GPT Terms – O

oblique ridge : the elevation in the enamel that runs obliquely across the occlusal surface of a maxillary molar

ob·tun·dent : an agent or remedy that lessens or relieves pain or sensibility

ob·tu·ra·tor: 1. a maxillofacial prosthesis used to close a congenital or acquired tissue opening, primarily of the hard palate and/or contiguous alveolar/soft tissue structures (GPT7)

2. that component of a prosthesis which fits into and closes a defect within the oral cavity or other body defect

3. a maxillofacial prosthesis used to close, cover or maintain the integrity of the oral and nasal compartments resulting from a congenital, acquired or developmental disease process, i.e., cancer, cleft palate, osteoradionecrosis of the palate. The prosthesis facilitates speech and deglutition by replacing those tissues lost due to the disease process and can, as a result, reduce nasal regurgitation and hypernasal speech, improve articulation, deglutition and mastication. An obturator prosthesis is classified as surgicalinterim or definitive and reflects the intervention time period used in the maxillofacial rehabilitation of the patient. Prosthetic restoration of a defect often includes use of a surgical obturator, interim obturator, and definitive obturator —see DEFINITIVE O., INTERIM O., SURGICAL O.—comp SPEECH AID PROSTHESIS

obturator prosthesis modification : revision or alteration of an existing obturator (surgical, interim, or definitive); possible revisions include relief of the denture base due to tissue compression, augmentation of the seal or border regions to effect adequate sealing or separation between the nasal and oral cavities

oc·clude oc·clud·edoc·clud·ing 1: to bring together; to shut 2: to bring or close the mandibular teeth into contact with the maxillary teeth

occluded gas porosity : porosity produced in castings due to the inability of gasses in the mold to escape

oc·clud·er : a name given to some articulators—see CAST RELATOR

occluding centric relation record : a registration of centric relation made at the established occlusal vertical dimension (GPT-4)

occluding frame : a name given to a device for relating casts to each other for the purpose of arranging teeth (GPT-1)

occluding jaw record : the registration of centric relation made at the occlusal vertical dimension

occluding relation : the jaw relation at which the opposing teeth occlude (GPT-4)

oc·clu·sal: pertaining to the masticatory surfaces of the posterior teeth, prostheses, or occlusion rims

occlusal adjustment 1: any change in the occlusion intended to alter the occluding relation 2: any alteration of the occluding surfaces of the teeth or restorations—see also OCCLUSAL RESHAPING

occlusal analysis: an examination of the occlusion in which the interocclusal relations of mounted casts are evaluated

occlusal balance : a condition in which there are simultaneous contacts of opposing teeth or tooth analogues (i.e., occlusion rims) on both sides of the opposing dental arches during eccentric movements within the functional range

occlusal clearance: see INTEROCCLUSAL CLEARANCE

occlusal contact 1: the touching of opposing teeth on elevation of the mandible 2: any contact relation of opposing teeth—see DEFLECTIVE O.C, INITIAL O.C


occlusal curvature : the curve of the dentition in which the occlusal surfaces lie, when viewed in the frontal and sagittal planes

occlusal device : any removable artificial occlusal surface used for diagnosis or therapy affecting the relationship of the mandible to the maxillae. It may be used for occlusal stabilization, for treatment of temporomandibular disorders, or to prevent wear of the dentition

occlusal disharmony: a phenomenon in which contacts of opposing occlusal surfaces are not in harmony with other tooth contacts and/or the anatomic and physiologic components of the craniomandibular complex

occlusal dysthesia : unusual sensory perceptions during occlusal contact

occlusal embrasure : the interdental space that is coronal to the contact area

occlusal equilibration : the modification of the occlusal form of the teeth with the intent of equalizing occlusal stress, producing simultaneous occlusal contacts or harmonizing cuspal relations

occlusal facet: see WEAR FACET

occlusal force : the result of muscular force applied on opposing teeth; the force created by the dynamic action of the muscles during the physiologic act of mastication; the result of muscular activity applied to opposing teeth

occlusal form : the form the occlusal surface of a tooth or a row of teeth (GPT-4)

occlusal harmony : a condition in centric and eccentric jaw relation in which there are no interceptive or deflective contacts of occluding surfaces (GPT-4)

occlusal interference : any tooth contact that inhibits the remaining occluding surfaces from achieving stable and harmonious contacts

occlusal path 1: a gliding occlusal contact 2: the path of movement of an occlusal surface (GPT-4)

occlusal pattern : the form or design of the masticatory surfaces of a tooth or teeth based on natural, modified anatomic or nonanatomic teeth

occlusal pivot : an elevation placed on the occlusal surface, usually in the molar region, designed to act as a fulcrum, thus limiting mandibular closure and inducing mandibular rotation

occlusal plane 1: the average plane established by the incisal and occlusal surfaces of the teeth. Generally, it is not a plane but represents the planar mean of the curvature of these surfaces 2: the surface of wax occlusion rims contoured to guide in the arrangement of denture teeth 3: a flat metallic plate used in arranging denture teeth—comp to CURVE OF OCCLUSION

occlusal position : the relationship of the mandible and maxillae when the jaw is closed and the teeth are in contact; this position may or may not coincide with centric occlusion (GPT-4)

occlusal prematurity : any contact of opposing teeth that occurs before the planned intercuspation

occlusal pressure : any force exerted on the occlusal surfaces of teeth (GPT-4)

occlusal reduction: the quantity (usually measured in millimeters) of tooth structure that is removed to establish adequate space for a restorative material between the occlusal aspect of the tooth preparation and the opposing dentition

occlusal reshaping : the intentional alteration of the occlusal surfaces of teeth to change their form

occlusal rest : a rigid extension of a partial removable dental prosthesis that contacts the occlusal surface of a tooth or restoration, the occlusal surface of which may have been prepared to receive it—see REST SEAT

occlusal rest arm : a minor connector used to attach an occlusal rest to a major part of a removable partial denture (GPT-1)

occlusal rim: see OCCLUSION RIM

occlusal splint: see OCCLUSAL DEVICE

occlusal stability : the equalization of contacts that prevents tooth movement after closure

occlusal stop: see OCCLUSAL REST

occlusal strength: see MASTICATORY FORCE

occlusal surface : a surface of a posterior tooth or occlusion rim that is intended to make contact with an opposing occlusal surface (GPT-1)

occlusal system : the form or design and arrangement of the occlusal and incised units of a dentition or the teeth on a denture (GPT-4)

occlusal table : the portion of the occlusal surfaces of posterior teeth that lies within the perimeter of the cusp tips and marginal ridges; the functional portion(s) of the occlusal surface(s) of a posterior tooth (teeth)

occlusal trauma : trauma to the periodontium from functional or parafunctional forces causing damage to the attachment apparatus of the periodontium by exceeding its adaptive and reparative capacities. It may be self-limiting or progressive—see PRIMARY O.T., SECONDARY O.T.

occlusal vertical dimension: the distance measured between two points when the occluding members are in contact

occlusal wear : loss of substance on opposing occlusal units or surfaces as the result of attrition or abrasion

occlusion 1: the act or process of closure or of being closed or shut off 2: the static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues—see CENTRIC O., COMPONENTS OF O., ECCENTRIC O., LINE OF O., LINEAR O., MONOPLANE O., PATHOGENIC O., SPHERICAL FORM OF O. —comp ARTICULATION

occlusion analysis : a systematic examination of the masticatory system with special consideration to the effect of tooth occlusion on the teeth and their related structures (GPT-4)

occlusion record : a registration of opposing occluding surfaces made at any maxillomandibular relationship (GPT-4)

occlusion rim : occluding surfaces fabricated on interim or final denture bases for the purpose of making maxillomandibular relation records and arranging teeth—called also record rim

occult cleft palate : a separation of muscle in the soft palate with mucous membrane covering the defect. This is often characterized by a notch in the hard palate, bifurcation of the uvula, displaced musculature, and an attenuated raphe—syn SUBMUCOUS CLEFT PALATE

oc·tant: Latin octant-,octans half quadrant, from octo eight 1: the position or aspect of a celestial body (as the moon or a planet) when halfway between conjunction or opposition and quadrature 2: an instrument used for observing altitudes of a celestial body from a moving ship or aircraft and having a maximum angle of 45 degrees between its reflecting mirrors –comp SEXTANT

ocular prosthesis: a maxillofacial prosthesis that artificially replaces an eye missing as a result of trauma, surgery, or congenital absence. The prosthesis does not replace missing eyelids or adjacent skin, mucosa or muscle—syn ARTIFICIAL EYE, GLASS EYE— comp INTERIM OCULAR PROSTHESIS

o·don·tal·gia : toothache; pain in a tooth

odontogenous pain : deep somatic pain originating in the dental pulp and/or periodontal ligament

o·don·to·graph : a device used to demonstrate irregularities occurring in the surface of tooth enamel

o·don·to·plasty: the reshaping of a portion of a tooth

ol·i·go·don·tia : the formation of less than a full complement of teeth; many such teeth are smaller than normal

on·lay : a restoration that restores one or more cusps and adjoining occlusal surfaces or the entire occlusal surface and is retained by mechanical or adhesive means

onlay graft: augmentation of the height or width of the alveolar ridge with autologous bone or bone substitutes placed beneath the periosteum

o·pac·i·ty : the quality or state of a body that makes it impervious to light

o·paque : the property of a material that absorbs and/or reflects all light and prevents any transmission of light

opaque dentin: modified body porcelain with increased opacity, used where fewer translucencies are required such as in the gingival area of a pontic or incisal mamelon to mimic existing anatomic features of adjacent natural teeth

opaque modifier: colored dental porcelain formulated to be selectively mixed with opaque porcelain to increase the saturation of the desired pigment

opaque porcelain: the first porcelain layer applied in the metal-ceramic technique to the underlying metal framework to establish the bond between the porcelain and metal while simultaneously masking the dark color of the metallic oxide layer. Opaque porcelain provides the primary source of color for the completed restoration


open fracture : any fracture in which there is an external wound leading to a break in the bone; called also compound fracture

open occlusal relationship : the lack of tooth contact in an occluding position—see ANTERIOR O.O.R., POSTERIOR O.O.R.

opening movement : movement of the mandible executed during jaw separation; movement executed during jaw separation (GPT-1)—see ENVELOPE OF MOTION

oral flora : the various bacterial and other microscopic forms of life inhabiting the oral cavity

oral mechanism : the functioning structures of the oral cavity

oral orifice : the longitudinal opening of the mouth between the lips that provides the entrance to the oral cavity

oral mucosa : the lining of the oral cavity

oral orthopedics 1: a concept in dentistry concerned with postural relationships of the jaws, both normal and abnormal2: analysis of the harmful effects of an improper relationship of the mandible and the maxillae on dental and other related structures 3: the diagnosis and correction of such relationships and the treatment and/or prevention of disturbances resulting therefrom

orbital prosthesis : a maxillofacial prosthesis that artificially restores the eye, eyelids, and adjacent hard and soft tissues

orbiting condyle: see NONWORKING SIDE CONDYLE

organ of mastication : the combination of all the structures involved in the reception, mastication, and deglutition of food


or·i·fice : an opening into a body cavity

oronasal fistula : a pathologic opening between the oral and nasal cavities

oro·phar·ynx : the part of the pharynx lying between the soft palate and the upper edge of the epiglottis—called also oral pharynxpars oralis pharyngispharyngo oral cavity, and vestibule of the pharynx

orthodontic band : a metal orthodontic device that holds a bracket or tube and encircles a tooth

orthognathic surgery: surgical repositioning of all or parts of the maxillae or mandible

or·tho·gnath·ous : pertaining to or characterized by minimal protrusion of the mandible or minimal prognathism

orthopedic craniofacial prosthesis : a dynamic orthopedic maxillofacial prosthesis used to maintain or position the craniofacial osseous segments that are malaligned due to trauma or craniofacial anomalies.

orthotic device : a device designed to brace, activate, or supplement a weakened limb or function

os·seo·in·te·gra·tion n [P.I. Branemark, ca. 1982]: see OSSEOUS INTEGRATION

os·se·ous : bony

osseous integration 1: the apparent direct attachment or connection of osseous tissue to an inert, alloplastic material without intervening connective tissue 2: the process and resultant apparent direct connection of an exogenous materials’ surface and the host bone tissues, without intervening fibrous connective tissue present 3: the interface between alloplastic materials and bone

os·si·fi·ca·tion 1: the natural process of bone formation; the hardening into a bony substance 2: a mass of ossified tissue

os·te·i·tis : inflammation of bone

os·te·o·ar·thri·tis : chronic degeneration and destruction of the articular cartilage and/or fibrous connective tissue linings of the joint components and disks, leading to bony spurs, pain, stiffness, limitation of movement, and changes in bone morphology. Advanced conditions may involve erosions and disk degeneration with crepitus—syn DEGENERATIVE JOINT DISEASE

os·te·o·gen·e·sis : development of bone; formation of bone

os·te·o·in·duc·tion : the capability of chemicals, procedures, etc., to induce bone formation through the differentiation and recruitment of osteoblasts

os·te·o·in·te·gra·tion n: see OSSEOUS INTEGRATION

os·te·o·tome : a chisel for use in cutting bone

os·tec·to·my : the excision of bone or a portion of a bone, usually by means of a saw or chisel, for the removal of a sequestrum, the correction of a deformity, or any other purpose

os·te·ot·o·my: the surgical cutting of a bone; frequently used to also describe smoothing, leveling, or altering external contours of the bone- see ALVEOLECTOMY; ALVEOPLASTY

os·teo·po·ro·sis , –ro·ses (1846): a medical condition characterized by a decrease in bone mass with diminished density and concurrent enlargement of bone spaces, which produces porosity and fragility—osteoporotic adj

outline form: the shape of the area of a tooth preparation that is included within the cavosurface margins

ovate pontic: a pontic that is shaped on its tissue surface like an egg in two dimensions, typically partially submerged in a surgically-prepared soft-tissue depression to enhance the illusion that a natural tooth is emerging from the gingival tissues

oven soldering: any soldering procedure using heat from a furnace to melt and refuse the solder as opposed to using a gas-air or gas-oxygen torch as the heat source

o·ver·biteslang: see VERTICAL OVERLAP

o·ver·clo·sure: an occluding vertical dimension at a reduced interarch distance; an occluding vertical dimension that results in excessive interocclusal distance when the mandible is in the rest position; it results in a reduced interridge distance when the teeth are in contact

o·ver·den·ture : any removable dental prosthesis that covers and rests on one or more remaining natural teeth, the roots of natural teeth, and/or dental implants; a dental prosthesis that covers and is partially supported by natural teeth, natural tooth roots, and/or dental implants ___ called also overlay dentureoverlay prosthesissuperimposed prosthesis

o·ver·glaze : the production of a glazed surface by the addition of a fluxed glass that usually vitrifies at a lower temperature

o·ver·hang : excess restorative material projecting beyond a cavity or preparation margin

o·ver·jet n, obs: see HORIZONTAL OVERLAP

o·ver·jut n, obs: see HORIZONTAL OVERLAP

o·ver·lap n, obs (1726): see HORIZONTAL OVERLAP, VERTICAL OVERLAP

overlay denture: see OVERDENTURE

overlay prosthesis: see OVERDENTURE

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