Changes in salivary microbiota due to gastric cancer resection and its relation to gastric fluid microbiota.

Gastric cancer is one of the leading causes of death worldwide, and resections are performed to cure the disease. We have previously reported the changes in the gastric microbiota after gastric cancer resection, which may be associated with the oral microbiota; however, the changes in the oral microbiota remain uncharacterized. This study aimed to characterize the changes in the salivary microbiota caused by gastric cancer resection and to evaluate their association with the gastric fluid microbiota. Saliva and gastric fluid samples were collected from 63 patients who underwent gastrectomy before and after surgery, and a 16S rRNA metagenomic analysis was performed to compare the microbiota composition. The number of bacterial species in the salivary microbiota decreased, and the bacterial composition changed after the resection of gastric cancer. In addition, we identified several bacterial genera that varied significantly in the salivary microbiota, some of which also showed similar changes in the gastric fluid microbiota. These findings indicate that changes in the gastric environment affect the oral microbiota, emphasizing the close association between the oral and gastric fluid microbiota. Our study signifies the importance of focusing on the oral microbiota in the perioperative period of gastrectomy in patients with gastric cancer.

Characterization of Oral Microbiota Following Chemotherapy in Patients With Hematopoietic Malignancies.

Oral microbiota may be associated with serious local or systemic medical conditions resulting from chemotherapy. This study was conducted to evaluate the changes in the oral microbiota following the initiation of chemotherapy in patients with hematopoietic malignancies and to identify the characteristics of the oral microbiota associated with oral mucositis. Oral samples were collected from 57 patients with hematopoietic malignancies at 2 time points: before the start of chemotherapy and 8 to 20 days after the start of chemotherapy, when chemotherapy-induced oral mucositis often occurs, and 16S rRNA metagenomic analyses were performed. Comparative and linear discriminant analysis effect size (LEfSe) analyses were used to determine the characteristic bacterial groups before and after the initiation of chemotherapy and in those who developed oral mucositis. The alpha and beta diversities of oral microbiota before and after the initiation of chemotherapy differed significantly (operational taxonomic unit index, P < .001; Shannon's index, P < .001; unweighted UniFrac distances, P = .001; and weighted UniFrac distances, P = .001). The LEfSe analysis revealed a group of bacteria whose abundance differed significantly before and after the initiation of chemotherapy. In the group of patients who developed oral mucositis, a characteristic group of bacteria was identified before the start of chemotherapy. In conclusion, we characterized the oral microbiota associated with the initiation of chemotherapy in patients with hematopoietic malignancies. In addition, our findings suggest that oral microbiota composition before the start of chemotherapy may be associated with oral mucositis. The results of this study emphasize the importance of oral management focusing on the oral microbiota during chemotherapy in patients with hematologic malignancies.

Salivary Microbiota Associated with Peripheral Microvascular Endothelial Dysfunction.

AIMS: Oral health is associated with atherosclerotic cardiovascular disease (ACVD). We previously identified the salivary microbiota characteristics of patients with ACVD. However, whether salivary microbiota is characteristic under impaired vascular endothelial function before ACVD onset remains unclear. Therefore, we aimed to evaluate the characteristics of salivary microbiota associated with peripheral microvascular endothelial dysfunction. METHODS: We collected saliva samples from 172 community-dwelling elderly individuals without a history of ACVD and performed 16S rRNA metagenomic analysis. We assessed the peripheral microvascular endothelial function using reactive hyperemia index (RHI) and compared the salivary microbiota in the groups with normal (RHI ≥ 2.10), borderline, and abnormal (RHI ＜1.67) peripheral endothelial function. Furthermore, we applied machine learning techniques to evaluate whether salivary microbiota could discriminate between individuals with normal and abnormal endothelial function. RESULTS: The number of operational taxonomic units (OTUs) was higher in the abnormal group than in the normal group (p=0.037), and differences were found in the overall salivary microbiota structure (unweighted UniFrac distances, p=0.038). The linear discriminant analysis (LDA) effect size (LEfSe) algorithm revealed several significantly differentially abundant bacterial genera between the two groups. An Extra Trees classifier model was built to discriminate between groups with normal and abnormal vascular endothelial function based on the microbial composition at the genus level (AUC=0.810). CONCLUSIONS: The salivary microbiota in individuals with endothelial dysfunction was distinct from that in individuals with normal endothelial function, indicating that the salivary microbiota may be related to endothelial function.

Comparison of the gastric microbiome in Billroth I and Roux-en-Y reconstructions after distal gastrectomy.

The changes in gastric microbiota following reconstruction after gastrectomy have not been reported. This study aimed to compare the gastric microbiota following Billroth I and Roux-en-Y reconstructions after distal gastrectomy. We enrolled 71 gastrectomized patients with gastric cancer; 31 and 40 underwent Billroth I and Roux-en-Y reconstructions, respectively. During upper gastrointestinal endoscopy, gastric fluid was collected immediately before and 6 months after distal gastrectomy. Deoxyribonucleic acid isolated from each sample was evaluated using 16S ribosomal ribonucleic acid metagenomic analysis. Analysis revealed that the gastric microbiota's species richness (expressed as the alpha diversity) was significantly lower after than before distal gastrectomy (operational taxonomic units, p = 0.001; Shannon index, p = 0.03). The interindividual diversity (beta diversity) was significantly different before and after distal gastrectomy (unweighted UniFrac distances, p = 0.04; weighted UniFrac distances, p = 0.001; Bray-Curtis, p = 0.001). Alpha and beta diversity were not significantly different between Billroth I and Roux-en-Y reconstructions (observed operational taxonomic units, p = 0.58; Shannon index, p = 0.95; unweighted UniFrac distances, p = 0.65; weighted UniFrac distances, p = 0.67; Bray-Curtis, p = 0.63). Our study demonstrated significant differences in gastric microbiota diversity, composition, and community before and after distal gastrectomy but no difference between Billroth I and Roux-en-Y reconstruction after distal gastrectomy.

Characterization of Salivary Microbiota in Patients with Atherosclerotic Cardiovascular Disease: A Case-Control Study.

AIMS: Oral bacteria have been reported to be associated with the pathogenesis of atherosclerosis; however, the relationship between the oral microbiota and atherosclerosis remains unclear. The present study aimed to investigate whether or not salivary microbiota of patients with atherosclerotic cardiovascular disease (ACVD) differs from that of subjects without ACVD, and to characterize the salivary microbiota of patients with ACVD. METHODS: This study included 43 patients with ACVD and 86 age- and sex-matched non-ACVD individuals. 16S rRNA metagenomic analysis were performed using DNA isolated from the saliva samples of the participants. To select unique operational taxonomic unit (OTU) sets of ACVD, we conducted the random forest algorithm in machine learning, followed by confirmation via 10-fold cross-validation Results: There was no difference in richness or evenness between the ACVD and non-ACVD groups (alpha diversity; observed OTU index, p=0.503; Shannon's index, p=0.478). However, significant differences were found in the overall salivary microbiota structure (beta diversity; unweighted UniFrac distances, p=0.001; weighted UniFrac distances, p=0.001). The Actinobacteria phylum was highly abundant in patients with ACVD, while the Bacteroidetes phylum was less abundant. The random forest classifier identified 43 OTUs as an optimal marker set of ACVD. In a 10-fold cross validation using the validation data, an area under the curve (AUC) of 0.933 (95% CI, 0.855-1.000) was obtained. CONCLUSIONS: The salivary microbiota in patients with ACVD was distinct from that of non-ACVD individuals, indicating that the salivary microbiota may be related to ACVD.

The effect of simple heat treatment on apatite formation on grit-blasted/acid-etched dental Ti implants already in clinical use.

Grit-blasted/acid-etched titanium dental implants have a moderately roughened surface that is suitable for cell adhesion and exhibits faster osseointegration. However, the roughened surface does not always maintain stable fixation over a long period. In this study, a simple heat treatment at 600°C was performed on a commercially available dental Ti implant with grit-blasting/acid-etching, and its effect on mineralization capacity was assessed by examining apatite formation in a simulated body fluid (SBF). The as-purchased implant displayed a moderately roughened surface at the micrometer scale. Its surface was composed of titanium hydride accompanied by a small amount of alumina particles derived from the grit-blasting. Heat treatment transformed the titanium hydride into rutile without evidently changing the surface morphology. The immersion in SBF revealed that apatite formed on the heated implant at 7 days. Furthermore, apatite formed on the Ti rod surface within 1 day when the metal was subjected to acid and heat treatment without blasting. These indicate that apatite formation was conferred on the commercially available dental implant by simple heat treatment, although its induction period was slightly affected by alumina particles remaining on the implant surface. The heat-treated implant should achieve stronger and more stable bone bonding due to its apatite formation.

Characterization of salivary microbiota in elderly patients with type 2 diabetes mellitus: a matched case-control study.

OBJECTIVE: The importance of oral health in type 2 diabetes mellitus (T2DM) is widely recognized; however, oral microbiota characteristics associated with T2DM in the elderly population are not well-understood. This study was conducted to evaluate the characteristics of the salivary microbiota in elderly Japanese patients with T2DM. METHODS: Saliva samples were collected from 42 elderly Japanese patients with T2DM and 42 age- and sex-matched subjects without T2DM (control). 16S ribosomal RNA metagenomic analysis and comparative analysis of both groups were performed. Random forest classification by machine learning was performed to discriminate between the salivary microbiota in the two groups. RESULTS: There were significant differences in the overall salivary microbiota structure between the T2DM and control groups (beta diversity; unweighted UniFrac distances, p = 0.001; weighted UniFrac distances, p = 0.001). The phylum Firmicutes was abundant in patients with T2DM, whereas the phylum Bacteroidetes was abundant in controls. The T2DM prediction model by random forest based on salivary microbiota data was verified with a high predictive potential in five cross-validation tests (area under the curve (AUC) = 0.938 (95% CI, 0.824-1.000)). CONCLUSION: Characterization revealed that the salivary microbiota profile of the elderly patients with T2DM is significantly distinct from that of the controls. CLINICAL RELEVANCE: These data indicate the necessity of oral health management based on the characteristics of the salivary microbiota in elderly patients with T2DM. Our findings will contribute to future research on the development of new diagnostic and therapeutic methods for this purpose.

Histological Evaluation of Porous Additive-Manufacturing Titanium Artificial Bone in Rat Calvarial Bone Defects.

Jaw reconstruction using an additive-manufacturing titanium artificial bone (AMTAB) has recently attracted considerable attention. The synthesis of a titanium artificial bone is based on three-dimensional computed tomography images acquired before surgery. A histological evaluation of porous AMTAB (pAMTAB) embedded in rat calvarial bone defects was conducted. This study examined three groups: rats implanted with mixed-acid and heat-treated pAMTAB, rats implanted with untreated pAMTAB, and rats with no implant. In both pAMTAB groups, bone defects were created in rat calvarial bones using a 5-mm trephine bar, followed by pAMTAB implantation. The pAMTAB was fixed to the defect using the fitting force of the surrounding bones. The rats were sacrificed at 4, 8, and 16 weeks after implantation, and the skull was dissected. Undecalcified ground slides were prepared and stained with Villanueva Goldner. Compared with the no implant control group, both pAMTAB groups exhibited new bone formation inside the defect, with greater bone formation in the mixed-acid and heat-treated pAMTAB group than in the untreated pAMTAB group, but the difference was not significant. These data suggest that pAMTAB induces bone formation after implantation in bone defects. Bone formation appears to be enhanced by prior mixed-acid and heat-treated pAMTAB.

Comparative evaluation of microbial profiles of oral samples obtained at different collection time points and using different methods.

OBJECTIVES: Recently, the oral microbiome has been found to be associated with oral and general health status. Although various oral sample collection protocols are available, the potential differences between the results yielded by these protocols remain unclear. In this study, we aimed to determine the effects of different time points and methods of oral sample collection on the outcomes of microbiome analysis. MATERIALS AND METHODS: Oral samples were collected from eight healthy individuals at four different time points: 2 h after eating, immediately after teeth brushing, immediately after waking up, and 2 h after eating on the subsequent day. Four methods of saliva collection were evaluated: spitting, gum chewing, cotton swab, and oral rinse. Oral microbiomes of these samples were compared by analyzing the bacterial 16S rRNA gene sequence data. RESULTS: The oral microbial composition at the genus level was similar among all sample collection time points and methods. Alpha diversity was not significantly different among the groups, whereas beta diversity was different between the spitting and cotton swab methods. Compared with the between-subject variations, the weighted UniFrac distances between the groups were not minor. CONCLUSIONS: Although the oral microbiome profiles obtained at different collection time points and using different methods were similar, some differences were detected. CLINICAL RELEVANCE: The results of the present study suggest that although all the described protocols are useful, comparisons among microbiomes of samples collected by different methods are not appropriate. Researchers must be aware of the issues regarding the impact of saliva collection methods.

Mechanical, Histological, and Scanning Electron Microscopy Study of the Effect of Mixed-Acid and Heat Treatment on Additive-Manufactured Titanium Plates on Bonding to the Bone Surface.

The additive manufacturing (AM) technique has attracted attention as one of the fully customizable medical material technologies. In addition, the development of new surface treatments has been investigated to improve the osteogenic ability of the AM titanium (Ti) plate. The purpose of this study was to evaluate the osteogenic activity of the AM Ti with mixed-acid and heat (MAH) treatment. Fully customized AM Ti plates were created with a curvature suitable for rat calvarial bone, and they were examined in a group implanted with the MAH-treated Ti in comparison with the untreated (UN) group. The AM Ti plates were fixed to the surface of rat calvarial bone, followed by extraction of the calvarial bone 1, 4, 8, and 12 weeks after implantation. The bonding between the bone and Ti was evaluated mechanically. In addition, AM Ti plates removed from the bone were examined histologically by electron microscopy and Villanueva-Goldner stain. The mechanical evaluation showed significantly stronger bone-bonding in the MAH group than in the UN group. In addition, active bone formation was seen histologically in the MAH group. Therefore, these findings indicate that MAH resulted in rapid and strong bonding between cortical bone and Ti.

Examination of new parameters for sex determination of mandible using Japanese computer tomography data.

OBJECTIVE: In the field of forensic science, sex discrimination of skeletons is an important identification item for personal identification. The individual sex discrimination method using skeletons includes a determination method using measurement values and a macroscopic form observation method. Both methods have advantage and disadvantage. In this study, we used the homologous model technique and principal component (PC) analysis to determine gender difference from morphology of the mandible. METHODS AND MATERIALS: 45 patients (23 males and 22 females) of CT imaging for tooth extraction from January 2018 to March 2019 at department of oral surgery, Osaka Medical College. The mean age was 43.1 ± 14.6. Patients with less than 14 remaining teeth were excluded because the number of remaining teeth may affect the shape of the mandible. 3D images were constructed, and 20 landmarks plotting on the 3D model surfaces. We generated template models of the mandible consisting of approximately 8434 polygons. The template model automatically fitted into the individually scanned point cloud of the mandible by minimising external and internal energy functions. As described above, the mandibles were constructed for each sample by using the Homologous Body Modeling software (HBM, Digital Human Technology, Inc.) and the mHBM-Rugle (Medic Engineering Corporation). The mandibles were analysed using the PCA. RESULTS: The contribution of the most important PC was found to be 27.2%. 12 PCs explained over 75% of the total variance. That is, it was able to express 75% or more of the mandible expression with 12 PCs. A significant difference between male and female was observed in the first PCs (Wilcoxon test, p < 0.05). Visualising the result of the first PC showed that the mandibular branch of male was larger than that of female, and the mandible angle was overhanging outside. CONCLUSION: This method is a combination of the determination method using the previous measurement values and the determination using macroscopic observation, and is considered to be innovative method.

Removal of a Fixation Screw That Was Forced Into the Postsuperior Maxillary Sinus Wall: Case Report.

We have encountered a rare case in which the subject underwent maxillary sinus floor elevation at another hospital, and a screw to fix the grafted bone substitute was forced into the maxillary sinus and intruded into the bone. Various different foreign bodies have been reported as being forced into the maxillary sinus due to dental treatment, and these foreign bodies are often retained on the maxillary sinus mucous membrane. However, no reports have described a screw forced in and intruded into the peculiar position in the bone, as seen in the present case, which we report here with additional discussion.

Reconstruction of the Alveolar Bone Using Bone Augmentation With Selective Laser Melting Titanium Mesh Sheet: A Report of 2 Cases.

Bone augmentation is used to supplement bone defects during dental implant treatment. In this technique, the area filled with bone prosthetic material is covered with an artificial space-making device or titanium mesh sheet, which must be manually adapted to the bone defect during the procedure before being fixed in place. Selective laser melting (SLM) method can be used to preadapt the titanium mesh sheet based on preoperative CT data. This method enables shorter surgery times compared with conventional titanium mesh sheet methods, as well as regeneration of an ideal alveolar bone shape. Here, we present 2 cases of bone augmentation using the SLM titanium mesh sheet method. The postoperative course was without complications in both cases; neither patient experienced mesh exposure or infection during healing. The SLM titanium mesh sheet method should be considered as a new and effective bone augmentation method.

Preoperative Administration of Jidabokuippo, a Kampo Medicine, Alleviates Postoperative Pain after Tooth Extraction with Mandible Bone Removal under General Anesthesia: A Prospective, Single-Blind, Randomized Controlled Trial.

OBJECTIVE: This study aimed to determine the efficacy of preoperative administration of Jidabokuippo (JDI), a Kampo medicine, in treating postoperative pain after tooth extraction with mandible bone removal. DESIGN: This single-blind, randomized controlled study was conducted among two groups of adult patients who were scheduled to undergo tooth extraction with mandible bone removal under general anesthesia. Patients were randomly assigned to either the JDI or control group. INTERVENTION: Before surgery, the JDI group received JDI (7.5 g), whereas the control group did not receive any treatment. Patients and the evaluator were blinded to the treatment status. At 0, 1, 3, and 24 h after anesthesia recovery, an investigator recorded the severity of postoperative pain and nausea using a numeric rating scale (0, no pain or nausea; 10, worst imaginable pain or nausea). The number of patients who requested nonsteroidal anti-inflammatory drug (NSAID) and that of additional NSAID administration within 24 h from anesthesia recovery, and the time to the first NSAID request from anesthesia recovery was also measured. RESULTS: The severity of postoperative pain was significantly lower in the JDI group compared with the control group at 3 and 24 h after anesthesia recovery (p < 0.001 each). Both the number of patients requesting NSAID and additional NSAID administration after anesthesia recovery were significantly smaller in the JDI group than in the control group (p = 0.006, p < 0.001). The time to first NSAID request from anesthesia recovery was significantly longer in the JDI group compared with control group (p < 0.001). The severity of nausea did not differ significantly between the groups. No significant side effects related to JDI were noted during the trial. CONCLUSIONS: JDI administration before general anesthesia effectively decreased the severity of postoperative pain after anesthesia recovery in patients who underwent tooth extraction with mandible bone removal.

Candida is a protractive factor of chronic oral ulcers among usual outpatients.

Although many oral ulcers have similar clinical appearances, their etiologies can range from reactive to neoplastic to oral manifestations of dermatological diseases. In patients with an HIV infection, fungal diseases may cause ulceration in the oral cavity; however, there have been few studies of oral ulcerative lesions associated with Candida in patients without an HIV infection. Nevertheless, we encountered chronic oral ulcer associated with Candida among our frequent outpatients without an HIV infection. The present article reviews the causes of oral ulcers, focusing on Candida as a protractive factor for chronic oral ulcers, and it is recommended that Candida involvement be considered in diagnosis of a certain chronic oral ulcer, that remains of unknown origin even if some examinations have been performed.

New Bone Formation Process Using Bio-Oss and Collagen Membrane for Rat Calvarial Bone Defect: Histological Observation.

PURPOSE: We carried out guided bone regeneration of cranial bone defects in rats using the bovine bone substitute Bio-Oss and a collagen membrane and performed histological observations of the bone repair process. MATERIALS AND METHODS: Bone defects were created in the cranial bones of 30 15-week-old Sprague-Dawley rats. We made 3 groups. A is unfilled, B is Bio-Oss, and C is Bio-Oss plus a collagen membrane. At 4 or 8 weeks postoperatively, tissue samples were taken. The Kawamoto technique was used for histological evaluation. RESULTS: There was no new bone formation in group A. In groups B and C, new bone formation was evident around the Bio-Oss. In group C, new bone formation was evident in the centers of the bone defects, detached from the cut edge of the cranial bone. CONCLUSION: Our results suggested that the Bio-Oss acts as a scaffold for bone repair, and the use of a collagen membrane may anchor the Bio-Oss closely to the cranial bone and assist the bone repair response.

Evaluation of pH on removed tracheal tubes after general anesthesia: a prospective observational study.

STUDY OBJECTIVE: Aspiration pneumonia is a complication of tracheal intubation and mechanical ventilation. We hypothesized that tracheal tubes removed after anesthesia that have an acidic pH may reflect latent regurgitation of gastric fluid. DESIGN: A prospective observational study. SETTING: Operating room. PATIENTS: Tracheal tubes removed from 200 patients (age range, 20-85 years) who had undergone general anesthesia with tracheal intubation and gastric tube placement were examined. MEASUREMENTS: To detect regurgitated gastric fluid on the tubes, we measured pH at 5 different points along the tubes and in the water in which the removed tracheal tubes were immersed. MAIN RESULTS: Of the 200 removed tracheal tubes, 5 had an acidic pH. The tubes were used in patients who were in the prone (1 patients) or head-down (4 patients) position while under anesthesia. The incidence of acidic pH was significantly higher in patients who were in the prone (1/32) or head-down (4/56) position, compared with those in the supine (0/92) or lateral (0/20) position (P<.05). CONCLUSION: Acidic pH was found on about 2.5% of removed tracheal tubes. These tubes were used in patients who were in the prone or head-down position during general anesthesia, although they did not exhibit significant aspiration symptom. Anesthesiologists should be aware of the inherent risk of gastric fluid regurgitation when their patients undergo general anesthesia in these positions.

[Ultrasound-guided Thoracic Epidural and Spinal Anesthesia for the Management of Patients Undergoing Systemic Neurofibroma Resection].

We report successful anesthetic management of a patient undergoing systemic neurofibroma resection using thoracic epidural and spinal anesthesia. A 40- year-old man (weight 66 kg) with von Recklinghausen's disease and intermittent convulsions was scheduled for large-scale tumor resection on the back and arms. He also had chronic obstructive pulmonary disease and stiff neck We decided not to perform operation under general anesthesia. Before epidural or spinal anesthesia, we confirmed that there were no fibromas -in the subdermal lesion for needle progression by ultraso- nography. Thoracic epidural anesthesia was performed at the T2-3 level with 0.25% ropivacaine 5.0 ml, and spinal anesthesia with 0.5% isobaric bupivacaine 3.0 ml. To calm his anxiety, we continuously adminis- tered dexmedetomidine 0.4-0.8 µg · kg(-1) - hr(-1). The operation was performed uneventfully without se- vere pain. Dexmedetomidine was continued until the next morning. The patient showed no signs of convul- sions or intractable pain postoperatively.