Three-Dimensional Analysis of Bone Remodeling After Closed Treatment for Mandibular Condylar Head Fracture.

Closed treatment of mandibular condylar fractures has been used for its indications based on the fracture site, fracture status, and patient age. Posttreatment mandibular condyle size is associated with mandibular function; however, a few studies have reported bone remodeling patterns and volume changes in the condyle and glenoid fossa after mandibular condylar head fractures (CHFs). Therefore, volumetric changes in the mandibular condyle and glenoid fossa were analyzed in the present study, and bone remodeling patterns were evaluated after mandibular CHFs. The present study included 16 condyles from 12 patients who received closed treatment for CHF. After reconstruction of a 3-dimensional skull model, including the mandible, using computed tomography data taken immediately after injury and 6 months after treatment, volume changes in the mandibular condyle and glenoid fossa were analyzed. The condylar volume increased by 0.32±0.66 cm3 during the 6-month healing period without statistical significance (P=0.093). Regarding the glenoid fossa, the fossa showed a statistically significant volume increase of 0.41±0.59 cm3 (P=0.021), and 12 glenoid fossae (75%) showed downward bone apposition; however, no change or only mild bone resorption was observed in 4 glenoid fossae (25%). The results of this study indicated that the volume changes in the mandibular condyle after closed treatment of a mandibular CHF are not significant, and the glenoid fossa adapts to the displaced mandibular condyle through downward growth accompanied by volume increase.

The Thyrohyoid Muscle: A Crucial Player in Deglutition and Vocalization

SUMMARY: The thyrohyoid muscle is one of the four infrahyoid muscles. Its role in vocalization and deglutition could be often overlooked, despite its crucial participation in these processes. Unlike other infrahyoid muscles, the thyrohyoid muscle receives innervation from the first cervical spinal nerves which contributes to its unique function. Its primary action involves hyolaryngeal elevation during swallowing, contributing to the opening of the upper esophageal sphincter. In conjunction with other muscles, it also protects the airway and facilitates the passage of food into the esophagus. Variations in the muscle's thickness may exist, and its function can be influenced by chewing habits. Weakened muscles involved in swallowing are often associated with dysphagia, a common complication in stroke and brain-injured patients. Advanced imaging techniques and sleep studies have provided insights into the dynamics and frequency of swallowing. This review explores the anatomic structures, function in action, diagnosis and clinical implications of this muscle. Overall, understanding the significance of the thyrohyoid muscle enhances our comprehension of the intricate interplay of laryngeal muscles during vocalization and deglutition.

El músculo tirohioideo es uno de los cuatro músculos infrahioideos. A menudo podría pasarse por alto su papel en la vocalización y la deglución, a pesar de su participación crucial en estos procesos. A diferencia de otros músculos infrahioideos, el músculo tirohioideo recibe inervación de los primeros nervios espinales cervicales, lo que contribuye a su función única. Su acción principal implica la elevación hiolaríngea durante la deglución, contribuyendo a la apertura del esfínter esofágico superior. Junto con otros músculos, también protege las vías respiratorias y facilita el paso de los alimentos al esófago. Pueden existir variaciones en el grosor del músculo y su función puede verse influenciada por los hábitos de masticación. Los músculos debilitados involucrados en la deglución a menudo se asocian con disfagia, una complicación común en pacientes con accidente cerebrovascular y lesión cerebral. Las técnicas de imagen avanzadas y los estudios del sueño han proporcionado información sobre la dinámica y la frecuencia de la deglución. Esta revisión explora las estructuras anatómicas, la función en acción, el diagnóstico y las implicaciones clínicas de este músculo. En general, comprender la importancia del músculo tirohioideo mejora nuestra comprensión de la intrincada interacción de los músculos laríngeos durante la vocalización y la deglución.

Multislice computed tomography demonstrating mental nerve paresthesia caused by periapical infection: A case report.

Components derived from an infected lesion within the bone can spread through various passages in the mandible, particularly via the mental foramen. Radiologically, the spread of infection is typically nonspecific and challenging to characterize; however, multislice computed tomography (MSCT) can effectively detect pathological changes in soft tissues and the bone marrow space. This report describes the case of a 55-year-old woman who experienced mental nerve paresthesia due to a periapical infection of the right mandibular second premolar. MSCT imaging revealed increased attenuation around the periapical lesion extending into the mandibular canal and loss of the juxtamental foraminal fat pad. Following endodontic treatment of the tooth suspected to be the source of the infection, the patient's symptoms resolved, and the previous MSCT imaging findings were no longer present. Increased bone marrow attenuation and obliteration of the fat plane in the buccal aspect of the mental foramen may serve as radiologic indicators of inflammation spreading from the bone marrow space.

Maxillary Sinus Augmentation and Implant Installation in Patients With Pseudocysts and Mucous Retention Cysts.

This case study systematically assessed diverse approaches to sinus augmentation in the presence of sinus pathology. Three patients were carefully selected and categorized as pseudocyst (PsC) (type 1), mucous retention cyst (MRC) smaller than 20 mm (type 2), and MRC larger than 20 mm in size (type 3). All patients underwent sinus augmentation procedures, with each case utilizing a unique surgical approach. Spontaneous drainage was performed for the patient with PsC (type 1), followed by uncomplicated sinus augmentation. For the patient with an MRC smaller than 20 mm (type 2), aspiration of the cyst contents preceded sinus augmentation. Conversely, the patient with a larger MRC (type 3) underwent cyst enucleation followed by sinus augmentation after complete recovery of the sinus membrane. No complications were noted in any of the cases, and follow-up revealed stable implant installation at the site of sinus augmentation. Within the constraints of this study, the choice of surgical procedure, whether involving spontaneous drainage, aspiration, or enucleation, should be guided by an anticipated pathologic diagnosis and the size of the sinus cyst. This informed approach empowers clinicians to make well-informed decisions for the best possible outcomes and sustained results. Overall, this study offers valuable insights for clinicians seeking to optimize sinus augmentation procedures in the presence of sinus pathology.

Application of double layer with collagen-elastin matrix (Matriderm®) and polyglycolic acid sheet (Neoveil®) for oroantral and oronasal fistula closure after maxillectomy: a retrospective single center experience.

PURPOSE: This study investigates the effectiveness of a new double-layer approach for closing oroantral and oronasal fistulas (OA/ONFs) using Matriderm® and Neoveil®. Matriderm®, an acellular dermal matrix composed of collagen and elastin fibers, supports tissue regeneration, while Neoveil®, a biodegradable mesh sheet, serves as a barrier to prevent leakage and scarring. MATERIAL AND METHODS: A retrospective study of 12 maxillectomy patients with oral cancer between January 2022 and May 2023 was conducted. Patient data, including tumor stage, bone invasion, and defect size, were analyzed. Surgical techniques included sinus mucosa preservation, and either buccal fat grafting combined with the double layer technique or the double layer technique alone, with statistical analysis performed using R software to evaluate outcomes. RESULTS: The results indicate a 41.7% incidence rate of fistula formation with lower T stages, absence of bone invasion, smaller defect dimensions, and intact sinus mucosa correlating with reduced fistula risk (p < 0.05). Notably, no patients required fistula-related surgical revisions, validating the efficacy of the approach. CONCLUSION: This study introduced a novel double-layer technique using Matriderm® and Neoveil® for closing OA/ONFs after maxillectomy. The technique demonstrated promising outcomes in addressing these post-operative complications. Lower tumor stages, no bone invasion, smaller defects, and intact sinus mucosa correlated with reduced fistula risk. This technique holds potential to enhance maxillectomy outcomes, offering a comprehensive approach to functional concerns, but warrants further investigation.

Removal of Calcium Hydroxide Paste Leaked Into the Maxillary Sinus.

Calcium hydroxide is a widely used endodontic medicament with antibacterial activity. When excessive pressure is applied during injection of calcium hydroxide paste or apical perforation occurs, calcium hydroxide can leak into the maxillary sinus and is adsorbed onto the sinus membrane. Although a leakage of calcium hydroxide may not usually cause clinical symptoms, when a large amount of leakage occurs, it can cause degeneration of adjacent tissue and functional disorder, requiring immediate surgical removal. However, due to adsorption to the sinus membrane, calcium hydroxide leaked into the maxillary sinus is difficult to remove completely. Here, we describe the case of a 47-year-old patient in whom a large amount of calcium hydroxide leaked into the maxillary sinus and was successfully removed using modified endoscopic-assisted sinus surgery, and favorable bone regeneration and sinus membrane regeneration were achieved. In addition, histological and ultrastructural changes of the membrane resulted from the calcium hydroxide were presented.

Validation of bone mineral density measurement using quantitative CBCT image based on deep learning.

The bone mineral density (BMD) measurement is a direct method of estimating human bone mass for diagnosing osteoporosis, and performed to objectively evaluate bone quality before implant surgery in dental clinics. The objective of this study was to validate the accuracy and reliability of BMD measurements made using quantitative cone-beam CT (CBCT) image based on deep learning by applying the method to clinical data from actual patients. Datasets containing 7500 pairs of CT and CBCT axial slice images from 30 patients were used to train a previously developed deep-learning model (QCBCT-NET). We selected 36 volumes of interest in the CBCT images for each patient in the bone regions of potential implants sites on the maxilla and mandible. We compared the BMDs shown in the quantitative CBCT (QCBCT) images with those in the conventional CBCT (CAL_CBCT) images at the various bone sites of interest across the entire field of view (FOV) using the performance metrics of the MAE, RMSE, MAPE (mean absolute percentage error), R2 (coefficient of determination), and SEE (standard error of estimation). Compared with the ground truth (QCT) images, the accuracy of the BMD measurements from the QCBCT images showed an RMSE of 83.41 mg/cm3, MAE of 67.94 mg/cm3, and MAPE of 8.32% across all the bone sites of interest, whereas for the CAL_CBCT images, those values were 491.15 mg/cm3, 460.52 mg/cm3, and 54.29%, respectively. The linear regression between the QCBCT and QCT images showed a slope of 1.00 and a R2 of 0.85, whereas for the CAL_CBCT images, those values were 0.32 and 0.24, respectively. The overall SEE between the QCBCT images and QCT images was 81.06 mg/cm3, whereas the SEE for the CAL_CBCT images was 109.32 mg/cm3. The QCBCT images thus showed better accuracy, linearity, and uniformity than the CAL_CBCT images across the entire FOV. The BMD measurements from the quantitative CBCT images showed high accuracy, linearity, and uniformity regardless of the relative geometric positions of the bone in the potential implant site. When applied to actual patient CBCT images, the CBCT-based quantitative BMD measurement based on deep learning demonstrated high accuracy and reliability across the entire FOV.

Metastasis of Renal Cell Carcinoma to the Mandible.

Renal cell carcinoma (RCC) is the most common tumor of the kidney. Although RCC often metastasizes to other organs, metastasis to the head and neck region is rare, and metastasis to the mandible is very unusual. Given the fact that metastasis of primary neoplasms is not always predictable, it is essential to rule out metastatic carcinoma in jaw lesions. We herein report a rare presentation of metastasis of RCC to the mandible, in which the metastatic lesion in the oral cavity was found first, followed by the primary lesion, in a 22-year-old girl who suffered from pain in the left temporomandibular joint on mouth opening and hypoesthesia of the left chin, left lower lip, and left lower gum.

Anatomical Characteristics of the Accessory Maxillary Ostium in Three-Dimensional Analysis.

Background and Objectives: The accessory maxillary ostium (AMO) can interfere with ventilation and drainage of the maxillary sinus, and therefore the importance of evaluating the anatomical features of the AMO has been emphasized. This study aimed to evaluate anatomical characteristics of the AMO together with the natural ostium (NO) using three-dimensional (3D) analysis and to assess the relationship between the AMO and maxillary sinus pathologies. Materials and Methods: This retrospective study included 394 sinuses in 197 patients. Using 3D computed tomography images, the prevalence of the AMO and concurrent sinus pathologies were examined. For patients with an AMO, 3D spatial positions of the AMO and NO related to adjacent anatomic structures and dimensions of the AMO and NO were evaluated. Results: A total of 84 sinuses showed single or multiple AMO, with a prevalence of 21.3%. The AMO was located superiorly by 30.1 mm from the maxillary sinus floor, inferiorly by 1.3 mm from the orbital floor, and posteriorly by 22.4 mm from the anterior sinus wall. The AMO was located 5.4 mm posteriorly and 0.7 mm inferiorly from the NO. On the same coronal plane as the NO or AMO, height from the maxillary sinus floor to the NO and AMO ranged from 19.4 to 45.8 mm and 14.5 mm to 41.9 mm, respectively. The mean horizontal and vertical dimensions were 5.9 mm and 4.6 mm for the NO and 2.8 mm and 3.0 mm for the AMO. We detected a significant association between the presence of the AMO and the mucosal thickening (p = 0.029). Conclusions: The results of this study suggest that, although the AMO and NO are mostly located in positions that do not limit sinus-related surgeries, such as maxillary sinus floor augmentation, the AMO and NO are also found in lower positions, which may be a detriment to the postoperative physiological function of the maxillary sinus and affect treatment outcomes.

Tapered, Sand-Blasted, Large-Grit, and Acid-Etched Surfaced Internal Dental Implant in the Diverse Pathologic Jaw.

PURPOSE: The treatment of pathologic lesions in jaws either through conservative or radical approaches, frequently leads to a loss of teeth. As a result, patients will experience diminished masticatory and phonetic function as well as esthetic deficits. In this manuscript, we report multiple cases of successful implant rehabilitation after the conservative treatment of pathologic lesions in jaws utilizing allogeneic bone grafts and the installation of implant fixtures. MATERIALS AND METHODS: In this study, we examined 8 patients with 8 different kinds of pathologic lesions in their jaws, who were treated with a conservative approach and rehabilitated with bone grafts and implant installations using internal dental implant type with tapered, sand-blasted, large-grit, acid-etched surfaces. Marginal bone loss was analyzed through radiograms, and the implant survival rates and graft outcome evaluations were recorded. RESULTS: No significant difference was found in the mean marginal bone loss throughout the follow-up period. The survival rate of the implant and the success rate of graft were recorded as 100%. CONCLUSIONS: The results of this study suggest that conservative surgical management for pathologic lesions based on the understanding of the pathologies can be helpful for successful oral rehabilitation. In bone grafting, it is necessary to determine an appropriate timing and method considering the risk of recurrence and the vascularity of the recipient site. For subsequent implant placement, selecting an implant system suitable for the site of placement and placing it within 3 to 6 months after bone grafting can help the long-term maintenance of the grafted bone and dental implant.

Clinical and radiographic outcomes of dental implant after maxillary sinus floor augmentation with rhBMP-2/hydroxyapatite compared to deproteinized bovine bone.

OBJECTIVES: This study aimed to evaluate the clinical and radiographic outcomes of early implant placement and functional loading in maxillary sinus floor augmentation (MSFA) using recombinant human bone morphogenetic protein 2/hydroxyapatite (rhBMP-2/HA) and to compare these outcomes with those of the conventional protocol in MSFA using deproteinized bovine bone (DBB). MATERIALS AND METHODS: The rhBMP-2/HA and DBB groups consisted of 14 and 13 patients who underwent MSFA with BMP and DBB, respectively. After placement of 22 implants and 21 implants in the rhBMP-2/HA and DBB groups, respectively, abutment connections were performed 3 months after implant placement for the rhBMP-2/HA group and 6 months after implant placement for the DBB group. Changes in grafted sinus height (GSH), marginal bone loss (MBL), and implant stability were evaluated up to one year after functional loading. RESULTS: Survival rates for the rhBMP-2/HA and DBB groups after one year of functional loading were 90.9% and 90.5%, respectively. Both groups exhibited no significant time-course changes in GSH until one year of functional loading (rhBMP-2/HA, p = 0.124; DBB, p = 0.075). Although significant MBL occurred after one year of functional loading for both groups (rhBMP-2/HA, p < 0.001; DBB, p < 0.001), there were no significant differences in time-course changes in MBL between the two groups (p = 0.450). The mean implant stability quotient values in the rhBMP-2/HA and DBB groups were 75.3 and 75.4 after one year of functional loading, respectively, and there were no significant differences between the two groups (p = 0.557). CONCLUSIONS: MSFA using rhBMP-2/HA allowed implant rehabilitation with early implant placement and functional loading and led to a comparable survival rate and implant stability after 1 year of functional loading with acceptable MBL and stable maintenance of GSH compared to the MSFA using DBB with 6 months of healing after implant placement.

Enhanced Bone Regeneration by Bone Morphogenetic Protein-2 after Pretreatment with Low-Intensity Pulsed Ultrasound in Distraction Osteogenesis.

BACKGROUND: Bone morphogenetic protein 2 (BMP-2) and low-intensity pulsed ultrasound (LIPUS) have been used to enhance bone healing in distraction osteogenesis (DO). The aim of this study was to assess the synergistic effect of BMP-2 and LIPUS on bone regeneration in DO and to determine the optimal treatment strategy for enhanced bone regeneration. METHODS: Rat mesenchymal stromal cells were treated with various application protocols of BMP-2 and LIPUS, and cell proliferation, alkaline phosphatase activity, and osteogenesis-related marker expression were evaluated. In vivo experiments were performed in a rabbit DO model according to the application protocols with different timings of BMP-2 and LIPUS application. RESULTS: Application of BMP-2 after LIPUS pretreatment (BMP-2 after LIPUS) showed greater cell proliferation than LIPUS treatment alone, and higher ALP activity than all other treatment protocols. BMP-2 after LIPUS also exhibited increased gene expression levels of ALP, Cbfa1, and Osterix compared with LIPUS treatment alone. In vivo experiments revealed no significant differences in bone healing based on the timing of LIPUS treatment in DO. The combination of BMP-2 and LIPUS resulted in increased bone volume and bone mineral density compared with BMP-2 or LIPUS. Regarding the timing of BMP-2 application, the application of BMP-2 after LIPUS pretreatment led to greater bone volume than the application of BMP-2 before LIPUS. CONCLUSION: The results of this study suggest that the combined treatment of BMP-2 and LIPUS can lead to enhanced bone healing in DO and that effective bone healing can be achieved through the application of LIPUS before BMP-2.

Accurate Mandible Reconstruction by Mixed Reality, 3D Printing, and Robotic-Assisted Navigation Integration.

ABSTRACT: Mandibular reconstruction is one of the most complex procedures concerning the patient's postoperative facial shape and occlusion condition. In this study, the authors integrated mixed reality, three-dimensional (3D) printing, and robotic-assisted navigation technology to complete the mandibular reconstruction in a novel and more accurate way. Mixed reality can visualize the significant anatomical structures of the operative area, but only be used in simulated operation by now. Three-dimensional printing surgical guide plate makes it easy to separate tissue, while imprecision often occurs due to the potential of displacement and deformation. In recent years, most robotic-assisted navigation surgery technology can only achieve precise position by 2D view on the screen but not realistic 3D navigation. in this study, the integrated 3 technologies were used in mandibular reconstruction. Preoperative imaging examination was performed, and the data were imported into the digital workstation before operation. First, the original data was edited and optimized to reconstruct the digital model and formulate the surgical plan. Then MR was used to output the visualized project and matched the 3D reconstruction model in reality. The 3D plate was printed for surgical guidance. Last, robotic-assisted navigation was used to guide and position the vascularized fibula autograft and the immediate dental implantation. In conclusion, the authors integrated the 3 technologies and constructed a new digital surgical procedure to improve surgical accuracy and simplify the procedure comparing with traditional surgery.

Efficacy and safety of rhBMP/ß-TCP in alveolar ridge preservation: a multicenter, randomized, open-label, comparative, investigator-blinded clinical trial.

BACKGROUND: The aim of this multicenter, randomized, open-label, comparative, investigator-blinded study was to investigate the efficacy and safety of recombinant human bone morphogenetic protein 2 (rhBMP-2) combined with ß-TCP (rhBMP-2/ß-TCP) in alveolar ridge preservation. MATERIALS AND METHODS: Eighty-four subjects from three centers were enrolled in this clinical trial. After tooth extraction, rhBMP-2/ß-TCP (n = 41, test group) or ß-TCP (n = 43, control group) were grafted to the extraction socket with an absorbable barrier membrane for alveolar ridge preservation. Using computed tomography images obtained immediately after and 12 weeks after surgery, changes in the alveolar bone height and width were analyzed for each group and compared between the two groups. RESULTS: Both the test and control groups showed a significant decrease in alveolar bone height in the 12 weeks after surgery (both groups, p < 0.0001). However, the test group exhibited a significantly lower decrease in alveolar bone height than the control group (p = 0.0004). Alveolar bone width also showed significantly less resorption in the test group than in the control group for all extraction socket levels (ESL) (p = 0.0152 for 75% ESL; p < 0.0001 for 50% ESL; p < 0.0001 for 25% ESL). There were no statistically significant differences in the incidence of adverse events between the two groups. No severe adverse events occurred in either group. CONCLUSIONS: The results of this study suggest that rhBMP-2/ß-TCP is a safe graft material that provides a high alveolar bone preservation effect in patients receiving dental extraction. TRIAL REGISTRATION: Clinicaltrials.gov , NCT02714829 , Registered 22 March 2016.

Medication Related Osteonecrosis of the Jaw: 2021 Position Statement of the Korean Society for Bone and Mineral Research and the Korean Association of Oral and Maxillofacial Surgeons.

Antiresorptives are the most widely prescribed drugs for the treatment of osteoporosis. They are also used in malignant bone metastases, multiple myeloma, and Paget's disease, and provide therapeutic efficacy on those diseases. However, it was reported that the occurrence of osteonecrosis of the jaw (ONJ) could be related to antiresorptive exposures, and there have been many cases regarding this issue. Therefore, a clearer definition and treatment guidelines were needed for this disease. The American Society for Bone and Mineral Research and the Amnerican Association of Oral and Maxillofacial Surgeons reported statements on bisphosphonate-related ONJ (BRONJ), and a revised version was recently presented. In the revised edition, the diagnosis BRONJ was changed to medication-related ONJ (MRONJ), which reflects consideration of the fact that ONJ also occurs for denosumab, a bone resorption inhibitor of the receptor activator of the nuclear factor-κB ligand antibody family, and bevacizumab, an anti-angiogenesis inhibitor. The Korean Society for Bone and Mineral Research and the Korean Association of Oral and Maxillofacial Surgeons had collectively formed a task force for the preparation of an official statement on MRONJ based on a previous position paper in 2015. The task force reviewed current knowledge and coordinated dental and medical opinions to propose the guideline customized for the local Korean situation.

Effect of Bone Buttressing at the Vertical Osteotomy Site on Postoperative Stability After Mandibular Setback Surgery.

ABSTRACT: This study aimed to assess the effect of bone buttressing at the vertical osteotomy site on postoperative stability after mandibular setback surgery and determine factors contributing to postoperative relapse. This retrospective study was conducted on patients who received mandibular setback surgery using bilateral sagittal split ramus osteotomy. Patients were divided into two groups: group I, intimate bony contact, and group II, bony gap of 2 mm or more. Using lateral cephalograms taken before surgery, 1 week after surgery, and 6 months after surgery, surgical changes, and postoperative relapse were compared between 2 groups. To assess associations between postoperative relapse and other variables, Pearson correlation analysis and multiple linear regression analysis were performed. Twenty-eight patients were evaluated (17 in group I and 11 in group II). Mean relapse was greater in group II (1.8 mm) than in group I (1.2 mm), although there were no significant differences between 2 groups (P = 0.203). Postoperative relapse was significantly associated with intraoperative clockwise rotation of the proximal segment (P < 0.001) and the amount of mandibular setback (P = 0.038). Bony gap was only correlated with postoperative counterclockwise rotation of the proximal segment (P = 0.014). In the regression analysis, intraoperative clockwise rotation of the proximal segment significantly predicted postoperative relapse (P < 0.001, R2 = 0.388). The absence of bone buttressing at the vertical osteotomy site may not significantly affect postoperative stability after mandibular setback surgery, and it is important to minimize intraoperative clockwise rotation of the proximal segment for better postoperative stability.

Robot-Assisted Maxillary Positioning in Orthognathic Surgery: A Feasibility and Accuracy Evaluation.

Several methods enabling independent repositioning of the maxilla have been introduced to reduce intraoperative errors inherent in the intermediate splint. However, the accuracy is still to be improved and a different approach without time-consuming laboratory process is needed, which can allow perioperative modification of unoptimized maxillary position. The purpose of this study is to assess the feasibility and accuracy of a robot arm combined with intraoperative image-guided navigation in orthognathic surgery. The experiments were performed on 12 full skull phantom models. After Le Fort I osteotomy, the maxillary segment was repositioned to a different target position using a robot arm and image-guided navigation and stabilized. Using the navigation and the postoperative computed tomography (CT) images, the achieved maxillary position was compared with the planned position. Although the maxilla showed mild displacement during the fixation, the mean absolute deviations from the target position were 0.16 mm, 0.18 mm, and 0.20 mm in medio-lateral, antero-posterior, and supero-inferior directions, respectively, in the intraoperative navigation. Compared with the target position using postoperative CT, the achieved maxillary position had a mean absolute deviation of less than 0.5 mm for all dimensions and the mean root mean square deviation was 0.79 mm. The results of this study suggest that the robot arm combined with the intraoperative image-guided navigation may have great potential for surgical plan transfer with the accurate repositioning of the maxilla in the orthognathic surgery.

Postsurgical changes of mandible based on vertical dimension increase in Skeletal Class III deformities.

The aim of this study was to evaluate the postsurgical mandibular changes after surgery based on vertical dimension increase in skeletal Class III deformities. Patients who underwent mandibular setback surgery for skeletal Class III malocclusion correction with surgery-first orthognathic treatment were enrolled in the study. Lateral cephalograms were obtained at initial visit, immediately after surgery, 6 months after surgery, and at post-treatment. Postsurgical change of the mandible based on the vertical dimension increase was estimated using a diagrammatic method before surgery and this amount was compared with the actual amount of mandibular forward movement at 6 months after the surgery, using a paired t-test and Bland-Altman plot. Thirty patients (16 men and 14 women; mean age, 22.6 years) with skeletal Class III deformities had undergone mandibular setback surgery with the surgery-first orthognathic treatment. Immediately after surgery, the mandible setback was 9.4 ± 3.7 mm at pogonion. Six months after surgery, the mandible moved forward at an average of 2.3 ± 1.5 mm which corresponded to the estimated value of 2.2 ± 0.9 mm. The estimated amount of postsurgical movement did not show a statistically significant difference from the actual value on paired t-test (p = 0.349). The Bland-Altman analysis showed that the difference between the two values was within the limits of agreement. The postsurgical changes based on vertical dimension increase in surgery-first orthognathic treatment might be predicted by using a diagrammatic method.

Changes in the temporomandibular joint clicking and pain disorders after orthognathic surgery: Comparison of orthodontics-first approach and surgery-first approach.

The purposes of this study were to investigate the influence of the orthodontics-first approach (OFA) and surgery-first approach (SFA) on changes in the signs and symptoms of temporomandibular joint disorders (TMDs) and to compare pre- and postoperative orthodontic treatment duration and total treatment duration between the two approaches. This retrospective study recruited 182 adult patients with malocclusions treated with OFA and SFA and recorded variables such as age, gender, skeletal classification, and signs and symptoms of TMD (clicking and pain disorders) before the start of the surgical-orthodontic treatment and after surgery. Changes in the signs and symptoms of TMD and treatment duration were evaluated within each approach and compared between two approaches. A binary logistic regression was performed to assess the influence of the variables on the postoperative signs and symptoms of TMD. There were no significant postoperative changes in temporomandibular joint (TMJ) pain for OFA and SFA, whereas a significant reduction was found in TMJ clicking after surgery for both approaches. According to binary logistic regression, the type of surgical-orthodontic treatment (OFA or SFA) was not a significant risk factor for postoperative TMJ clicking and pain, and the risk of postoperative TMJ clicking and pain was significant only when TMJ clicking (OR = 10.774, p < 0.001) and pain (OR = 26.876, p = 0.008) existed before the start of the entire treatment, respectively. With regard to the treatment duration, SFA (21.1 ± 10.3 months) exhibited significantly shorter total treatment duration than OFA (34.4 ± 11.9 months) (p < 0.001). The results of this study suggest that surgical-orthodontic treatment using SFA can be a feasible option of treatment for dentofacial deformities based on the equivalent effect on TMD and shorter overall treatment period compared to conventional surgical-orthodontic treatment using OFA.

Comparison of postoperative condylar changes after unilateral sagittal split ramus osteotomy and bilateral sagittal split ramus osteotomy using 3-dimensional analysis.

OBJECTIVE: This study aimed to evaluate postoperative changes in the condyle after unilateral sagittal split ramus osteotomy (USSRO) and to compare them with changes occurring after bilateral sagittal split ramus osteotomy (BSSRO). STUDY DESIGN: For 50 condyles from 25 patients, positional and volumetric changes of condyle were analyzed by using computed tomography images taken before, immediately after, and 6 months after surgery and compared between the USRRO and BSSRO groups. RESULTS: The condyle showed lateral and inferior displacement immediately after surgery and medial and superior movement at 6 months after surgery in the USSRO and BSSRO groups. No statistically significant difference was found between the 2 groups in the time-course positional change and rotation of the condyle. In the comparison of bodily shift and rotation between operated and nonoperated sides in USSRO group, there were no significant differences between the 2 sides, except for the perioperative rotation pattern on the coronal plane. At 6 months after surgery, the changed volume relative to preoperative condylar volume was only 5.2% in the USSRO group and 2.7% in the BSSRO group. CONCLUSIONS: The findings from this study suggest that USSRO can be used effectively in appropriately selected patients; however, temporomandibular joint (TMJ) problems may arise when condylar displacement is excessive enough to exceed physiologic tolerances.