Chi-Square Distribution: A distribution in which a variable is distributed like the sum of the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another.Cross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.BrazilRetrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.IndiaLogistic Models: Statistical models which describe the relationship between a qualitative dependent variable (that is, one which can take only certain discrete values, such as the presence or absence of a disease) and an independent variable. A common application is in epidemiology for estimating an individual's risk (probability of a disease) as a function of a given risk factor.Dentition, Permanent: The 32 teeth of adulthood that either replace or are added to the complement of deciduous teeth. (Boucher's Clinical Dental Terminology, 4th ed)Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.TurkeySocioeconomic Factors: Social and economic factors that characterize the individual or group within the social structure.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Malocclusion: Such malposition and contact of the maxillary and mandibular teeth as to interfere with the highest efficiency during the excursive movements of the jaw that are essential for mastication. (Jablonski, Illustrated Dictionary of Dentistry, 1982)Sex Factors: Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.Fingersucking: Sucking of the finger. This is one of the most common manipulations of the body found in young children.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Health Knowledge, Attitudes, Practice: Knowledge, attitudes, and associated behaviors which pertain to health-related topics such as PATHOLOGIC PROCESSES or diseases, their prevention, and treatment. This term refers to non-health workers and health workers (HEALTH PERSONNEL).IranOpen Bite: A condition in which certain opposing teeth fail to establish occlusal contact when the jaws are closed.Statistics, Nonparametric: A class of statistical methods applicable to a large set of probability distributions used to test for correlation, location, independence, etc. In most nonparametric statistical tests, the original scores or observations are replaced by another variable containing less information. An important class of nonparametric tests employs the ordinal properties of the data. Another class of tests uses information about whether an observation is above or below some fixed value such as the median, and a third class is based on the frequency of the occurrence of runs in the data. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1284; Corsini, Concise Encyclopedia of Psychology, 1987, p764-5)Time Factors: Elements of limited time intervals, contributing to particular results or situations.Prognosis: A prediction of the probable outcome of a disease based on a individual's condition and the usual course of the disease as seen in similar situations.Esthetics, Dental: Skills, techniques, standards, and principles used to improve the art and symmetry of the teeth and face to improve the appearance as well as the function of the teeth, mouth, and face. (From Boucher's Clinical Dental Terminology, 4th ed, p108)Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Students, Dental: Individuals enrolled a school of dentistry or a formal educational program in leading to a degree in dentistry.Orthodontic Brackets: Small metal or ceramic attachments used to fasten an arch wire. These attachments are soldered or welded to an orthodontic band or cemented directly onto the teeth. Bowles brackets, edgewise brackets, multiphase brackets, ribbon arch brackets, twin-wire brackets, and universal brackets are all types of orthodontic brackets.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.Toothbrushing: The act of cleaning teeth with a brush to remove plaque and prevent tooth decay. (From Webster, 3d ed)Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.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.China: A country spanning from central Asia to the Pacific Ocean.Dental Prosthesis: An artificial replacement for one or more natural teeth or part of a tooth, or associated structures, ranging from a portion of a tooth to a complete denture. The dental prosthesis is used for cosmetic or functional reasons, or both. DENTURES and specific types of dentures are also available. (From Boucher's Clinical Dental Terminology, 4th ed, p244 & Jablonski, Dictionary of Dentistry, 1992, p643)Epidemiologic Methods: Research techniques that focus on study designs and data gathering methods in human and animal populations.Gene Frequency: The proportion of one particular in the total of all ALLELES for one genetic locus in a breeding POPULATION.Predictive Value of Tests: In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.Diastema: An abnormal opening or fissure between two adjacent teeth.Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Rural Population: The inhabitants of rural areas or of small towns classified as rural.Orthodontics: A dental specialty concerned with the prevention and correction of dental and oral anomalies (malocclusion).Tooth Injuries: Traumatic or other damage to teeth including fractures (TOOTH FRACTURES) or displacements (TOOTH LUXATION).Multivariate Analysis: A set of techniques used when variation in several variables has to be studied simultaneously. In statistics, multivariate analysis is interpreted as any analytic method that allows simultaneous study of two or more dependent variables.Pacifiers: Devices that babies can suck on when they are not feeding. The extra sucking can be comforting to the babies and pacify them. Pacifiers usually are used as a substitute for the thumb in babies who suck on their thumb or fingers almost constantly.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.Risk Assessment: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)Urban Population: The inhabitants of a city or town, including metropolitan areas and suburban areas.Odds Ratio: The ratio of two odds. The exposure-odds ratio for case control data is the ratio of the odds in favor of exposure among cases to the odds in favor of exposure among noncases. The disease-odds ratio for a cohort or cross section is the ratio of the odds in favor of disease among the exposed to the odds in favor of disease among the unexposed. The prevalence-odds ratio refers to an odds ratio derived cross-sectionally from studies of prevalent cases.Age Distribution: The frequency of different ages or age groups in a given population. The distribution may refer to either how many or what proportion of the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.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.Oral Health: The optimal state of the mouth and normal functioning of the organs of the mouth without evidence of disease.Incisor: Any of the eight frontal teeth (four maxillary and four mandibular) having a sharp incisal edge for cutting food and a single root, which occurs in man both as a deciduous and a permanent tooth. (Jablonski, Dictionary of Dentistry, 1992, p820)Students: Individuals enrolled in a school or formal educational program.Sex Distribution: The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.Infant, Newborn: An infant during the first month after birth.Tooth, Deciduous: The teeth of the first dentition, which are shed and replaced by the permanent teeth.Surgery, Oral: A dental specialty concerned with the diagnosis and surgical treatment of disease, injuries, and defects of the human oral and maxillofacial region.Trinidad and Tobago: An independent state in the Lesser Antilles in the West Indies, north of Venezuela, comprising the islands of Trinidad and Tobago. Its capital is Port of Spain. Both islands were discovered by Columbus in 1498. The Spanish, English, Dutch, and French figure in their history over four centuries. Trinidad and Tobago united in 1898 and were made part of the British colony of Trinidad and Tobago in 1899. The colony became an independent state in 1962. Trinidad was so named by Columbus either because he arrived on Trinity Sunday or because three mountain peaks suggested the Holy Trinity. Tobago was given the name by Columbus from the Haitian tambaku, pipe, from the natives' habit of smoking tobacco leaves. (Webster's New Geographical Dictionary, 1988, p1228, 1216 & Room, Brewer's Dictionary of Names, 1992, p555, 547)United StatesTertiary Healthcare: Care of a highly technical and specialized nature, provided in a medical center, usually one affiliated with a university, for patients with unusually severe, complex, or uncommon health problems.Shear Strength: The internal resistance of a material to moving some parts of it parallel to a fixed plane, in contrast to stretching (TENSILE STRENGTH) or compression (COMPRESSIVE STRENGTH). Ionic crystals are brittle because, when subjected to shear, ions of the same charge are brought next to each other, which causes repulsion.Bicuspid: One of the eight permanent teeth, two on either side in each jaw, between the canines (CUSPID) and the molars (MOLAR), serving for grinding and crushing food. The upper have two cusps (bicuspid) but the lower have one to three. (Jablonski, Dictionary of Dentistry, 1992, p822)Educational Status: Educational attainment or level of education of individuals.Anodontia: Congenital absence of the teeth; it may involve all (total anodontia) or only some of the teeth (partial anodontia, hypodontia), and both the deciduous and the permanent dentition, or only teeth of the permanent dentition. (Dorland, 27th ed)Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Genetic Predisposition to Disease: A latent susceptibility to disease at the genetic level, which may be activated under certain conditions.Sucking Behavior: Any suction exerted by the mouth; response of the mammalian infant to draw milk from the breast. Includes sucking on inanimate objects. Not to be used for thumb sucking, which is indexed under fingersucking.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.Croatia: Created 7 April 1992 as a result of the division of Yugoslavia.PakistanTemporomandibular Joint Disorders: A variety of conditions affecting the anatomic and functional characteristics of the temporomandibular joint. Factors contributing to the complexity of temporomandibular diseases are its relation to dentition and mastication and the symptomatic effects in other areas which account for referred pain to the joint and the difficulties in applying traditional diagnostic procedures to temporomandibular joint pathology where tissue is rarely obtained and x-rays are often inadequate or nonspecific. Common diseases are developmental abnormalities, trauma, subluxation, luxation, arthritis, and neoplasia. (From Thoma's Oral Pathology, 6th ed, pp577-600)Maxilla: One of a pair of irregularly shaped bones that form the upper jaw. A maxillary bone provides tooth sockets for the superior teeth, forms part of the ORBIT, and contains the MAXILLARY SINUS.DMF Index: "Decayed, missing and filled teeth," a routinely used statistical concept in dentistry.Nigeria: A republic in western Africa, south of NIGER between BENIN and CAMEROON. Its capital is Abuja.Radiography, Bitewing: Technique involving the passage of X-rays through oral structures to create a film record while a central tab or wing of dental X-ray film is being held between upper and lower teeth.Mouth DiseasesModels, Statistical: Statistical formulations or analyses which, when applied to data and found to fit the data, are then used to verify the assumptions and parameters used in the analysis. Examples of statistical models are the linear model, binomial model, polynomial model, two-parameter model, etc.Molar: The most posterior teeth on either side of the jaw, totaling eight in the deciduous dentition (2 on each side, upper and lower), and usually 12 in the permanent dentition (three on each side, upper and lower). They are grinding teeth, having large crowns and broad chewing surfaces. (Jablonski, Dictionary of Dentistry, 1992, p821)Universities: Educational institutions providing facilities for teaching and research and authorized to grant academic degrees.Dental Prophylaxis: Treatment for the prevention of periodontal diseases or other dental diseases by the cleaning of the teeth in the dental office using the procedures of DENTAL SCALING and DENTAL POLISHING. The treatment may include plaque detection, removal of supra- and subgingival plaque and calculus, application of caries-preventing agents, checking of restorations and prostheses and correcting overhanging margins and proximal contours of restorations, and checking for signs of food impaction.Dental Occlusion: The relationship of all the components of the masticatory system in normal function. It has special reference to the position and contact of the maxillary and mandibular teeth for the highest efficiency during the excursive movements of the jaw that are essential for mastication. (From Jablonski, Dictionary of Dentistry, 1992, p556, p472)Polymorphism, Single Nucleotide: A single nucleotide variation in a genetic sequence that occurs at appreciable frequency in the population.Mandible: The largest and strongest bone of the FACE constituting the lower jaw. It supports the lower teeth.Tooth Apex: The tip or terminal end of the root of a tooth. (Jablonski, Dictionary of Dentistry, 1992, p62)Odontometry: Measurement of tooth characteristics.Resin Cements: Dental cements composed either of polymethyl methacrylate or dimethacrylate, produced by mixing an acrylic monomer liquid with acrylic polymers and mineral fillers. The cement is insoluble in water and is thus resistant to fluids in the mouth, but is also irritating to the dental pulp. It is used chiefly as a luting agent for fabricated and temporary restorations. (Jablonski's Dictionary of Dentistry, 1992, p159)Dental Arch: The curve formed by the row of TEETH in their normal position in the JAW. The inferior dental arch is formed by the mandibular teeth, and the superior dental arch by the maxillary teeth.Dentists: Individuals licensed to practice DENTISTRY.Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.Asian Continental Ancestry Group: Individuals whose ancestral origins are in the southeastern and eastern areas of the Asian continent.Acid Etching, Dental: Preparation of TOOTH surfaces and DENTAL MATERIALS with etching agents, usually phosphoric acid, to roughen the surface to increase adhesion or osteointegration.Radiography, Panoramic: Extraoral body-section radiography depicting an entire maxilla, or both maxilla and mandible, on a single film.Dental Enamel: A hard thin translucent layer of calcified substance which envelops and protects the dentin of the crown of the tooth. It is the hardest substance in the body and is almost entirely composed of calcium salts. Under the microscope, it is composed of thin rods (enamel prisms) held together by cementing substance, and surrounded by an enamel sheath. (From Jablonski, Dictionary of Dentistry, 1992, p286)Dental Care: The total of dental diagnostic, preventive, and restorative services provided to meet the needs of a patient (from Illustrated Dictionary of Dentistry, 1982).Stainless Steel: Stainless steel. A steel containing Ni, Cr, or both. It does not tarnish on exposure and is used in corrosive environments. (Grant & Hack's Chemical Dictionary, 5th ed)Attitude to Health: Public attitudes toward health, disease, and the medical care system.Smoking: Inhaling and exhaling the smoke of burning TOBACCO.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Dental Plaque Index: An index which scores the degree of dental plaque accumulation.Dental Cements: Substances used to bond COMPOSITE RESINS to DENTAL ENAMEL and DENTIN. These bonding or luting agents are used in restorative dentistry, ROOT CANAL THERAPY; PROSTHODONTICS; and ORTHODONTICS.Tooth Eruption, Ectopic: An abnormality in the direction of a TOOTH ERUPTION.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Health Education, Dental: Education which increases the awareness and favorably influences the attitudes and knowledge relating to the improvement of dental health on a personal or community basis.Dentist's Practice Patterns: Patterns of practice in dentistry related to diagnosis and treatment.Radiography, Dental: Radiographic techniques used in dentistry.Periodontal Pocket: An abnormal extension of a gingival sulcus accompanied by the apical migration of the epithelial attachment and bone resorption.Toothpastes: Dentifrices that are formulated into a paste form. They typically contain abrasives, HUMECTANTS; DETERGENTS; FLAVORING AGENTS; and CARIOSTATIC AGENTS.Malaysia: A parliamentary democracy with a constitutional monarch in southeast Asia, consisting of 11 states (West Malaysia) on the Malay Peninsula and two states (East Malaysia) on the island of BORNEO. It is also called the Federation of Malaysia. Its capital is Kuala Lumpur. Before 1963 it was the Union of Malaya. It reorganized in 1948 as the Federation of Malaya, becoming independent from British Malaya in 1957 and becoming Malaysia in 1963 as a federation of Malaya, Sabah, Sarawak, and Singapore (which seceded in 1965). The form Malay- probably derives from the Tamil malay, mountain, with reference to its geography. (From Webster's New Geographical Dictionary, 1988, p715 & Room, Brewer's Dictionary of Names, 1992, p329)European Continental Ancestry Group: Individuals whose ancestral origins are in the continent of Europe.Regression Analysis: Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.Attitude of Health Personnel: Attitudes of personnel toward their patients, other professionals, toward the medical care system, etc.Burning Mouth Syndrome: A group of painful oral symptoms associated with a burning or similar sensation. There is usually a significant organic component with a degree of functional overlay; it is not limited to the psychophysiologic group of disorders.PolandPreventive Dentistry: The branch of dentistry concerned with the prevention of disease and the maintenance and promotion of oral health.TaiwanPeriapical Periodontitis: Inflammation of the PERIAPICAL TISSUE. It includes general, unspecified, or acute nonsuppurative inflammation. Chronic nonsuppurative inflammation is PERIAPICAL GRANULOMA. Suppurative inflammation is PERIAPICAL ABSCESS.Root Resorption: Resorption in which cementum or dentin is lost from the root of a tooth owing to cementoclastic or osteoclastic activity in conditions such as trauma of occlusion or neoplasms. (Dorland, 27th ed)Physician's Practice Patterns: Patterns of practice related to diagnosis and treatment as especially influenced by cost of the service requested and provided.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.Quality of Life: A generic concept reflecting concern with the modification and enhancement of life attributes, e.g., physical, political, moral and social environment; the overall condition of a human life.Survival Analysis: A class of statistical procedures for estimating the survival function (function of time, starting with a population 100% well at a given time and providing the percentage of the population still well at later times). The survival analysis is then used for making inferences about the effects of treatments, prognostic factors, exposures, and other covariates on the function.Survival Rate: The proportion of survivors in a group, e.g., of patients, studied and followed over a period, or the proportion of persons in a specified group alive at the beginning of a time interval who survive to the end of the interval. It is often studied using life table methods.Dental Bonding: An adhesion procedure for orthodontic attachments, such as plastic DENTAL CROWNS. This process usually includes the application of an adhesive material (DENTAL CEMENTS) and letting it harden in-place by light or chemical curing.KuwaitProportional Hazards Models: Statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study population is multiplicative and does not change over time.KentuckyBreast Neoplasms: Tumors or cancer of the human BREAST.Postoperative Complications: Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.Orthodontic Retainers: Orthodontic appliances, fixed or removable, used to maintain teeth in corrected positions during the period of functional adaptation following corrective treatment. These appliances are also used to maintain the positions of the teeth and jaws gained by orthodontic procedures. (From Zwemer, Boucher's Clinical Dental Terminology, 4th ed, p263)African Americans: Persons living in the United States having origins in any of the black groups of Africa.