base (redirected from narrow base)

base (bas)

1. the lowest part or foundation of anything; see also basis.

2. the main ingredient of a compound.

3. in chemistry, a substance that combines with acids to form salts; a substance that dissociates to give hydroxide ions in aqueous solutions; a substance whose molecule or ion can combine with a proton (hydrogen ion); a substance capable of donating a pair of electrons (to an acid) for the formation of a coordinate covalent bond.

4. a unit of a removable dental prosthesis.

5. in genetics, a nucleotide, particularly one in a nucleic acid sequence.

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buffer base  the sum of all the buffer anions in the blood, used as an index of the degree of metabolic disturbance in the acid-base balance.

denture base  the material in which the teeth of a denture are set and which rests on the supporting tissues when the denture is in place in the mouth.

nitrogenous base  an aromatic, nitrogen-containing molecule that serves as a proton acceptor, e.g., purine or pyrimidine.

ointment base  a vehicle for the medicinal substances carried in an ointment.

purine bases  a group of chemical compounds of which purine is the base, including adenine, guanine, hypoxanthine, theobromine, uric acid, and xanthine.

pyrimidine bases  a group of chemical compounds of which pyrimidine is the base, including uracil, thymine, and cytosine.

record base  baseplate.

base of stapes  footplate.

temporary base , trial base baseplate.

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base (bs)

n.

1. The part of an organ nearest its point of attachment.

2. A fundamental ingredient; a chief constituent of a mixture.

3. Any of a large class of compounds, including the hydroxides and oxides of metals, having a bitter taste, a slippery solution, the capacity to turn litmus blue, and to react with acids to form salts.

4. A molecular or ionic substance capable of combining with a proton to form a new substance. Also called Brønsted base.

5. A nitrogen-containing organic compound that combines in such a manner.

6. A substance that provides a pair of electrons for a covalent bond with an acid.

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base,

n 1. a compound that can react with an acid in aqueous solutions to form salts.
2. in aromatherapy, an ingredient specifically prepared to represent a particular natural fragrance source, a blend of natural sources of fragrance sources, or an abstract fragrance concept.

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base,

n 1. the foundation or support on which something rests; the point of attachment of a part; the principal ingredient of a material.
n 2. a compound that yields hydroxyl ions in water solution and causes neutralization of acid to form a salt and water.
3. the part of a denture that supports the prosthetic teeth and receives support from the oral mucosa, anchoring teeth, or alveolar ridge. See also basic. Opposite: acid.

base, acrylic resin,

n a denture base made of an acrylic resin.

base, apical (basal arch),

n the portion of the jawbone that gives support to the teeth.

base, cement,

n a layer of insulated, sometimes medicated dental cement placed in the deep portions of a cavity preparation to protect the pulp, reduce the bulk of the metallic restoration, or eliminate undercuts in a tapered preparation.

base, denture,

n 1. the part of a denture that fits the oral mucosa of the basal seat, restores the normal contours of the soft tissues of the dentulous oral cavity, and supports the artificial teeth.
n 2. the portion of a denture that overlies the soft tissue, usually fabricated of resin or combinations of resins and metal.

base, extension (free-end),

n a unit of a removable prosthesis that extends anteriorly or posteriorly, terminating without end support by a natural tooth.

base, film,

n a thin, flexible, transparent sheet of cellulose acetate or similar material.

base, mandibular,

n the body of the mandible, on which the teeth and alveolar tissues are situated.

base, material,

n a substance from which a denture base may be made (e.g., acrylic resin, vulcanite, polystyrene resin, and metal).

base, metal,

n the basal surface of a denture constructed of metal (e.g., aluminum, gold, and cobalt-chromium) to which the teeth are attached.

base, plastic,

n a denture base, baseplate, or record base made of a plastic material.

base, record,

n See baseplate.

base, shellac,

n a resinous material adapted to maxillary or mandibular casts to form baseplates.

base, sprue,

n See crucible former.

base, temporary,

n See baseplate.

base, tinted denture,

n a denture base that simulates the coloring and shading of natural oral tissues.

base, trial,

n See baseplate.

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base

1. the lowest part or foundation of anything. See also basis.

2. the main ingredient of a compound.

3. a molecule or ion with a tendency to take up a proton according to Bronsted and Lowry theory; a substance that combines with acids to form salts. In the chemical processes of the body, bases are essential to the maintenance of a normal acid-base balance. Excessive concentration of bases in the body fluids leads to alkalosis. See also basal.

4. the primary entity against which all other entities are compared.

5. the non-sugar components of nucleotides in DNA and RNA.

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acid-base pairs

the two molecules forming the matching acid and conjugate base.

base composition

refers to the relative components of a nucleic acid.

conjugate base

the anion or uncharged molecule of an acid once it has given up its proton, e.g. Cl^- is the conjugate base of the acid, HCl.

base deficit

see base excess (below).

base excess

the amount of acid or base required to titrate a sample of whole arterial blood to the normal pH of 7.4. The base excess is determined mathematically by calculations that include measurement of the blood Pco₂ and pH and take into account the hemoglobin level. It is negative (base deficit) in acidosis and positive in alkalosis.

heart base

the wide dorsal part of the heart carrying the atria and the large blood vessels and the attachment to the pericardial sac.

horn base

the widest part of the horn, at its attachment to the skin. In the adult horned animal the horn is hollow at this point, encloses the horn process of the frontal bone and merges with the skin. This is covered with a thin layer of horn similar to the periople of the hoof, called the epiceras.

narrow base

a mandible which is narrow relative to the maxilla; often causes the lower canine teeth to strike the hard palate. See also anisognathism.

nitrogenous base

an aromatic, nitrogen-containing molecule that serves as a proton acceptor, e.g. purine or pyrimidine.

omasal base

faces cranially and to the left where it is attached to the reticulum and the abomasum at the reticulo-omasal and omasoabomasal orifices.

base pair

two hydrogen bonded nucleotides in a DNA or RNA molecule.

purine b's

a group of compounds of which purine is the base, including uric acid, adenine, guanine, xanthine and theobromine.

pyrimidine b's

a group of chemical compounds of which pyrimidine is the base, including uracil, thymine and cytosine, which are common constituents of nucleic acids.

stapedal base

the footplate of the stapes in the middle ear from which the two legs originate. The stapes lies horizontally with the base facing medially and attached to the vestibular window by the annular ligament.