Molar, Third: The aftermost permanent tooth on each side in the maxilla and mandible.Mandible: The largest and strongest bone of the FACE constituting the lower jaw. It supports the lower teeth.Tooth, Impacted: A tooth that is prevented from erupting by a physical barrier, usually other teeth. Impaction may also result from orientation of the tooth in an other than vertical position in the periodontal structures.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.Tooth Root: The part of a tooth from the neck to the apex, embedded in the alveolar process and covered with cementum. A root may be single or divided into several branches, usually identified by their relative position, e.g., lingual root or buccal root. Single-rooted teeth include mandibular first and second premolars and the maxillary second premolar teeth. The maxillary first premolar has two roots in most cases. Maxillary molars have three roots. (Jablonski, Dictionary of Dentistry, 1992, p690)Tooth Movement: Orthodontic techniques used to correct the malposition of a single tooth.Tooth, Deciduous: The teeth of the first dentition, which are shed and replaced by the permanent teeth.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)Odontometry: Measurement of tooth characteristics.Tooth Crown: The upper part of the tooth, which joins the lower part of the tooth (TOOTH ROOT) at the cervix (TOOTH CERVIX) at a line called the cementoenamel junction. The entire surface of the crown is covered with enamel which is thicker at the extremity and becomes progressively thinner toward the cervix. (From Jablonski, Dictionary of Dentistry, 1992, p216)Hydatidiform Mole: Trophoblastic hyperplasia associated with normal gestation, or molar pregnancy. It is characterized by the swelling of the CHORIONIC VILLI and elevated human CHORIONIC GONADOTROPIN. Hydatidiform moles or molar pregnancy may be categorized as complete or partial based on their gross morphology, histopathology, and karyotype.Tooth: One of a set of bone-like structures in the mouth used for biting and chewing.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)Radiography, Panoramic: Extraoral body-section radiography depicting an entire maxilla, or both maxilla and mandible, on a single film.Alveolar Process: The thickest and spongiest part of the maxilla and mandible hollowed out into deep cavities for the teeth.Tooth Germ: The collective tissues from which an entire tooth is formed, including the DENTAL SAC; ENAMEL ORGAN; and DENTAL PAPILLA. (From Jablonski, Dictionary of Dentistry, 1992)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 Pulp Cavity: The space in a tooth bounded by the dentin and containing the dental pulp. The portion of the cavity within the crown of the tooth is the pulp chamber; the portion within the root is the pulp canal or root canal.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.Odontogenesis: The process of TOOTH formation. It is divided into several stages including: the dental lamina stage, the bud stage, the cap stage, and the bell stage. Odontogenesis includes the production of tooth enamel (AMELOGENESIS), dentin (DENTINOGENESIS), and dental cementum (CEMENTOGENESIS).Tooth, Unerupted: A normal developing tooth which has not yet perforated the oral mucosa or one that fails to erupt in the normal sequence or time interval expected for the type of tooth in a given gender, age, or population group.Dentin: The hard portion of the tooth surrounding the pulp, covered by enamel on the crown and cementum on the root, which is harder and denser than bone but softer than enamel, and is thus readily abraded when left unprotected. (From Jablonski, Dictionary of Dentistry, 1992)Dental Models: Presentation devices used for patient education and technique training in dentistry.Orthodontic Appliances: Devices used for influencing tooth position. Orthodontic appliances may be classified as fixed or removable, active or retaining, and intraoral or extraoral. (Boucher's Clinical Dental Terminology, 4th ed, p19)Cuspid: The third tooth to the left and to the right of the midline of either jaw, situated between the second INCISOR and the premolar teeth (BICUSPID). (Jablonski, Dictionary of Dentistry, 1992, p817)Tooth Migration: The movement of teeth into altered positions in relationship to the basal bone of the ALVEOLAR PROCESS and to adjoining and opposing teeth as a result of loss of approximating or opposing teeth, occlusal interferences, habits, inflammatory and dystrophic disease of the attaching and supporting structures of the teeth. (From Boucher's Clinical Dental Terminology, 4th ed)Malocclusion, Angle Class II: Malocclusion in which the mandible is posterior to the maxilla as reflected by the relationship of the first permanent molar (distoclusion).Mesial Movement of Teeth: Migration of the teeth toward the midline or forward in the DENTAL ARCH. (From Boucher's Clinical Dental Terminology, 4th ed)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)Periodontal Ligament: The fibrous CONNECTIVE TISSUE surrounding the TOOTH ROOT, separating it from and attaching it to the alveolar bone (ALVEOLAR PROCESS).Cephalometry: The measurement of the dimensions of the HEAD.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)Orthodontic Appliance Design: The planning, calculation, and creation of an apparatus for the purpose of correcting the placement or straightening of teeth.Paleodontology: The study of the teeth of early forms of life through fossil remains.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)Trismus: Spasmodic contraction of the masseter muscle resulting in forceful jaw closure. This may be seen with a variety of diseases, including TETANUS, as a complication of radiation therapy, trauma, or in association with neoplastic conditions.Root Canal Therapy: A treatment modality in endodontics concerned with the therapy of diseases of the dental pulp. For preparatory procedures, ROOT CANAL PREPARATION is available.Tooth Exfoliation: Physiologic loss of the primary dentition. (Zwemer, Boucher's Clinical Dental Terminology, 4th ed)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)Dental Cementum: The bonelike rigid connective tissue covering the root of a tooth from the cementoenamel junction to the apex and lining the apex of the root canal, also assisting in tooth support by serving as attachment structures for the periodontal ligament. (Jablonski, Dictionary of Dentistry, 1992)Pericoronitis: Inflammation of the gingiva surrounding the crown of a tooth.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.OdontoblastsDental 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.Mandibular Nerve: A branch of the trigeminal (5th cranial) nerve. The mandibular nerve carries motor fibers to the muscles of mastication and sensory fibers to the teeth and gingivae, the face in the region of the mandible, and parts of the dura.Ameloblasts: Cylindrical epithelial cells in the innermost layer of the ENAMEL ORGAN. Their functions include contribution to the development of the dentinoenamel junction by the deposition of a layer of the matrix, thus producing the foundation for the prisms (the structural units of the DENTAL ENAMEL), and production of the matrix for the enamel prisms and interprismatic substance. (From Jablonski's Dictionary of Dentistry, 1992)Pulpectomy: Dental procedure in which the entire pulp chamber is removed from the crown and roots of a tooth.Tooth Socket: A hollow part of the alveolar process of the MAXILLA or MANDIBLE where each tooth fits and is attached via the periodontal ligament.Dental Pulp: A richly vascularized and innervated connective tissue of mesodermal origin, contained in the central cavity of a tooth and delimited by the dentin, and having formative, nutritive, sensory, and protective functions. (Jablonski, Dictionary of Dentistry, 1992)Enamel Organ: Epithelial cells surrounding the dental papilla and differentiated into three layers: the inner enamel epithelium, consisting of ameloblasts which eventually form the enamel, and the enamel pulp and external enamel epithelium, both of which atrophy and disappear before and upon eruption of the tooth, respectively.Orthodontic Wires: Wires of various dimensions and grades made of stainless steel or precious metal. They are used in orthodontic treatment.Bite Force: The force applied by the masticatory muscles in dental occlusion.Tooth Apex: The tip or terminal end of the root of a tooth. (Jablonski, Dictionary of Dentistry, 1992, p62)Dentition: The teeth collectively in the dental arch. Dentition ordinarily refers to the natural teeth in position in their alveoli. Dentition referring to the deciduous teeth is DENTITION, PRIMARY; to the permanent teeth, DENTITION, PERMANENT. (From Jablonski, Dictionary of Dentistry, 1992)Dry Socket: A condition sometimes occurring after tooth extraction, particularly after traumatic extraction, resulting in a dry appearance of the exposed bone in the socket, due to disintegration or loss of the blood clot. It is basically a focal osteomyelitis without suppuration and is accompanied by severe pain (alveolalgia) and foul odor. (Dorland, 28th ed)Dental Restoration, Permanent: A restoration designed to remain in service for not less than 20 to 30 years, usually made of gold casting, cohesive gold, or amalgam. (Jablonski, Dictionary of Dentistry, 1992)Tooth Cervix: The constricted part of the tooth at the junction of the crown and root or roots. It is often referred to as the cementoenamel junction (CEJ), the line at which the cementum covering the root of a tooth and the enamel of the tooth meet. (Jablonski, Dictionary of Dentistry, 1992, p530, p433)Orthodontic Anchorage Procedures: Attachment of orthodontic devices and materials to the MOUTH area for support and to provide a counterforce to orthodontic forces.Malocclusion, Angle Class I: Malocclusion in which the mandible and maxilla are anteroposteriorly normal as reflected by the relationship of the first permanent molar (i.e., in neutroclusion), but in which individual teeth are abnormally related to each other.Tooth Eruption, Ectopic: An abnormality in the direction of a TOOTH ERUPTION.Crowns: A prosthetic restoration that reproduces the entire surface anatomy of the visible natural crown of a tooth. It may be partial (covering three or more surfaces of a tooth) or complete (covering all surfaces). It is made of gold or other metal, porcelain, or resin.Orthodontics, Corrective: The phase of orthodontics concerned with the correction of malocclusion with proper appliances and prevention of its sequelae (Jablonski's Illus. Dictionary of Dentistry).Kinetics: The rate dynamics in chemical or physical systems.Dental Sac: Dense fibrous layer formed from mesodermal tissue that surrounds the epithelial enamel organ. The cells eventually migrate to the external surface of the newly formed root dentin and give rise to the cementoblasts that deposit cementum on the developing root, fibroblasts of the developing periodontal ligament, and osteoblasts of the developing alveolar bone.Dental Stress Analysis: The description and measurement of the various factors that produce physical stress upon dental restorations, prostheses, or appliances, materials associated with them, or the natural oral structures.Tooth Abnormalities: Congenital absence of or defects in structures of the teeth.Root Canal Preparation: Preparatory activities in ROOT CANAL THERAPY by partial or complete extirpation of diseased pulp, cleaning and sterilization of the empty canal, enlarging and shaping the canal to receive the sealing material. The cavity may be prepared by mechanical, sonic, chemical, or other means. (From Dorland, 28th ed, p1700)Mandibular Fractures: Fractures of the lower jaw.Dental Alloys: A mixture of metallic elements or compounds with other metallic or metalloid elements in varying proportions for use in restorative or prosthetic dentistry.Mandibular DiseasesDental Enamel Hypoplasia: An acquired or hereditary condition due to deficiency in the formation of tooth enamel (AMELOGENESIS). It is usually characterized by defective, thin, or malformed DENTAL ENAMEL. Risk factors for enamel hypoplasia include gene mutations, nutritional deficiencies, diseases, and environmental factors.Tooth Mobility: Horizontal and, to a lesser degree, axial movement of a tooth in response to normal forces, as in occlusion. It refers also to the movability of a tooth resulting from loss of all or a portion of its attachment and supportive apparatus, as seen in periodontitis, occlusal trauma, and periodontosis. (From Jablonski, Dictionary of Dentistry, 1992, p507 & Boucher's Clinical Dental Terminology, 4th ed, p313)Mastication: The act and process of chewing and grinding food in the mouth.Amelogenesis: The elaboration of dental enamel by ameloblasts, beginning with its participation in the formation of the dentino-enamel junction to the production of the matrix for the enamel prisms and interprismatic substance. (Jablonski, Dictionary of Dentistry, 1992).Cone-Beam Computed Tomography: Computed tomography modalities which use a cone or pyramid-shaped beam of radiation.Glass Ionomer Cements: A polymer obtained by reacting polyacrylic acid with a special anion-leachable glass (alumino-silicate). The resulting cement is more durable and tougher than others in that the materials comprising the polymer backbone do not leach out.Inlays: Restorations of metal, porcelain, or plastic made to fit a cavity preparation, then cemented into the tooth. Onlays are restorations which fit into cavity preparations and overlay the occlusal surface of a tooth or teeth. Onlays are retained by frictional or mechanical factors.Trigeminal Nerve Injuries: Traumatic injuries to the TRIGEMINAL NERVE. It may result in extreme pain, abnormal sensation in the areas the nerve innervates on face, jaw, gums and tongue and can cause difficulties with speech and chewing. It is sometimes associated with various dental treatments.Dentin-Bonding Agents: Cements that act through infiltration and polymerization within the dentinal matrix and are used for dental restoration. They can be adhesive resins themselves, adhesion-promoting monomers, or polymerization initiators that act in concert with other agents to form a dentin-bonding system.Space MaintenanceDental 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.Radiography, Dental, Digital: A rapid, low-dose, digital imaging system using a small intraoral sensor instead of radiographic film, an intensifying screen, and a charge-coupled device. It presents the possibility of reduced patient exposure and minimal distortion, although resolution and latitude are inferior to standard dental radiography. A receiver is placed in the mouth, routing signals to a computer which images the signals on a screen or in print. It includes digitizing from x-ray film or any other detector. (From MEDLINE abstracts; personal communication from Dr. Charles Berthold, NIDR)Tooth Wear: Loss of the tooth substance by chemical or mechanical processesResin 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)Materials Testing: The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.Molecular Weight: The sum of the weight of all the atoms in a molecule.Alveolar Bone Loss: Resorption or wasting of the tooth-supporting bone (ALVEOLAR PROCESS) in the MAXILLA or MANDIBLE.Tooth Attrition: The wearing away of a tooth as a result of tooth-to-tooth contact, as in mastication, occurring only on the occlusal, incisal, and proximal surfaces. It is chiefly associated with aging. It is differentiated from TOOTH ABRASION (the pathologic wearing away of the tooth substance by friction, as brushing, bruxism, clenching, and other mechanical causes) and from TOOTH EROSION (the loss of substance caused by chemical action without bacterial action). (Jablonski, Dictionary of Dentistry, 1992, p86)Pit and Fissure Sealants: Agents used to occlude dental enamel pits and fissures in the prevention of dental caries.Diastema: An abnormal opening or fissure between two adjacent teeth.Carticaine: A thiophene-containing local anesthetic pharmacologically similar to MEPIVACAINE.Dentigerous Cyst: Most common follicular odontogenic cyst. Occurs in relation to a partially erupted or unerupted tooth with at least the crown of the tooth to which the cyst is attached protruding into the cystic cavity. May give rise to an ameloblastoma and, in rare instances, undergo malignant transformation.Radiography, Dental: Radiographic techniques used in dentistry.Age Determination by Teeth: A means of identifying the age of an animal or human through tooth examination.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Dental Pulp Capping: Application of a protective agent to an exposed pulp (direct capping) or the remaining thin layer of dentin over a nearly exposed pulp (indirect capping) in order to allow the pulp to recover and maintain its normal vitality and function.Composite Resins: Synthetic resins, containing an inert filler, that are widely used in dentistry.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)Dental Restoration Failure: Inability or inadequacy of a dental restoration or prosthesis to perform as expected.Dentinogenesis: The formation of dentin. Dentin first appears in the layer between the ameloblasts and odontoblasts and becomes calcified immediately. Formation progresses from the tip of the papilla over its slope to form a calcified cap becoming thicker by the apposition of new layers pulpward. A layer of uncalcified dentin intervenes between the calcified tissue and the odontoblast and its processes. (From Jablonski, Dictionary of Dentistry, 1992)Lingual Nerve Injuries: Traumatic injuries to the LINGUAL NERVE. It may be a complication following dental treatments.Extraoral Traction Appliances: Extraoral devices for applying force to the dentition in order to avoid some of the problems in anchorage control met with in intermaxillary traction and to apply force in directions not otherwise possible.Maxillary DiseasesPhotography, Dental: Photographic techniques used in ORTHODONTICS; DENTAL ESTHETICS; and patient education.Pulpotomy: Dental procedure in which part of the pulp chamber is removed from the crown of a tooth.Liposomes: Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.Uterine Neoplasms: Tumors or cancer of the UTERUS.Phosphatidylcholines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Palate, Hard: The anteriorly located rigid section of the PALATE.Dental Pulp Exposure: The result of pathological changes in the hard tissue of a tooth caused by carious lesions, mechanical factors, or trauma, which render the pulp susceptible to bacterial invasion from the external environment.Decalcification Technique: Removal of minerals from bones during bone examination.Serial Extraction: The selective extraction of deciduous teeth during the stage of mixed dentition in accordance with the shedding and eruption of the teeth. It is done over an extended period to allow autonomous adjustment to relieve crowding of the dental arches during the eruption of the lateral incisors, canines, and premolars, eventually involving the extraction of the first premolar teeth. (Dorland, 28th ed)Dental Pulp CalcificationDenture, Partial, Fixed: A partial denture attached to prepared natural teeth, roots, or implants by cementation.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.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Spectrophotometry: The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.Dental Enamel Proteins: The proteins that are part of the dental enamel matrix.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Dental Implants, Single-Tooth: Devices, usually alloplastic, surgically inserted into or onto the jawbone, which support a single prosthetic tooth and serve either as abutments or as cosmetic replacements for missing teeth.Jaw Relation Record: A registration of any positional relationship of the mandible in reference to the maxillae. These records may be any of the many vertical, horizontal, or orientation relations. (Jablonski, Illustrated Dictionary of Dentistry)Overbite: A malocclusion in which maxillary incisor and canine teeth project over the mandiblar teeth excessively. The overlap is measured perpendicular to the occlusal plane and is also called vertical overlap. When the overlap is measured parallel to the occlusal plane it is referred to as overjet.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Dental Occlusion, Centric: Contact between opposing teeth during a person's habitual bite.Tooth, Supernumerary: An extra tooth, erupted or unerupted, resembling or unlike the other teeth in the group to which it belongs. Its presence may cause malposition of adjacent teeth or prevent their eruption.Periodontal Cyst: An epithelium-lined sac containing fluid; usually found at the apex of a pulp-involved tooth. The lateral type occurs less frequently along the side of the root.Tooth Calcification: The process whereby calcium salts are deposited in the dental enamel. The process is normal in the development of bones and teeth. (Boucher's Clinical Dental Terminology, 4th ed, p43)Amelogenin: A major dental enamel-forming protein found in mammals. In humans the protein is encoded by GENES found on both the X CHROMOSOME and the Y CHROMOSOME.Maxillofacial Development: The process of growth and differentiation of the jaws and face.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Epithelial Attachment: A wedge-shaped collar of epithelial cells which form the attachment of the gingiva to the tooth surface at the base of the gingival crevice.Rubber Dams: Sheets of latex rubber punched and placed over the teeth during dental procedures to isolate the field of operation from the rest of the oral cavity (Jablonski; Illustrated Dictionary of Dentistry, 1982). Rubber dams are useful in preventing the swallowing of instruments or restorations during dental work.Bisphenol A-Glycidyl Methacrylate: The reaction product of bisphenol A and glycidyl methacrylate that undergoes polymerization when exposed to ultraviolet light or mixed with a catalyst. It is used as a bond implant material and as the resin component of dental sealants and composite restorative materials.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.Spectrophotometry, Ultraviolet: Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Chromatography, Gel: Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.Palatal Expansion Technique: An orthodontic method used for correcting narrow or collapsed maxillary arches and functional cross-bite. (From Jablonski's Dictionary of Dentistry),Rumen: The first stomach of ruminants. It lies on the left side of the body, occupying the whole of the left side of the abdomen and even stretching across the median plane of the body to the right side. It is capacious, divided into an upper and a lower sac, each of which has a blind sac at its posterior extremity. The rumen is lined by mucous membrane containing no digestive glands, but mucus-secreting glands are present in large numbers. Coarse, partially chewed food is stored and churned in the rumen until the animal finds circumstances convenient for rumination. When this occurs, little balls of food are regurgitated through the esophagus into the mouth, and are subjected to a second more thorough mastication, swallowed, and passed on into other parts of the compound stomach. (From Black's Veterinary Dictionary, 17th ed)Dental Fissures: Deep grooves or clefts in the surface of teeth equivalent to class 1 cavities in Black's classification of dental caries.Gingival DiseasesFermentation: Anaerobic degradation of GLUCOSE or other organic nutrients to gain energy in the form of ATP. End products vary depending on organisms, substrates, and enzymatic pathways. Common fermentation products include ETHANOL and LACTIC ACID.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Dental Marginal Adaptation: The degree of approximation or fit of filling material or dental prosthetic to the tooth surface. A close marginal adaptation and seal at the interface is important for successful dental restorations.Water: A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Phospholipids: Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.Dentin Permeability: The property of dentin that permits passage of light, heat, cold, and chemical substances. It does not include penetration by microorganisms.Chemistry: A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.Open Bite: A condition in which certain opposing teeth fail to establish occlusal contact when the jaws are closed.Fatty Acids, Volatile: Short-chain fatty acids of up to six carbon atoms in length. They are the major end products of microbial fermentation in the ruminant digestive tract and have also been implicated in the causation of neurological diseases in humans.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Dental Instruments: Hand-held tools or implements especially used by dental professionals for the performance of clinical tasks.Zinc Oxide-Eugenol Cement: Used as a dental cement this is mainly zinc oxide (with strengtheners and accelerators) and eugenol. (Boucher's Clinical Dental Terminology, 4th ed, p50)Periodontium: The structures surrounding and supporting the tooth. Periodontium includes the gum (GINGIVA), the alveolar bone (ALVEOLAR PROCESS), the DENTAL CEMENTUM, and the PERIODONTAL LIGAMENT.Phytic Acid: Complexing agent for removal of traces of heavy metal ions. It acts also as a hypocalcemic agent.Chemical Phenomena: The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.Dental Service, Hospital: Hospital department providing dental care.Nickel: A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.Dentin, Secondary: Dentin formed by normal pulp after completion of root end formation.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.Carbohydrates: The largest class of organic compounds, including STARCH; GLYCOGEN; CELLULOSE; POLYSACCHARIDES; and simple MONOSACCHARIDES. Carbohydrates are composed of carbon, hydrogen, and oxygen in a ratio of Cn(H2O)n.Dental Abutments: Natural teeth or teeth roots used as anchorage for a fixed or removable denture or other prosthesis (such as an implant) serving the same purpose.X-Ray Film: A film base coated with an emulsion designed for use with x-rays.Forensic Dentistry: The application of dental knowledge to questions of law.Phosphoric Acids: Inorganic derivatives of phosphoric acid (H3PO4). Note that organic derivatives of phosphoric acids are listed under ORGANOPHOSPHATES.Tooth Loss: The failure to retain teeth as a result of disease or injury.Dental Caries Activity Tests: Diagnostic tests conducted in order to measure the increment of active DENTAL CARIES over a period of time.Orthodontic Appliances, Functional: Loose, usually removable intra-oral devices which alter the muscle forces against the teeth and craniofacial skeleton. These are dynamic appliances which depend on altered neuromuscular action to effect bony growth and occlusal development. They are usually used in mixed dentition to treat pediatric malocclusions. (ADA, 1992)Sodium Hypochlorite: It is used as an oxidizing and bleaching agent and as a disinfectant. (From Grant & Hackh's Chemical Dictionary, 5th ed)Palate: The structure that forms the roof of the mouth. It consists of the anterior hard palate (PALATE, HARD) and the posterior soft palate (PALATE, SOFT).Oral Surgical Procedures: Surgical procedures used to treat disease, injuries, and defects of the oral and maxillofacial region.Titanium: A dark-gray, metallic element of widespread distribution but occurring in small amounts; atomic number, 22; atomic weight, 47.90; symbol, Ti; specific gravity, 4.5; used for fixation of fractures. (Dorland, 28th ed)Periapical 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.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Maxillary Sinus: The air space located in the body of the MAXILLARY BONE near each cheek. Each maxillary sinus communicates with the middle passage (meatus) of the NASAL CAVITY on the same side.Toothache: Pain in the adjacent areas of the teeth.Vertical Dimension: The length of the face determined by the distance of separation of jaws. Occlusal vertical dimension (OVD or VDO) or contact vertical dimension is the lower face height with the teeth in centric occlusion. Rest vertical dimension (VDR) is the lower face height measured from a chin point to a point just below the nose, with the mandible in rest position. (From Jablonski, Dictionary of Dentistry, 1992, p250)Macromolecular Substances: Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.Lipid Bilayers: Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.Pain, Postoperative: Pain during the period after surgery.Dental Pulp Necrosis: Death of pulp tissue with or without bacterial invasion. When the necrosis is due to ischemia with superimposed bacterial infection, it is referred to as pulp gangrene. When the necrosis is non-bacterial in origin, it is called pulp mummification.Dental Papilla: Mesodermal tissue enclosed in the invaginated portion of the epithelial enamel organ and giving rise to the dentin and pulp.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.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)Plastic Embedding: The infiltrating of histological specimens with plastics, including acrylic resins, epoxy resins and polyethylene glycol, for support of the tissues in preparation for sectioning with a microtome.Dental Leakage: The seepage of fluids, debris, and micro-organisms between the walls of a prepared dental cavity and the restoration.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.X-Ray Intensifying Screens: Screens which absorb the energy in the x-ray beam that has penetrated the patient and convert this energy into a light pattern which has as nearly as possible the same information as the original x-ray beam. The more light a screen produces for a given input of x-radiation, the less x-ray exposure and thus shorter exposure time are needed to expose the film. In most film-screen systems, the film is sandwiched between two screens in a cassette so that the emulsion on each side is exposed to the light from its contiguous screen.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.Zygoma: Either of a pair of bones that form the prominent part of the CHEEK and contribute to the ORBIT on each side of the SKULL.Dental Pulp Test: Investigations conducted on the physical health of teeth involving use of a tool that transmits hot or cold electric currents on a tooth's surface that can determine problems with that tooth based on reactions to the currents.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Dental Prosthesis Design: The plan and delineation of dental prostheses in general or a specific dental prosthesis. It does not include DENTURE DESIGN. The framework usually consists of metal.Nasal Bone: Either one of the two small elongated rectangular bones that together form the bridge of the nose.Trophoblastic Neoplasms: Trophoblastic growth, which may be gestational or nongestational in origin. Trophoblastic neoplasia resulting from pregnancy is often described as gestational trophoblastic disease to distinguish it from germ cell tumors which frequently show trophoblastic elements, and from the trophoblastic differentiation which sometimes occurs in a wide variety of epithelial cancers. Gestational trophoblastic growth has several forms, including HYDATIDIFORM MOLE and CHORIOCARCINOMA. (From Holland et al., Cancer Medicine, 3d ed, p1691)Dental Amalgam: An alloy used in restorative dentistry that contains mercury, silver, tin, copper, and possibly zinc.X-Ray Microtomography: X-RAY COMPUTERIZED TOMOGRAPHY with resolution in the micrometer range.Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.