Root Canal Filling Materials: Materials placed inside a root canal for the purpose of obturating or sealing it. The materials may be gutta-percha, silver cones, paste mixtures, or other substances. (Dorland, 28th ed, p631 & Boucher's Clinical Dental Terminology, 4th ed, p187)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)Gutta-Percha: Coagulated exudate isolated from several species of the tropical tree Palaquium (Sapotaceae). It is the trans-isomer of natural rubber and is used as a filling and impression material in dentistry and orthopedics and as an insulator in electronics. It has also been used as a rubber substitute.Root Canal Obturation: Phase of endodontic treatment in which a root canal system that has been cleaned is filled through use of special materials and techniques in order to prevent reinfection.Hydrocarbons, IodinatedRoot 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)Calcium Hydroxide: A white powder prepared from lime that has many medical and industrial uses. It is in many dental formulations, especially for root canal filling.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.Zinc Oxide: A mild astringent and topical protectant with some antiseptic action. It is also used in bandages, pastes, ointments, dental cements, and as a sunblock.Epoxy Resins: Polymeric resins derived from OXIRANES and characterized by strength and thermosetting properties. Epoxy resins are often used as dental materials.Tooth, Deciduous: The teeth of the first dentition, which are shed and replaced by the permanent teeth.Dental Leakage: The seepage of fluids, debris, and micro-organisms between the walls of a prepared dental cavity and the restoration.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 Apex: The tip or terminal end of the root of a tooth. (Jablonski, Dictionary of Dentistry, 1992, p62)Retreatment: The therapy of the same disease in a patient, with the same agent or procedure repeated after initial treatment, or with an additional or alternate measure or follow-up. It does not include therapy which requires more than one administration of a therapeutic agent or regimen. Retreatment is often used with reference to a different modality when the original one was inadequate, harmful, or unsuccessful.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)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.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.Periapical Tissue: Tissue surrounding the apex of a tooth, including the apical portion of the periodontal membrane and alveolar bone.Root Canal Irrigants: Chemicals used mainly to disinfect root canals after pulpectomy and before obturation. The major ones are camphorated monochlorophenol, EDTA, formocresol, hydrogen peroxide, metacresylacetate, and sodium hypochlorite. Root canal irrigants include also rinsing solutions of distilled water, sodium chloride, etc.Drug Combinations: Single preparations containing two or more active agents, for the purpose of their concurrent administration as a fixed dose mixture.Retrograde Obturation: Procedure that involves the removal of infectious products from a root canal space through use of special instruments and fillings. This procedure is performed when root canal treatment fails.Dental Instruments: Hand-held tools or implements especially used by dental professionals for the performance of clinical tasks.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.Tooth, Nonvital: A tooth from which the dental pulp has been removed or is necrotic. (Boucher, Clinical Dental Terminology, 4th ed)Calcium Compounds: Inorganic compounds that contain calcium as an integral part of the molecule.Thymol: A phenol obtained from thyme oil or other volatile oils used as a stabilizer in pharmaceutical preparations, and as an antiseptic (antibacterial or antifungal) agent. It was formerly used as a vermifuge.Silicates: The generic term for salts derived from silica or the silicic acids. They contain silicon, oxygen, and one or more metals, and may contain hydrogen. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th Ed)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)Endodontics: A dental specialty concerned with the maintenance of the dental pulp in a state of health and the treatment of the pulp cavity (pulp chamber and pulp canal).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)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.Aluminum Compounds: Inorganic compounds that contain aluminum as an integral part of the molecule.Radiography, Dental: Radiographic techniques used in dentistry.Periapical Diseases: Diseases of the PERIAPICAL TISSUE surrounding the root of the tooth, which is distinguished from DENTAL PULP DISEASES inside the TOOTH ROOT.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)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)Salicylates: The salts or esters of salicylic acids, or salicylate esters of an organic acid. Some of these have analgesic, antipyretic, and anti-inflammatory activities by inhibiting prostaglandin synthesis.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.Bismuth: A metallic element that has the atomic symbol Bi, atomic number 83 and atomic weight 208.98.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)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)Sodium Hypochlorite: It is used as an oxidizing and bleaching agent and as a disinfectant. (From Grant & Hackh's Chemical Dictionary, 5th ed)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.Dental Debonding: Techniques used for removal of bonded orthodontic appliances, restorations, or fixed dentures from teeth.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.Oxides: Binary compounds of oxygen containing the anion O(2-). The anion combines with metals to form alkaline oxides and non-metals to form acidic oxides.Apicoectomy: Excision of the apical portion of a tooth through an opening made in the overlying labial, buccal, or palatal alveolar bone. (Dorland, 28th ed)Semicircular Canals: Three long canals (anterior, posterior, and lateral) of the bony labyrinth. They are set at right angles to each other and are situated posterosuperior to the vestibule of the bony labyrinth (VESTIBULAR LABYRINTH). The semicircular canals have five openings into the vestibule with one shared by the anterior and the posterior canals. Within the canals are the SEMICIRCULAR DUCTS.Mandible: The largest and strongest bone of the FACE constituting the lower jaw. It supports the lower teeth.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)Radiography, Panoramic: Extraoral body-section radiography depicting an entire maxilla, or both maxilla and mandible, on a single film.Dental Soldering: The joining of pieces of metal through the use of an alloy which has a lower melting point, usually at least 100 degrees Celsius below the fusion temperature of the parts being soldered. In dentistry, soldering is used for joining components of a dental appliance, as in assembling a bridge, joining metals to orthodontic bands, or adding to the bulk of certain structures, such as the establishment of proper contact areas on inlays and crowns with adjacent teeth. (Illustrated Dictionary of Dentistry, 1982)Ear Canal: The narrow passage way that conducts the sound collected by the EAR AURICLE to the TYMPANIC MEMBRANE.Apexification: Endodontic procedure performed to induce TOOTH APEX barrier development. ROOT CANAL FILLING MATERIALS are used to repair open apex or DENTAL PULP NECROSIS in an immature tooth. CALCIUM HYDROXIDE and mineral trioxide aggregate are commonly used as the filling materials.Dental Clinics: Facilities where dental care is provided to patients.Spinal Canal: The cavity within the SPINAL COLUMN through which the SPINAL CORD passes.Smear Layer: Adherent debris produced when cutting the enamel or dentin in cavity preparation. It is about 1 micron thick and its composition reflects the underlying dentin, although different quantities and qualities of smear layer can be produced by the various instrumentation techniques. Its function is presumed to be protective, as it lowers dentin permeability. However, it masks the underlying dentin and interferes with attempts to bond dental material to the dentin.Bleaching Agents: Chemicals that are used to oxidize pigments and thus effect whitening.Methylmethacrylates: The methyl esters of methacrylic acid that polymerize easily and are used as tissue cements, dental materials, and absorbent for biological substances.Calcium Sulfate: A calcium salt that is used for a variety of purposes including: building materials, as a desiccant, in dentistry as an impression material, cast, or die, and in medicine for immobilizing casts and as a tablet excipient. It exists in various forms and states of hydration. Plaster of Paris is a mixture of powdered and heat-treated gypsum.Resins, Synthetic: Polymers of high molecular weight which at some stage are capable of being molded and then harden to form useful components.Lasers, Solid-State: Lasers which use a solid, as opposed to a liquid or gas, as the lasing medium. Common materials used are crystals, such as YAG (YTTRIUM aluminum garnet); alexandrite; and CORUNDUM, doped with a rare earth element such as a NEODYMIUM; ERBIUM; or HOLMIUM. The output is sometimes additionally modified by addition of non-linear optical materials such as potassium titanyl phosphate crystal, which for example is used with neodymium YAG lasers to convert the output light to the visible range.Odontometry: Measurement of tooth characteristics.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)Castor Oil: Oil obtained from seeds of Ricinus communis that is used as a cathartic and as a plasticizer.Dental Amalgam: An alloy used in restorative dentistry that contains mercury, silver, tin, copper, and possibly zinc.Dental Materials: Materials used in the production of dental bases, restorations, impressions, prostheses, etc.Pulpectomy: Dental procedure in which the entire pulp chamber is removed from the crown and roots of a tooth.Dental Pulp Diseases: Endodontic diseases of the DENTAL PULP inside the tooth, which is distinguished from PERIAPICAL DISEASES of the tissue surrounding the root.