2016 Glossary - 47
airflow through the nasal passages and to reduce
nasal turbulence n: air that is forced through a small
opening in the nasal passages causing movement
of secretions above the opening resulting in a rustling-like noise.
nasality n: the quality of speech sounds when the
sounds are produced as a result of the nasal cavity
being used as a resonator.
nasion n: on the human skull, it is the point at which the
midsagittal plane bisects the intersection between
the nasal bones and the frontal bone. It is used as a
landmark on cephalometric radiographs.
nasopharynx n: the portion of the pharynx that is superior to the soft palate.
Natural Color System n: six elementary colors are the
basis for the Natural Color System: white, black, yellow, red, blue, and green. The system uses percentages of individual component colors to determine
necrosis n: the death of cells by unprogrammed methods as opposed to apoptosis, which is a programmed
death. Pyknosis (shrunken and hyperkeratosis or
darkened basophilic nuclear staining), karyolysis
(swollen and pale basophilic nuclear staining), and
karyorrhexis (nuclear rupture or fragmentation) are
typical events in necrosis of cells. The release of intracellular contents leads to an inflammatory response.
necrotizing ulcerative periodontitis n: see under
nerve fiber n: see under fiber.
neuritis n: inflammation of the nerve(s).
neurogenous pain n: pain caused by abnormalities in
the structure of nerves that innervate affected areas. Pain can occur with nociception. The pain is frequently described as burning or sharp. A sensation
may occur along the pathway of the nerve. While the
patient may locate the pain, the apparent area may
not be the source, and the severity of the pain is usually more intense than expected given the degree of
neuropathy n: an assortment of neuronal pathological
conditions that occur as a consequence of trauma,
infections, metabolic disorders, or exposure to toxins
that induce injury to the nerve axons of the peripheral nervous system. Neuropathy typically induces
pain and numbness in the affected area.
neutral zone n: the potential intraoral space where
denture teeth should be preferably located, so the
function of the musculature will not unseat the denture and forces generated by the tongue are counterbalanced by the forces produced by the lips and
nickel-chromium alloy n: dental casting alloys made
primarily of nickel 70% and chromium 30% with
trace amounts of molybdenum, manganese, silicon, carbon, and aluminum. The greater the nickel
content, the more ductile the alloy; however, its
strength, hardness, modulus of elasticity, and fusion
temperature are adversely affected. Chromium, by
its passivation effect, ensures corrosion resistance of
nidus n: (1) a central point or focus where a morbid process begins; (2) nucleus or center.
night guard n: see occlusal guard.
noble metal n: a metal consisting of elements that resist oxidation and corrosion in a moist or humid environment; see also base metal.
noble metal alloy n: a dental casting material that
consists of gold, palladium, and silver with lesser
amounts of iridium, ruthenium, and platinum. These
metal alloys are used for inlays, onlays, complete
metal crowns, and backings for ceramic baking.
nociceptive adj: caused by or responding to a painful
nociceptive pathway n: an afferent neural path (conduit) initiating at a peripheral site in the body and
ending in the central nervous system's somatosensory cortex where the original peripheral stimulus is
perceived as pain.
nociceptor n: a sensory receptor that is activated by
nodule n: a small solid mass of tissue collection; a knot
or aggregation of cells that can be easily felt by touch.
nonadjustable articulator n: an articulator that has
limited hinge opening and closing arcs about a fixed