| PFO | patent foramen ovale |
|---|---|
| DRG | Dorsal Root Ganglia |
| AR | absolute risk; accounts receivable; achievement ratio; actinic reticuloid [syndrome]; active resista... |
| ARA | Academy of Rehabilitative Audiometry; acetylene reduction activity; American Rheumatism Association;... |
| ARR | aortic root replacement |
| 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. (12 Dec 1998) |
|---|---|
| root canal restoration | A gutta-percha, silver, or plastic cone that has been carried into a root canal, either alone or in conjunction with a cement, paste, or solvent, for the purpose of obturating the canal space. (05 Mar 2000) |
| 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. (12 Dec 1998) |
| root canal treatment | The means by which painful or diseased teeth, in which the pulp is involved, are restored to a healthy state, removal of a normal, diseased, or dead pulp by biochemical and mechanical means, enlargement and sterilization of the root canal, followed by filling the canal, to effect healing of diseased periapical tissues, the diagnosis and treatment of diseases of the pulp and their sequelae. Synonym: endodontic treatment. (05 Mar 2000) |
| root cap | <botany> A mass of parenchymtous cells which covers and protects the growing cells at the end of a root; a pileorhiza. The issue found at the apex of roots, overlying the root apical meristem and protecting it from friction as the root grows through the soil. Secretes a glycoprotein mucilage as a lubricant. (18 Nov 1997) |
| root caries | Dental caries involving the tooth root, cementum, or cervical area of the tooth. (12 Dec 1998) |
| root caries index | The ratio of the number of teeth with carious lesions of the root, and/or restorations of the root, to the number of teeth with exposed root surfaces. (05 Mar 2000) |
| root cutting | <botany> Part of a root of a woody plant which, under suitable conditions, takes root and forms a new plant. (09 Oct 1997) |
| root dehiscence | A loss of the buccal or lingual bone overlaying the root portion of a tooth, leaving that area covered by soft tissue only. (05 Mar 2000) |
| root end cyst | An inflammatory odontogenic cyst derived histogenetically from Malassez' epithelial rests surrounding the root apex of a nonvital tooth. Synonym: periapical cyst, radicular cyst, root end cyst. (05 Mar 2000) |
| root end granuloma | Chronic nonsuppurative inflammation of periapical tissue resulting from irritation following pulp disease or endodontic treatment. (12 Dec 1998) |
| root filaments | The small, individual fibre fascicles into which the roots of all of the spinal nerves and several cranial nerves (hypoglossus, vagus, oculomotorius) divide in fanlike fashion before entering or leaving the spinal cord or brainstem; the spinal dorsal root may divide into 8 to 12 such rootlets. Synonym: fila radicularia, root filaments. (05 Mar 2000) |
| root hair cell | <botany> Root epidermal cell, part of which projects from the root surface as a thin tube, thus increasing the root surface area and promoting absorption of water and ions. (18 Nov 1997) |
| root nodule | <plant biology> Globular structure formed on the roots of certain plants, notably legumes and alder, by symbiotic association between the plant and a nitrogen fixing microorganism (Rhizobium in the case of legumes and Frankia in the case of alder and a variety of other plants). (18 Nov 1997) |
| root of facial nerve | <anatomy, nerve> Fibres running from the facial motor nucleus upward to the facial colliculus where they curve around the abducens nucleus and then pass peripherally between the superior olive and sensory nucleus of the trigeminal, to emerge as the facial nerve from the pontomedullary groove. Synonym: radix nervi facialis. (05 Mar 2000) |