Radicular Cyst: Slow-growing fluid-filled epithelial sac at the apex of a tooth with a nonvital pulp or defective root canal filling.Odontogenic Cysts: Cysts found in the jaws and arising from epithelium involved in tooth formation. They include follicular cysts (e.g., primordial cyst, dentigerous cyst, multilocular cyst), lateral periodontal cysts, and radicular cysts. They may become keratinized (odontogenic keratocysts). Follicular cysts may give rise to ameloblastomas and, in rare cases, undergo malignant transformation.Maxillary DiseasesDentigerous 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.Mandibular DiseasesAmeloblastoma: An immature epithelial tumor of the JAW originating from the epithelial rests of Malassez or from other epithelial remnants of the ENAMEL from the developmental period. It is a slowly growing tumor, usually benign, but displays a marked propensity for invasive growth.Cyst Fluid: Liquid material found in epithelial-lined closed cavities or sacs.Periapical Granuloma: Chronic nonsuppurative inflammation of periapical tissue resulting from irritation following pulp disease or endodontic treatment.Jaw Neoplasms: Cancers or tumors of the MAXILLA or MANDIBLE unspecified. For neoplasms of the maxilla, MAXILLARY NEOPLASMS is available and of the mandible, MANDIBULAR NEOPLASMS is available.Cysts: Any fluid-filled closed cavity or sac that is lined by an EPITHELIUM. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues.Radiculopathy: Disease involving a spinal nerve root (see SPINAL NERVE ROOTS) which may result from compression related to INTERVERTEBRAL DISK DISPLACEMENT; SPINAL CORD INJURIES; SPINAL DISEASES; and other conditions. Clinical manifestations include radicular pain, weakness, and sensory loss referable to structures innervated by the involved nerve root.Jaw DiseasesTooth, Deciduous: The teeth of the first dentition, which are shed and replaced by the permanent teeth.Ovarian Cysts: General term for CYSTS and cystic diseases of the OVARY.Epidermal Cyst: Intradermal or subcutaneous saclike structure, the wall of which is stratified epithelium containing keratohyalin granules.Spinal Nerve Roots: Paired bundles of NERVE FIBERS entering and leaving the SPINAL CORD at each segment. The dorsal and ventral nerve roots join to form the mixed segmental spinal nerves. The dorsal roots are generally afferent, formed by the central projections of the spinal (dorsal root) ganglia sensory cells, and the ventral roots are efferent, comprising the axons of spinal motor and PREGANGLIONIC AUTONOMIC FIBERS.Sciatica: A condition characterized by pain radiating from the back into the buttock and posterior/lateral aspects of the leg. Sciatica may be a manifestation of SCIATIC NEUROPATHY; RADICULOPATHY (involving the SPINAL NERVE ROOTS; L4, L5, S1, or S2, often associated with INTERVERTEBRAL DISK DISPLACEMENT); or lesions of the CAUDA EQUINA.Synovial Cyst: Non-neoplastic tumor-like lesions at joints, developed from the SYNOVIAL MEMBRANE of a joint through the JOINT CAPSULE into the periarticular tissues. They are filled with SYNOVIAL FLUID with a smooth and translucent appearance. A synovial cyst can develop from any joint, but most commonly at the back of the knee, where it is known as POPLITEAL CYST.Injections, Epidural: The injection of drugs, most often analgesics, into the spinal canal without puncturing the dura mater.