Periodontal Index: A numerical rating scale for classifying the periodontal status of a person or population with a single figure which takes into consideration prevalence as well as severity of the condition. It is based upon probe measurement of periodontal pockets and on gingival tissue status.Periodontal Diseases: Pathological processes involving the PERIODONTIUM including the gum (GINGIVA), the alveolar bone (ALVEOLAR PROCESS), the DENTAL CEMENTUM, and the PERIODONTAL LIGAMENT.Oral Hygiene Index: A combination of the debris index and the dental calculus index to determine the status of oral hygiene.Dental Calculus: Abnormal concretion or calcified deposit that forms around the teeth or dental prostheses.Benzoylarginine-2-Naphthylamide: An enzyme substrate which permits the measurement of peptide hydrolase activity, e.g. trypsin and thrombin. The enzymes liberate 2-naphthylamine, which is measured by colorimetric procedures.Gingivitis: Inflammation of gum tissue (GINGIVA) without loss of connective tissue.Periodontal Pocket: An abnormal extension of a gingival sulcus accompanied by the apical migration of the epithelial attachment and bone resorption.Gingival Hemorrhage: The flowing of blood from the marginal gingival area, particularly the sulcus, seen in such conditions as GINGIVITIS, marginal PERIODONTITIS, injury, and ASCORBIC ACID DEFICIENCY.Dental Health Surveys: A systematic collection of factual data pertaining to dental or oral health and disease in a human population within a given geographic area.DMF Index: "Decayed, missing and filled teeth," a routinely used statistical concept in dentistry.Oral Hygiene: The practice of personal hygiene of the mouth. It includes the maintenance of oral cleanliness, tissue tone, and general preservation of oral health.Oral Health: The optimal state of the mouth and normal functioning of the organs of the mouth without evidence of disease.Tooth Loss: The failure to retain teeth as a result of disease or injury.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 Caries: Localized destruction of the tooth surface initiated by decalcification of the enamel followed by enzymatic lysis of organic structures and leading to cavity formation. If left unchecked, the cavity may penetrate the enamel and dentin and reach the pulp.Body Mass Index: An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.