Porphyromonas gingivalis impairs glucose uptake in skeletal muscle associated with altering gut microbiota.

Skeletal muscles have a high metabolic capacity, which play key roles in glucose metabolism. Although periodontal disease increases the risk of metabolic syndrome, the relationship between periodontal bacterial infection and skeletal muscle metabolic dysfunction is unclear. We found that anti-Porphyromonas gingivalis (Pg) antibody titers positively correlated with intramuscular adipose tissue content (IMAC), fasting blood glucose, and HOMA-IR in metabolic syndrome patients. In C57BL/6J mice fed a high-fat diet, recipients of oral Pg (HFPg) had impaired glucose tolerance, insulin resistance, and higher IMAC compared to recipients of saline (HFco). The soleus muscle in HFPg mice exhibited fat infiltration and lower glucose uptake with higher Tnfa expression and lower insulin signaling than in HFco mice. Gene set enrichment analysis showed that TNFα signaling via NFκB gene set was enriched in the soleus muscle of HFPg mice. Moreover, TNF-α also decreased glucose uptake in C2C12 myoblast cells in vitro. Based on 16S rRNA sequencing, Pg administration altered the gut microbiome, particularly by decreasing the abundance of genus Turicibacter. Microbial network of the gut microbiome was dramatically changed by Pg administration. Our findings suggest that infection with Pg is a risk factor for metabolic syndrome and skeletal muscle metabolic dysfunction via gut microbiome alteration.

High-frequency pulsed diode laser irradiation inhibits bone resorption in mice with ligature-induced periodontitis.

AIM: The purpose of this study was to elucidate the suppressive effect of high-frequency pulsed diode laser irradiation on bone resorption and its biological effects on gene expression and microbiome composition on the gingival tissue in ligature-induced periodontitis in mice. MATERIALS AND METHODS: Ligating ligature around the teeth and/or laser irradiation was performed on the gingival tissue in mice as follows: Co (no ligature and no laser irradiation), Li (ligation without laser irradiation), La (no ligature but with laser irradiation), and LiLa (ligation with laser irradiation). Bone resorption was evaluated using micro-computed tomography. RNA-seq analysis was performed on gingival tissues of all four groups at 3 days after ligation. The differences in microbial composition between Li and LiLa were evaluated based on the number of 16S rRNA gene sequences. RESULTS: Bone resorption caused by ligation was significantly suppressed by laser irradiation. RNA-seq in Co and La gingival tissue revealed many differentially expressed genes, suggesting diode laser irradiation altered gene expression. Gene set enrichment analysis revealed mTORC1 signalling and E2F target gene sets were enriched in gingival tissues both in La and LiLa compared with that in Co and Li, respectively. The amount of extracted DNA from ligatures was reduced by laser irradiation, and bacterial network structure was altered between the Li and LiLa. CONCLUSIONS: High-frequency pulsed diode laser irradiation showed biological effects and suppressed bone resorption in ligature-induced periodontitis.

Application of digital prosthodontics and connective tissue grafting in the management of peri-implant mucosal recession around a malpositioned 1-piece implant: A clinical report.

This clinical report describes a conservative approach to improve an unesthetic implant-supported crown and peri-implant mucosal recession around a malpositioned, 1-piece implant in the maxillary right central incisor region by using digital technology. In such clinical situations, the implants are usually removed because of an unpredictable definitive esthetic outcome. However, this clinical report describes the preservation of such a compromised implant by improving the esthetic outcome with a connective-tissue graft, and a digital approach used a 1-step preformed zirconia coping technique with an appropriate emergence profile.

Patient-specific establishment of bacterial composition within the peri-implant microbiota during the earliest weeks after implant uncovering.

BACKGROUND AND OBJECTIVE: Dysbiosis, a loss of balance in the microbiota, is a potential factor of peri-implantitis. However, compositional change of the peri-implant microbiota soon after implant uncovering is still unknown. In this study, bacterial composition in the peri-implant sulcus was examined to understand the establishment of bacterial composition within the peri-implant microbiota during the earliest weeks after implant uncovering. METHODS: Microbiota samples were collected at weeks 1, 2, 4, and 6 after stage-two surgery. Bacterial DNA was isolated from the samples, and a 16S rRNA gene library was constructed. Sequence reads were obtained using a high-throughput sequencing platform and were taxonomically assigned at the phylum and genus levels. RESULTS: Alpha diversity indices, which did not include taxonomic information, were at similar levels throughout the four time points. At 1 and 2 weeks, the bacterial composition was similar among patients with the predominance of Firmicutes and Proteobacteria. However, the composition was diverse at 4 and 6 weeks and significantly dissimilar to the composition at 1 week. CONCLUSIONS: At 1 week, the peri-implant microbiota was already formed with alpha diversity as high as that at the later time points. However, the bacterial composition was not highly dissimilar among patients at 1 week. The composition changed over the passage of several weeks and was specific for each patient.

Application of Ligature-Induced Periodontitis in Mice to Explore the Molecular Mechanism of Periodontal Disease.

Periodontitis is an inflammatory disease characterized by the destruction of the periodontium. In the last decade, a new murine model of periodontitis has been widely used to simulate alveolar bone resorption and periodontal soft tissue destruction by ligation. Typically, 3-0 to 9-0 silks are selected for ligation around the molars in mice, and significant bone loss and inflammatory infiltration are observed within a week. The ligature-maintained period can vary according to specific aims. We reviewed the findings on the interaction of systemic diseases with periodontitis, periodontal tissue destruction, the immunological and bacteriological responses, and new treatments. In these studies, the activation of osteoclasts, upregulation of pro-inflammatory factors, and excessive immune response have been considered as major factors in periodontal disruption. Multiple genes identified in periodontal tissues partly reflect the complexity of the pathogenesis of periodontitis. The effects of novel treatment methods on periodontitis have also been evaluated in a ligature-induced periodontitis model in mice. This model cannot completely represent all aspects of periodontitis in humans but is considered an effective method for the exploration of its mechanisms. Through this review, we aimed to provide evidence and enlightenment for future studies planning to use this model.

Accuracy of cone beam computed tomography in evaluation of palatal mucosa thickness.

AIM: The purpose of this study was to investigate the accuracy of the measurement of palatal mucosa thickness using cone beam computed tomography (CBCT) and to create a conversion formula to evaluate palatal mucosa thickness more accurately. We then evaluated the palatal mucosa thickness in a Japanese population using CBCT and the conversion formula. MATERIALS AND METHODS: We evaluated palatal mucosa thickness in 10 healthy subjects at 15 sites using CBCT, digital impression, and K file. Multiple regression analysis was performed to create a conversion formula to measure thickness accurately. We then obtained CBCT data from 174 patients retrospectively, applied the conversion formula, and evaluated palatal mucosa thickness. RESULTS: Sites of measurement affected measurement error. Measurement using CBCT was 0.34 ± 0.04 mm smaller than actual measurement; therefore, a conversion formula was created. Male, age ≥60 years, and probing pocket depth ≥4 mm had significant and positive associations with palatal mucosa thickness; however, no association was observed between bleeding on probing and palatal mucosa thickness. CONCLUSION: CBCT is useful for the noninvasive and accurate measurement of palatal mucosa thickness.

Japanese subgingival microbiota in health vs disease and their roles in predicted functions associated with periodontitis.

The present study aimed to identify and compare the microbial signatures between periodontally healthy and periodontitis subjects using 454 sequences of 16S rRNA genes. Subgingival plaque samples were collected from ten periodontally healthy subjects and ten matched chronic periodontitis patients. Bacterial DNA was extracted and next-generation sequencing of 16S rRNA genes was performed. The microbial composition differed between healthy subjects and periodontitis patients at all phylogenetic levels. Particularly, 16 species, including Lautropia mirabilis and Neisseria subflava predominated in healthy subjects, whereas nine species, including Porphyromonas gingivalis and Filifactor alocis predominated in periodontitis. UniFrac, a principal coordinate and network analysis, confirmed distinct community profiles in healthy subjects and periodontitis patients. Using predicted function profiling, pathways involved in phenylpropanoid, GPI-anchor biosynthesis, and metabolism of alanine, arginine, aspartate, butanoate, cyanoamino acid, fatty acid, glutamate, methane, proline, and vitamin B6 were significantly over-represented in periodontitis patients. These results highlight the oral microbiota alterations in microbial composition in periodontitis and suggest the genes and metabolic pathways associated with health and periodontitis. Our findings help to further elucidate microbial composition and interactions in health and periodontitis.

Influence of Porphyromonas gingivalis in gut microbiota of streptozotocin-induced diabetic mice.

OBJECTIVES: Increasing evidence suggests that periodontitis can exacerbate diabetes, and gut bacterial dysbiosis appears to be linked with the diabetic condition. The present study examined the effects of oral administration of the periodontopathic bacterium, Porphyromonas gingivalis, on the gut microbiota and systemic conditions in streptozotocin-induced diabetic mice. MATERIALS AND METHODS: Diabetes was induced by streptozotocin injection in C57BL/6J male mice (STZ). STZ and wild-type (WT) mice were orally administered P. gingivalis (STZPg, WTPg) or saline (STZco, WTco). Feces were collected, and the gut microbiome was examined by 16S rRNA gene sequencing. The expression of genes related to inflammation, epithelial tight junctions, and glucose/fatty acid metabolism in the ileum or liver were examined by quantitative PCR. RESULTS: The relative abundance of several genera, including Brevibacterium, Corynebacterium, and Facklamia, was significantly increased in STZco mice compared to WTco mice. The relative abundances of Staphylococcus and Turicibacter in the gut microbiome were altered by oral administration of P. gingivalis in STZ mice. STZPg mice showed higher concentrations of fasting blood glucose and inflammatory genes levels in the ileum, compared to STZco mice. CONCLUSIONS: Oral administration of P. gingivalis altered the gut microbiota and aggravated glycemic control in streptozotocin-induced diabetic mice.

Deep sequencing reveals specific bacterial signatures in the subgingival microbiota of healthy subjects.

OBJECTIVES: This study aimed to define the comprehensive bacterial flora of the healthy oral cavity by identifying and comparing bacterial species in different subgingival sites using 454 sequencing of 16S rRNA genes. MATERIALS AND METHODS: Subgingival plaque samples were taken from six target teeth (central incisor, first premolar, and first molar in both the maxilla and mandible) of 10 periodontally healthy patients. Bacterial DNA was extracted and next-generation sequencing of 16S rRNA genes was performed. RESULTS: Bacterial composition in phylum level was similar for all sites within the same individual irrespective of tooth location. Unweighted UniFrac distance values of microbiome also showed that average distance was significantly larger between subjects than between tooth locations of the same subjects. CONCLUSIONS: The present results clarify the lack of effect of tooth location in the healthy subgingival microbiota. Results may suggest that any subgingival site can demonstrate similar subject-specific microbiota. CLINICAL RELEVANCE: This investigation offers a better understanding of the uniqueness of the oral microbiome. The present study will facilitate sampling in future subgingival microbiological studies.

Effect of Porphyromonas gingivalis infection in the placenta and umbilical cord in pregnant mice with low birth weight.

OBJECTIVE: Growing evidence indicates an association between periodontitis and delivery outcome; however, the mechanism is unclear. This study aimed to investigate the influence of Porphyromonas gingivalis (Pg) infection on delivery outcome in mice. MATERIALS AND METHODS: Bacteremia was induced in pregnant Slc:ICR mice (8 weeks old) by intravenous injection of Pg. Mice were randomly divided into a control group (CO), and those receiving Pg injection at gestational day 1 (GD1), gestational day 15 (GD15) or every day (ED). Delivery outcome, Pg infection, and gene expression in the placenta and umbilical cord were evaluated. RESULTS: Birth weight was lower in the ED and GD15 groups than in the CO group. A remarkable increase in anti-Pg IgG antibody was observed in the ED and GD1 groups, although Pg was not detected in the placenta or umbilical cord. mRNA expression of Tnfα and Il6 in the placenta, and Hif1α in the umbilical cord, was significantly increased in the ED group. Microarray analysis of the umbilical cord revealed increased expression of several genes including Orm1, Mgl2, Rps6ka3 and Trim15 in the ED group. CONCLUSIONS: Pg infection during the third trimester caused low birth weight and inflammation in the placenta and umbilical cord.