Prevotella intermedia: A species of gram-negative, anaerobic, rod-shaped bacteria originally classified within the BACTEROIDES genus. This bacterium is a common commensal in the gingival crevice and is often isolated from cases of gingivitis and other purulent lesions related to the mouth.Prevotella: A genus of gram-negative, anaerobic, nonsporeforming, nonmotile rods. Organisms of this genus had originally been classified as members of the BACTEROIDES genus but overwhelming biochemical and chemical findings in 1990 indicated the need to separate them from other Bacteroides species, and hence, this new genus was established.Bacteroidaceae Infections: Infections with bacteria of the family BACTEROIDACEAE.Fusobacterium nucleatum: A species of gram-negative, anaerobic, rod-shaped bacteria isolated from the gingival margin and sulcus and from infections of the upper respiratory tract and pleural cavity.Porphyromonas gingivalis: A species of gram-negative, anaerobic, rod-shaped bacteria originally classified within the BACTEROIDES genus. This bacterium produces a cell-bound, oxygen-sensitive collagenase and is isolated from the human mouth.Bacteroides: A genus of gram-negative, anaerobic, rod-shaped bacteria. Its organisms are normal inhabitants of the oral, respiratory, intestinal, and urogenital cavities of humans, animals, and insects. Some species may be pathogenic.Porphyromonas: A genus of gram-negative, anaerobic, nonsporeforming, nonmotile rods or coccobacilli. Organisms in this genus had originally been classified as members of the BACTEROIDES genus but overwhelming biochemical and chemical findings indicated the need to separate them from other Bacteroides species, and hence, this new genus was created.Periodontal Diseases: Pathological processes involving the PERIODONTIUM including the gum (GINGIVA), the alveolar bone (ALVEOLAR PROCESS), the DENTAL CEMENTUM, and the PERIODONTAL LIGAMENT.Periodontitis: Inflammation and loss of connective tissues supporting or surrounding the teeth. This may involve any part of the PERIODONTIUM. Periodontitis is currently classified by disease progression (CHRONIC PERIODONTITIS; AGGRESSIVE PERIODONTITIS) instead of age of onset. (From 1999 International Workshop for a Classification of Periodontal Diseases and Conditions, American Academy of Periodontology)Dental Plaque: A film that attaches to teeth, often causing DENTAL CARIES and GINGIVITIS. It is composed of MUCINS, secreted from salivary glands, and microorganisms.Campylobacter rectus: A species of CAMPYLOBACTER isolated from cases of human PERIODONTITIS. It is a microaerophile, capable of respiring with OXYGEN.Gingiva: Oral tissue surrounding and attached to TEETH.Treponema denticola: A species of bacteria in the family SPIROCHAETACEAE, frequently isolated from periodontal pockets (PERIODONTAL POCKET).Periapical Abscess: Acute or chronic inflammation of tissues surrounding the apical portion of a tooth, associated with the collection of pus, resulting from infection following pulp infection through a carious lesion or as a result of an injury causing pulp necrosis. (Dorland, 27th ed)Bacteria, AnaerobicPeriodontal Pocket: An abnormal extension of a gingival sulcus accompanied by the apical migration of the epithelial attachment and bone resorption.Chicory: A thick-rooted perennial (Cichorium intybus) native to Europe but widely grown for its young leaves used as salad greens and for its roots, dried and ground-roasted, used to flavor or adulterate coffee. (From Webster, 3d ed)Mouth: The oval-shaped oral cavity located at the apex of the digestive tract and consisting of two parts: the vestibule and the oral cavity proper.Noma: A severe gangrenous process occurring predominantly in debilitated and malnourished children, especially in underdeveloped countries. It typically begins as a small vesicle or ulcer on the gingiva that rapidly becomes necrotic and spreads to produce extensive destruction of the buccal and labial mucosa and tissues of the face, which may result in severe disfigurement and even death. Various bacteria have been implicated in the etiology. (Dorland, 27th ed)Periodontal Abscess: Localized circumscribed purulent area of inflammation in the periodontal tissue. It is a derivative of marginal periodontitis and commonly associated with suprabony and infrabony pockets and interradicular involvements, in contrast to periapical abscess which is attributable to pulp necrosis.Acidic Glycosphingolipids: A subclass of GLYCOSPHINGOLIPIDS containing large polar heads made up of several sugar units. One or more of their terminal sugar units are bound to a negatively charged molecule at pH 7. Members of this class include: GANGLIOSIDES, uronoglycosphingolipids, SULFOGLYCOSPHINGOLIPIDS, phosphoglycosphingolipids, and phosphonoglycosphingolipids.Pulpitis: Inflammation of the DENTAL PULP, usually due to bacterial infection in dental caries, tooth fracture, or other conditions causing exposure of the pulp to bacterial invasion. Chemical irritants, thermal factors, hyperemic changes, and other factors may also cause pulpitis.Gingivitis: Inflammation of gum tissue (GINGIVA) without loss of connective tissue.Aggregatibacter actinomycetemcomitans: A species of Gram-negative, facultatively anaerobic spherical or rod-shaped bacteria indigenous to dental surfaces. It is associated with PERIODONTITIS; BACTERIAL ENDOCARDITIS; and ACTINOMYCOSIS.Eikenella corrodens: Gram-negative bacteria isolated from infections of the respiratory and intestinal tracts and from the buccal cavity, intestinal tract, and urogenital tract. They are probably part of the normal flora of man and animals.Prevotella nigrescens: A species of gram-negative bacteria in the family Prevotellaceae. It is the species most commonly isolated from endodontic infections (PULPITIS).Prevotella ruminicola: A saccharolytic species of gram-negative bacteria in the family Prevotellaceae. It ferments a wide range of CARBOHYDRATES in the RUMEN of animals.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Chronic Periodontitis: Chronic inflammation and loss of PERIODONTIUM that is associated with the amount of DENTAL PLAQUE or DENTAL CALCULUS present. Chronic periodontitis occurs mostly in adults and was called adult periodontitis, but this disease can appear in young people.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.beta-Thalassemia: A disorder characterized by reduced synthesis of the beta chains of hemoglobin. There is retardation of hemoglobin A synthesis in the heterozygous form (thalassemia minor), which is asymptomatic, while in the homozygous form (thalassemia major, Cooley's anemia, Mediterranean anemia, erythroblastic anemia), which can result in severe complications and even death, hemoglobin A synthesis is absent.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Psychodidae: Small, hairy, moth-like flies which are of considerable public health importance as vectors of certain pathogenic organisms. Important disease-related genera are PHLEBOTOMUS, Lutzomyia, and Sergentomyia.