were designed with ProPlan CMF® 2.2 software and manufactured with a Selective Laser Melting (SLM) "layer-by-layer" 3D-printing of pure porous titanium powder beds. Primary endpoints were implant exposure and implant removal calculated using Gray's tests. Secondary endpoints were predictive factors of implant exposure and implant removal, and rates of dental rehabilitation. RESULTS: Thirty-six patients were operated between 2015 and 2017 and were included in this study. Reconstruction using a porous titanium 3D-printed implant was proposed due to medical contraindication for a fibula free flap (n = 13), due to the failure of a previous fibula free flap reconstruction (n = 7), or due to refusal of a fibula free flap reconstruction by the patient (n = 16). The medical indications for mandibular reconstruction were a primary tumor requiring mandibulectomy in nine patients, mandibular osteoradionecrosis requiring mandibulectomy in nineteen patients, and secondary reconstruction in eight patients. The 2-year rates of implant exposure and implant removal were 69.4% and 52.8%. Reconstruction of the symphysis was a high-risk exposure variable (OR 30; p = 0.0003). Only one patient underwent a successful dental rehabilitation. CONCLUSION: The use of a porous titanium 3D- implant for mandibular reconstruction in head and neck cancer patients resulted in high rates of implant exposure and of implant removal, notably when symphysis involvement.

Hypoxia-induced factor 1α promotes osteotomy-induced regional acceleratory phenomenon via DC-STAMP mediated membrane fusion.

OBJECTIVES: The mechanisms of regional acceleratory phenomenon (RAP) induced by orthognathic osteotomy are unclear. It was not known if locally hypoxic microenvironment changes were involved in this phenomenon. METHODS: Hypoxia-induced factor-1α knockout mice harboring Cathepsin K (CTSK) Cre were used to investigate the effect of hypoxia-driven osteoclasts on alveolar bone remodeling. RAW264.7 cells were induced by CoCl2 to observe the effects of dendritic cell-specific transmembrane protein (DC-STAMP) on the fusion and differentiation of osteoclasts. RESULTS: We found mandibular osteotomy of C57 mice induced active alveolar osteoclasts and increased hypoxia-induced factor-1α (HIF-1α) positive staining areas. Alveolar bone density of the 10-week-old HIF-1α conditional knockout (CKO) mouse was increased at 10 and 14 days after bilateral mandibular osteotomy. Moreover, decreased numbers of osteoclasts and matrix metalloproteinase 9 (MMP-9)-positive cells were observed on the surface of bone resorption lacunae in the CKO group. HIF-1α could increase the expression level of DC-STAMP to enhance osteoclastogenesis and cell fusion in active RAW264.7 cells. CONCLUSION: Our data considered hypoxia-driven osteoclasts resorption to be an adaptive mechanism to permit alveolar bone loss after bilateral mandibular osteotomy of mice.

Cone beam computed tomography volumetric airway changes after orthognathic surgery: a systematic review.

The aim of this systematic review was to provide a structured overview of three-dimensional airway volume changes in relation to various orthognathic surgeries. Clinical human studies performing pre- and postoperative three-dimensional airway volume assessments to investigate volumetric changes of the airway after orthognathic surgery were included. Pre-determined inclusion and exclusion criteria were applied in an extensive search of the PubMed, Embase, and Web of Science electronic databases. The cut-off date was set to January 1, 2022. Forty-one articles reporting retrospective and prospective case-control and case series studies were included. All studies were determined to be of medium quality (moderate risk of bias). The included studies were categorized by type of intervention. Pre- and postoperative volumes were extracted from the available data, and volume changes as a percentage of the preoperative levels were calculated. Isolated mandibular setback surgery generally decreased the airway volume. Isolated maxillary or mandibular advancement, bimaxillary advancement, and surgically assisted maxillary expansion generally increased the airway volume in the total airway and oropharynx, among which the effect of bimaxillary advancement surgery appeared most significant. High heterogeneity exists in the terminology and definitions of the airway and its segments. A more uniform methodology for airway volume measurement is needed to provide an insight into the impact on the airway of specific types of surgical intervention. In conclusion, airway volumes are affected after orthognathic surgery, which may be of clinical significance, especially in patients who are predisposed to obstructive sleep apnoea.

Micro-computed tomography evaluation of bone architecture in various forms of unilateral condylar hyperplasia.

Condylar hyperplasia is one of the causes of facial asymmetry and malocclusion, characterized by enlargement of the lower jaw due to excessive condyle growth activity. The aim of this study was to use micro-computed tomography (micro-CT) to evaluate the bone architecture of the condylar head and determine whether there are differences between patients with various forms of unilateral condylar hyperplasia (UCH): hemimandibular hyperplasia, elongation, and mixed form. The cohort consisted of 28 patients with a mean age of 21.9 years. All patients underwent surgical treatment (condylar shaving) for active pathological growth activity. The portion of the condylar head removed was imaged by micro-CT and subsequently evaluated. Micro-CT imaging and semiquantitative and quantitative evaluation of the bone structure (percentage bone volume, surface density, trabecular thickness, trabecular separation, degree of anisotropy, and porosity of the subchondral bone) did not reveal significant differences between the individual types of condylar hyperplasia (P > 0.05). There were no significant differences in bone structure between the anterior and posterior portions of the condylar head. No statistically significant differences between individual groups of UCH were found in the micro-CT evaluation of the condylar head bone architecture.

Impact of Mandibular Angle Osteotomy Using a Geometric Mathematical Design on the Aesthetic Osteotomy Line: A Retrospective Observational Study.

BACKGROUND: Mandibular angle osteotomy (MAO) is a frequently described technique in Eastern females. The success hinges on the precise positioning of the osteotomy line. The geometric mathematical method is viable. Therefore, we explored the impact of mandibular angle osteotomy using aesthetic standards and printed digital osteotomy templates (DOTs) on the aesthetic osteotomy line. METHODS: This retrospective observational study included female patients with prominent mandibular angle (PMA) who underwent MAO at our hospital between January 2020 and March 2021. Thirty-three female patients were included, 22 in the DOTs group using new DOTs, and 11 in the traditional group using traditional free-hand techniques. RESULTS: Regarding the width of the excised bone, the postoperative deviation from the preoperative plan was not significant in the DOTs group (0.5 ± 0.3 mm, P > 0.05), while the deviation was significant for the traditional group (2.5 ± 1.2 mm, P<0.05). The preparation time was longer in the DOTs group than in the traditional group (82 ± 11 vs. 53±4 min, P < 0.001). The osteotomy time and the operation time were shorter in the DOTs group than in the traditional group (osteotomy: 54 ± 5 vs. 73 ± 6 min; preparation: 124 ± 10 vs. 169 ± 13 min; both P < 0.001). The Likert (4.0 ± 0.5 vs. 1.0 ± 0.6, P = 0.006) and FACE-Q scores (17.5 ± 1.7 vs. 15.6 ± 1.3, P = 0.029) were higher in the DOTs group. CONCLUSIONS: The new method of positioning the new aesthetic osteotomy line based on geometric analysis might provide a possible osteotomy method that strongly suggests effectiveness, safety, individualization, and accuracy, with a shorter operation and higher patient satisfaction. 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 .

What are the surgical risks and 2-year stability of mandibular anterior subapical osteotomy in the treatment of dentoalveolar protrusion?

OBJECTIVE: To investigate the stability and complications of mandibular anterior subapical osteotomy (ASO) in the treatment of bimaxillary dentoalveolar protrusion by way of a retrospective study. MATERIALS AND METHODS: One hundred and twenty patients who received orthognathic surgery at a single center between 2008 and 2017 were included. Relapse was assessed by serial tracings of lateral cephalograms which were obtained pre-operatively (T1), within 6 weeks after surgery (T2) and at 2 years after surgery. The changes between T2 and T3 represented stability and were tested using the paired t test. The relationship between the extents of surgical repositioning (T2-T1) and relapse (T3-T2) was investigated using the Pearson correlation coefficient. The associations between the variables and the occurrence of relapse and complications identified the risk factors and were evaluated using the χ2 test or Fisher's exact test. When r > 0.80, clinical correlation was considered significant; and statistical significance was set at P < 0.05, while confidence interval was set at 95%. RESULTS: There was a mean uprighting of L1-MP by 12.7°. At 2 years after surgery, 96.7% of the patients experienced a mean relapse of L1-MP by 2.9°. The extent of surgical repositioning was only weakly correlated with that of relapse and no specific factor that increased the risk of relapse could be identified. The most frequent complications were blood loss requiring transfusion, wound dehiscence or infection, gingival recession, and periodontal bone loss, involving 25.8 to 43.3% of the patients. The remaining complications included tooth root damage, fixation hardware exposure or infection, lingual mucosal laceration, and tooth devitalization. There were no cases of avascular necrosis or nonunion. CONCLUSIONS: Although relapse occurred in most of the patients after 2 years, the actual extent was small (2.9°) which was not likely to be clinically significant. TRIAL REGISTRATION: HKUCTR-2964 CLINICAL RELEVANCE: Although ASO may be valuable in correcting mandibular dentoalveolar protrusion, the procedure brings with it risks and complications and should be reserved for severe deformities.

Surgical cutting guide and single plate fixation for intraoral vertical ramus osteotomy.

With the advancement of digital technology over the last few decades, the use of virtual surgical planning and fabrication of surgical guides have tremendously improved the outcomes of various maxillofacial surgical procedures. The intraoral vertical ramus osteotomy (IVRO) is an orthognathic surgical procedure largely employed for mandibular setback in correcting dentofacial deformities. This study describes the design and application of a surgical cutting guide for IVRO. The guide can also be used to facilitate the placement of miniplate fixation. The initial experience at the authors' centre suggests that the guide has allowed the osteotomy to be performed with increased precision and confidence. Furthermore, the use of miniplate fixation decreased the period of maxillomandibular fixation. However, a larger series is required to evaluate the utility of this system more thoroughly.