Oral bacteria directly affect the disease status of dental caries and periodontal diseases. The dynamic oral microbiota cooperates with the host to reflect the information and status of immunity and metabolism through two-way communication along the oral cavity and the systemic organs. The oral cavity is one of the most important interaction windows between the human body and the environment. The microenvironment at different sites in the oral cavity has different microbial compositions and is regulated by complex signaling, hosts, and external environmental factors. These processes may affect or reflect human health because certain health states seem to be related to the composition of oral bacteria, and the destruction of the microbial community is related to systemic diseases. In this review, we discussed emerging and exciting evidence of complex and important connections between the oral microbes and multiple human systemic diseases, and the possible contribution of the oral microorganisms to systemic diseases. This review aims to enhance the interest to oral microbes on the whole human body, and also improve clinician's understanding of the role of oral microbes in systemic diseases. Microbial research in dentistry potentially enhances our knowledge of the pathogenic mechanisms of oral diseases, and at the same time, continuous advances in this frontier field may lead to a tangible impact on human health.
Bacteria ; Dental Caries/microbiology* ; Humans ; Microbiota ; Mouth/microbiology* ; Mouth Diseases/microbiology* ; Periodontal Diseases/microbiology*

Periodontitis is an inflammatory disease involving the destruction of both soft and hard tissue in the periodontal region. Although dysbiosis of the local microbial community initiates local inflammation, over-activation of the host immune response directly activates osteoclastic activity and alveolar bone loss. Many studies have reported on the cytokine network involved in periodontitis and its crucial and pleiotropic effect on the recruitment of specific immunocytes, control of pathobionts and induction or suppression of osteoclastic activity. Nonetheless, particularities in the stimulation of pathogens in the oral cavity that lead to the specific and complex periodontal cytokine network are far from clarified. Thus, in this review, we begin with an up-to-date aetiological hypothesis of periodontal disease and summarize the roles of cytokines in the host immune response. In addition, we also summarize the latest cytokine-related therapeutic measures for periodontal disease.
Alveolar Bone Loss ; etiology ; Cytokines ; metabolism ; physiology ; Humans ; Inflammation ; Periodontal Diseases ; Periodontitis ; immunology ; microbiology ; Tumor Necrosis Factor-alpha ; physiology

A human oral microbiota is the ecological community of commensal, symbiotic, and pathogenic microorganisms found in human oral cavity. Oral microbiota exists mostly in the form of a biofilm and maintains a dynamic ecological equilibrium with the host body. However, the disturbance of this ecological balance inevitably causes oral infectious diseases, such as dental caries, apical periodontitis, periodontal diseases, pericoronitis, and craniofacial bone osteomyelitis. Oral microbiota is also correlated with many systemic diseases, including cancer, diabetes mellitus, rheumatoid arthritis, cardiovascular diseases, and preterm birth. Hence, oral microbiota has been considered as a potential biomarker of human diseases. The "Human Microbiome Project" and other metagenomic projects worldwide have advanced our knowledge of the human oral microbiota. The integration of these metadata has been the frontier of oral microbiology to improve clinical translation. By reviewing recent progress on studies involving oral microbiota-related oral and systemic diseases, we aimed to propose the essential role of oral microbiota in the prediction of the onset, progression, and prognosis of oral and systemic diseases. An oral microbiota-based prediction model helps develop a new paradigm of personalized medicine and benefits the human health in the post-metagenomics era.
Biomarkers ; Cardiovascular Diseases ; microbiology ; Dental Caries ; microbiology ; Diabetes Mellitus ; microbiology ; Humans ; Metagenomics ; Microbiota ; Mouth ; microbiology ; Mouth Diseases ; microbiology ; Neoplasms ; microbiology ; Oral Health ; Periodontal Diseases ; microbiology

Bacterial biofilms have emerged as potential critical triggers in the pathogenesis of bisphosphonate (BP)-related osteonecrosis of the jaw (ONJ) or BRONJ. BRONJ lesions have shown to be heavily colonized by oral bacteria, most of these difficult to cultivate and presents many clinical challenges. The purpose of this study was to characterize the bacterial diversity in BRONJ lesions and to determine host immune response. We examined tissue specimens from three cohorts (n=30); patients with periodontal disease without a history of BP therapy (Control, n=10), patients with periodontal disease having history of BP therapy but without ONJ (BP, n=5) and patients with BRONJ (BRONJ, n=15). Denaturing gradient gel electrophoresis of polymerase chain reaction (PCR)-amplified 16S rRNA gene fragments revealed less bacterial diversity in BRONJ than BP and Control cohorts. Sequence analysis detected six phyla with predominant affiliation to Firmicutes in BRONJ (71.6%), BP (70.3%) and Control (59.1%). Significant differences (P<0.05) in genera were observed, between Control/BP, Control/BRONJ and BP/BRONJ cohorts. Enzyme-linked immunosorbent assay (ELISA) results indicated that the levels of myeloperoxidase were significantly lower, whereas interleukin-6 and tumor necrosis factor-alpha levels were moderately elevated in BRONJ patients as compared to Controls. PCR array showed significant changes in BRONJ patients with downregulation of host genes, such as nucleotide-binding oligomerization domain containing protein 2, and cathepsin G, the key modulators for antibacterial response and upregulation of secretory leukocyte protease inhibitor, proteinase 3 and conserved helix-loop-helix ubiquitous kinase. The results suggest that colonization of unique bacterial communities coupled with deficient innate immune response is likely to impact the pathogenesis of ONJ.
Actinobacteria ; classification ; Bacteria ; classification ; Bacteroidetes ; classification ; Biofilms ; Bisphosphonate-Associated Osteonecrosis of the Jaw ; immunology ; microbiology ; Bone Density Conservation Agents ; therapeutic use ; Cathepsin G ; analysis ; Cohort Studies ; Down-Regulation ; Female ; Fusobacteria ; classification ; Gram-Negative Bacteria ; classification ; Host-Pathogen Interactions ; immunology ; Humans ; I-kappa B Kinase ; analysis ; Immunity, Innate ; immunology ; Interleukin-6 ; analysis ; Male ; Middle Aged ; Mouth ; immunology ; microbiology ; Myeloblastin ; analysis ; antagonists & inhibitors ; Nod2 Signaling Adaptor Protein ; analysis ; Periodontal Diseases ; microbiology ; Peroxidase ; analysis ; Proteobacteria ; classification ; Tumor Necrosis Factor-alpha ; analysis

Halitosis ; etiology ; metabolism ; microbiology ; Helicobacter Infections ; complications ; Helicobacter pylori ; Humans ; Oral Hygiene ; Periodontal Diseases ; complications ; Smoking ; Volatile Organic Compounds ; metabolism

Humans ; Periodontal Diseases ; complications ; microbiology ; Periodontium ; microbiology ; Systemic Inflammatory Response Syndrome ; microbiology

China ; Chronic Periodontitis ; microbiology ; Dental Restoration, Permanent ; Genotype ; Humans ; Periodontal Diseases ; surgery ; Periodontics ; trends ; Periodontitis ; genetics ; immunology ; surgery ; Porphyromonas gingivalis ; isolation & purification

Fusobacteria are anaerobic gram-negative, non-spore forming bacilli found in normal flora of the oral cavity, urogenital tract, and gastrointestinal tract. Fusobacterium nucleatum has been seldom reported as a cause of liver abscess, particularly in immunocompetent hosts. A 55-year-old man with frequent periodontal disease visited our hospital with intermittent fever and headache for 2 months. Abdominal CT scan revealed an 8.2x6 cm mass in the right hepatic lobe with central low density. Abscess culture revealed F. nucleatum as the causative organism. Percutaneous abscess drainage and intravenous administration of antibiotics for 4 weeks improved symptoms and decreased the abscess size. We report a rare case of liver abscess due to F. nucleatum in an immunocompetent man with periodontal disease.
Ampicillin/therapeutic use ; Anti-Bacterial Agents/therapeutic use ; Fusobacterium Infections/complications/*diagnosis/drug therapy ; Fusobacterium nucleatum/*isolation & purification ; Humans ; Injections, Intravenous ; Liver Abscess/*diagnosis/etiology/microbiology ; Male ; Middle Aged ; Periodontal Diseases/*diagnosis ; Sulbactam/therapeutic use

Since the initial observations of oral bacteria within dental plaque by van Leeuwenhoek using his primitive microscopes in 1680, an event that is generally recognized as the advent of oral microbiological investigation, oral microbiology has gone through phases of "reductionism" and "holism". From the small beginnings of the Miller and Black period, in which microbiologists followed Koch's postulates, took the reductionist approach to try to study the complex oral microbial community by analyzing individual species; to the modern era when oral researchers embrace "holism" or "system thinking", adopt new concepts such as interspecies interaction, microbial community, biofilms, poly-microbial diseases, oral microbiological knowledge has burgeoned and our ability to identify the resident organisms in dental plaque and decipher the interactions between key components has rapidly increased, such knowledge has greatly changed our view of the oral microbial flora, provided invaluable insight into the etiology of dental and periodontal diseases, opened the door to new approaches and techniques for developing new therapeutic and preventive tools for combating oral polymicrobial diseases.
Bacteria ; classification ; Bacterial Infections ; prevention & control ; Bacterial Physiological Phenomena ; Biofilms ; Dental Plaque ; microbiology ; Humans ; Mouth ; microbiology ; Periodontal Diseases ; microbiology ; prevention & control ; Tooth Diseases ; microbiology ; prevention & control

Aggregatibacter actinomycetemcomitans ; physiology ; Bacterial Adhesion ; Biofilms ; Periodontal Diseases ; microbiology ; Porphyromonas endodontalis ; physiology