NA: acronym for NAsion; a cephalometric landmark located where the intranasal and nasofrontal sutures meet
nano·me·ter : unit of length to measure the wavelength of light. It is equivalent to 1 x 10-9 M or 10 angstroms. 1 nm
=1/1,000,000 mm
narrative report : a complete description of the clinical findings, diagnosis, and treatment rendered for a given patient
nasal grimace : movements in the tissue of the nares reflecting the attempts of the oronasal system to compensate for palatopharyngeal insufficiency
nasal prosthesis : a removable maxillofacial prosthesis that artificially restores part or the entire nose—syn ARTIFICIAL NOSE
nasal turbulence : the excessive “noise” or air passing over resistance in the nasal passages
nasal septal prosthesis : a maxillofacial prosthesis used to occlude (obturate) a hole within the nasal septal wall—syn SEPTAL BUTTON, SEPTAL PLUG
nasal spine : a sharp bony protuberance of the lower margin of the anterior aperture of the nares formed by the forward prolongation of the two maxillae
nasal stent : a removable intranasal maxillofacial prosthesis used to support the form of the nose
na·sal·i·ty : the quality of speech sounds when the nasal cavity is used as a resonator
nas·ion : a bony cephalometric landmark at which the nasofrontal suture is bisected by the midsagittal plane
nasion relator: an adjustable arbitrary facebow component that engages the outer point of intersection between the nasion-sella line and the soft tissue profile to stabilize the bow while recording the position of the maxillary teeth
nas·o·phar·ynx : the part of the pharynx situated above the soft palate
natural color system : a color order system derived by Anders Hard that defines six color perceptions using the concept of percentage for localizing nuances within the three part system. The six perceptions are white, black, red, green, yellow, and blue. The dimensions of hue, blackness or whiteness, and chrome are used to relate colors within this system
natural dentition: the natural teeth, as considered collectively, in the dental arch, which may be deciduous, permanent, or mixed
natural glaze : the production of a glazed surface by the vitrification of the material itself and without addition of other fluxes or glasses
neck of the condylar process : the constricted inferior portion of the mandibular condylar process that is continuous with the ramus of the mandible; that portion of the condylar process that connects the mandibular ramus to the condyle
ne·cro·sis , pl ne·cro·ses : localized death of living tissue
needlepoint tracing: see CENTRAL BEARING TRACING DEVICE
Nesbit prosthesis [Norman Nesbit, dentist, Boston, Massachusetts, U.S.] obs: eponym for a unilateral partial removable dental prosthesis design that Dr. Nesbit introduced in 1918
neu·ral·gia : neurogenous pain felt along the peripheral distribution of a nerve trunk
neu·ri·tis : inflammation of a nerve
neurogenous pain : pain that is generated within the nervous system as a result of some abnormality of neural structures
neuromuscular dysfunction: a collective term for muscle disorders of the masticatory system with two observable major symptoms: pain and dysfunction. Common observations include muscle fatigue, muscle tightness, myalgia, spasm, headaches, decreased range of motion and acute malocclusion. The five types of masticatory muscle disorders include protective co-contraction (muscle splinting), local muscle soreness (noninflammatory myalgia), myofascial pain (trigger point myalgia), myospasm (tonic contraction myalgia), and chronic centrally mediated myalgia (chronic myositis)
neu·rop·a·thy : a general term used to designate an abnormality or pathologic change in a peripheral nerve
neutral zone : the potential space between the lips and cheeks on one side and the tongue on the other; that area or position where the forces between the tongue and cheeks or lips are equal
neu·tro·oc·clus·ion: see ANGLE’S CLASSIFICATION OF OCCLUSION
nickel-chromium alloy: a low density, large grained base metal dental casting alloy with prominent dendritic structure, composed of up to 30% Cr and 70% Ni with trace elements that may include small amounts of Mo, Mn, Si, C, and Al. Chromium, by its passivation effect insures corrosion resistance of the alloy. Increased nickel content tends to result in reduced strength, hardness, modulus of elasticity and fusion temperature while ductility may increase
ni·dus ; ni·di or ni·dus·es (1742): a place or substance in an animal or plant where bacteria or other organisms lodge and multiply
night guard slang: see OCCLUSAL DEVICE
NMR: acronym for Nuclear Magnetic Resonance; a radiologic procedure that gives images in any plane without radiation or any biologic after effect by picking up signals from resonating hydrogen nuclei
noble metal : those metal elements that resist oxidation, tarnish, and corrosion during heating, casting, or soldering and when used intraorally; examples include gold and platinum—comp BASE METAL
noble metal alloy: as classified by the American Dental Association (1984) any dental casting alloy containing a minimum of 25% by weight of Au, Pt, or/and Pd
no·ci·cep·tive : receiving injury; applicable to a neuron receptive to painful sensations
nociceptive pathway : an afferent neural pathway that mediates pain impulses
no·ci·cep·tor : a sensory receptor preferentially sensitive to noxious or potentially noxious stimuli
nocturnal electromyography : electromyographic registrations made during sleep
nonadjustable articulator: an articulator that does not allow adjustment to replicate mandibular movements—see also CAST RELATOR
nonarcon articulator: 1: any articulator which broadly replicates the three dimensional motions of the left and right condylar compartments 2:any articulator design in which the condylar element (analog) is not part of the lower member of the articulator and may be used to simulate the three dimensional motions of the left and right condylar compartments
nonanatomic teeth : artificial teeth with occlusal surfaces that are not anatomically formed. The term nonanatomic as applied to artificial posterior teeth, and especially their occlusal forms, means that such teeth are designed in accordance with mechanical principles rather than from the viewpoint of anatomic replication. I. R. Hardy, DDS, first introduced nonanatomic teeth with flat occlusal surfaces set to a flat occlusal plane
nonfunctioning condyle: see NONWORKING SIDE CONDYLE
nonpivoting condyle: see NONWORKING SIDE CONDYLE
nonprecious metal: see BASE METAL
non·re·sorb·able : the property exhibited by substances that demonstrate relatively limited in-vivo degradation
nonrigid connector: any connector that permits limited movement between otherwise independent members of a fixed dental prosthesis
nonworking side : that side of the mandible that moves toward the median line in a lateral excursion. The condyle on that side is referred to as the nonworking side condyle
nonworking side condyle : the condyle on the nonworking side
nonworking side condyle path : the path the condyle traverses on the nonworking side when the mandible moves in a lateral excursion, which may be viewed in the three reference planes of the body
nonworking side interference : undesirable contacts of the opposing occlusal surfaces on the nonworking side
nonworking side occlusal contacts : contacts of the teeth on the side opposite to the side toward which the mandible moves in articulation
notch n: see PTERYGOMAXILLARY N.
noxious stimulus : a tissue damaging stimulus
nu·ance , nu·anced adj (1781) 1: a subtle distinction or variation, such as in tone or color 2: a subtle quality3: delicate shading
null detector : a detector of the point at which there is no color difference between two samples. The human eye is an excellent null detector; it is considerably less trustworthy in estimating how large a given difference is
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