Efficacy of Computed Tomography-Based Evaluation of Myocardial Extracellular Volume Combined With Red Flags for Early Screening of Concealed Cardiac Amyloidosis in Patients With Atrial Fibrillation.

BACKGROUND: The prevalence of transthyretin amyloid cardiomyopathy (ATTR-CM) in atrial fibrillation (AF) patients remains unclear. We explored the efficacy of computed tomography-based myocardial extracellular volume (CT-ECV) combined with red flags for the early screening of concealed ATTR-CM in AF patients undergoing catheter ablation.Methods and Results: Patients referred for AF ablation at Oita University Hospital were prescreened using the red-flag signs defined by echocardiographic or electrocardiographic findings, medical history, symptoms, and blood biochemical findings. Myocardial CT-ECV was quantified in red flag-positive patients using routine pre-AF ablation planning cardiac CT with the addition of delayed-phase cardiac CT scans. Patients with high (>35%) ECV were evaluated using technetium pyrophosphate (99 mTc-PYP) scintigraphy. A cardiac biopsy was performed during the planned AF ablation procedure if 99 mTc-PYP scintigraphy was positive. Between June 2022 and June 2023, 342 patients were referred for AF ablation. Sixty-seven (19.6%) patients had at least one of the red-flag signs. Myocardial CT-ECV was evaluated in 57 patients because of contraindications to contrast media, revealing that 16 patients had high CT-ECV. Of these, 6 patients showed a positive 99 mTc-PYP study, and 6 patients were subsequently diagnosed with wild-type ATTR-CM via cardiac biopsy and genetic testing. CONCLUSIONS: CT-ECV combined with red flags could contribute to the systematic early screening of concealed ATTR-CM in AF patients undergoing catheter ablation.

A Case of Vascular Malformation in the Buccal Fat Pad.

Vascular anomalies are categorized as vascular tumors or vascular malformations (VMs) based on the system of classification (updated in 2018) established by the International Society for the Study of Vascular Anomalies. In the orofacial region, such anomalies are most likely to occur in the lips or tongue, and only rarely in the buccal fat pad. This report describes a case of a VM in the buccal fat pad. A 47-year-old woman was referred to our hospital with a mass lesion in her left cheek. On palpation, an elastic, hard, painless, and mobile mass was found anterior to the left masseter muscle. Computed tomography, magnetic resonance imaging, and ultrasonography revealed a mass in the left buccal fat pad. The lesion was identified as a benign tumor and surgical excision performed under general anesthesia. Histopathological examination revealed that the lesion was composed of a large number of vascular structures of various sizes covered with endothelial cells. Based on the clinical and histopathological findings, a diagnosis of a venous VM was made. One year has passed since the operation and no recurrence has been observed. Long-term follow-up is planned.

Three-dimensional Culture Using Atelocollagen Sponge and Self-assembling Peptide Hydrogel.

This study aimed to assess the combined application of two biomaterials, a selfassembling peptide hydrogel (SPH) and an atelocollagen sponge (ACS). The ACS was combined with SPH (PuraMatrixⓇ or PanaceaGelⓇ) and its osteogenic effects on mouse osteoblastic cell line MC3T3 then evaluated. Each type of SPH was successfully incorporated into the ACS. The MC3T3 cells showed uniform distribution within the scaffold. No necrotic cells were observed throughout the experimental procedures. When the SPH was combined with the ACS, the MC3T3 cells differentiated toward the osteo-lineage, expressing Alp, Runx2, Osx, Bsp, and Oc. PanaceaGelⓇ exhibited a stronger osteogenic effect on the cells than PuraMatrixⓇ.

Second Primary Metachronous Malignancies Occurring in Oral Cavity of Young Adult-A Case Report.

The incidence of oral cancer in Japan is increasing. Interestingly, the number of young patients with oral cancer is also rising. A 19-year-old man with no history of smoking or drinking alcohol presented with a 20×15-mm elastic, hard, protruding mass with a white surface on the right-hand margin of the tongue. A biopsy resulted in a diagnosis of a well-differentiated squamous cell carcinoma of the tongue, for which a partial resection was subsequently performed. During regular follow-up, the patient demonstrated no clinical or imaging abnormalities until 4 years and 9 months later, when erosion was observed at the right palatoglossal arch. A malignant tumor of the right palatoglossal arch was diagnosed based on cytology and imaging findings, and total resection of the lesion performed. Histopathological examination of the resected lesion revealed a moderately differentiated squamous cell carcinoma. Epithelial dysplasia on the right-hand margin of the tongue was diagnosed 4 years and 9 months after the second surgery and was subsequently resected. The patient's condition has been favorable for 7 years since the diagnosis of the second cancer, with no noted recurrence. This case emphasizes the importance of follow-up after initial treatment, as even young people, who are likely to have to endure long-lasting consequences from treatment, can develop metachronous cancer in the oral cavity.

Proposal criteria of paradoxical low-flow low-gradient aortic stenosis for predicting prognosis in patients undergoing transcatheter aortic valve implantation.

BACKGROUND: Paradoxical low-flow, low-gradient (PLF-LG) aortic stenosis (AS) is associated with poor prognosis in patients undergoing transcatheter aortic valve implantation (TAVI). This study aimed to verify the conventional criteria of PLF-LG AS (left ventricular ejection fraction [LVEF] > 50%, mean aortic valve pressure gradient [AVPG] < 40 mm Hg and stroke volume index [SVI] < 35 ml/m2 by measuring Doppler method) compatible for predicting prognosis in patients undergoing TAVI. MATERIALS AND METHODS: A total of 128 consecutive patients who underwent TAVI for AS with LVEF > 50% were enrolled. The primary endpoint was the hospital readmission due to heart failure (HRHF) and the secondary endpoint was all-cause mortality after hospital discharge. The patients were classified by both the conventional criteria of PLF-LG AS and the proposal criteria of PLF-LG AS if mean aortic valve pressure gradient (AVPG) < 40 mmHg and SVI by measuring Simpson's method < cut off value based on the ROC curve for predicting HRHF. RESULTS: According to the conventional criteria, only 6 patients were diagnosed with PLF-LG AS. However, according to the proposal criteria, 16 patients were diagnosed with PLF-LG AS. Fourteen patients developed HRHF during the follow-up period after TAVI. Based on the ROC curves, SVI by measuring Simpson's method (cut off value = 25 ml/m2) had higher sensitivity and specificity for predicting HRHF (AUC = 0.74, p = 0.0013) than SVI by measuring Doppler method (AUC = 0.63, p = 0.045). The multivariate analysis revealed that PLF-LG AS defined by the proposal criteria (HR: 5.25; 95% CI: 1.60-17.16; p = 0.0073) but not by the conventional criteria was independently associated with HRHF. PLF-LG AS defined by the conventional criteria and the proposal criteria were not associated with all-cause mortality in the univariate analysis. CONCLUSIONS: Our results demonstrated that new criteria of PLF-LG AS defined as SVI < 25 ml/m2 measured by Simpson's method could predict HRHF in patients with severe AS who underwent TAVI.

Ameloblastic Fibroma in Mandibular Anterior Tooth Region: A Case Report.

An ameloblastic fibroma (AF) is a proliferative mixed tumor which includes components of both odontogenic epithelium and mesenchymal tissue. It is a relatively rare neoplasm, accounting for approximately only 1.5－4.5% of odontogenic tumors. This case report describes an AF that occurred in the mandibular anterior tooth region in a 9-year-old girl who presented with the chief complaint of swelling in the left mandibular anterior tooth region. Intraoral examination revealed a swelling along the labial gingiva, extending from the left mandibular lateral incisor region to the left mandibular canine. Upon palpation, the swelling appeared to comprise a hard tissue. Computed tomography revealed a supernumerary impacted tooth; soft tissue density in the bone surrounding the region extending from the left mandibular lateral incisor to the left mandibular canine; labial bone expansion; and thinning of the labial cortical bone. A biopsy was performed under local anesthesia and the lesion subsequently diagnosed as an AF. Tumor resection and extraction of the supernumerary impacted tooth were carried out under general anesthesia. At 2 years postoperatively the prognosis is good. Although relapse with an AF is rarer than that with an ameloblastoma, strict follow-up is required, as malignant transformation to an ameloblastic fibrosarcoma has been reported in relapsed cases.

Which Factors Affect the Long-Term Survival of Patients With Oral Squamous Cell Carcinoma With Distant Metastasis?

PURPOSE: The development of distant metastases (DMs) in patients with oral squamous cell carcinoma (OSCC) leads to dismal prospects for survival. The present study aimed to identify the risk factors for DM development and long-term survival. PATIENTS AND METHODS: The present study was a retrospective cohort study of patients with OSCC at a single institution. The predictor variables were age, gender, lymph node classification, histologic grade, neck dissection, infiltrative growth pattern (INF), vascular/lymphatic invasion, perineural invasion (PI), extranodal extension, local recurrence, nodal metastasis, DMs, interval to the diagnosis of DMs, and surgery for DMs. The primary outcome variables were the 5-year overall survival (OS) and median survival time (MST), which were estimated using the Kaplan-Meier method. Cox hazard models were used to identify the risk factors for DM development. RESULTS: The cohort included 526 patients; the data from 402 were available for analysis. Of these 402 patients, 37 developed DMs. On multivariate analysis, clinical N1 (cN1)-cN2 (hazard ratio [HR], 3.36), moderate/poor differentiation (HR, 2.51), INFc (HR, 3.27), vascular/lymphatic invasion (HR, 2.95), and PI (HR, 2.17) were independent predictors of DM development. The 5-year OS was 84.6% for the non-DM patients and 9.7% for the DM patients, with a MST of 16.9 months. In those with DMs with cN0, the 5-year OS was 18.2% and the MST was 37.2 months. For those with DMs with cN1-cN2, the 5-year OS was 4.7% and the MST was 12.9 months. In patients with an interval to the DM diagnosis of 10.0 months or longer, the 5-year OS was 20.0% and the MST was 38.6 months. In the patients with an interval to the DM diagnosis of less than 10.0 months, the MST was 11.7 months. The 5-year OS of the patients who had undergone pulmonary metastasectomy was 60.0% and the MST of the nonsurgery group was 16.0 months. CONCLUSIONS: In the patients with DMs, stage cN0 and a late interval to DM diagnosis were associated with long-term survival. Pulmonary metastasectomy could be worth considering to improve survival.

Ten-year Clinical Trends among 575 Consecutive Oral Cancer Patients at Tokyo Dental College Oral Cancer Center.

The facilities comprising Tokyo Dental College (TDC) -the college itself and its medical institutions at Suidobashi, Ichikawa, and Chiba - have been officially recognized as a center for treating oral cancer. The TDC Oral Cancer Center (OCC) was established on April 1, 2006. It provides comprehensive medical care, including that aimed at recovery of postoperative function, such as restoration of stomatognathic function, dysphagia therapy, and placement of maxillary prostheses. The purpose of this study was to investigate patient trends at TDC-OCC over the 10 years following its establishment in order to determine how the safe and high-quality cancer care already provided might be even further improved. Oral cancer patients attending TDC-OCC between April 2007 and March 2017 were investigated. Clinical information was obtained from medical records and analyzed, including that on patient numbers, age, sex, primary site of tumor, clinical stage, and surgery provided. There were 758 new cases, and the number of new cases showed an annual increase. Among the total number of new patients, 575 (75.9%) represented primary cases. The number of operations also showed an increase, which correlated with the increase in the number of patients. The incidence in oral cancer has increased in several countries, including Japan. Oral cancer can be observed macroscopically and touched. In contrast to with cancers at many other sites, and despite various diagnostic devices for early detection having been developed, however, cases are often advanced when first encountered. Many advanced cases were treated at TDC-OCC, and the number of reconstructive operations following progressive cancer also increased over time.

A Case of Infratemporal Fossa Abscess with Signs of Chronic Maxillary Osteomyelitis.

The infratemporal fossa is bordered superiorly by the infratemporal surface of the greater wing of the sphenoid bone and part of the temporal bone; medially by the lateral plate of the pterygoid process of the sphenoid bone; and anteriorly by the posterior surface of the maxilla. As it is completely surrounded by bone, it is frequently difficult to determine whether an abscess is present by direct visual observation or palpation alone. We report an extremely rare case of an infratemporal fossa abscess arising from chronic maxillary osteomyelitis developing after extraction of a maxillary molar. Despite drainage during initial oral anti-inflammatory treatment, pus continued to drain from the wound over a long period of time. This drainage ended when the eroded bone of the maxillary tuberosity on the affected side was curetted in a secondary procedure. The harvested bone tissue exhibited histological findings of chronic osteomyelitis. This suggests that the route of infection involved acute transformation of maxillary osteomyelitis by odontogenic infection advancing posteriorly and superiorly.

A 5-year activity report from the Oral Cancer Center, Tokyo Dental College.

The Tokyo Dental College Oral Cancer Center was established on April 1st, 2006 at our Ichikawa General Hospital for the purpose of providing multimodal treatment for oral cancer. This report summarizes the Center's activities over the last 5 years. The total number of oral cancer patients treated was 360 (April 2006 to March 2011), with 205 primary cases. We investigated the following treatment-related items: 1) site, 2) age, 3) sex, 4) pathological examination, 5) staging, 6) systemic disorder, 7) double cancer, 8) treatment, and 9) prognosis. Out of 205 patients, 60% were men and 40% were women. Men in their 60s and women in their 80s were seen the most. The most common site was the tongue, at 42%, followed by the mandibular gingiva, maxillary gingiva, oral floor, and buccal mucosa. Squamous cell carcinomas were seen most frequently, at 94% (15% were stage I, 33% stage II, 15% stage III, and 34% stage IV). The most common treatment method was surgical treatment, at 83%. The 5-year survival rate at all stages was 85.4%. At the Oral Cancer Center, oral surgeons take the initiative in establishing treatment in cooperation with other departments and branches. Since the establishment of the Ambulatory Center for Maxillary Prosthetics in October 2011, 26 patients have undergone treatment. Related departments and branches work in teams, enabling comprehensive treatment, from the preoperative state to postoperative functional recovery. We wish to use these strengths to improve oral cancer treatment in Japan and will continue to work toward providing the best possible care for our patients.

Ameloblastic carcinoma of the mandible: a case report.

BACKGROUND: Ameloblastic carcinoma is a malignant form of ameloblastoma and a very rare odontogenic tumor. We report a case of ameloblastic carcinoma that occurred after removal of a right-sided mandibular dental implant. CASE PRESENTATION: A 72-year-old female patient visited her family dentist with a complaint of pain around a lower right implant placed 37 years previously. Although the dental implant was removed with the diagnosis of peri-implantitis, the patient experienced dullness of sensation in the lower lip and was followed up by her dentist, but after no improvement. She was referred to a highly specialized institution where she was diagnosed with osteomyelitis and treated the patient with medication; however, there was no improvement. In addition, granulation was observed in the same area leading to a suspicion of malignancy, and the patient was referred to our oral cancer center. The diagnosis of squamous cell carcinoma was made after a biopsy at our hospital. Under general anesthesia, the patient underwent mandibulectomy, right-sided neck dissection, free flap reconstruction with an anterolateral thigh flap, immediate reconstruction with a metal plate, and tracheostomy. Histological analysis of the resected specimen on hematoxylin and eosin staining showed structures reminiscent of enamel pulp and squamous epithelium in the center of the tumor. The tumor cells were highly atypical, with nuclear staining, hypertrophy, irregular nuclear size, and irregular nuclear shape, all of which were suggestive of cancer. Immunohistochemical analysis showed that Ki-67 was expressed in more than 80% of the targeted area, and the final diagnosis was primary ameloblastic carcinoma. CONCLUSION: After reconstructive flap transplantation, occlusion was re-established using a maxillofacial prosthesis. The patient remained disease-free at the 1-year 3-month follow-up.

Intraoral Minor Salivary Gland Tumors: A Retrospective, Clinicopathologic, Single-Center Study of 432 Cases in Japan and a Comparison with Epidemiological Data.

BACKGROUND: Intraoral minor salivary gland tumors are relatively rare lesions with histological subtypes not commonly found in major salivary glands. This study aimed to retrospectively evaluate the clinicopathologic features of intraoral minor salivary gland tumors from the Tokyo Dental College Hospital, Japan, and compare them with findings from other epidemiological studies. METHODS: We conducted a retrospective clinicopathologic evaluation of 432 cases of intraoral minor salivary gland tumors [161 male (37.3%) and 271 female (62.7%) patients; mean age: 52.5 and 48.6 years for males and females, respectively; age at diagnosis: 7-87 (mean: 50.1) years] from the Tokyo Dental College Hospital between 1975 and 2022, including 283 benign tumors (65.5%) and 149 malignant tumors (34.5%). RESULTS: The most common benign tumor was pleomorphic adenoma (n = 239), whereas mucoepidermoid carcinoma was the most common malignant tumor (n = 74). The mean age of patients with benign and malignant tumors was 48.4 and 53.2 years, respectively, with patients with malignant tumors being significantly older (P = 0.0042). The mean age of patients with malignant tumors was significantly higher in males (56.7 years) than in females (50.9 years) (P = 0.0376), although the mean age of patients with benign tumors did not differ by sex. Tumors were commonly located in the palate [250 cases (57.9%)]. Benign tumors were more frequent in the palate, upper lip, and buccal mucosa, whereas malignant tumors were more frequent in the palate, floor of the mouth, buccal mucosa, and retromolar area. CONCLUSIONS: Understanding the features of intraoral minor salivary gland tumors is useful for diagnosis. Our study provides important epidemiological data (patient differences in age at occurrence, sex, and site of origin) that will inform clinicians and researchers.

Empagliflozin Suppresses the Differentiation/Maturation of Human Epicardial Preadipocytes and Improves Paracrine Secretome Profile.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce epicardial adipose tissue (EAT) in humans, enhancing cardioprotective effects on heart failure and atrial fibrillation. We investigated the direct effect of the SGLT2 inhibitor empagliflozin on human primary epicardial adipocytes and preadipocytes. SGLT2 is primarily expressed in human preadipocytes in the EAT. The expression levels of SGLT2 significantly diminished when the preadipocytes were terminally differentiated. Adipogenesis of preadipocytes was attenuated by empagliflozin treatment without affecting cell proliferation. The messenger RNA levels and secreted protein levels of interleukin 6 and monocyte chemoattractant protein 1 were significantly decreased in empagliflozin-treated adipocytes. Coculture of human induced pluripotent stem cell-derived atrial cardiomyocytes and adipocytes pretreated with or without empagliflozin revealed that empagliflozin significantly suppressed reactive oxygen species. IL6 messenger RNA expression in human EAT showed significant clinically relevant associations. Empagliflozin suppresses human epicardial preadipocyte differentiation/maturation, likely inhibiting epicardial adipogenesis and improving the paracrine secretome profile of EAT, particularly by regulating IL6 expression.

Association between interatrial septum adiposity and atrial fibrillation: transesophageal echocardiography imaging and autopsy study.

Recent clinical evidence has suggested that interatrial septal (IAS) adiposity contributes to atrial fibrillation (AF). The present study aimed to confirm the usefulness of transesophageal echocardiography (TEE) to estimate IAS adiposity in patients with AF. The histological IAS analysis based on autopsy samples sought to clarify characteristics that underlie the contribution of IAS adiposity to AF. The imaging study analyzed the TEE results in patients with AF (n = 184) in comparison with transthoracic echocardiography (TTE) and computed tomography (CT) results. The autopsy study histologically analyzed IAS in subjects with (n = 5) and without (n = 5) history of AF. In the imaging study, the ratio of interatrial septum adipose tissue (IAS-AT) volume per epicardial adipose tissue (EpAT) volume was greater in patients with persistent AF compared (PerAF) to those with paroxysmal AF (PAF). Multivariable analysis revealed that both TEE-assessed IAS thickness and TTE-assessed left atrial dimension were predicted by CT-assessed IAS-AT volume. In the autopsy study, the histologically-assessed IAS section thickness was greater in the AF group than that in the non-AF group and was positively correlated with the IAS-AT area percentage. In addition, the size of adipocytes in IAS-AT was smaller, compared to EpAT and subcutaneous adipose tissue (SAT). IAS-AT infiltrated into the IAS myocardium, as if adipose tissue split the myocardium (designated as myocardial splitting by IAS-AT). The number of island-like myocardium pieces as a result of myocardial splitting by IAS-AT was greater in the AF group than in the non-AF group and was positively correlated with the IAS-AT area percentage. The present imaging study confirmed the usefulness of TEE to estimate IAS adiposity in patients with AF without radiation exposure. The autopsy study suggested that the myocardial splitting by IAS-AT may contribute to atrial cardiomyopathy leading to AF.

A translocator protein ligand PK11195 shows antigrowth activity in human choriocarcinoma cells.

The potential anticancer agent 1-(2-chlorophenyl-N-methylpropyl)-3-isoquinolinecarboxamide (PK11195), a translocator protein ligand (initially described as a ligand for the peripheral benzodiazepine receptor), induces apoptosis in some lines of human tumor cells. We investigated the effect of PK11195 in the choriocarcinoma cell line, BeWo. BeWo cells were treated with various concentrations of PK11195, and changes in cell growth, the cell cycle, apoptosis, and related parameters were examined. A WST-1 assay showed that BeWo cells were sensitive to the growth inhibitory effect of PK11195. In contrast, the nonsite selective ligand diazepam has a little effect on these cells. Cell cycle analysis indicated that exposure to PK11195 decreased the proportion of cells in the S phase and increased the proportion in the G0/G1 phases of the cell cycle. Induction of apoptosis was confirmed by Annexin V staining of externalized phosphatidylserine, by the loss of mitochondrial transmembrane potential, and by antibodies directed against histones from fragmented DNA. This induction occurred in conjunction with the altered expression of genes related to cell growth, malignant phenotype, and apoptosis. These results suggest that PK11195 may serve as a therapeutic agent for the treatment of choriocarcinoma.

A case of mucoepidermoid carcinoma associated with maxillary cyst.

We report a case of a mucoepidermoid carcinoma associated with a maxillary cyst. The patient was an 18-year-old man presenting with the chief complaint of left buccal swelling. The left maxillary third molar was semi-impacted in the direction of the crown on the buccal side. Orthopantomography revealed a cystic radiolucency extending over a wide area, ranging from the left maxilla to the maxillary sinus and nasal cavity. Computed tomography revealed a multilocular lesion surrounded by a thin shell of bone. Biopsy findings revealed a cystic lesion, but the cause could not be identified preoperatively. The cystic lesion was resected under general anesthesia. The lesion was multilocular and surrounded by a bone shell, and had expanded into the maxillary sinus. At the same time, indurated soft tissue adhering strongly to the palatine bone on the inferior palatine side of the lesion was resected. Histopathological examination showed a cystic lesion and mucoepidermoid carcinoma. An additional resection was planned and the maxilla partially resected. Mucoepidermoid carcinomas usually occur in the parotid and minor salivary glands, but in rare cases appear in the center of a jaw bone, almost always in the mandible. In the present case, the carcinoma was associated with a cystic lesion believed to have developed from maxillary bone and involved an impacted tooth adjacent to the tumor. This suggested a central mucoepidermoid carcinoma in the maxillary cyst. Postoperatively, the missing teeth have been replaced with a denture and the course has been good, with no recurrences or metastases identified.

A case of Sotos syndrome treated with distraction osteogenesis in maxilla and mandible.

Sotos syndrome is inherited in an autosomal-dominant manner and is characterized by increased birth weight, excessive growth, advanced bone age, and distinctive facial features, including dolichocephaly, hypertelorism, and a prominent mandible. We treated a jaw deformity due to Sotos syndrome consisting of malocclusion due to a narrow maxillary dental arch and mandibular retrusion from hypoplasia of the rami. The patient was a 17-year-old man. Malocclusion due to a narrow maxillary dental arch and mandibular retrusion was diagnosed. Rapid maxillary expansion with Lines corticotomy and mandibular advancement with distraction osteogenesis were performed. The maxilla was expanded laterally a total of 3 mm and the mandible prolonged 12 mm in the posterior area of the mandibular body. Subsequently, orthodontic treatment was continued. At present, 5 years after surgery, occlusion remains good and stable.

A clinico-statistical study of factors associated with intraoperative bleeding in orthognathic surgery.

BACKGROUND: Excessive bleeding is a major intraoperative risk associated with orthognathic surgery. This study aimed to investigate the factors involved in massive bleeding during orthognathic surgeries so that safe surgeries can be performed. Patients (n=213) diagnosed with jaw deformities and treated with bimaxillary orthognathic surgery (Le Fort I osteotomy and bilateral sagittal split ramus osteotomy) in the Department of Oral and Maxillofacial Surgery at the Suidobashi Hospital, Tokyo Dental College between January 2014 and December 2016 were included. Using the patients' medical and operative records, the number of cases according to sex, age at the time of surgery, body mass index (BMI), circulating blood volume, diagnosis of maxillary deformity, direction of maxillary movement, operative duration, incidence of bad split, injury of nasal mucosa, and blood type were analyzed. RESULTS: The results revealed that BMI, circulating blood volume, nasal mucosal injury, and operative time were associated with the risk of intraoperative massive bleeding in orthognathic surgeries. Chi-square tests and binomial logistic regression analyses showed significant differences in BMI, circulating blood volume, direction of maxillary movement, operative duration, and injury to the nasal mucosa. Operative duration emerged as the most important risk factor. Furthermore, a >4-mm upward migration of the posterior nasal spine predicted the risk of massive bleeding in orthognathic surgery. CONCLUSIONS: The upward movement of the maxilla should be recognized during the preoperative planning stage as a risk factor for intraoperative bleeding, and avoiding damage to the nasal mucosa should be considered a requirement for surgeons to prevent massive bleeding during surgery.

Osteotomy training for dental students using three-dimensional simulation software and maxillofacial three-dimensional-printed models.

PURPOSE/OBJECTIVES: Simulated educational models of teeth, bones, and gums have been used for a long time in procedural skills training in dentistry.  The advent of three-dimensional (3D) printing technologies and additive manufacturing has facilitated the production of more advanced 3D printed models that can be utilized for surgical and dental training together with other technologies (e.g., 3D scanners and image analysis software). METHODS: We conducted training on osteotomy in the maxilla and mandible using maxillofacial simulation software (MSS) and a 3D-printed model for 5th-year undergraduate dental students (13 students in 2017 and 11 students in 2018 with more than half of their results). We compared the group (13 students) who performed osteotomy after participating in the simulation lecture with those (11 students) who performed osteotomy after performing self-simulation (they were instructed to bring their personal computers and install the MSS) using tests and questionnaires (pre- and post-curriculum). RESULTS: The average test score was significantly higher in the group who performed osteotomy using the 3D-printed model after performing self-simulation; participants in this group had acquired a better understanding of the surgical procedure. Comparison using questionnaires showed a significant difference in the students' understanding of instruments and surgical techniques between both groups. CONCLUSION: The MSS and 3D printed models are widely used clinically. Incorporating these in the curriculum will help accelerate student development. In addition, prompt education on the purpose and usefulness of these tools will not only facilitate simulation software and 3D-printed model-based treatment plan in the clinic but also promote further research.