Transcutaneous carbon dioxide suppresses skeletal muscle atrophy in a mouse model of oral squamous cell carcinoma

Cancer cachexia causes skeletal muscle atrophy, impacting the treatment and prognosis of patients with advanced cancer, but no treatment has yet been established to control cancer cachexia. We demonstrated that transcutaneous application of carbon dioxide (CO2) could improve local blood flow and reduce skeletal muscle atrophy in a fracture model. However, the effects of transcutaneous application of CO2 in cancer-bearing conditions are not yet known. In this study, we calculated fat-free body mass (FFM), defined as the skeletal muscle mass, and evaluated the expression of muscle atrophy markers and uncoupling protein markers as well as the cross-sectional area (CSA) to investigate whether transcutaneous application of CO2 to skeletal muscle could suppress skeletal muscle atrophy in cancer-bearing mice. Human oral squamous cell carcinoma was transplanted subcutaneously into the upper dorsal region of nude mice, and 1 week later, CO2 gas was applied to the legs twice a week for 4 weeks and FFM was calculated by bioimpedance spectroscopy. After the experiment concluded, the quadriceps were extracted, and muscle atrophy markers (muscle atrophy F-box protein (MAFbx), muscle RING-finger protein 1 (MuRF-1)) and uncoupling protein markers (uncoupling protein 2 (UCP2) and uncoupling protein 3 (UCP3)) were evaluated by real-time polymerase chain reaction and immunohistochemical staining, and CSA by hematoxylin and eosin staining. The CO2-treated group exhibited significant mRNA and protein expression inhibition of the four markers. Furthermore, immunohistochemical staining showed decreased MAFbx, MuRF-1, UCP2, and UCP3 in the CO2-treated group. In fact, the CSA in hematoxylin and eosin staining and the FFM revealed significant suppression of skeletal muscle atrophy in the CO2-treated group. We suggest that transcutaneous application of CO2 to skeletal muscle suppresses skeletal muscle atrophy in a mouse model of oral squamous cell carcinoma.

Risk factors associated with prognosis of patients with medication-related osteonecrosis of the jaw

OBJECTIVES

Medication-related osteonecrosis of the jaw (MRONJ) is a severe adverse effect of antiresorptive and/or antiangiogenic agents. As the treatment application for MRONJ is controversial, we aimed to identify the risk factors for poor prognosis and to help determine appropriate management.

METHODS

This study included 119 patients. Relevant clinical data were obtained for all the patients. In computed tomography images, osteosclerosis, osteolysis, cortical perforation (buccal or lingual), periosteal reaction, and sequestration were evaluated.

RESULTS

Multivariate analyses showed statistically significant associations between poor prognosis in patients with MRONJ and conservative treatment alone (hazard ratio [HR] 1.89), osteolysis (HR 4.67), and the absence of sequestration (HR 5.33).

CONCLUSIONS

Conservative treatment alone without clear objectives needs to be avoided, and osteolytic change could be the criteria for surgical intervention. As the boundary between the lesion and vital bone is indistinct, we recommend extensive surgery in cases with unpredictable sequestration.

Is withdrawal of antiresorptive agents necessary before and after tooth extraction? A systematic review

OBJECTIVES

The need for prevention and management of medication-related osteonecrosis of the jaw (MRONJ) has increased with the growing number of patients using antiresorptive agents. The scope of this systematic review (SR) was to determine whether the withdrawal of antiresorptive agents is necessary for tooth extractions in patients receiving each of the antiresorptive medications.

MATERIALS AND METHODS

The searches were performed using the MEDLINE databases. We selected SRs, randomized controlled trials (RCTs), prospective and retrospective non-randomized clinical (observational) studies, and case reports/case series in this order of preference.

RESULTS

We included one SR, one RCT, five observational studies, and three case reports. Meta-analyses were not conducted because the RCT had an extremely small sample size and the observational studies had different definitions of intervention and comparison that could not be integrated across studies. In this SR, no studies showed a benefit (i.e., a reduction in the incidence of osteonecrosis of the jaw) of short-term withdrawal of antiresorptive agents for tooth extraction. Additionally, no studies examined the harm (i.e., an increase in femoral and vertebral fractures and skeletal-related events during bone metastasis) of withdrawal for tooth extraction.

CONCLUSIONS

We were unable to determine whether withdrawal before and after tooth extraction is necessary with a high certainty of evidence. Future systematic reviews including RCTs with larger samples are expected to provide such evidence.

CLINICAL RELEVANCE

This systematic review provides evidence-based information for multidisciplinary collaborations related to patients receiving antiresorptive agents.

The Efficacy of Carbon Dioxide Paste in Alleviating Pain in Patients After Neck Dissection: Protocol for a Double-Blinded, Randomized Controlled Trial

BACKGROUND

Head and neck cancers that cause severe aesthetic and functional disorders normally metastasize to the cervical lymph nodes. Patients with cervical lymph node metastasis are undergoing neck dissection. Shoulder complaints are common after neck dissection, with patients reporting symptoms such as pain, weakness, shoulder droop, and disability. However, no safe and effective treatment is available for this condition at present. We will conduct a double-blinded, randomized controlled trial to evaluate the efficacy of carbon dioxide (CO2) paste in relieving pain in patients after neck dissection.

OBJECTIVE

This will be the first clinical study to compare the efficacy of CO2 paste with placebo in relieving postoperative pain in patients who underwent neck dissection.

METHODS

We will perform this trial at the Kobe University Hospital in Japan. Patients will be randomized 1:1 into the CO2 paste and control groups. Patients in the CO2 paste group will have the CO2 paste applied to the cervical surface skin for 10 minutes once per day for 14 consecutive days. The primary end point of the study is a change in the visual analog scale (VAS) scores of neck pain from baseline on day 1 (preapplication) to the end of drug application (day 15). Secondary end points include changes in the following parameters from baseline on day 1 to the end of drug application (day 15) or the study (day 29): neck pain VAS score (days 1-29), grip strength (days 1-15 and 1-29), VAS scores for subjective symptoms (the feeling of strangulation, numbness, swelling, and warmth in the neck and shoulder region) for days 1-15 and 1-29, whether the VAS score improved more than 30% (days 1-15), the arm abduction test (days 1-15 and 1-29), shoulder range of motion (abduction and flexion) for days 1-15 and 1-29, occurrence of skin disorders, and occurrence of serious side effects. Periodic monitoring will be conducted for participants during the trial. This study was approved by the certified review board of Kobe University.

RESULTS

The intervention commenced in May 2021 and will continue until March 2024. The collected data will provide information on the efficacy of the CO2 paste treatment. The primary end point will be compared using the Wilcoxon test, with the 1-sided significance level set at 5%. Each evaluation item will be summarized. Secondary efficacy end points will be analyzed to provide additional insights into the primary analysis. Findings based on the treatment effects are expected to be submitted for publication in 2025.

CONCLUSIONS

This trial will provide exploratory evidence of the efficacy and safety of CO2 paste in relieving pain in patients after neck dissection.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (jRCT) identifier: jRCTs051210028; https://jrct.niph.go.jp/en-latest-detail/jRCTs051210028.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/50500.

Development of Cu application using dual-energy computed tomography for detecting medication-related osteonecrosis of the jaw

INTRODUCTION

The present study developed an application using dual-energy computed tomography (DECT) focused on Cu for detecting medication-related osteonecrosis of the jaw (MRONJ).

MATERIALS AND METHODS

First, we performed two types of phantom studies using a Cu wire syringe and pig mandible with Cu wire to detect Cu on DECT. Second, DECT examinations of 44 patients with MRONJ were performed to compare lesion and normal bone sites using single-energy CT, DECT-virtual non-calcium (VNCa), and DECT-Cu applications. Quantitative analyses of VNCa CT and CT values were performed, and a cut-off value was calculated using receiver operating characteristic analysis. Third, we compared the Cu content in the MRONJ and normal bone groups using inductively coupled plasma atomic emission spectroscopy (ICP-AES).

RESULTS

The material-specific differences in attenuation between the two different energies enabled the accurate separation of Cu from Ca in phantom studies. The sensitivity and specificity for single-energy CT, DECT-VNCa, and DECT-Cu applications were 97.7% and 2.3%, 86.4% and 81.8%, and 88.6% and 97.7%, respectively. Thus, VNCa CT values obtained on DECT-Cu application images showed the highest area under the curve value and maximal diagnostic efficacy in differentiating lesion sites from normal bone sites. On ICP-AES analyses, the Cu content was significantly higher in the MRONJ group than in the normal bone group.

CONCLUSION

DECT-Cu application demonstrated better diagnostic performance in detecting MRONJ compared with single-energy CT or DECT-VNCa.

Photodynamic therapy with verteporfin accelerates apoptotic bleb formation in human ameloblastoma

OBJECTIVE

Although benign, ameloblastoma is a locally aggressive lesion in some patients and the development of additional treatments is needed. Verteporfin (VP) is a photosensitizer exhibiting considerable photocytotoxicity in various tumor cells. We aimed to investigate the effects of verteporfin photodynamic therapy (VP PDT) on ameloblastoma.

METHODS

Eighteen patients who underwent surgery for ameloblastoma were randomly selected. We performed an immunohistochemical assessment to investigate the expression of low-density lipoprotein receptor (LDLR) and Yes-associated protein (YAP), targets of VP, in human ameloblastoma tissues and cultured human ameloblastoma cell line (HAM1). The effect of VP PDT on cell proliferation and apoptosis in HAM1 was analyzed.

RESULTS

The expression of LDLR and YAP were detected in human ameloblastoma tissues and HAM1. LDLR expression was significantly higher in patients who had previously undergone surgery than in patients who were receiving it for the first time. The cytotoxic effect of the combination of low-concentration VP administration and laser irradiation was comparable to high-concentration VP administration with and without laser irradiation. The addition of laser irradiation to VP administration significantly accelerated apoptotic bleb formation compared with VP administration alone.

CONCLUSION

VP PDT has the potential to become an additional treatment for large-sized ameloblastoma.

Transcutaneous carbon dioxide application suppresses the expression of cancer-associated fibroblasts markers in oral squamous cell carcinoma xenograft mouse model

Oral squamous cell carcinoma (OSCC) is the most common head and neck cancer. Cancer-associated fibroblasts (CAFs) are the main stromal cells in the tumor microenvironment (TME). As CAFs promote tumor progression and hypoxia in the TME, regulating the conversion of normal fibroblasts (NFs) into CAFs is essential for improving the prognosis of patients with OSCC. We have previously reported the antitumor effects of transcutaneous carbon dioxide (CO2) application in OSCC. However, the effects of reducing hypoxia in the TME remain unclear. In this study, we investigated whether CO2 administration improves the TME by evaluating CAFs marker expression. Human OSCC cells (HSC-3) and normal human dermal fibroblasts (NHDF) were coinjected subcutaneously into the dorsal region of mice. CO2 gas was applied twice a week for 3 weeks. The tumors were harvested six times after transcutaneous CO2 application. The expression of CAFs markers (α-SMA, FAP, PDPN, and TGF-β) were evaluated by using real-time polymerase chain reaction and immunohistochemical staining. The expression of α-SMA, FAP, PDPN, and TGF-β was significantly increased over time after co-injection. In the CO2-treated group, tumor growth was significantly suppressed after treatment initiation. In addition, the mRNA expression of these markers was significantly inhibited. Furthermore, immunohistochemical staining revealed a significant decrease in the protein expression of all CAFs markers in the CO2-treated group. We confirmed that transcutaneous CO2 application suppressed CAFs marker expression and tumor growth in OSCC xenograft mouse model.

Relationship of Mitochondrial-Related Protein Expression with the Differentiation, Metastasis, and Poor Prognosis of Oral Squamous Cell Carcinoma

Mitochondrial dysfunction and respiratory function changes have been consistently associated with the initiation and progression of cancer. The purpose of this study was to retrospectively investigate the expression of mitochondrial tumor-suppressor and DNA-repair proteins in patients with oral squamous cell carcinoma (OSCC) and to evaluate the relationship between their expression and prognosis. We enrolled 197 patients with OSCC who underwent surgical resection between August 2013 and October 2018. Clinical, pathological, and epidemiological data were retrospectively collected from hospital records. The expression of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), mitochondrial transcription factor A, mitochondrial tumor suppressor gene 1, silent information regulator 3, and 8-hydroxyguanine DNA glycosylase was investigated using immunochemistry. The 3-year disease-specific survival (DSS) rates of patients showing positive expression of all selected proteins were significantly higher than those of patients showing a lack of expression. Multivariate analysis revealed that the expression of PGC-1α (hazard ratio, 4.684) and vascular invasion (hazard ratio, 5.690) can predict the DSS rate (p < 0.001). Low PGC-1α expression and vascular invasion are potential clinically effective predictors of the prognosis of OSCC.

Expression of JCAD and EGFR in Perineurial Cell-Cell Junctions of Human Inferior Alveolar Nerve

Although perineurium has an important role in maintenance of the blood-nerve barrier, understanding of perineurial cell-cell junctions is insufficient. The aim of this study was to analyze the expression of junctional cadherin 5 associated (JCAD) and epidermal growth factor receptor (EGFR) in the perineurium of the human inferior alveolar nerve (IAN) and investigate their roles in perineurial cell-cell junctions using cultured human perineurial cells (HPNCs). In human IAN, JCAD was strongly expressed in endoneurial microvessels. JCAD and EGFR were expressed at various intensities in the perineurium. In HPNCs, JCAD was clearly expressed at cell-cell junctions. EGFR inhibitor AG1478 treatment changed cell morphology and the ratio of JCAD-positive cell-cell contacts of HPNCs. Therefore, JCAD and EGFR may have a role in the regulation of perineurial cell-cell junctions.

Risk factors for pathological fracture in patients with mandibular osteoradionecrosis

Osteoradionecrosis (ORN) often results in pathological fractures through progression. We aimed to identify the risk factors for pathological fracture in patients with mandibular ORN. Seventy-four patients with mandibular ORN were included in this retrospective study. We investigated various risk factors for pathological fracture in patients with mandibular ORN, including number of mandibular teeth with a poor prognosis each at initial evaluation before radiation therapy (RT) and when fracture occurred, and the proportion of antibiotic administration period in a follow-up duration after RT. The rate of occurrence of pathological fractures in patients with mandibular ORN was 25.7%. The median of duration between RT completion and fracture occurrence was 74.0 months. We found that pathological fracture was significantly associated with a larger number of mandibular teeth with a poor prognosis at initial evaluation before RT (P = 0.024) and when fracture occurred (P = 0.009). Especially, a larger number of mandibular teeth with P4 periodontitis, in other words severe periodontal status, was related to pathological fracture in both timings. The proportion of antibiotic administration period in a follow-up duration was also significant risk factor (P = 0.002). Multivariate analyses showed statistically significant associations between pathological fracture and a larger number of mandibular teeth with a poor prognosis when fracture occurred (hazard ratio 3.669). The patient with a larger number of mandibular teeth with P4 periodontitis may have a risk of not only occurrence of ORN but resulting in pathological fracture by accumulation of infection. Surgeons should consider extraction of those teeth regardless of before/after RT if necessary for infection control.

Local application of a transcutaneous carbon dioxide paste prevents excessive scarring and promotes muscle regeneration in a bupivacaine-induced rat model of muscle injury

In postoperative patients with head and neck cancer, scar tissue formation may interfere with the healing process, resulting in incomplete functional recovery and a reduced quality of life. Percutaneous application of carbon dioxide (CO₂ ) has been reported to improve hypoxia, stimulate angiogenesis, and promote fracture repair and muscle damage. However, gaseous CO₂ cannot be applied to the head and neck regions. Previously, we developed a paste that holds non-gaseous CO₂ in a carrier and can be administered transdermally. Here, we investigated whether this paste could prevent excessive scarring and promote muscle regeneration using a bupivacaine-induced rat model of muscle injury. Forty-eight Sprague Dawley rats were randomly assigned to either a control group or a CO₂ group. Both groups underwent surgery to induce muscle injury, but the control group received no treatment, whereas the CO₂ group received the CO₂ paste daily after surgery. Then, samples of the experimental sites were taken on days 3, 7, 14, and 21 post-surgery to examine the following: (1) inflammatory (interleukin [IL]-1β, IL-6), and transforming growth factor (TGF)-β and myogenic (MyoD and myogenin) gene expression by polymerase chain reaction, (2) muscle regeneration with haematoxylin and eosin staining, and (3) MyoD and myogenin protein expression using immunohistochemical staining. Rats in the CO₂ group showed higher MyoD and myogenin expression and lower IL-1β, IL-6, and TGF-β expression than the control rats. In addition, treated rats showed evidence of accelerated muscle regeneration. Our study demonstrated that the CO₂ paste prevents excessive scarring and accelerates muscle regeneration. This action may be exerted through the induction of an artificial Bohr effect, which leads to the upregulation of MyoD and myogenin, and the downregulation of IL-1β, IL-6, and TGF-β. The paste is inexpensive and non-invasive. Thus, it may be the treatment of choice for patients with muscle damage.

Time to Recurrence Associated With Poor Prognosis in Japanese Oral Squamous Cell Carcinoma Patients

Purpose

Recurrence in oral squamous cell carcinoma (OSCC) is not rare. Due to lack of studies assessing characteristics of recurrent OSCC, including time to recurrence and outcomes, we sought to investigate its characteristics, time to recurrence, and outcomes in Japanese OSCC patients.

Methods

This study was a nonrandomized retrospective cohort study in a tertiary referral centre. It included 208 (117 men and 91 women) patients with recurrent oral cancer who underwent major curative surgery in the Department of Oral and Maxillofacial Surgery at Kobe University Hospital between January 1999 and April 2017. The outcomes were disease-specific survival (DSS) and overall survival (OS).

Results

In multivariable Cox proportional hazards analysis, the time to recurrence (hazard ratio [HR] 3.55, 95% confidence interval [CI] 1.69-6.63; P = 0.001), extranodal extension (ENE, HR 2.72, 95% CI 1.51-4.89; P = 0.001), and high T stage (HR 2.00, 95% CI 1.01-3.97; P = 0.046) were independent predictors of DSS. The time to recurrence (HR 3.29, 95% CI 1.82-5.96; P < 0.001) and ENE (HR 2.64, 95% CI 1.52-4.56; P = 0.001) were independent predictors of OS.

Conclusion

Time to recurrence, extranodal extension, and higher T stage were independent prognosis predictors in OSCC.

Exploratory clinical trial to evaluate the efficacy and safety of carbon dioxide paste in healthy people

INTRODUCTION

Scarring and pain are postoperative complications in patients after head and neck cancer treatment; however, there is no effective treatment. These complications are affected by local blood flow disorders, and it is well known that the transcutaneous application of carbon dioxide (CO2) improves local blood flow. Previously, we have shown that the transcutaneous application of carbon dioxide causes absorption of CO2 and increase the oxygen (O2) pressure in the treated tissue; it is expected that the application of CO2 may reduce scarring and pain caused by cancer treatment. We newly introduced the CO2 paste as a new CO2 application method, which does not need to use CO2 gas directly. In this study, we aimed to apply of CO2 paste to healthy people and to investigate its usefulness, safety and feasibility by analysing the increase in blood flow and frequency of adverse events.

METHODS

We applied carbon dioxide paste to skin over the sternocleidomastoid and gastrocnemius muscles of eight healthy volunteers. The changes in blood flow before and after the CO2 paste application using dynamic MRI, and changes in the vital signs were evaluated.

RESULTS

In the neck area and middle layer of the lower leg, the signal intensity (SI) significantly increased 60 seconds after application. In the surface layer of the lower leg, the SI was significantly increased 60 and 300 seconds after paste application. Although mild heat was noted after the paste application, no obvious adverse events occurred.

CONCLUSION

We demonstrated the increase in SI by dynamic MRI at the site of the carbon dioxide paste application, which indicates the paste application is effective in improving the blood flow.

Effect of compression on mandibular fracture haematoma-derived cells

Mechanical stress induces a variety of biochemical and morphological reactions in bone cell biology. This study aimed to investigate appropriate pressures of osteogenesis on the biological responses of 3-dimensional cultured human mandibular fracture haematoma-derived cells by compressive loading. Six patients with mandibular fractures who underwent open reduction and internal fixation were included in the study. During the operation, fracture haematomas that formed fibrin clots were manually removed before irrigation. First, pressures were applied to human mandibular fracture haematoma-derived cell-seeded collagen sponges. The sponges were subjected to mechanical compression using loading equipment applied at no compression, 0.5, or 1 mm. Compressive loading was applied to the samples prior to compression for 0, 6, 12, or 24 hours. Collagen sponge samples were collected for quantification of mRNA using several parameters including alkaline phosphatase (ALP), osteopontin (OPN), osterix (OSX), runt-related gene 2 (RUNX2), protein level, and immunocytochemistry (anti-sclerostin). Among these the 0.5 mm compression group compared with the control and 1.0 mm compression groups upregulated mRNA expression of OPN and OSX after 24 hours. Additionally, compared with the control group, a significantly higher OSX gene expression was observed in both the 0.5 mm and 1.0 mm groups after 6, 12, and 24 hours of compression (p < 0.05). However, no significant differences were observed regarding ALP and RUNX2 expression. These results indicated increased stimulation of osteogenesis of the mandibular fracture-line gap in the 0.5 mm compression group compared with the control and 1.0 mm compression groups.

Factors Associated with Treatment Outcomes and Pathological Features in Patients with Osteoradionecrosis: A Retrospective Study

A standard treatment for osteoradionecrosis (ORN) has not yet been established because of the diversity. Therefore, identifying the risk factors for a poor prognosis is essential. This study retrospectively investigated the factors associated with the prognosis of ORN in 68 patients. Relevant clinical data of all patients were obtained. Of the patients, 16 who underwent extensive surgery underwent histopathological analysis. The necrotic changes of the anterior and posterior margins in the cortical and cancellous bones were investigated. Multivariate analyses showed statistically significant associations between poor prognosis in patients with ORN and high radiation dose (hazard ratio [HR] 1.15), orocutaneous fistula (HR 2.93), and absence of sequestration (HR 2.49). Histopathological analysis showed a viable anterior margin of the middle portion of the cortical bone for all recovered cases; in contrast, most cases (75%) with a poor prognosis showed necrotic changes. The anterior margin of the cancellous bone was viable and resilient to high irradiation, regardless of the prognosis. These results suggest that patients with orocutaneous fistula should receive early surgical intervention, even if the affected area is limited or asymptomatic. In extensive surgery, a sufficient safety margin of necrotic bone, particularly in the anterior region, is required to improve the prognosis.

Local Application of Transcutaneous Carbon Dioxide Paste Decreases Inflammation and Accelerates Wound Healing

INTRODUCTION

 Delayed wound healing after surgery lowers the long-term quality of a patient's life and leads to discomfort and pain. However, treatments for wound healing are often difficult and have not yet been fully established. In this study, we investigated the effect of a special paste that can be administered transdermally and holds a non-gaseous carbon dioxide (CO₂) source in its carrier, which can be applied to the head and neck region for wound healing in a rat skin defect model.

METHODS

Forty-eight Sprague Dawley rats were randomized into control and CO₂ groups. We punched a 6.2-mm wound on the back of each rat. The control rats were left untreated, whereas rats in the CO₂ group were treated with the CO₂ paste every day after surgery. We evaluated wound healing 3, 7, 14, and 21 days after wounding by analyzing the diameter of the wound, gene expression of inflammatory markers vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β, hypoxia-inducible factor (HIF)-1α, interleukin (IL)-1β, and IL-6 using quantitative real-time polymerase chain reaction, hematoxylin and eosin, and immunohistochemical staining patterns.

RESULTS

Rats in the CO₂ group showed accelerated wound healing compared to those in the control group. Furthermore, VEGF and TGF-β were overexpressed, whereas HIF-1α, IL-1β, and IL-6 were downregulated in the rats treated with CO₂. Immunohistochemical analysis also revealed similar patterns of expression.

CONCLUSION

Taken together, the CO₂ paste promoted wound healing by regulating the hypoxic environment, reducing inflammation, and accelerating angiogenesis.

Success of dental implants in patients with large bone defect and analysis of risk factors for implant failure: a non-randomized retrospective cohort study

OBJECTIVES

This study aimed to retrospectively investigate the success and survival rates of dental implants used for dentomaxillary prostheses at our hospital and the risk factors associated with large bone defects.

MATERIALS AND METHODS

A total of 138 external joint system implants used for dentomaxillary prostheses in 40 patients with large bone defects were included in this study. The alveolar bone at the site of implant insertion was evaluated using panoramic radiography and computed tomography. Various risk factors (demographic characteristics, dental status, and operative factors such as the employment of alveolar bone augmentation, the site, the length, and diameter of implants) for implant failure and complete implant loss were investigated using univariate and multivariate analyses. The associations between the variables and the success and survival rates of dental implants were analyzed using the multivariate Cox proportional hazard models.

RESULTS

The 10-year overall success and survival rates were 81.3% and 88.4% in this study. Multivariable analysis showed that the male sex (HR 6.22), shorter implants (≤ 8.5 mm) (HR 5.21), and bone augmentation (HR 2.58) were independent predictors of success rate. Bone augmentation (HR 5.14) and narrow implants (≤ 3.3 mm) (HR 3.86) were independent predictors of the survival rate.

CONCLUSION

Male sex, shorter or narrow implants, and bone augmentation were independent risk factors for dental implants used in dentomaxillary prostheses in patients with large bone defects.

CLINICAL RELEVANCE

Clinicians should consider these risk factors and pay close attention to the management of these patients.

Peripheral facial nerve schwannoma at the inferior mandibular margin: a case report

Schwannomas commonly occur in the head and neck region as acoustic neuromas. Facial nerve schwannomas are rare and usually occur in the temporal region. A 57-year-old woman presented with a mass at the right mandibular margin. Magnetic resonance imaging revealed a schwannoma located immediately caudal to the mental foramen. We were initially uncertain whether it arose from the trigeminal nerve or the facial nerve. Excision was performed under general anesthesia. The mass was encapsulated and easily detached from the surrounding tissue. The nerve of origin was identified proximal to the tumor. A facial nerve origin was confirmed as the muscles supplied by the marginal mandibular branch of the facial nerve moved on nerve stimulation. Nerve fibers were not found distal to the tumor, possibly because they had been cut during excision. We believe that this is the first report of a schwannoma arising from the peripheral facial nerve.

Transcutaneous Carbon Dioxide Decreases Immunosuppressive Factors in Squamous Cell Carcinoma In Vivo

INTRODUCTION

In recent years, the tumour immunosuppressive mechanism has attracted attention as a cause of tumour chemoresistance. Although chemoresistance and immunosuppression of tumours have been reported to be associated with a hypoxic environment, effective treatments to improve hypoxia in tumours have not yet been established. We have previously applied carbon dioxide (CO2) to squamous cell carcinoma and have shown that improvement in local oxygenation has an antitumour effect. However, the effects of local CO2 administration on tumour immunosuppression, chemoresistance, and combination with chemotherapy are unknown. In this study, we investigated the effects of local CO2 administration on squamous cell carcinoma and the effects of combined use with chemotherapy, focusing on the effects on tumour immunosuppressive factors.

METHODS

Human oral squamous cell carcinoma (HSC-3) was transplanted subcutaneously into the back of a nude mouse, and CO2 and cisplatin were administered. After administration twice a week for a total of 4 times, tumours were collected and the expression of tumour immunosuppressive factors (PD-L1, PD-L2, and galectin-9) was evaluated using real-time polymerase chain reaction and immunostaining.

RESULTS

Compared with the control group, a significant decrease in the mRNA expression of PD-L1 was observed in both, CO2-treated and combination groups. Similarly, the expression of PD-L2 and galectin-9 decreased in the CO2-treated and combination groups. Furthermore, immunostaining also showed a significant decrease in the protein expression of tumour immunosuppressive factors in the CO2-treated and combination groups.

CONCLUSION

It was confirmed that the tumour immunosuppressive factors decreased due to local CO2 administration to the mouse model. CO2 administration has the potential to improve the hypoxic environment in tumours, and combined use with chemotherapy may also improve tumour immunosuppression.

A Case Report of Tongue Lymphoepithelial Carcinoma with a Histological Diagnostic Dilemma

Most head and neck lymphoepithelial carcinomas (LECs) arise in the nasopharynx and harbor Epstein–Barr virus (EBV). LEC is also a rare subtype of the oral squamous cell carcinoma (SCC). Morphologically, LEC is defined as resembling non-keratinizing nasopharyngeal carcinoma, undifferentiated subtype. The histological features and pathogenesis of oral LEC are not established. We describe a case of tongue LEC with histopathological diagnostic difficulties. A 72-year-old Japanese female presented with a whitish change on her left-side tongue. The diagnosis was atypical epithelium; neoplastic change could not be ruled out by a biopsy. Although the lesion was monitored at our hospital per her request, invasive carcinoma was detected 11 months later. Microscopically, conventional SCC was observed with the characteristic features as LEC confined to the deep part of the lesion. We briefly discuss this unusual histological finding and make a novel proposal for distinguishing oral LEC from LECs in other regions based on these histological findings.

Occurrence and Treatment Outcome of Late Complications After Free Fibula Flap Reconstruction for Mandibular Osteoradionecrosis

PURPOSE

This study aimed to evaluate the occurrence and treatment outcome of late complications after free fibula osteocutaneous flap reconstruction for mandibular osteoradionecrosis (ORN).

METHODS

We enrolled 15 consecutive patients (14 men, one woman; median age 65 years, range 57-80 years) who underwent free fibula reconstruction for advanced mandibular ORN during 2013-2017 with two or more years of follow-up. Late complications included infection, plate exposure, and recurrence at the resection margin. The effect of perioperative antibiotic administration on late complications was also assessed.

RESULTS

Late complications occurred in 33.3% (5/15) of patients, including two infections (local and distant), two plate exposures, and two recurrences (plate exposure and recurrence occurred in one patient). Perioperative antibiotic administration duration did not significantly affect the occurrence of postoperative late complications. All late complications were treated without problems.

CONCLUSIONS

Late complications after ORN reconstructive surgery are not uncommon, but can be treated properly.

The prospective evaluation and risk factors of dysphagia after surgery in patients with oral cancer

Background

This prospective study investigated the change of swallowing ability using the Swallowing Ability Scale System (SASS) and swallowing-related quality of life (QOL) by Performance Status Scale for Head and Neck Cancer patients (PSS-H&N). This study also investigated the risk factors for postoperative dysphagia in patients who received reconstructive surgery for oral cancer.

Subjects and Methods

This study included 64 patients (33 men and 31 women) who underwent radical surgery with neck dissection and reconstructive surgery for oral cancers between July 2014 and February 2018. We evaluated risk factors for poor swallowing ability after treatment, including demographic factors, preoperative factors and perioperative factors, with univariate and multivariate analyses. The change of swallowing ability by the SASS and swallowing-related QOL by PSS-H&N were evaluated prospectively prior to the initiation of surgery within 1 week and at 1 and 3 months after treatment.

Results

Advanced T stage (T3, 4) (odds ratio (OR) = 79.71), bilateral neck dissection (OR = 20.66) and the resection of unilateral or bilateral suprahyoid muscles (OR = 17.00) were associated with poor swallowing ability after treatment. The scores for time for food intake and Eating in Public were associated with decrease of QOL in the poor group.

Conclusions

We propose that clinicians consider the risk factors identified in this study and pay close attention to the management of oral cancer patients with reconstructive surgery.

Graphical abstract

Can CT predict the development of oroantral fistula in patients undergoing maxillary third molar removal?

PURPOSE

In maxillary wisdom tooth extraction, the necessity of CT is unknown. The purpose of this study was to investigate whether CT adding to orthopantomography is useful for predicting oroantral perforation during maxillary third molar extraction.

METHODS

Various risk factors for oroantral perforation during maxillary third molar extraction were investigated by univariate and multivariate analyses. We analyzed those of all patients and the patients who underwent CT, respectively. The proximity of the roots to the maxillary sinus floor (root-sinus [RS] classification) and Archer classification were assessed using panoramic radiography. The number of roots and vertical relationship were assessed using CT.

RESULTS

A total of 604 out of 3299 patients underwent CT adding to orthopantomography. In all cases, multivariate analyses except for CT findings showed that the RS classification type III/IV and the Archer classification Type B/C/D in panoramic findings were significantly correlated with oroantral perforation as radiological findings. In cases for which CT was performed, multivariate analyses showed that one root (OR 12.87) and the vertical relationship Type D (OR 5.63) in CT findings, besides the RS classification type III/IV (OR 4.47) in panoramic findings, were significantly related to oroantral perforation.

CONCLUSION

The RS classification and the Archer classification in panoramic findings can predict the risk of oroantral perforation. The usefulness of CT adding to orthopantomography is limited. However, when the relationship between the upper wisdom tooth and maxillary sinus floor (RS classification) is unclear, to check whether the number of roots is one and the apex of one root is projecting into the maxillary sinus in CT findings, is useful for the prediction.

Neutrophil-lymphocyte ratio associated with poor prognosis in oral cancer: a retrospective study

Background

Prognostic biomarkers provide essential information about a patient’s overall outcome. However, existing biomarkers are limited in terms of either sample collection, such as requiring tissue specimens, or the process, such as prolonged time for analysis. In view of the need for convenient and non-invasive prognostic biomarkers for oral cancer, we aimed to investigate the prognostic values of neutrophil-to-lymphocyte ratio, lymphocyte-to-monocyte ratio, and platelet-to-lymphocyte ratio in patient survival. We also aimed to explore the associations of these ratios with the clinicopathologic characteristics of Japanese oral squamous cell carcinoma patients.

Methods

This study was a non-randomized retrospective cohort study in a tertiary referral center. We included 433 patients (246 men, 187 women) who underwent radical surgery for oral cancers between January 2001 and December 2013. We evaluated various risk factors for poor prognosis including neutrophil-to-lymphocyte ratio, lymphocyte-to-monocyte ratio, and platelet-to-lymphocyte ratio with univariate and multivariate analyses. The disease-specific survival and overall survival rates of patients were compared among the factors and biomarkers.

Results

In multivariable Cox proportional hazards analysis, high neutrophil-to-lymphocyte ratio (hazard ratio 2.87, 95% confidence interval 1.59–5.19, P <  0.001), moderately or poorly differentiated histology (hazard ratio 2.37, 95% confidence interval 1.32–4.25, P <  0.001), and extranodal extension (hazard ratio 1.95, 95% confidence interval 1.13–3.35, P = 0.016) were independent predictors of disease-specific survival. High neutrophil-to-lymphocyte ratio (hazard ratio 2.30, 95% confidence interval 1.42–3.72, P <  0.001), moderately or poorly differentiated (hazard ratio 1.72, 95% confidence interval 1.07–2.76, P = 0.025), and extranodal extension (hazard ratio 1.79, 95% confidence interval 1.13–2.84, P = 0.013) were independent predictors of overall survival.

Conclusions

Neutrophil-to-lymphocyte ratio might be a potential independent prognostic factor in Japanese oral squamous cell carcinoma patients.

Effect of low-intensity pulsed ultrasound after intraoral vertical ramus osteotomy

OBJECTIVE

The present study investigated the effect of low-intensity pulsed ultrasound (LIPUS) on long-term osseous healing of the cleavage space between bone fragments after intraoral vertical ramus osteotomy (IVRO).

STUDY DESIGN

Patients undergoing IVRO were randomly assigned to the LIPUS group (n = 12) or the control group (n = 9) after surgery. LIPUS treatments were applied daily to the cleavage space between bone fragments for 3 weeks. We observed 3-dimensional quantitative color mapping of the whole mandible created by computed tomography (CT) data at 1 month, 6 months, and 1 year postoperatively. On the basis of CT values, the color grades were classified as D1 to D5 by using the Misch criteria. We then calculated mean CT values and rated each color grade in different selection ranges.

RESULTS

The mean CT values of the LIPUS group were significantly higher than those of the control group at 1 month, 6 months and 1 year postoperatively (P < .01). The color grades of the cleavage between bone fragments increased from D5 to D1 over time.

CONCLUSIONS

Our results indicated that LIPUS promoted osseous healing after IVRO, thus improving bone density and offering clinical benefits.

A radiologic evaluation of the incidence and morphology of maxillary sinus septa in Japanese dentate maxillae

PURPOSE

Evaluation of the inner aspect of the maxillary sinus is important for the success of a sinus lift procedure. The most common surgical complication is perforation of the Schneiderian membrane, which is thought to occur because of the presence of maxillary sinus septa. Therefore, we retrospectively investigated the incidence and morphology of maxillary sinus septa using multiplanar reformatted computed tomographic (CT) images from dentate Japanese patients.

METHODS

A total of 276 patients and 552 maxillary sinus segments were evaluated. The maxillary sinus septa were divided into four locations: forefront, anterior, middle, and posterior. The heights of the septa were measured at three sites from the deepest point of the sinus floor: lateral, mid-point, and medial.

RESULTS

Sinus septa were identified in 191 of 552 (34.6%) maxillary sinus segments obtained from 111 of 276 (40.2%) patients. One unilateral septum was most commonly detected, and the sinus septa were most often located in the middle of the maxillary sinus. The average height of the identified septa was 8.69 ± 4.68 mm (mean ± standard deviation).

CONCLUSION

Multiplanar reformatted CT images can identify maxillary sinus septa in any plane. The height of maxillary sinus septa in the dentate maxillae was higher than detected in previous studies. Appropriate treatment planning using CT images should be considered to prevent surgical complications.

Induced Pluripotent Stem Cell-related Genes Correlate With Poor Prognoses of Oral Squamous Cell Carcinoma

BACKGROUND/AIM

We recently investigated the contribution of the iPS-related genes SOX2, OCT4, and Nanog to de-differentiation by assaying for their mRNA levels. Given that mRNA expression does not always correlate with the protein levels, the aim of this study was to retrospectively determine the expression of these four iPS-related factors in human OSCC specimens by immunohistochemistry and examine their association with patient prognosis.

MATERIALS AND METHODS

iPS cell-related gene expression in 89 OSCC patients by tissue microarray, and its correlation with clinicopathological factors, differentiation, metastasis, and poor prognoses were investigated.

RESULTS

No evidence of statistically significant relationships was found between the expression of iPS cell-related genes and clinicopathological parameters. However, our data indicated that KLF4 expression was associated with survival, and poor tumor differentiation. In addition, high expression of KLF4 was an independent poor prognostic factor (p=0.004) for OSCC patients.

CONCLUSION

In preoperative biopsies, higher KLF4 and poor differentiation may be clinically effective predictors for the prognosis of oral cancer.

A literature review of perioperative antibiotic administration in surgery for medication-related osteonecrosis of the jaw

PURPOSE

Few studies exist that focus on the details of perioperative antibiotic administration for surgery to treat medication-related osteonecrosis of the jaw (MRONJ). The regime and duration of perioperative antibiotics applied in published studies were reviewed to clarify appropriate perioperative antibiotic use in MRONJ surgery.

METHODS

A literature search was conducted using the MEDLINE database via PubMed.

RESULTS

The search resulted in 453 hits on PubMed. After reading the downloaded full-text articles, 17 articles met the inclusion and exclusion criteria. The most common perioperative antibiotic used for MRONJ surgery was a combination of penicillin-based antibiotics and β-lactamase inhibitor (52.9%), and the second most common regime was penicillin-based antibiotics with metronidazole (17.6%). The duration of administration was 2 weeks postoperatively in nine studies, whereas four studies applied long-term administration (2-6 weeks postoperatively).

CONCLUSIONS

Oral and maxillofacial surgeons mostly prefer penicillin-based antibiotics plus β-lactamase inhibitor or metronidazole for MRONJ surgery. The duration of administration of these medications may be based on empirical experience.

Effect of local application of transcutaneous carbon dioxide on survival of random-pattern skin flaps

INTRODUCTION

Skin flap procedures are widely used to reconstruct skin and soft tissue defects. Skin flap necrosis is a serious postoperative complication. Many researchers have introduced pharmacological agents to improve flap ischemia in experimental studies. However, outcomes of these studies remain controversial. We previously demonstrated that transcutaneous CO₂ application improves hypoxia in fracture repair. In this study, we hypothesized that improving hypoxia by transcutaneous CO₂ application can improve the blood flow in skin flaps and increase angiogenesis. We investigated whether transcutaneous CO₂ application can increase the survival of random-pattern skin flaps.

MATERIALS AND METHODS

Six-week-old male Sprague-Dawley rats were divided into two equal groups: the control group (n = 6) and CO₂ group (n = 6). A random-pattern skin flap was constructed in these rats. Topical CO₂ was applied using a hydrogel every day for 5 days in the CO₂ group. The flap survival area was measured on postoperative days 1, 3, and 5. The vessel density and expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and hypoxia-inducible factor-1α (HIF-1α) were evaluated on postoperative day 5.

RESULTS

A statistically significant difference was found in the percentage of the flap survival area between the two groups on postoperative days 3 and 5 (p < 0.05). Furthermore, the expression of VEGF and bFGF was significantly higher and that of HIF-1α was significantly lower in the CO₂ than in the control group (p < 0.05).

CONCLUSIONS

Transcutaneous CO₂ application can improve the blood flow in skin flaps and increase angiogenesis, thus increasing the survival of random-pattern skin flaps.

Transcutaneous carbon dioxide enhances the antitumor effect of radiotherapy on oral squamous cell carcinoma

Radiotherapy (RT) is one of the main treatment modalities for oral squamous cell carcinoma (OSCC), however, radioresistance is a major impediment to its clinical success and poses as a concern that needs to be addressed. Tumor hypoxia is known to be significantly associated with radioresistance in various malignancies, hence, resolving the hypoxic state of a tumor may improve the antitumor effect of RT on OSCC. We have previously revealed that transcutaneous CO2 induced mitochondrial apoptosis and suppressed tumor growth in OSCC by resolving hypoxia. Considering the previous study, we hypothesized that transcutaneous CO2 may enhance the antitumor effect of RT on OSCC by improving intratumoral hypoxia, thereby overcoming radioresistance. In the present study, the combination of transcutaneous CO2 and RT significantly inhibited tumor growth compared with other treatments. This combination therapy also led to decreased expression of HIF-1α in parallel with increased expression of the cleaved forms of caspase-3-8-9 and PARP, which play essential roles in mitochondrial apoptosis. Additionally, the combination therapy increased the expression of ROS modulator 1 and subsequent mitochondrial ROS production, compared to RT alone. These results indicated that transcutaneous CO2 could potentially improve the antitumor effect of RT by decreasing the intratumoral hypoxia and increasing the mitochondrial apoptosis. Our findings indicated that CO2 therapy may be a novel adjuvant therapy in combination with RT for OSCC.

Differences between osteoradionecrosis and medication-related osteonecrosis of the jaw

PURPOSE

The appearance of osteoradionecrosis (ORN) and medication-related osteonecrosis of the jaw (MRONJ) is similar, but clinically important differences between ORN and MRONJ exist. The aim of this study was to compare the clinical data between ORN and MRONJ and to reveal the critical differences between these diseases.

METHODS

We retrospectively reviewed the epidemiological data, clinical findings, and treatment in 27 ORN and 61 MRONJ patients. Radiographic signs before the initiation of treatment were also assessed.

RESULTS

The median age (P = 0.0474) and the ratio of female to male patients (P < 0.0001) were significantly higher in MRONJ patients. There were significantly more MRONJ patients who reported a history of pain when compared with ORN patients (P = 0.0263). As an aetiological factor, tooth extraction was significantly more relevant to MRONJ than ORN (P = 0.0352). When assessing the radiographic signs on computed tomographic images, periosteal reaction was found only in MRONJ patients (P = 0.0158). Minimal debridement was performed significantly more frequently for MRONJ (P = 0.0093), and by contrast, surgical resection was performed more frequently for ORN (P = 0.0002).

CONCLUSIONS

Understanding the clinical and underlying pathological differences between ORN and MRONJ probably contributes to the selection of appropriate treatment for each patient.

A multicenter retrospective study of the risk factors associated with medication-related osteonecrosis of the jaw after tooth extraction in patients receiving oral bisphosphonate therapy: can primary wound closure and a drug holiday really prevent MRONJ?

Root amputation, extraction of a single tooth, bone loss or severe tooth mobility, and an unclosed wound were significantly associated with increased risk of developing medication-related osteonecrosis of the jaw (MRONJ). We recommend a minimally traumatic extraction technique, removal of any bone edges, and mucosal wound closure as standard procedures in patients receiving bisphosphonates.

INTRODUCTION

Osteonecrosis of the jaws can occur following tooth extraction in patients receiving bisphosphonate drugs. Various strategies for minimizing the risk of MRONJ have been advanced, but no studies have comprehensively analyzed the efficacy of factors such as primary wound closure, demographics, and drug holidays in reducing its incidence. The purpose of this study was to retrospectively investigate the relationships between these various risk factors after tooth extraction in patients receiving oral bisphosphonate therapy.

METHODS

Risk factors for MRONJ after tooth extraction were evaluated using univariate and multivariate analysis. All patients were investigated with regard to demographics; type and duration of oral bisphosphonate use; whether they underwent a discontinuation of oral bisphosphonates before tooth extraction (drug holiday), and the duration of such discontinuation; and whether any additional surgical procedures (e.g., incision, removal of bone edges, root amputation) were performed.

RESULTS

We found that root amputation (OR = 6.64), extraction of a single tooth (OR = 3.70), bone loss or severe tooth mobility (OR = 3.60), and an unclosed wound (OR = 2.51) were significantly associated with increased risk of developing MRONJ.

CONCLUSIONS

We recommend a minimally traumatic extraction technique, removal of any bone edges, and mucosal wound closure as standard procedures in patients receiving bisphosphonates. We find no evidence supporting the efficacy of a pre-extraction short-term drug holiday from oral bisphosphonates in reducing the risk of MRONJ.

Induced Pluripotent-stem-cell Related Genes Contribute to De-differentiation in Oral Squamous Cell Carcinoma

BACKGROUND/AIM

Cancer stem cells are suspected to contribute to malignancy in tumors. Hypoxia affects cell differentiation and induces stem-cell-like characteristics in malignancies. Induced pluripotency was demonstrated in mouse fibroblasts by reprogramming with four transcriptional factors: Oct3/4, Sox2, c-Myc, and Klf4. Conversely, oncogenic transformations frequently express transcriptional factors and Nanog. Therefore, cancer cells present some similarities with induced pluripotent stem (iPS) cells.

MATERIALS AND METHODS

We investigated the expression of iPS-related genes in vitro and in clinical samples to identify their relationships with hypoxia and tumorigenesis.

RESULTS

Oral squamous cell carcinoma (SCC) cells were used to show that expression levels of Oct3/4, Sox2, and Nanog were significantly increased in hypoxic condition in vitro and in moderately- and poorly-differentiated samples.

CONCLUSION

We propose that Oct3/4, Sox2 and Nanog are associated with tumor hypoxia characterized in oral SCC and that these factors may also contribute to the undifferentiated potency observed in oral SCC clinically.

Upregulated Expression of Transient Receptor Potential Cation Channel Subfamily V Receptors in Mucosae of Patients with Oral Squamous Cell Carcinoma and Patients with a History of Alcohol Consumption or Smoking

Objectives

Transient receptor potential cation channel (subfamily V, members 1–4) (TRPV1–4) are expressed in skin and neurons and activated by external stimuli in normal mucosae of all oral cavity sites. The oral cavity is exposed to various stimuli, including temperature, mechanical stimuli, chemical substances, and changes in pH, and, notably, the risk factors for oncogenic transformation in oral squamous epithelium are the same as the external stimuli received by TRPV1–4 receptors. Hence, we examined the relationship between oral squamous cell carcinoma (SCC) and TRPV1–4 expression.

Materials and Methods

Oral SCC patients (n = 37) who underwent surgical resection were included in this study. We investigated the expression of TRPV1–4 by immunohistochemical staining and quantification of TRPV1–4 mRNA in human oral mucosa. In addition, we compared the TRPV1–4 levels in mucosa from patients with SCC to those in normal oral mucosa.

Results

The receptors were expressed in oral mucosa at all sites (tongue, buccal mucosa, gingiva, and oral floor) and the expression was stronger in epithelia from patients with SCC than in normal epithelia. Furthermore, alcohol consumption and tobacco use were strongly associated with the occurrence of oral cancer and were found to have a remarkable influence on TRPV1–4 receptor expression in normal oral mucosa. In particular, patients with a history of alcohol consumption demonstrated significantly higher expression levels.

Conclusion

Various external stimuli may influence the behavior of cancer cells. Overexpression of TRPV1-4 is likely to be a factor in enhanced sensitivity to external stimuli. These findings could contribute to the establishment of novel strategies for cancer therapy or prevention.

Risk factors associated with oroantral perforation during surgical removal of maxillary third molar teeth

PURPOSE

The relationship between radiographic findings and the occurrence of oroantral perforation is controversial. Few studies have quantitatively analyzed the risk factors contributing to oroantral perforation, and no study has reported multivariate analysis of the relationship(s) between these various factors. This retrospective study aims to fill this void.

METHODS

Various risk factors for oroantral perforation during maxillary third molar extraction were investigated by univariate and multivariate analysis. The proximity of the roots to the maxillary sinus floor (root-sinus [RS] classification) was assessed using panoramic radiography and classified as types 1-5. The relationship between the maxillary second and third molars was classified according to a modified version of the Archer classification. The relative depth of the maxillary third molar in the bone was classified as class A-C, and its angulation relative to the long axis of the second molar was also recorded.

RESULTS

Performance of an incision (OR 5.16), mesioangular tooth angulation (OR 6.05), and type 3 RS classification (i.e., significant superimposition of the roots of all posterior maxillary teeth with the sinus floor; OR 10.18) were all identified as risk factors with significant association to an outcome of oroantral perforation.

CONCLUSION

To our knowledge, this is the first multivariate analysis of the risk factors for oroantral perforation during surgical extraction of the maxillary third molar. This RS classification may offer a new predictive parameter for estimating the risk of oroantral perforation.

Generation of camelid VHH bispecific constructs via in-cell intein-mediated protein trans-splicing

Production of various combinations of bispecific variable domain of heavy chain of heavy chain-only antibody (VHH) constructs to evaluate their therapeutic potential usually requires several gene-engineering steps. Here, we present an alternative method of creating bispecific VHH constructs in vivo through protein trans-splicing (PTS) reaction; this method may reduce the number of gene manipulation steps required. As a proof-of-concept, we constructed a bispecific antibody (bsAb) containing an anti-epidermal growth factor receptor VHH and anti-green fluorescent protein VHH, and we evaluated and confirmed its bispecificity. We also tested antibody labeling by fluorescent protein tagging using the PTS reaction. Compared with the conventional gene construction method, bsAb construction via PTS is a promising alternative approach for generating multiple bsAb combinations.

Survival of Brånemark System Mk III implants and analysis of risk factors associated with implant failure

The purpose of this study was to retrospectively investigate the outcomes of Brånemark System Mk III TiUnite/Groovy implants placed in patients at Kobe University Hospital. Various risk factors for implant failure, including mechanical coupling, were investigated by univariate and multivariate analysis. The predictive variables investigated included age, sex, smoking habit, general health, history of radiation therapy, application of a dentomaxillary prosthesis, type of prosthesis, use of alveolar bone augmentation, site of implant insertion, mechanical coupling between implants, and the length and diameter of the implants. Of the 907 implants investigated, only 23 were unsuccessful; the overall survival rate was 96.7%. Increased age, radiation therapy, application of a removable prosthesis or dentomaxillary prosthesis, lack of mechanical coupling between implants, and shorter implants (≤8.5mm) were significant risk factors for implant failure according to univariate analysis (P<0.05). Multivariate analysis identified a significant association (P<0.05) between dental implant failure and a lack of mechanical coupling between implants (odds ratio 6.88) and shorter implants (≤8.5mm) (odds ratio 3.43). The findings of this study demonstrated multivariate relationships between various risk factors and dental implant failure.

Prognosis of oral squamous cell carcinoma patients with level IV/V metastasis: An observational study

PURPOSE

The objectives of this study were to retrospectively describe the characteristics and outcomes of patients with oral squamous cell carcinoma (OSCC) with level IV/V metastases, and to evaluate the multivariate relationships among potential risk factors for metastasis and prognosis.

MATERIALS AND METHODS

We evaluated 291 patients (178 men and 113 women; mean age, 65.9 ± 13.5 years). Clinicopathological data, time of development of level IV/V metastases, and clinical course were investigated.

RESULTS

Twenty-three patients (7.9%) developed level IV/V metastases. The 3-year overall survival rates when level IV/V metastasis first developed were 27.3% upon initial treatment, 57.1% when metachronous neck metastasis developed, and 40.0% when the tumor recurred. Oral tongue tumor subsite, high N staging, neck dissection when metachronous neck metastasis developed, as well as recurrence were independent risk factors for level IV/V metastasis.

CONCLUSION

We demonstrate here the multivariate relationships among the risk factors indicated above for level IV/V metastasis and their prognostic significance for patients with OSCC. Oral tongue tumors, high N staging, and neck dissection upon the occurrence of metachronous neck metastasis or recurrence were risk factors for level IV/V metastasis and positive extracapsular spread, presence of multiple lymph metastases, and moderate or poor differentiation were poor prognostic factors.

Erosion and sedimentation during the September 2015 flooding of the Kinu River, central Japan

Erosional and sedimentary features associated with flooding have been documented in both modern and past cases. However, only a few studies have demonstrated the relationship between these features and the corresponding hydraulic conditions that produced them, making it difficult to evaluate the magnitude of paleo-flooding. This study describes the characteristics associated with inundation depth and flow direction, as well as the erosional and sedimentary features resulting from the disastrous flooding of the Kinu River, central Japan, in September 2015. Water levels rose rapidly due to heavy rainfall that eventually overtopped, and subsequently breached, a levee in Joso City, causing destructive flooding on the surrounding floodplain. Distinctive erosional features are found next to the breached levee, while depositional features, such as a sandy crevasse-splay deposit are found further away from the breach. The deposit can be divided into three units based on sedimentary facies. The vertical and lateral changes of these sedimentary facies may be the result of temporal and spatial changes associated with flow during the single flooding event. These observations and quantitative data provide information that can be used to reveal the paleohydrology of flood deposits in the stratigraphic record, leading to improved mitigation of future flooding disasters.

Decreased mitochondrial copy numbers in oral squamous cell carcinoma

BACKGROUND

Mitochondrial dysfunction and altered respiration have long been suspected to affect the development and progression of cancer. Although quantitative changes in mitochondrial DNA (mtDNA) have been reported in head and neck squamous cell carcinoma (SCC), differences in mtDNA copy numbers between normal and cancerous tissues from same patients have not been assessed.

METHODS

We compared mtDNA copy numbers and expressions of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) and mitochondrial transcription factor A (TFAM) between normal mucous membrane and cancerous tissues resected from 35 patients with oral SCC, using TaqMan quantitative real-time polymerase chain reaction (PCR) and immunohistochemical staining.

RESULTS

We found mtDNA copy numbers and expressions of PGC-1α and TFAM were decreased in cancerous tissues compared with normal tissues from the same patients.

CONCLUSION

The PGC-1α-TFAM mitochondrial pathway may be associated with malignant potential in human oral SCC, and could be an attractive therapeutic target. © 2016 Wiley Periodicals, Inc. Head Neck 38:1170-1175, 2016.

Transcutaneous carbon dioxide suppresses epithelial-mesenchymal transition in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common form of oral cancers. Recent studies have shown that the malignant transformation of various carcinomas, including OSCC, is associated with epithelial-mesenchymal transition (EMT), and that expression of the EMT factors are significantly associated with tumor invasion, tumor metastasis, and survival rates in OSCC patients. Hence, there is a possibility that EMT suppression may improve the prognosis of OSCC patients. Hypoxia inducible factor-1α (HIF-1α) is a crucial microenvironmental factor in tumor progression, which induces the expression of EMT factors. We previously reported that transcutaneous CO2 suppresses both human OSCC tumor growth and metastasis to the regional lymph nodes by improving hypoxia in treated tissue. According to this background, we hypothesized that increased EMT with HIF-1α expression may increase the progression and the metastatic potential of OSCC, and that decreased hypoxia by transcutaneous CO2 could suppress EMT. In the present study, in vitro studies showed that hypoxic conditions increased the expression of HIF-1α and EMT factors in OSCC cells. In addition, in vivo studies revealed that transcutaneous CO2 increased E-cadherin expression with the decreased expression of HIF-1α, Snail, Slug, N-cadherin, and Vimentin in tumor treatment. These results suggest that transcutaneous CO2 could suppress EMT by improving hypoxia, resulting in the reduction of metastatic potential of OSCC. The findings indicate that transcutaneous CO2 may be able to improve the prognosis of OSCC patients through the suppression of EMT.

Yeast Interspecies Comparative Proteomics Reveals Divergence in Expression Profiles and Provides Insights into Proteome Resource Allocation and Evolutionary Roles of Gene Duplication

Omics analysis is a versatile approach for understanding the conservation and diversity of molecular systems across multiple taxa. In this study, we compared the proteome expression profiles of four yeast species (Saccharomyces cerevisiae, Saccharomyces mikatae, Kluyveromyces waltii, and Kluyveromyces lactis) grown on glucose- or glycerol-containing media. Conserved expression changes across all species were observed only for a small proportion of all proteins differentially expressed between the two growth conditions. Two Kluyveromyces species, both of which exhibited a high growth rate on glycerol, a nonfermentative carbon source, showed distinct species-specific expression profiles. In K. waltii grown on glycerol, proteins involved in the glyoxylate cycle and gluconeogenesis were expressed in high abundance. In K. lactis grown on glycerol, the expression of glycolytic and ethanol metabolic enzymes was unexpectedly low, whereas proteins involved in cytoplasmic translation, including ribosomal proteins and elongation factors, were highly expressed. These marked differences in the types of predominantly expressed proteins suggest that K. lactis optimizes the balance of proteome resource allocation between metabolism and protein synthesis giving priority to cellular growth. In S. cerevisiae, about 450 duplicate gene pairs were retained after whole-genome duplication. Intriguingly, we found that in the case of duplicates with conserved sequences, the total abundance of proteins encoded by a duplicate pair in S. cerevisiae was similar to that of protein encoded by nonduplicated ortholog in Kluyveromyces yeast. Given the frequency of haploinsufficiency, this observation suggests that conserved duplicate genes, even though minor cases of retained duplicates, do not exhibit a dosage effect in yeast, except for ribosomal proteins. Thus, comparative proteomic analyses across multiple species may reveal not only species-specific characteristics of metabolic processes under nonoptimal culture conditions but also provide valuable insights into intriguing biological principles, including the balance of proteome resource allocation and the role of gene duplication in evolutionary history.

Risk factors associated with postoperative delirium after surgery for oral cancer

OBJECTIVE

The purpose of this study was to retrospectively investigate the multivariate relationships among the various risk factors for postoperative delirium in patients undergoing oral cancer surgery.

MATERIAL AND METHODS

The medical records of all patients with oral cancer who underwent curative head and neck surgery between April 2011 and March 2013 at our institution were retrospectively reviewed. There was a total of 188 patients, including 110 males and 78 females.

RESULTS

We found that older age, extensive surgical procedure, longer operation, excessive hemorrhage, blood transfusion, longer postoperative management in the intensive care unit, longer postoperative hospital stay, lower albumin level in the preoperative blood test, and lower total protein, albumi, n and hemoglobin levels and a higher C-reactive protein (CRP) level in the postoperative blood tests were significant variables in the univariate analysis (p < 0.05). We also determined that an older age (odds ratio [OR] = 6.83), intraoperative lower hemoglobin levels (OR = 6.82), and excessive hemorrhage (OR = 3.62) during surgery were significant variables in the multivariate analysis.

CONCLUSION

Clinicians should pay special attention to preventing delirium during the postoperative management of older patients with these risk factors. Furthermore, increasing the hemoglobin levels during surgery may be able to prevent postoperative delirium.