Expression analysis of zinc-metabolizing enzymes in the saliva as a new method of evaluating zinc content in the body: two case reports and a review of the literature.

BACKGROUND: The activity level of alkaline phosphatase, a zinc-requiring enzyme in the serum, is used to indicate zinc nutritional status; however, it does not correlate with serum zinc levels or subjective symptoms of taste disorder in many cases. Hence, this study focused on the total activity of alkaline phosphatase, a zinc-requiring enzyme. The total alkaline phosphatasa activity level in the saliva was measured before and after zinc supplementation, and the results were compared with serum zinc levels. CASE PRESENTATION: This study included patients with hypozincemia, specifically a patient with zinc-deficient taste disorder (patient 1: a 69-year-old Japanese woman) and a patient with glossodynia with zinc deficiency (patient 2: an 82-year-old Japanese woman). Saliva samples were collected, and blood tests were performed before and after zinc supplementation. Subjective symptoms and serum zinc levels were simultaneously evaluated. Zinc supplementation was performed using zinc acetate hydrate or Polaprezinc. CONCLUSIONS: Total alkaline phosphatase activity levels were found to be associated with serum zinc levels and subjective symptoms. A further study with a higher number of patients is necessary to confirm whether total alkaline phosphatase activity levels more accurately reflect the amounts of zinc in the body than serum zinc levels.

Contrast-enhanced computed tomography of retromandibular vein position and course patterns relative to the mandible during sagittal split ramus osteotomy.

Background: Sagittal split ramus osteotomy is an established procedure used in oral and maxillofacial surgery. Major bleeding is representative intraoperative complication involves vessels such as the inferior alveolar, facial, and maxillary arteries and accompanying veins, in particular the retromandibular vein (RMV). We previously described the RMV course patterns using embalmed cadavers. However, owing to the possible influence of formalin fixation and unclear skeletal classification of the jaws, the present study aimed to use contrast-enhanced computed tomography to confirm the RMV in patients with defined jaw deformities. Methods: Twenty patients with orthognathic jaw deformities (40 sides) were included. The RMV and the lateral and posterior views of the mandible were evaluated using contrast-enhanced computed tomography. Course patterns and RMV positions were classified as previously reported. Results: Three patterns were identified in the lateral view. Type A: RMV posterior to the posterior border of the ramus (n=25; 62.5%). Type B: adjoining the posterior border of the ramus (n=12; 30.0%). Type C: anterior to the posterior border of the ramus (n=3; 7.5%). Five course patterns were identified in the posterior view. Pattern I: rectilinear course running medial to the posterior border of the ramus (n=3; 7.5%). Pattern II: diagonal course running medially from immediately posterior to posterior border of the ramus (n=11; 27.5%). Pattern III: rectilinear course running immediately posterior to the posterior border of the ramus (n=12; 30.0%). Pattern IV: diagonal course running from lateral to medial relative to the posterior border of the ramus (n=8; 20.0%). Pattern V: diagonal course running from lateral to immediately posterior relative to the posterior border of the ramus (n=6; 15.0%). In the no-course pattern group, the RMV inferior to the lingula was lateral to its position and superior to that of the lingula. In half of the cases, the left and right sides exhibited different running patterns. We observed no correlation between the skeletal patterns of jaw deformities and the course of the RMV. Conclusions: Type B/Pattern II that runs in a straight line bordering the posterior margin of the ramus requires the most attention during surgery. These findings suggest the possibility of predicting intraoperative bleeding risk.

Enhanced Precision in Genioplasty: A Novel Intraoperative Spatial Repositioning Using Computer-Aided Design and Manufacturing Technology and a Holographic Mixed Reality Application.

Genioplasty is performed for the orthognathic surgical correction of dentofacial deformities. This article reports a safe and accurate method for genioplasty combining a novel three-dimensional (3D) device with mixed reality (MR)-assisted surgery using a registration marker and a head-mounted display. Four types of devices were designed based on the virtual operation: a surgical splint with a connector; an osteotomy device; a repositioning device; and a registration marker. Microsoft HoloLens 2 and Holoeyes MD were used to project holograms created using computed tomography (CT) data onto the surgical field to improve the accuracy of the computer-aided designed and manufactured (CAD/CAM) surgical guides. After making an incision on the oral vestibule, the splint was fitted on the teeth and the osteotomy device was mounted at the junction site, placed directly on the exposed mandible bone surface. Temporary screws were fixed into the screw hole. An ultrasonic cutting instrument was used for the osteotomy. After separating the bone, a repositioning device was connected to the splint junction and bone segment, and repositioning was performed. At the time of repositioning, the registration marker was connected to the splint junction, and mandible repositioning was confirmed three-dimensionally through HoloLens 2 into the position specified in the virtual surgery. The rate of overlay error between the preoperative virtual operation and one-month postoperative CT data within 2 mm was 100%. CAD/CAM combined with MR enabled accurate genioplasty.

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.

Mixed reality for extraction of maxillary mesiodens.

BACKGROUND: Mesiodentes are the most common supernumerary teeth. The cause is not fully understood, although proliferations of genetic factors and the dental lamina have been implicated. Mesiodentes can cause delayed or ectopic eruption of permanent incisors, which can further alter occlusion and appearance. Careful attention should be paid to the position and direction of the mesiodentes because of possible damage to adjacent roots in the permanent dentition period, errant extraction in the deciduous and mixed dentition periods, and damage to the permanent tooth embryo. To avoid these complications, we applied mixed reality (MR) technology using the HoloLens® (Microsoft, California). In this study, we report on three cases of mesiodentes extraction under general anesthesia using MR technology. RESULTS: The patients ranged in age from 6 to 11 years, all three were boys, and the direction of eruption was inverted in all cases. The extraction approach was palatal in two cases and labial in one case. The average operative time was 32 min, and bleeding was minimal in all cases. No intraoperative or postoperative complications occurred. An image was shared preoperatively with all the surgeons using an actual situation model. Three surgeons used Microsoft HoloLens® during surgery, shared MR, and operated while superimposing the application image in the surgical field. CONCLUSIONS: The procedure was performed safely; further development of MR surgery support systems in the future is suggested.

Clinical investigation of patients with jaw deformity with comorbidities.

BACKGROUND: With improvements in the safety and stability of surgeries, the number of orthognathic surgeries is increasing. Most patients who undergo orthognathic surgeries are younger, and the number of orthognathic surgeries for patients with comorbidities is also increasing. We report a survey and clinical investigation of patients with comorbidities who underwent orthognathic surgeries at our department to improve the safety of orthognathic surgery. RESULTS: The participants included 296 men and 712 women, with a mean age of 28 years (13-19 years, n=144; 20-29 years, n=483; 30-39 years, n=236; 40-49 years, n=102; 50-59 years, n=39; ≥60 years, n=4). In total, 347 patients underwent one-stage Le Fort type I osteotomy and sagittal split ramus osteotomy (SSRO), 243 underwent SSRO, 287 underwent plate removal, 126 underwent genioplasty and plate removal, and five underwent other surgeries. In total, 529 patients had comorbidities (52%), including allergic diseases (n=220, 33%), respiratory diseases (n=107, 16%), neurologic and psychiatric diseases (n=69, 10%), gynecologic diseases (n=28, 4%), hematologic diseases (n=27, 4%), cardiovascular diseases (n=24, 4%), digestive diseases (n=22, 3%), metabolic and endocrine diseases (n=18, 3%), spinal diseases (n=11, 2%), ophthalmologic diseases (n=11, 2%), renal and urological diseases (n=9, 1%), and other diseases (n=117, 18%). Among the patients with comorbidities, 11 with hemorrhagic diatheses (hemophilia and von Willebrand disease), arrhythmia (atrioventricular block), psychiatric disease (adjustment disorder), and metabolic disease (diabetes) required cautious perioperative management. The patient with hemophilia was managed with regular low-dose recombinant factor VIII replacement therapy, and the patient with type I diabetes mellitus was administered continuous insulin infusion and sliding-scale insulin therapy; both patients had an uneventful course. CONCLUSIONS: The study findings suggest that with the increase in orthognathic surgeries, oral and maxillofacial surgeons should adequately manage cases requiring cautious perioperative control and highlight the importance of preoperative screening. Despite the well-established safety and postoperative stability of orthognathic surgeries, oral surgeons should adopt appropriate additional preventive measures for patients with comorbidities.

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.

Mixed reality and three dimensional printed models for resection of maxillary tumor: a case report.

In the field of oral and maxillofacial surgery, many institutions have recently begun using three-dimensional printers to create three-dimensional models and mixed reality in a variety of diseases. Here, we report the actual situation model which we made using three-dimensional printer from virtual operation data and the resection that was performed while grasping a maxillary benign tumor and neighboring three-dimensional structure by designing an application for Microsoft® HoloLens, and using Mixed Reality surgery support during the procedure.

Retromandibular vein position and course patterns in relation to mandible: anatomical morphologies requiring particular vigilance during sagittal split ramus osteotomy.

Major bleeding associated with sagittal split ramus osteotomy (SSRO) involves vessels such as the inferior alveolar, facial, and maxillary arteries and veins, and the retromandibular vein (RMV). The present study aimed to clarify and classify the three-dimensional variations in RMV position and course direction in relation to the mandible. Specimens comprised a total of 15 scientific cadavers, and the relationship between RMV and the mandible lateral and posterior views was observed. We identified 3 patterns on the lateral view, the mean distance between the RMV and the posterior border of the ramus was 3.9 mm at the height of the lingula. A total of five course patterns were identified on the posterior view. In no course pattern, the RMV inferior to the lingula was lateral to its position superior to the lingual. The present findings suggest that it may be possible to predict correlations with intraoperative bleeding risk. Further study is planned using contrast computed tomography in patients with jaw deformity for skeletal classification.

A safe, stable, and convenient three-dimensional device for high Le Fort I osteotomy.

BACKGROUND: Le Fort I osteotomy is a highly effective treatment for skeletal jaw deformities and is commonly performed. High Le Fort I osteotomy is a modified surgical procedure performed for improving the depression of the cheeks by setting the osteotomy higher than the conventional Le Fort I osteotomy. Developments in three-dimensional (3D) technology have popularized the use of 3D printers in various institutions, especially in orthognathic surgeries. In this study, we report a safe and inexpensive method of performing a high Le Fort I osteotomy using a novel 3D device and piezosurgery, which prevent tooth root injury without disturbing the operation field for patients with a short midface and long tooth roots. RESULTS: A 17-year-old woman presented with facial asymmetry, mandibular protrusion, a short midface, and long tooth roots. We planned high Le Fort I osteotomy and bilateral sagittal split ramus osteotomy. Prevention of damage to the roots of the teeth and the infraorbital nerve and accurate determination of the posterior osteotomy line were crucial for clinical success. Le Fort I osteotomy using 3D devices has been reported previously but were particularly large in size for this case. Additionally, setting the fixing screw of the device was difficult, because of the risk of damage to the roots of the teeth. Therefore, a different surgical technique, other than the conventional Le Fort I osteotomy and 3D device, was required. The left and right parts of the 3D device were fabricated separately, to prevent any interference in the surgical field. Further, the 3D device was designed to accurately cover the bone surface from the piriform aperture to the infra-zygomatic crest with two fixation points (the anterior nasal spine and the piriform aperture), which ensured stabilization of the 3D device. The device is thin and does not interfere with the surgical field. Safe and accurate surgical performance is possible using this device and piezosurgery. The roots of the teeth and the infraorbital nerve were unharmed during the surgery. CONCLUSIONS: This device is considerably smaller than conventional devices and is a simple, low-cost, and efficient method for performing accurate high Le Fort I osteotomy.

Relationship between the immunohistological examination and fluorescence visualization of oral squamous cell carcinoma.

Disorders of the oral mucosa are considered easy to diagnose since they can be visualized and examined directly. A change in the color of the oral mucosa reflects histopathological changes and is an important diagnostic parameter. However, the subjective perception of color varies. To determine the extent of resection for oral mucosa conditions, it is necessary to digitize the color and perform objective assessments. In recent years, fluorescence visualization devices and analysis software that measure tissue luminance G have been employed for the identification of oral mucosa diseases. Fluorescence visualization is presumably based on the decrease in epithelial flavin adenine dinucleotide content and luminance G values due to the destruction of collagen cross-links [fluorescence visualization loss (FVL)]. However, cases with differences between luminance values and histopathological presentation exist. Therefore, additional factors may affect fluorescence visualization. The present study used a portable, non-contact oral mucosa fluorescence visualization device for luminance measurements in seven patients with oral squamous cell carcinoma. Furthermore, Picro-Sirius Red and immunohistochemical staining were performed for CK13, CK17, Ki67, p53 and E-cadherin in the FVL(+) (lesion) and FVL(-) (resection stump) areas to elucidate the principle of fluorescence visualization. Fluorescence was significantly lower in the FVL(+) than in the FVL(-) areas, and the mean luminance G value was 56. The Picro-Sirius Red stain revealed collagen destruction in the FVL(+) areas but no collagen disruption in the FVL(-) areas. CK13 was negative in the FVL(+) and positive in the FVL(-) areas, whereas the opposite pattern was observed for CK17. In the FVL(+) area, p53 staining was positive. E-cadherin expression was enhanced in the FVL(-) areas and reduced in the FVL(+) areas. Furthermore, the luminance G value tended to be lower in cases with weaker E-cadherin staining. The aforementioned results suggest that decreased E-cadherin expression may be a factor that regulates fluorescence visualization.

Maxillary reconstruction using tunneling flap technique with 3D custom-made titanium mesh plate and particulate cancellous bone and marrow graft: a case report.

BACKGROUND: Reconstructive surgery is often required for tumors of the oral and maxillofacial region, irrespective of whether they are benign or malignant, the area involved, and the tumor size. Recently, three-dimensional (3D) models are increasingly used in reconstructive surgery. However, these models have rarely been adapted for the fabrication of custom-made reconstruction materials. In this report, we present a case of maxillary reconstruction using a laboratory-engineered, custom-made mesh plate from a 3D model. CASE PRESENTATION: The patient was a 56-year-old female, who had undergone maxillary resection in 2011 for intraoral squamous cell carcinoma that presented as a swelling of the anterior maxillary gingiva. Five years later, there was no recurrence of the malignant tumor and a maxillary reconstruction was planned. Computed tomography (CT) revealed a large bony defect in the dental-alveolar area of the anterior maxilla. Using the CT data, a 3D model of the maxilla was prepared, and the site of reconstruction determined. A custom-made mesh plate was fabricated using the 3D model (Okada Medical Supply, Tokyo, Japan). We performed the reconstruction using the custom-made titanium mesh plate and the particulate cancellous bone and marrow graft from her iliac bone. We employed the tunneling flap technique without alveolar crest incision, to prevent surgical wound dehiscence, mesh exposure, and alveolar bone loss. Ten months later, three dental implants were inserted in the graft. Before the final crown setting, we performed a gingivoplasty with palate mucosal graft. The patient has expressed total satisfaction with both the functional and esthetic outcomes of the procedure. CONCLUSION: We have successfully performed a maxillary and dental reconstruction using a custom-made, pre-bent titanium mesh plate.

Novel condylar repositioning method for 3D-printed models.

BACKGROUND: Along with the advances in technology of three-dimensional (3D) printer, it became a possible to make more precise patient-specific 3D model in the various fields including oral and maxillofacial surgery. When creating 3D models of the mandible and maxilla, it is easier to make a single unit with a fused temporomandibular joint, though this results in poor operability of the model. However, while models created with a separate mandible and maxilla have operability, it can be difficult to fully restore the position of the condylar after simulation. The purpose of this study is to introduce and asses the novel condylar repositioning method in 3D model preoperational simulation. METHODS: Our novel condylar repositioning method is simple to apply two irregularities in 3D models. Three oral surgeons measured and evaluated one linear distance and two angles in 3D models. RESULTS: This study included two patients who underwent sagittal split ramus osteotomy (SSRO) and two benign tumor patients who underwent segmental mandibulectomy and immediate reconstruction. For each SSRO case, the mandibular condyles were designed to be convex and the glenoid cavities were designed to be concave. For the benign tumor cases, the margins on the resection side, including the joint portions, were designed to be convex, and the resection margin was designed to be concave. The distance from the mandibular ramus to the tip of the maxillary canine, the angle created by joining the inferior edge of the orbit to the tip of the maxillary canine and the ramus, the angle created by the lines from the base of the mentum to the endpoint of the condyle, and the angle between the most lateral point of the condyle and the most medial point of the condyle were measured before and after simulations. Near-complete matches were observed for all items measured before and after model simulations of surgery in all jaw deformity and reconstruction cases. CONCLUSIONS: We demonstrated that 3D models manufactured using our method can be applied to simulations and fully restore the position of the condyle without the need for special devices.