osteoinduction Recruitment of mesenchymal stem cells from the surrounding bed, and their differentiation into osteoblasts. The recruitment and differentiation of cells are modulated by bone morphogenetic proteins. The activity of BMP does not require viable graft cells. It is present not only in autografts, but also in modified allografts.
osteotomy Surgical procedure that involves the cutting of bone.
overbite Vertical overlap of maxillary teeth over mandibular anterior teeth, usually measured perpendicular to the occlusal plane.
overjet Horizontal projection of maxillary teeth beyond the mandibular anterior teeth, usually measured parallel to the occlusal plane. When not otherwise specified, the term is generally assumed to refer to central incisors and is measured from the labial surface of the mandibular tooth to the lingual surface of the maxillary at the level of the edge of the upper incisor. Unique conditions may sometimes require other measuring techniques.
- P -
palate The bone and soft tissue that “closes” the space encompassed by the maxillary alveolar arch. There is a posterior extension to the pharynx. Forms the roof of the mouth and is connected to the nasal septum and floor of the nose in the midline.
hard palate The anterior part of the palate that is supported by and includes the palatal extensions of the maxillary and palatine bones.
velum Posterior appendicular portion of the soft palate.
palatal bar Maxillary lingual appliance, usually transpalatal, connected to the first molars and used to maintain width and increase anchorage.
palatal expansion The lateral movement of the maxillae to increase palatal width.
palpation Digital manipulation and assessment of tissue in physical diagnosis.
panoramic radiograph A radiographic tomograph of the jaws, taken with a specialized machine designed to present a panoramic view of the full circumferential length of the jaws on a single film. Also know by several proprietary brand names of machines, most of which include 'pan' as a part of the name. (Also termed panoral or panorex.)
papilla (interdental) The gingival structure that occupies the space between adjoining teeth.
passivation A process by which metals and alloys are made corrosion resistant through surface treatment. This process usually produces a thin and stable oxide layer on the surface that is protective.
periapical Pertaining to the area and tissues around the apex (tip) of the root of a tooth.
perikymata Small transverse ridges on the surface of the enamel where the prisms of enamel overlap.
perimolysis Decalcification of the teeth from exposure to gastric acid in individuals with chronic vomiting.
periodontal ligament The periodontal membrane which serves a ligamentous function in tooth attachment.
periodontal membrane (or ligament) The fibrous tissue that occupies the space between tooth root and alveolar bone. It provides a ligamentous physical attachment of the tooth to the bone and nourishment to the cementum surface of the root and the cells that permit tooth movement.
periodontal pocket A periodontal disease condition characterized by an abnormally enlarged space between tooth and alveolar bone with destruction of the attaching periodontal membrane and invasion by oral epithelium. Often progressive, it results in bone and tooth loss if not arrested by treatment.
periodontics The dental specially concerned with the maintenance of the health and integrity of the periodontal tissues that support the teeth.
periodontium The investing and supporting tissues of the teeth; the periodontal membrane and alveolar process.
periosteum A membrane that lines the outer surface of all bones, except at the joints of long bones.
permanent dentition Those teeth that succeed the primary teeth and the additional permanent molars.
pharynx That part of the respiratory tract extending from the larynx to the nasal cavity; the throat is a part of the pharynx.
pixel The smallest part of a digitized or Digital Image. It is also used in measuring image size and resolution of a digital image.
pogonion The most anterior point on the chin. A cephalometric landmark in the lateral view.
point A The deepest point in the bony concavity in the midline below the anterior nasal spine. It is often called maxillary apical base. This is a landmark on the lateral cephalometric radiograph.
point B The deepest point in the profile curvature of the mandible from pogonion on the chin to infradentale (junction of alveolar bone and the lower incisors). It is often called mandibular apical base. A landmark on the lateral cephalometric film.
porion The superior surface of the external auditory meatus. In craniometry it is identified as the margin of the bony canal on the skull. In cephalometrics it may be identified from the earpost of the cephalostat (machine porion) or from bony landmarks on the film (anatomical porion).
positioner (tooth positioner) A removable elastic orthodontic appliance molded to teeth when their positions have been altered with a 'setup' made by repositioning the teeth from a plaster cast. The material may be rubber or elastomeric plastic. It is typically used to achieve fine adjustments and retain corrected positions during the finishing stages of treatment.
posterior nasal spine The radiographic image on the lateral cephalogram that denotes the posterior terminus of the palatal plane.
postural rest position The resting position of the mandible in normal posture. See freeway space, rest position.
PPO (Preferred Provider Organization) A formal agreement between a purchaser of a dental benefits program and a defined group of dentists for the delivery of dental services to a specific patient population, as an adjunct to a traditional plan.
preangulated bracket An orthodontic bracket that has its slot inclined to the ordinary mesiodistal direction but permits the generation of second-order action from a passive archwire. See straight-wire.
preventive orthodontic treatment Intended to mitigate the development of a malocclusion. Typical services may include dental restorations, temporary prostheses space maintainers, to replace prematurely lost deciduous teeth and removal of deciduous teeth that fail to shed normally when this might allow their permanent successors to erupt more favorably.
primary dentition See dentition.
proclination Anterior coronal tipping of anterior teeth, as opposed to bodily protrusion, which indicates positional variation.
pronasale Most forward point of the tip of the nose.
proportional limit Highest stress at which stress is directly proportional to strain. It is the highest stress at which the curve in a stress-strain diagram is a straight line. Proportional limit is equal to elastic limit for many metals.
prostaglandins (PG) A member of a group of lipid compounds that are derived enzymatically from fatty acids and have important functions in the human body. They play a role in inflammation and pain that occurs during tooth movement.
prosthion The lowest and most forward point of the alveolar process between the maxillary central incisors.
protraction Anterior displacement of the teeth and/or bones of the face.
protrusion The state of being anteriorly positioned.
proximal segment In surgery, that portion of a sectioned mandible that contains the articulating portion.
pulp (dental) The soft tissue occupying the inner (pulp) chamber of a tooth. Consists of specialized loose connective tissue, blood vessels and nerves.
pure rotation A displacement of a body, produced by couple action, characterized by the center of rotation coinciding with the center of resistance.
- Q -
quadhelix A “W” shaped fixed or removable maxillary expansion lingual arch that incorporates four helices. Usually attached to the maxillary first molar teeth.
- R -
R point (registration point) A cephalometric reference point introduced by Broadbent in his original presentation of the cephalometric technique. It is the midpoint on a perpendicular drawn from the center of sella turcica to the Bolton-nasion line.
radiographA permanent image, typically on film, produced by ionizing radiation. Sometimes called an x-ray after the most common source of image-producing radiation.
radiographic imaging The process of acquiring representations of structures using ionizing radiation.
ramus Paired vertical posterior parts of the mandible that serve as attachment areas for the muscles of mastication and also contain the condyles that articulate with the temporal bones. Plural-rami.
rapid palatal or rapid maxillary expansion (RPE, RME) An orthopedic procedure which uses a fixed or removable appliance to separate the two maxillary bones at the mid-palatine suture.
rare earth screens Intensifying screens that are coated with special compounds to reduce x-ray exposure for cephalometric and panoral films.
reciprocal anchorage The use of equal and opposite equilibrium forces from an appliance to produce desired tooth movement on different teeth.
reference frame A set of two or three intersecting axes, ordinarily mutually perpendicular, used as a basis for location of points and directions of lines, graphically expressing relationships among variables, or undertaking vector analysis, in a plane or in space.
replantation The replacement of a tooth that has been avulsed, usually as the result of an accident.
reproximation (slenderizing) Abrasive elimination of small amounts of enamel from the proximal surfaces of the teeth, in order to reduce combined toothwidth.
resection Surgical removal of part or all of a structure.
root resection Removal of the apical portion of the root of a tooth, usually to eliminate infection.
resilience The amount of energy transferred by mechanical work to take a body from an initial, passive state to its elastic limit; the area under the load-deformation plot up to the elastic limit.
resorption Physiologic or pathologic removal of hard tissue (bone or root).
rest position The normal resting position of the mandible with teeth apart and muscles relaxed.
retainer Any orthodontic appliance, fixed or removable, that is used to maintain the position of the teeth following corrective treatment.
retention The passive treatment period following active orthodontic correction during which retaining appliances may be used.
retraction Pertaining to desired posteriorly directed, orthodontic or orthopedic displacements of teeth or of bones of the face.
retroinclination Lingual (palatal) angulation (inclination) of anterior teeth.
retrognathic A mandible or maxilla that is retruded in its relationship with other facial structures due to a size discrepancy or positional abnormality.
retrusion Teeth or jaws that are posterior to normal position or movement toward the distal.
reverse-pull or protraction headgear An (primarily) extraoral orthodontic or orthopedic appliance designed to deliver force to the dentition that is principally or totally anteriorly directed.
ribbon arch appliance An appliance developed by E.H. Angle prior to the Edgewise appliance which used a rectangular wire in a vertical slot to gain multidirectional control. The bracket was inverted and used by P.R. Begg for his technique.
rigid fixation Stabilization of two bony segments with metal plates or screws to eliminate movement between the parts.
Risk Retention Group (RRG) Formed under the Risk Retention Act of 1986, Risk Retention Groups are corporations or limited liability associations with the purpose of assuming the liability exposure of their members. RRG’s are chartered and licensed as insurance companies in a specific state known as the domiciliary state. A risk retention group must contain the phrase “Risk Retention Group” in its official name. See American Association of Orthodontists Insurance Company (a Risk Retention Group).
roentgenography Production of permanent images through the use of Roentgen rays (x-rays).
root That part of the tooth not covered by enamel. It normally lies within the alveolus where it is attached to the bone by the periodontal membrane (ligament).
root movement The transverse tooth movement characterized by little displacement of the crown and the center of rotation located on the long axis and at or near bracket level.
root resorption Resorption of a part of the root of a tooth. May be either internal (pulpal) or external.
rotation Can occur around any axis. Orthodontic rotation usually refers to motion around the long axis of the tooth.
RRG See Risk Retention Group.
- S -
sagittal splitosteotemy A surgical procedure in which the rami of the mandible are split parallel with the sagittal plane to allow repositioning of the mandibular body either anteriorly or posteriorly into a more favorable relationship with the maxilla.
SARPE Acronym for Surgically Assisted Rapid Palatal Expansion. Used interchangeably with SARME.
SARME Acronym for Surgically Assisted Rapid Maxillary Expansion. Used interchangeably with SARPE.
screen (intensifying) See intensifying screen.
second-order clearance The angle through which an engaged archwire may be tipped within the bracket slot, relative to the 'slot-parallel' configuration, before making contact with the occlusogingival slot surfaces.
second-order rotation A tooth as a whole rotates about a faciolingual axis and the angulation/orientation of the long axis of the tooth changes.
self ligation Specifically used with brackets that have within them the ligation mechanism to hold the wire.
sella-nasion(S-N) A frequently used cephalometric reference line connecting the center of the sella turcica with nasion.
sella turcica (sella; S) The pituitary fossa. The center is used as a cephalometric landmark.
separation An orthodontic procedure for slightly separating teeth to facilitate placing bands.
separator An object/ agent (elastic module, brass wire, spring) used for separating teeth.
serial extraction A program of selective or guided extraction of primary and sometimes permanent teeth over a period of time, with the objective of relieving crowding and facilitating the eruption of remaining teeth into improved positions.
sheath A synonym for a tube used as an orthodontic attachment.
shield See vestibular screen.
sialorrhea Excessive flow of saliva.
sinus Air cavities within the facial bones, lined by mucous membranes similar to those in other parts of the airways.
sleep apnea A temporary suspension of breathing which occurs repeatedly during sleep.
soft palate See palate.
soldering Joining metals by fusion of alloys that have relatively low melting points - most commonly, lead-base or tin-base alloys, which are the soft solders. Hard solders are alloys that have silver, copper or nickel bases. Use of these alloys with melting points higher than 800oF, 427oC is properly called "Brazing".
space maintainer A prosthetic replacement for prematurely lost primary teeth intended to prevent closure of the space before eruption of the permanent successors. Often an urgent necessity in the buccal segment to prevent impaction of the permanent teeth and other complications.
space regainer An appliance that corrects tooth displacement that results from premature loss of one or more primary teeth without timely space maintenance. Effective when the space loss is recent and small. May be accomplished with varying types of corrective appliances. Often most efficiently accomplished as a part of a comprehensive orthodontic treatment plan.
specialist 1. A person with practice limited to diagnosis and treatment of one specific discipline. 2. A healthcare practitioner who devotes attention to a particular class of diseases, patients, etc.
Spee, curve of See curve of Spee.
splint A rigid appliance used to connect and mutually support teeth or bones. A removable form is often used to temporarily relieve occlusal interferences in functional disorders of the temporomandibular joint and related musculature.
spring-back The recovery exhibited by a beam, shaft, wire, or wire loop upon its unloading (deactivation).
stabilizing wire A stiff rectangular archwire that fills the bracket slot and is commonly used to distribute a responsive force system throughout a dental segment.
stiffness The ratio of change in load to accompanying change in deformation of a member fabricated of a Hookean material and activated within its elastic limit; the slope of the load-versus-deformation plot beneath the elastic limit.
stomatognathic system Literally, the mouth-jaw system; the entire complex of structures of the head and neck involved in the functions of mastication, swallowing, respiration and speech.
stomion Intersection of the closed upper and lower lips.
stop A bend or auxiliary attachment placed on or incorporated into a wire to limit its sliding into a tube or into other orthodontic attachments.
straight wireappliance A variation of the edgewise appliance in which brackets are angulated to minimize multiple archwire bends. Brackets and molar tubes have specific orientation in three planes of space.
strain Local unit volumetric or distortional deformation experienced by a nonrigid body or structure subjected to external force.
stress (mechanical) Local intensity of distributed internal force experienced by a body or structure as a response to the application of external force to that body or structure.
stress-relief A heat-treatment process intended to reduce the magnitudes of residual ('locked-in') stresses induced by inelastic deformation.
stripping of teeth Term used for reproximating or slenderizing mesiodistal width of teeth, usually incisors.
subnasale The intersection of the columella of the nose and the upper lip.
subspinale (Downs Point A) The most posterior point in the concavity between the anterior nasal spine and prosthion, i.e., apical base.
subtraction radiography A darkroom technique in radiology which makes important radiographic information easier to see because it subtracts less important information from the image.
succedaneous teeth Those permanent teeth that replace (succeed) the primary teeth which include all the permanent teeth except the permanent molars.
superelastic Refers to a metallic alloy having a relatively substantial elastic range; within a specific range of temperatures, the elastic portion of the force-deformation relationship for the alloy has two distinct, sequential parts because of a (submicroscopic) metallurgic phase-change that occurs as the force-magnitude is increased; a reversal of the phase-change occurs as the magnitude of force is subsequently decreased toward the passive state.
superimposition A technique of placing two roentgenographic tracings upon each other when registering on structures that remain relatively stable during the time period separating the two images useful to evaluate the changes brought about as a result of a growth and/or treatment.
superoinferior The global direction perpendicular to the transverse plane of the dentofacial complex or the occlusal plane of one dental arch; the superior direction/sense is upward, and the inferior direction/sense is downward.
supernumerary teeth Teeth in excess of the normal number. Often malformed or erupting abnormally.
supracrestal fiberotomy The procedure of severing the insertion of the supracrestal group of gingival fibers from the tooth; used as an aid to retain the correction of rotation.
supramentale (Downs point B) The deepest point on the profile curvature from Pogonion to infradentale (i.e., apical base).
supraocclusion Overeruption of a tooth or teeth beyond the normal level, often as a result of tooth-loss or irregularity in the opposing arch.
surgical fixation Stabilization of two bony segments for purposes of improving healing.
suture In anatomy - a fibrous junction between bones, as in the face and skull.
symphysis (mental) The union in the median plane of the two halves of the mandible.
synchondroses Joints that connect two bony structures by hyaline cartilage. As the skeleton matures, the hyaline cartilage eventually ossifies. Examples are the ends of long bones, where the bone growth is not yet complete. In the craniofacial skeleton the speno-occipital synchondroses is of great importance.
syndrome A group of symptoms and/or deformities that occur together in a recognizable pattern that define a specific disease or condition.
- T -
technique (appliance) A method or procedure based upon the use of certain appliances in specific ways. There are numerous variations and combinations.
telescoping bite Total lingual crossbite of the mandibular arch.
temporary anchorage device(TAD) A device that is temporarily fixed to bone for the purpose of enhancing orthodontic anchorage either by supporting the teeth of the reactive unit or by obviating the need for the reactive unit altogether, and which is subsequently removed after use.
temporomandibular articulation The bony articulation between the mandible and the temporal bones which consists of the right and left temporomandibular joints.
TENS Acronym for Transcutaneous Electrical Nerve Stimulation