COVID-19 transmission in dental and oral/maxillofacial surgical practice during pandemic: questionnaire survey in 51 university hospitals in Japan.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has become a major public health problem. Dental procedures that generate aerosols are considered to impose a high risk of infection; therefore, dental professionals, such as dentists and dental hygienists, may be at high risk of viral transmission. However, few studies have reported COVID-19 clusters in dental care settings. AIM: To investigate whether dental and oral/maxillofacial procedures are associated with the occurrence of COVID-19 clusters and measures taken to prevent nosocomial infection in dental clinics. METHODS: An online questionnaire survey on clinical activities (administrative control), infection control measures (environmental/engineering control, personal protective equipment, etc.), and confirmed or probable COVID-19 cases among patients and clinical staff was administered to the faculties of the dental and oral/maxillofacial surgical departments of university hospitals. FINDINGS: Fifty-one faculty members completed the questionnaire. All members were engaged in the treatment of dental and oral surgical outpatients and actively implemented standard precautions. Fourteen faculty members treated patients with COVID-19, but no infections transmitted from the patients to the medical staff were observed. In seven facilities, patients were found to have the infection after treatment (medical staff came in close contact), but there was no transmission from patients to medical staff. Four facilities had medical staff with infections, but none of them exhibited disease transmission from staff to patients. CONCLUSION: COVID-19 clusters are unlikely to occur in dental and oral surgical care settings if appropriate protective measures are implemented.

The Fe-FeSi phase diagram at Mercury's core conditions.

Mercury's metallic core is expected to have formed under highly reducing conditions, resulting in the presence of significant quantities of silicon alloyed to iron. Here we present the phase diagram of the Fe-FeSi system, reconstructed from in situ X-ray diffraction measurements at pressure and temperature conditions spanning over those expected for Mercury's core, and ex situ chemical analysis of recovered samples. Under high pressure, we do not observe a miscibility gap between the cubic fcc and B2 structures, but rather the formation of a re-entrant bcc phase at temperatures close to melting. Upon melting, the investigated alloys are observed to evolve towards two distinct Fe-rich and Fe-poor liquid compositions at pressures below 35-38 GPa. The evolution of the phase diagram with pressure and temperature prescribes a range of possible core crystallization regimes, with strong dependence on the Si abundance of the core.

Impact of muscle volume loss on acute oral mucositis in patients undergoing concurrent chemoradiotherapy after oral cancer resection.

This study evaluated the association between skeletal muscle mass depletion and severe oral mucositis in patients undergoing concurrent chemoradiotherapy after oral cancer resection. Skeletal muscle mass was evaluated in 60 patients using the skeletal muscle index, which was based on skeletal muscle cross-sectional area (on computed tomography) at the level of the third lumbar vertebra. In accordance with the grading criteria of the Radiation Therapy Oncology Group, patients with a grade ≥3 were defined as having severe oral mucositis. Multivariate logistic regression analysis was used to evaluate independent risk factors for severe oral mucositis. Eleven patients (18.3%) were diagnosed with low skeletal muscle mass. Severe oral mucositis occurred in 17 (28.3%) patients, and the mean skeletal muscle index was 42.8 cm2/m2. A low skeletal muscle mass (hazard ratio 18.1; P=0.001) and a chemotherapy regimen consisting of 5-fluorouracil and cisplatin (versus cisplatin only) (hazard ratio 5.5; P=0.015) were independent risk factors for severe oral mucositis. Future prospective studies are warranted to identify effective pre- and perioperative exercises and nutrition programmes to increase low skeletal muscle mass and reduce the incidence of severe oral mucositis in patients undergoing concurrent chemoradiotherapy after oral cancer resection.

Impact of sarcopenia on postoperative surgical site infections in patients undergoing flap reconstruction for oral cancer.

Sarcopenia is characterized by progressive and generalized loss of skeletal muscle mass and strength. The aim of the study was to investigate the impact of skeletal muscle mass on surgical site infection (SSI) in flap reconstruction for defects after oral cancer resection. The subjects were a non-randomized, retrospective cohort of 106 patients who underwent this procedure after preoperative abdominal-lumbar computed tomography (CT). Cross-sectional areas (cm2) of skeletal muscles in the L3 region were measured by manual outlining on CT images. These areas were then normalized for height (cm2/m2) and defined as the skeletal muscle index (SMI). Recipient site SSI occurred in 28 patients (26.4%). Lower body mass index, haemoglobin and SMI were significantly related to recipient site SSI in univariate analysis (P<0. 05). In a multiple logistic regression model, lower SMI was a significant risk factor for recipient site SSI (odds ratio = 3.95 per 10 cm2/m2 decrease, P=0. 005). This result suggests that increasing skeletal muscle mass by exercise or nutrition before surgery may prevent recipient site SSI after resection of oral cancer and subsequent reconstruction.

Tongue surface model can predict radiation tongue mucositis due to intensity-modulated radiation therapy for head and neck cancer.

Acute radiation tongue mucositis has a profound effect on talking and eating. We examined whether the dose-volume histogram obtained from the tongue surface model correlates with mucositis severity, and whether it is useful for predicting acute radiation tongue mucositis in patients with head and neck cancer treated with intensity-modulated radiation therapy. Thirty-six patients who received intensity-modulated radiation therapy for head and neck cancer were analysed for acute radiation tongue mucositis according to the Common Terminology Criteria for Adverse Events, version 4.0, as well as the Radiation Therapy Oncology Group scoring systems. The corresponding high-dose locations in anatomical sub-regions in the tongue surface model and the development of high-grade acute radiation tongue mucositis were compared. The mucositis sites coincided with the high-dose anatomical sub-regions in the tongue surface model. There was a clear dose-response relationship between the mean dose to the tongue and the acute radiation tongue mucositis Radiation Therapy Oncology Group grade. According to the dose-volume histogram, patients receiving 16.0-73.0 Gy to the tongue were susceptible to grade 2-3 toxicity. The tongue surface model can predict the site and severity of acute radiation tongue mucositis. In future, radiation treatment plans ccould be optimized using this model.

Clinicopathological investigation of odontogenic fibroma in tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant inherited disease characterized by systemic hamartoma and diverse systemic features. TSC1 and TSC2 are the causative genes, and mental retardation, epileptic seizures, and facial angiofibroma develop in many patients with the disease. The case of a patient with TSC who developed a central odontogenic fibroma of the mandible is reported here. The patient was a 21-year-old woman who was referred with a swelling of the labial gingiva in the region of the right lower lateral incisor and canine. Dental radiography revealed a multilocular radiolucent region with a clear boundary. The right lower lateral incisor and canine were continuous with the lesion and thus were excised en bloc. The lesion was encapsulated and easily dissected. The diagnosis on immunohistological staining was odontogenic fibroma without an epithelial component. TSC1/2 gene mutation causes abnormal activation of mammalian target of rapamycin (mTOR) downstream of the PI3K-AKT pathway. The odontogenic fibroma in this patient was positive for mTOR, suggesting that the development of the odontogenic fibroma was the result of abnormal activation of mTOR, as in angiofibroma. The clinical course of this patient is presented and the developmental mechanism of central odontogenic fibroma is discussed.

Risk factors for postoperative delirium in patients undergoing free flap reconstruction for oral cancer.

The aim of this study was to investigate risk factors for postoperative delirium in patients undergoing free flap reconstruction for defects after oral cancer resection. This was a non-randomized, retrospective cohort study involving 102 patients who underwent oral cancer resection and free flap reconstruction. Data were collected from the medical records. Postoperative delirium occurred in 34 patients (33.3%), of whom 27 were male and seven were female. High preoperative total protein and albumin, diabetes mellitus, history of smoking, use of hypnotics or antipsychotics, time until getting out of bed after surgery, and postoperative insomnia were significantly related to delirium in the univariate analysis (P<0.05). In a multiple logistic regression model, high preoperative albumin (odds ratio 4.45), postoperative insomnia (odds ratio 10.72), and history of smoking (odds ratio 2.91) were significant risk factors for delirium (P<0.05). The analysis of laboratory data before and after surgery showed greater decreases in albumin, total protein, and haemoglobin after surgery in patients with postoperative delirium than in those without this condition. These results show that the perioperative maintenance of nutritional status and early postoperative management of the sleep cycle are important to prevent delirium after oral cancer resection and free flap reconstruction.

Standard morphology of the oral commissure and changes resulting from reconstruction for defects involving the commissure.

The aim of this study was to characterize the standard morphology of the oral commissure and to describe the changes after reconstruction in patients with through-and-through cheek defects involving the oral commissure. Indices for the morphological analyses of the commissure were derived from examinations of 50 normal Japanese volunteers. Ten patients with full-thickness cheek defects involving the commissure were then evaluated. All of these patients underwent free flap reconstruction with vermilion advancement flaps from the remaining vermilion. The morphology of the commissure with the mouth closed was classified based on the point of entrance of the vermilion into the oral cavity. In normal volunteers, the commissure pattern consisting of the entrance of the upper vermilion into the oral cavity before the lower vermilion and just prior to forming the oral commissure was considered to be the standard. However, in the reconstructed cases, there was an increase in the pattern in which the lower vermilion enters the oral cavity before the upper vermilion for the remaining commissure postoperatively, especially when the lower lip defects were greater than those of the upper lip. It is important to refer not only to the standard morphology of the commissure, but also to the changes according to the extent of resection and the method of reconstruction.

Factors influencing internal jugular vein patency after neck dissection in oral cancer.

The objective was to investigate factors influencing internal jugular vein stenosis or occlusion after neck dissection, including the reconstructive procedure. The subjects were 73 patients (81 veins) who underwent a modified radical neck dissection, in which the internal jugular vein was preserved, or an extended supraomohyoid neck dissection (E-SOHND). All procedures were performed by the same surgeon. Internal jugular vein patency was evaluated by contrast-enhanced computed tomography. Patency was evaluated in relation to gender, side of dissection, number of pathological lymph node metastases, extracapsular spread of lymph node metastases, radiotherapy, and the reconstruction method (no reconstruction, free flap, or pedicle flap). All internal jugular vein occlusions were on the left side and all except one of these patients underwent radiotherapy. Thus, radiotherapy and left side dissection were significant risk factors for occlusion. Free flap reconstruction was not a risk factor for vein stenosis or occlusion. Patients undergoing reconstruction with pedicled musculocutaneous flaps or E-SOHND were less likely to have vein occlusion. Particular care is required for left neck dissection in patients who have undergone radical neck dissection on the right side. This study suggests that covering the internal jugular vein with the muscle might prevent vein occlusion.

Lower lip repair using double opposing rectangular rotation flaps with reconstruction of the mentolabial groove and mental protuberance.

The use of a rectangular flap is a well known technique for upper lip repair in cleft lip, but is less common for lower lip repair after tumour resection. We have found this type of flap to be favourable for lower lip reconstruction, especially for the lip to mental region. We describe herein an improvement to the technique in which two opposing rectangular flaps, with the length of one side equal to the vertical distance from the mentolabial groove to the vermilion border, were raised on the lateral sides of a U-shaped defect. Reconstruction was performed by interdigitation of the two flaps and a bilateral vermilion advancement flap. This new approach allows a distinct mentolabial groove and mental protuberance to be created by utilizing two opposing rectangular flaps and redundant tissue, without sacrificing sensation and muscle function. Our results suggest that the technique provides excellent functional and cosmetic outcomes in restoration of the lower lip in properly selected patients.

Effects of postoperative chemotherapy and radiotherapy on patients with squamous cell carcinoma of the oral cavity and multiple regional lymph node metastases.

Nodal metastasis in oral squamous cell carcinoma (OSCC) is considered to be a predictor of a poor prognosis. The aim of this study was to investigate the relationship between the number of positive lymph nodes and the prognosis in OSCC patients with nodal metastases and to assess the effects of postoperative radiotherapy (RT) or concurrent chemoradiotherapy (CCRT) on this patient group. A retrospective investigation of 98 patients with OSCC who underwent radical neck dissection and had at least three pathologically positive lymph nodes was performed. The 5-year disease-specific survival rate was 66.7% for patients with 3 positive nodes, while it was significantly lower for those with 4 positive nodes and those with ≥ 5 positive nodes (21.5% and 46.1%, respectively; P < 0.01). The loco-regional control and disease-specific survival rates for the surgery alone, surgery plus RT, and surgery plus CCRT groups were 46.2% and 40.5%, 66.3% and 54.4%, and 81.7% and 52.4%, respectively. For patients with ≥ 4 positive nodes, the loco-regional control rate after surgery plus CCRT was better than that observed after surgery alone (77.5% vs. 32.6%, P = 0.01). Postoperative RT and CCRT have positive impacts on the prognosis of OSCC patients with advanced stage neck disease.

Ultrasound-guided intralesional laser treatment of venous malformation in the oral cavity.

An ultrasound-guided intralesional photocoagulation (ILP) technique using a laser is described for treatment of deep venous malformations in the oral cavity. ILP is basically a blind operation and has a risk of unintended destruction of surrounding normal tissue, therefore the authors now routinely use guidance by ultrasonography using a mini-probe to improve the safety and reliability of ILP. This approach enables safe fibre insertion, appropriate laser irradiation, and intraoperative assessment of coagulation. The use of this technique is described in 8 patients. The authors conclude that ultrasound-guided ILP with a laser is a promising technique for less-invasive treatment of a vascular malformation in the oral cavity.

Osseous healing after a sagittal splitting ramus osteotomy.

The purpose of this study was to examine osseous healing in the cleavage between the bone fragments after sagittal splitting ramus osteotomy (SSRO) utilizing computed tomography (CT). The subjects were 13 patients with mandibular prognathism who underwent bilateral SSRO. CT was used to study the rami immediately after surgery, then 6 months, 1 year, and 2 years after surgery. Many concave type (the angle between the cleavage >90°) anterior borders developed into the stairway type (the angle between the cleavage <90°) 6-12 months after surgery. Few borders changed to the smooth type. Almost all of the stairway and concave posterior borders changed to the smooth type in the 6-12 months after surgery. Regarding the posterior borders 1 year after surgery, the cleavage of distal and proximal bone fragments demonstrated stable osseous healing (smooth type) in cases where the length and width between the bone fragments were large. In conclusion, the authors successfully demonstrated detailed osseous healing in the cleavage between the bone fragments after SSRO. Remodelling between bone fragments is a major mechanism of osseous healing after this procedure.

Metastasis to the lateral retropharyngeal lymph node from squamous cell carcinoma of the oral cavity: report of three cases.

Carcinoma of the oral cavity sometimes metastasizes to the lateral retropharyngeal lymph node (LRPLN), especially when posteriorly invading the soft palate or oropharynx. CT or MRI imaging has enabled detection of LRPLN metastasis in the early stage, but the prognosis of patients with metastasis to this node is extremely poor. The authors report three patients with squamous cell carcinoma of the oral cavity with no posterior invasion who developed metastasis to LRPLN during observation. The primary sites of these three cases were gingiva of the upper incisor region, gingiva of the lower premolar region, and maxillary bone of the upper incisor region. Each patient underwent surgery as their initial therapy, but a recurrent tumor in the LRPLN was detected by CT or MRI despite good loco-regional control. A salvage operation with postoperative radiation therapy was performed for two patients, but only one is still alive with no evidence of tumor 14 months after the last surgery. Management of LRPLN metastasis in oral cancer patients is a challenge for oral surgeons, but early detection by CT or MRI and surgery with postoperative radiation therapy is likely to yield the best local control.

A comparison of brachytherapy and surgery for the treatment of stage I-II squamous cell carcinoma of the tongue.

The treatment method for early stage tongue cancer is still controversial in Japan. The aim of this study is to compare the prognosis for patients with early tongue cancer treated with brachytherapy and surgery. A retrospective study was conducted to compare the efficacy of low-dose-rate brachytherapy (LDR), high-dose-rate brachytherapy (HDR), and surgery for early tongue cancer. A total of 180 patients with stage I-II tongue cancer were divided into three treatment groups: LDR (78), HDR (26), and surgery (71). Local recurrence was seen in thirteen patients (17%) of the LDR, nine (35%) of the HDR, and four (6%) of the surgery group. After salvage therapy, final local cure was obtained for 71 patients (91%) of the LDR, 22 (85%) of the HDR, and 71 (100%) of the surgery group. Neck failure was recorded for eight patients in the LDR, six in the HDR, and three in the surgery group. The respective 5-year overall survival rates for the LDR, HDR and surgery groups were 84.0%, 72.9%, 95.4% for stage I, and 72.2%, 51.5%, 93.8% for stage II. These findings show that surgery is the optimal treatment method for patients with stage I-II tongue cancer.

Aderência e formação do biofilme por Staphylococcus aureus ao polietilenotereftalato (PET) usado como embalagem para acondicionamento de medicamentos e cosméticos / Staphylococcus aureus attachment and biofilm formation on polyethylene terephthalate (PET) used for packaging drugs and cosmetics

O polietilenotereftalato (PET) é utilizado como matéria prima para elaborar frascos, os quais podem ser empregados no acondicionamento de medicamentos e cosméticos. Esta pesquisa teve por objetivo examinar por microscópio eletrônico de varredura a aderência e formação do biofilme por Staphylococcus aureus sobre a superfície do polietilenotereftalato (PET) e pelo método de aderência ao hidrocarboneto determinar a hidrofobicidade do S. aureus. Uma suspensão de S. aureus foi inoculada em caldo Mueller-Hinton e os corpos-de-prova de polietilenotereftalato foram inoculados por 30 minutos, duas, 24 e 48 horas, 15 e 30 dias. O meio de cultura foi trocado a cada três dias. Após os períodos de incubação, os corpos-de-prova foram preparados para MEV. A aderência e formação do biofilme foi observada sobre as superfícies do PET. Os resultados da análise por MEV, mostraram que as superfícies do PET permitiram a aderência de S. aureus com a formação do biofilme. O teste de hidrofobicidade mostrou que o S. aureus tem características hidrofóbicas

Therapeutic importance of transplantation of a vascularised free flap for an oromandibular injury with infection and severe scar contracture.

We report three patients who had transplantation of vascularised free flaps, peroneal osteocutaneous flap in two patients and radial forearm flap in one patient, for the treatment of oromandibular injuries that had not healed as a result of infection after initial treatment.

Evaluation of T-classifications of upper gingival and hard palate carcinomas--a proposition for new criterion of T4.

Most carcinomas of upper gingiva and hard palate are classified as T4 stage on the basis of the UICC criteria, since they easily invade the underlying bone tissue. We classified 43 patients with squamous cell carcinoma of the upper gingiva in terms of three criteria: (1) the original T-classification by UICC, (2) the classification by the Japan Society for Head and Neck Cancer (JSHNC), and (3) a new classification in which the maxillary sinus or nasal floor is used as the defining borderline for T4 (MSF classification). Our study demonstrated that the new classification was superior with regard to distribution of patients by T stage, correlation with prognosis and choice of treatment method.

Establishment and characterization of a human adenoid cystic carcinoma line of the salivary gland which is serially transplantable and spontaneously metastasises to the lung in nude mice.

Adenoid cystic carcinoma (ACC) is a rare malignant tumour of the head and neck occurring in the salivary glands. We established a human ACC line which is serially transplantable in nude mice and designated it as KOA-1. The KOA-1 tumour doubled in 9.3 days and retained the histological characteristics of a solid pattern of ACC even after 22 serial passages. The KOA-1 metastasised to the lung when transplanted subcutaneously into the back. This tumour line may serve as a useful model for exploration of the biological behaviour and treatment of human ACC.

Experimental model of invasion and metastasis by orthotopic transplantation of oral squamous and adenoid cystic carcinomas into the tongue of nude mice.

Three squamous cell carcinoma (SCC) cell lines established from oral cancer, seven specimens of SCC and three of adenoid cystic carcinomas taken from the oral cavity during operations were transplanted into the tongues of nude mice. Metastases to the regional lymph nodes and the lungs were examined histologically. We were able to transplant every cell line or specimen of tissue into the tongue of nude mice, and found that cancer transplanted in the tongue invaded diffusely to the surrounding tissues without forming a capsule, and that the mode of invasion of the transplanted SCC was similar to that of the biopsy specimen of the patient from whom the material had been obtained. We also found that all three of the SCC cell lines, 3 of the 7 SCC specimens and 2 of the 3 adenoid cystic carcinoma tissues metastasized to the regional lymph node. SCC did not metastasize to the lung, but in two of the three adenoid cystic carcinomas we did see micrometastases to the lung. The study indicates that this method can be used as a model of metastasis in oral squamous cell carcinoma and adenoid cystic carcinoma to show the stages of metastasis in cancer.