Bloomfield Hills, MI (Michigan) Orthodontist Roy D. McAnnally, MS, PHD, DMD

A B C D E F G H I J L M N O P R S T U V W X

AAO See American Association of Orthodontists.

abutment The teeth on either side of a missing tooth.

acrylic An organic resin, usually methyl methacrylate, commonly used for the construction of dental appliances, including orthodontic treatment and retention appliances.

activation The process of deforming an orthodontic component from its passive state, e.g., stretching elastic rubber bands or engaging a deformed arch wire in brackets to transmit force to the dentition.

Adams clasp A circumferential clasp engaged in mesiobuccal and distobuccal undercuts of individual teeth used to stabilize removable appliances.

alveolar bone The bone that surrounds and supports the roots of the teeth.

alveolar process The ridge of maxillary or mandibular bone that surrounds and supports the roots of the teeth.

amalgam A silver and mercury mixture which is used for filling decayed teeth.

American Association of Orthodontists (AAO) The AAO is a professional association of educationally qualified orthodontic specialists dedicated to advancing the art and science of orthodontics and dentofacial orthopedics, improving the health of the public by promoting quality orthodontic care, and supporting the successful practice of orthodontics.

anatomy The arrangement of the bones in the skeleton. Also the study of the arrangement of the bones in the skeleton.

anchorage A means of resisting unwanted tooth movement caused by the application of orthodontic force. Anchorage refers to the intraoral and extraoral structures that supply the resistance to unwanted tooth movement. Anchorage may be provided by intraoral structures, teeth, bone, and soft tissue, or by extraoral head gear.

Angle’s classification of malocclusion A classification of malocclusion introduced by Edward H. Angle. The governing criterion is the anteroposterior relationship of the upper and lower first permanent molars.

Angle’s Class I malocclusion A malocclusion with correct mesiodistal relationships of the first permanent molars. The mesiobuccal cusp of the maxillary first permanent molar occludes in the buccal groove of the mandibular first permanent molar. Class I is sometimes incorrectly used as a synonym for normal occlusion. However, Class I only signifies a normal sagittal relationship of upper and lower first molars. Class I malocclusions, though normal sagittally, can be abnormal in many other respects. For example, there can be excessive spacing, crowding, and rotations of teeth, excessive bite depth, crossbite, or anterior openbite.

Angle’s Class II malocclusion A malocclusion in which the lower first permanent molar is positioned distally relative to the opposing upper first permanent molar. A distal or posterior placement of the lower first permanent molar; a mesial or anterior relationship of the upper first permanent molar; or a combination of the two will result in a Class II malocclusion. The mesiobuccal cusp of the upper first permanent molar occludes mesial to the buccal groove of the lower first permanent molar, usually near the embrasure between the lower first permanent molar and second bicuspid. To classify a unilateral Class II malocclusion see subdivision.

Angle’s Class II, Division 1 An Angle Class II molar relationship in which the upper incisors are flared, proclined or positioned forward in relation to the lower incisors. This results in a marked overjet.
Angle’s Class II, Division 2 An Angle Class II molar malocclusion in which the maxillary central incisors are in close relationship to the lower incisors. Typically, upper central incisors are tipped lingually, upper lateral incisors tipped labially, and the overbite is excessive. Subdivision denotes a unilateral malocclusion, e.g., Class II, division 2, subdivision right or left.

Angle’s Class III malocclusion A malocclusion in which the lower first permanent molar is positioned mesially relative to the upper first permanent molar. A mesial or anterior relationship of the lower first permanent molar to the upper first permanent molar; a distal or posterior relationship of the upper first permanent molar to the lower first permanent molar; or a combination of the two will result in a Class III malocclusion. The mesiobuccal cusp of the upper first permanent molar will typically occlude near the embrasure between the lower first and second permanent molars.

angulation The tilt of the long axis of a tooth in a mesial or distal direction. Contrast this with inclination in which the tilt of the long axis of a tooth is in the buccolingual or faciolingual direction.

ankylosis Abnormal immobility, union or fusion. Ankylosis can occur between two bones at their articulation or between teeth and supporting alveolar bone. Pathologic fusion of the temporal bone and mandible at their articulating surfaces would result in ankylosis or abnormal immobility of the TMJ. More commonly fusion occurs between teeth and alveolar bone. In such a case, the periodontal ligament is obliterated by a ‘bony bridge’ and the tooth root is fused to the alveolar bone. Dental ankylosis prevents both eruption and orthodontic movement. In a growing child, an ankylosed tooth appears to ‘submerge’ as adjacent unaffected teeth and alveolar bone continue their normal pattern of growth occlusally.

anterior crossbite One or more upper front teeth are lingual to one or more of the opposing lower teeth in maximum intercuspation.

anterior guidance Contact of maxillary and mandibular incisors guide the mandible downward in protrusive and lateral excursive movements to separate the posterior teeth. This reduces wear and eliminates harmful lateral forces on the posterior teeth.

anterior segment All of the canine and incisor teeth in a given dental arch. The six front teeth.
anteroposterior Front to back. The anterior direction is forward. The posterior direction is rearward or back.

apical base The underlying (basal) maxillary and mandibular bone that supports and is continuous with the alveolar bone supporting the roots of the teeth. Although the demarcation between basal and alveolar bone is not specific, it is generally considered to lie at the level of the apices of the roots.

appliance Any device designed to influence the shape and/or function of the stomatognathic system. Anything the orthodontist attaches to the teeth to move the teeth or to change the shape of the jaw.
fixed appliance A bonded or banded appliance affixed to individual teeth or groups of teeth.
orthodontic appliance Any device used to influence growth or the position of teeth and jaws.
removable appliance An appliance that is freely removable from the mouth. It is not secured by cementation.

orthopedic appliance Any device used to influence the growth, size, form or position of bones.
functional appliance Any device, removable or fixed, designed primarily to effect skeletal and/or dental changes by modifying and utilizing the neuromuscular forces of the stomatognathic system. Examples include the Frankel appliance, activator, and bionator variations.

alveolar arch The U-shaped alveolar ridge that encloses the roots of teeth in either jaw.
arch The composite structure including the teeth and supporting alveolar and basal bone of either jaw. See dental arch.

dental arch The composite structure of the dentition, alveolar ridge, and basal arch.
arch circumference or arch perimeter The distance from the mesial contact of one first permanent molar to its antimere, the permanent molar on the other side, measured through the contact points or buccal cusp tips of all of the intervening teeth, ignoring those teeth that are malpositioned or blocked out so that the measurement represents an ideal arch form. See arch length.

arch depth The perpendicular distance from a point between the central incisors to a line connecting the mesial contacts of the first permanent molars. See arch length.

arch form The shape of an individual dental arch or of an arch wire formed to fit or shape that arch. An orthodontist could say that you have a U-shaped arch form or a V-shaped arch form.

arch length available and arch length required These are measurements of space available to align the teeth and required to align the teeth. Arch length and arch depth are synonymous. You should note, however, that Arch length is often used as a synonym for arch circumference or arch perimeter.
arch length deficiency The difference between the space required and the space available to align crowded teeth. See discrepancy.

arch wire or archwire A wire engaged in orthodontic attachments, usually affixed to the crowns of two or more teeth by brackets, and capable of causing or guiding tooth movement.
arch wire, sectional or segmental An arch wire that engages a limited number of adjacent teeth, perhaps only the four incisors or only a posterior dental segment.

armamentarium A general term for materials, equipment, and devices used by the orthodontist.
band, orthodontic A thin stainless steel band placed around the crown of a tooth to which orthodontic attachments are secured. The band, with orthodontic attachments welded or soldered to it, is closely adapted to fit the contours of the tooth and then cemented into place.

banding The process of cementing orthodontic bands to the teeth.
basal bone The bone that underlies, supports, and is continuous with the alveolar process. See apical base.

base, bracket The part of a bracket that is attached either to a metal band or bonding pad.
beta-titanium A beta titanium-molybdenum alloy.

bilabial protrusion Both upper and lower lips are too far forward.

bimaxillary Both the upper and lower jaws. Bimaxillary is a collective term used to describe the combination of maxilla and mandible.

bimaxillary protrusion Anterior protrusive position of both jaws in relation to other cranial and facial structures. Orthodontists refer to a bimaxillary protrusion when both jaws, the maxilla and mandible, are too far forward.

bimaxillary dentoalveolar protrusion The teeth and supporting alveolar bone in both jaws are protrusive. The basal bone and anteroposterior position of the jaws may be in normal position.
biomechanics The relationship between the forces you apply to living tissue such as teeth and gums and how the tissue responds.

bionator A modified removable functional appliance, developed by Dr. Balters to provide better control of the buccal musculature.

biteplate or bite plane A removable orthodontic appliance designed to open the bite and/or prevent selected teeth from occluding.

blocked out A tooth that is positioned away from its proper position in the dental arch due to insufficient space.

bodily movement Translational movement of a tooth or dental segment ordinarily understood to be perpendicular to the long axis/axes.

Bolton analysis A method developed by Wayne Bolton for the evaluation of tooth-size discrepancies (mesiodistal crown diameter) between the upper and lower arches.

bonding The process by which orthodontic attachments are affixed to the teeth by an adhesive.
bonding, direct An intraoral procedure in which orthodontic attachments are oriented by inspection and bonded individually to the tooth surface.

bonding, indirect A two-step process by which orthodontic attachments are affixed temporarily to the teeth of a study model and then transferred en masse to the mouth by means of a molded matrix that preserves their predetermined orientation and permits them to be bonded simultaneously.
braces See fixed appliance.

bruxism Habitual grinding or gnashing of the teeth, usually during sleep. May cause attrition of the teeth, muscle ischemia, and pain and damage to the supporting tissues. Bruxism is frequently associated with clenching and TMJ problems.

bracket A metal or ceramic orthodontic attachment that is secured to a tooth, either by bonding or banding, for the purpose of engaging an arch wire. Brackets can be fabricated from metal, ceramic or plastic.

bracket slot That portion of a bracket which receives an arch wire. Edgewise bracket slots are rectangular in cross section. Either 0.018 x 0.025 or 0.022 x 0.028 inches in dimension with the shorter dimension open go the buccal or labial.

bracket tie wing The portion of a bracket which retains a ligature.

buccal Toward the cheeks.

buccal segment All of the premolar (bicuspid) and molar teeth in a given quadrant.
buccal tube A fixed attachment which is open only at each end. Tubes may be round or rectangular in cross section. Round tubes are usually .045 inches in diameter to receive auxiliaries such as a face bow or lip bumper. Rectangular tubes are either .018 x .025 or .022 x .028 inches in diameter in order to receive arch wires and generally are placed on the most distal molar teeth in the appliance.

buccoversion Buccal malposition of a tooth or groups of teeth.

calculus A hard deposit that forms when you do not brush the teeth and plaque hardens. Calculus is also known as tartar.

caries Tooth decay.

casts, dental - study models - working models Plaster replicas or plaster models of the teeth and surrounding tissues, typically made from an alginate impression and used for diagnosis and treatment planning (study models) and appliance fabrication (working models), and as a part of the patient’s permanent record.

cavity A hole in a tooth caused by tooth decay.

centric occlusion Mandibular position dictated by maximum and habitual intercuspation of the upper and lower teeth. Centric occlusion has been variously referred to as intercuspal position, maximum intercuspal position, habitual centric, usual occlusal position. The condylar position may or may not be in harmony with centric occlusion. Because of this, the term habitual occlusion is preferable.
centric relation A gnathologic term, signifying optimal condyle-articular eminence-glenoid fossa relationships. Centric relation is determined by neuromuscular balance and temporomandibular joint relationships and not by tooth intercuspation. Changing concepts no longer accept the most retruded, rear most or hinge axis definition of centric relation, originally derived from prosthetic articulators. The condylar position can vary somewhat but is generally in a reasonably well-centered position within the temporal fossa. The bearing surface of the condyle rests upon a cartilaginous articular disk. In the mandibular rest position the condyle is somewhat high along the posterior slope of the articular eminence and separated from the eminence by 2.5 mm, the thickness of the articular disk. The average superior and posterior joint space ranges between 3.0 to 3.4 mm. This space contains the supratemporal artery and auriculotemporal nerve. Any discrepancy or lack of harmony between centric occlusion and centric relation is particularly important in the diagnosis and management of TMJ problems.

cephalogram or ceph An abbreviated synonym for a cephalometric radiograph. The term is sometimes used to refer to a fine-line tracing of the salient craniomandibular structures, landmarks and pertinent measurements on an acetate film overlay. The linear and angular measurements are used for diagnostic purposes. Today, the salient structures and landmarks can be captured directly with digital radiography. X-ray film is eliminated and measurements can be derived using computerized cephalometry programs.

cephalometric analysis The process of evaluating dental and skeletal relationships using linear and angular measurements obtained directly from the living head or, more commonly, from cephalometric radiographs and tracings. Standardized sets of cephalometric measurements are commonly used in the evaluation.

cephalometric radiograph An X-ray of the head that allows linear and angular measurements of the teeth, jaws, and other facial and cranial structures. The cephalometric radiograph is also called a cephalometric x-ray, a lateral skull radiograph or lateral skull x-ray, or simply a ceph. It is used to assess the structural development and compare an individual’s development to normal standards. A standardized radiograph of the head is characterized by a precisely defined relationship between x-ray source, subject and film. By convention, the distance between x-ray source and the center of the subject, midsagittal plane or transporionic axis, is either 5 feet or 1 52.4 cm. The distance between the midsagittal plane or transporionic axis of the subject and film is approximately 12 cm but may be standardized at a different value, or varied according to head size and recorded for each exposure. The standard projections are a lateral profile and posteroanterior (P-A).

ceramic brackets Crystalline alumina tooth-shade or clear synthetic sapphire brackets. These brackets are commonly considered esthetically more pleasing than metal brackets.
chain, orthodontic – C-chain, power chain, or elastomeric chain A elastic ligating chain used to apply traction and close spaces between teeth.

clenching Nocturnal parafunctional activity of temporalis, masseter and pterygoid muscles that is considered to be part of a stress-strain-tension release syndrome. Clenching is frequently associated with bruxism and temporomandibular joint disturbances.

clicking A term applied to abnormal sounds emanating from one or both temporomandibular joints, usually due to anterior or anteromedial or anterolateral displacement of the articular disk during functional movements.

closed bite A malocclusion with excessive vertical overlap of the anterior teeth. Also called a deep bite or referred to as excessive bite depth.

comprehensive orthodontic therapy The coordinated diagnosis and treatment leading to the correction of craniofacial dysfunction, dentofacial deformity, and dentoalveolar malocclusion. Anatomic, functional and esthetic relationships are optimized. Treatment usually, but not necessarily, utilizes fixed orthodontic appliances. Adjunctive procedures such as extractions, maxillofacial surgery, nasopharyngeal surgery, myofunctional or speech therapy, and restorative or periodontal care require coordination of disciplines. Optimal care requires long term consideration of a patient’s needs and periodic reevaluation. Treatment may incorporate several phases with specific objectives at various stages of dentofacial development.

computerized axial tomography (CAT scan) Images made by computed tomography. Anatomical information from a cross-sectional plane of the body is derived by computer synthesis of an image from x-rays.

conditioner (also Acid etch) A weak solution of orthophosphoric acid placed on the surfaces of the teeth to prepare the tooth surfaces for bracket bonding. The conditioner increases the adhesion of brackets to the tooth surfaces.

condyle The superior portion of the ramus of the mandible that articulates with the temporal eminence in the glenoid fossa. The mandibular condyle articulates with the temporal bone of the skull in front of the ear.

condylar displacement A functional abnormality in which one or both mandibular condyles are displaced from their normal relationships with their articular disks and eminentia in the glenoid fossae as the mandible closes into habitual occlusion.

condylar guidance The functional movements of the mandible are guided by the morphology of the mandibular condyles, the articular disks, and the temporal eminentia in the glenoid fossae.
condylar growth Proliferation of condylar cartilage, followed by its endochondral ossification. The condyle is a site of growth that is important to the overall development of the mandible. Condylar growth normally stops shortly after that of the rest of the face, although it may continue well beyond adolescence, particularly in males, or it may stop and begin again.

consultation (also diagnostic and treatment planning conference) A meeting with the orthodontist to discuss the diagnostic findings, treatment recommendations, alternative plans of treatment, their potential benefits, risks, estimated treatment times, and mechanotherapies. Progress consultations may also be held to discuss the progress of treatment, difficulties encountered, and possible alterations in the treatment plan.

continuous orthodontic force Action of an appliance against the dentition that decreases little in magnitude between appointments.

cosmetic orthodontics Orthodontic therapy whose purpose is improving the appearance of the face, teeth, and smile.

cranial base The endochondral bone that forms the anteroinferior aspect of the brain case. Because the bones of the cranial base stop growing relatively early, they are often used in the superimposition of serial cephalograms or tracings.

crepitus In orthodontics, a grating or grinding sound in a moving temporomandibular joint. Crepitus has been likened to the sound of crumpling dry leaves or rubbing two bricks together.

crossbite An abnormal relationship of a tooth or teeth to the opposing teeth in which normal buccolingual or labiolingual relationships are reversed. A malocclusion where one or more upper teeth are inside the lower teeth when you bite down.

crowding Inadequate space for the teeth leading to misalignment of teeth. The sum of the mesiodistal widths of the teeth in an arch exceeds the arch circumference.

crown An prosthetic or artificial replacement for the outer structures of a tooth, usually shaped from gold, ceramic or porcelain to resemble a natural tooth.

curve of Spee When viewed from a lateral or sagittal perspective, the occlusal and incisal surfaces of the teeth in both dental arches collectively describe a curve. The concave aspect of the curve of the mandibular arch faces upward. The convex aspect of the curve of the maxillary arch faces downward.

curve of Wilson Because the long axes of the mandibular molars and premolars converge towards the midline, the occlusal surfaces of these teeth bilaterally form a curve in a buccolingual direction. This imaginary curve as defined by lines tangent to the buccal and lingual cusps of the mandibular posterior teeth bilaterally is termed the curve of Wilson.

debanding The removal of cemented orthodontic bands.

debonding The removal of bonded orthodontic attachments.

decalcification The loss of calcium from the surfaces teeth. Surface erosion resembles “white rust” and can lead to deeper decay.

DDS, Doctor of Dental Surgery, and DMD, Doctor of Dental Medicine. The degrees are awarded by dental schools to graduates of doctoral dental programs. Some dental schools grant the DDS degree. Others grant the DMD degree. The two degrees are equivalent.

deep bite Excessive vertical overlap of upper and lower front teeth. Also referred to as excessive overbite or closed bite.

dehiscence A clefting defect in the gingival margin of a tooth; a type of gum recession.
dental plaque Colonized bacteria growing in a thick, mucous-like glycan, also referred to as a mucopolysaccharide matrix. Plaque removal is accomplished by tooth brushing and use of dental floss after eating. Failure to regularly remove plaque can lead to caries, gum inflammation, and periodontal disease.

dentition A collective term for the teeth. The character of a set of teeth especially with regard to their number, kind, and arrangement.

dentition, primary The first set, primary, deciduous, or “baby” teeth. These are the first teeth to develop and erupt into the mouth. These teeth are normally replaced by permanent successors.

dentition, adult The adult teeth.

dental or dentoalveolar malocclusion A malocclusion characterized by abnormally positioned teeth and supporting alveolar bone. The size, shape, and position of craniofacial bones are within the normal range. A dental malocclusion in which the teeth are not in their correct positions can be contrasted with a skeletal malocclusion in which the craniofacial bones are not within their normal range.

dentofacial deformity Dentofacial malformation characterized by one or more of the following: Disharmonies in size, form and position of skeletal structures, malocclusion, cleft lip or palate, and other skeletal or soft-tissue deformities. These deformities may be accompanied by various types of muscular dysfunction.

dentofacial orthopedics The treatment of the skeletal aspect of malocclusions. Dentofacial orthopedics and orthodontics more fully describes the scope of a contemporary orthodontic practice. See orthodontic.

developmental guidance See guidance. Preventive, interceptive, and corrective dentofacial orthopedic and orthodontic supervision and growth guidance during the primary and mixed dentitions to maturity. Services insure that growth and development of the craniofacial complex, including the occlusion, proceeds normally.

diagnosis The process of identifying the nature of a disorder. A statement or conclusion from such an analysis.

diastema A space between two teeth.

disocclusion Separation of opposing occlusal surfaces as the mandible moves into different functional positions.

discrepancy, arch length Arch length deficiency.

displacement Any movement of a particle or a body as a whole.

distal Behind or towards the back of the mouth. You might say that the first bicuspid is distal to the cuspid. A direction oriented along the dental arch away from the dental midline: right or left in the anterior segment; posteriorly in the buccal segments.

distal segment Synonymous with posterior segment.

distocclusion Lower teeth occluding distal to their normal relationship to the uppers, as in an Angle Class II malocclusion.

distoversion A term sometimes used to describe a tooth positioned distal (posterior) to its normal position.

drift See mesial drift. Teeth exhibit a physiologic mesial drift.

dysfunction Impaired or abnormal function.

dysplasia Abnormal development.

E-space The difference between the mesiodistal widths of the primary second molar and the second premolar (second bicuspid). Generally the permanent second premolar is smaller than the primary second molar.

early orthodontic treatment Orthodontic treatment started while patient is still in the primary or transitional dentition. Permanent teeth are not fully erupted.

ectopic Located away from normal position; often used to describe a condition in which a tooth develops, erupts, or rests in an abnormal position.

ectopic eruption Any tooth can erupt ectopically. When applied to the first permanent molar, it describes a condition wherein the first permanent molar erupts with excessive mesial angulation. This often results in resorption of the second primary molar and lack of full eruption of the first permanent molar.

edentulous Without teeth. All of the teeth are missing from either the upper or lower jaw.
edge-to-edge occlusion An occlusion in which the anterior or posterior teeth of both jaws meet along their incisal or buccal cuspal edges. Often associated with a Class III molar relationship.

edgewise appliance A fixed orthodontic appliance characterized by attachment brackets with a rectangular slot for engagement of an orthodontic wire. The most common appliance in use today.

elastic Capable of recovering size and shape after deformation. Capable of ready change or easy expansion or contraction : not rigid or constricted. A flexible appliance element that exhibits substantial elastic range.

elastics (rubber bands) Elastomeric bands used to provide orthodontic traction. Class I elastics, Class II elastics, Class III elastics, vertical elastics, and diagonal or cross-elastics describe the elastic connections and force vectors. Usually made of latex.

elastomeric ligature An elastic band or thread that is stretched around the tie-wings of an orthodontic bracket to prevent disengagement of an arch wire or auxiliary from the bracket slot.

endodontist (Endo) A dentist who specializes in root canals and the treatment of diseases or injuries that affect the root tips, nerves, and blood vessels within the teeth.

equilibrate Reshaping the occlusal (functional) surfaces of the teeth. Equilibration may be undertaken to eliminate bite interferences, redistribute and balance the functional load on the teeth, or for esthetic reasons.

erupt, eruption Movement of teeth in an incisal or occlusal direction through the supporting bone and gingival tissue into the oral cavity. A new tooth is said to erupt when the tooth breaks through the surface of the gums and can be seen in the mouth.

exfoliate To fall out. The deciduous teeth exfoliate and permanent teeth erupt into the space.

esthetics, facial See facial esthetics.

etch The application of a weak acidic solution to the labial or lingual surfaces of teeth as part of the preparation for bonding orthodontic attachments to the teeth.

etiology The cause of a medical or dental condition.

exfoliate Physiological loss or shedding, as when a primary tooth is lost prior to the eruption of the permanent tooth.

expansion Enlargement; often used to describe the mechanical widening of the dental arches.

expansion screw A mechanical device incorporated in a removable appliance or a fixed appliance used to enlarge the dental arch in some dimension.

expansion, rapid palatal (RPE) See rapid palatal expansion.

extraction Removal of a tooth.

extraoral Outside of the mouth. For example, head gear is said to be extraoral since it is an orthodontic auxiliary that is used outside of the mouth.

extraoral anchorage Anchorage that is located outside the mouth.

extraoral force or traction Force originating outside the oral cavity.

extraoral photographs Facial photographs used for the assessment of facial form.

extrusion A translational form of tooth displacement with movement directed occlusally and parallel to the long axis.

facial Often used to identify the surface of a tooth located nearest the face.

facial asymmetry A term used in the negative sense to describe a reduction of similarity or proportion between the right and left sides of the face or the craniofacial skeleton. May also be applied to any structure that is too large or small so as to be out of balance or not proportional to other structures.

facial esthetics A term pertaining to facial beauty, symmetry, balance and proportion.

facial form The configuration, shape or appearance of the face.

facial growth The developmental process leading to maturation and enlargement of the craniofacial skeleton and soft tissues.

facial pattern A term generally used to describe the facial form or the direction and type of facial growth.

facial proportions An assessment of the balance of the face from a frontal or profile view. The intent of the assessment is to determine asymmetry or imbalance.

fenestration A window defect or perforation of the gingival tissue or alveolar bone contiguous to the root surface.

finishing A stage of treatment near the end of comprehensive orthodontic care in which the teeth are placed in their final detailed positions.

fixed appliance An orthodontic appliance whose attachments are bonded or cemented to the teeth and cannot be removed by the patient. Generally termed ‘braces’ by the lay public.

fluoride A chemical solution or gel applied to the teeth to harden the teeth and help prevent tooth decay.

force A mechanical action of one body on another that tends to displace and/or deform the body receiving it. Force may be continuous, intermittent, intraoral, extraoral, orthodontic, orthopedic, elastic, spring, magnetic, etc. depending on the need.

fossa, glenoid See glenoid fossa. The concavity within the temporal bone in front of the ear within which the condyle of the mandible rotates and translates during movements of the lower jaw.

Fränkel appliance An activator type functional appliance intended to stimulate or inhibit jaw growth, retrain muscles or widen the dental arches.

free-way space The clearance or interocclusal distance between the upper and lower teeth when the mandible is in the postural rest position.

frenectomy The surgical removal or repositioning of a frenum or frenal attachment. Performed to enhance the stability of a corrected diastema or to alleviate a tongue tie.

frenum A fold of mucous membrane and underlying fibrous tissue connecting the lip, cheek or tongue to the alveolar mucosa. There are both labial and lingual frenal attachments.

friction A resistance to the relative displacement of contacting bodies in a direction tangent to the plane of contact. Resistance aids anchorage but impairs translational movements of teeth.

frontal cephalometric radiograph A radiograph taken with the x-ray source located behind the head and the x-ray film located in front of the face taken according to cephalometric conventions. More correctly termed a posters-anterior (P-A) cephalometric radiograph. See cephalometric radiograph.

full treatment Comprehensive orthodontic treatment of upper and lower dental arches.

functional appliance A term applied to a class of removable appliances which utilizes the muscle action of the patient to produce orthodontic or orthopedic forces.

functional jaw orthopedics The form of therapy, usually with activator-type appliances, that utilizes the musculature to create dentofacial changes.

functional matrix A theory, which explains the interrelationship between osteogenesis (bone formation) and local functional demands, proposed by J. Moss. The functional matrix is the entire structural and functional milieu of the tissues enclosing or enveloping the developing bone.

functional occlusion An arrangement of the teeth intended to minimize stress on the temporomandibular joint; maximize function, stability and esthetics of the teeth; and provide for protection and health of the periodontium.

gingiva The tissues that surround the teeth, consisting of a fibrous and vascularized zones of tissue that are continuous with the periodontal ligament and mucosal covering of the alveolar bone.

gingival attachment The fibrous attachment of the gingiva to the teeth.

gingival display A vertical measure of the amount of gingiva (gum) visibly seen above the upper front teeth when smiling. See gummy smile.

gingival hypertrophy The abnormal enlargement of the gingiva surrounding the teeth caused by poor oral hygiene.

gingival recession Shifting of the gingival margin apically exposing part of the root of the tooth.

gingivitis Inflammation of the gingiva. Inflammation of the gums caused by improper brushing. The first sign of periodontal or gum disease.

glenoid fossa The depression or fossa in the temporal bone in which the condyle of the mandible is positioned. Part of the temporomandibular joint (TMJ).

grinding A term synonymous with bruxism or parafunctional activity.

growth An age-related increase in size.

guidance, developmental A planned orthodontic and orthopedic effort to influence the growth of the jaws and eruption of the teeth, with the objective of guiding abnormal development into a normal situation. This generally requires a combination of carefully timed appliance therapies and supervisory examinations throughout progressive stages of development. This may be required from the earliest date of detection of a developing malformation until the craniofacial skeleton is mature.

gummy smile A popular term for excessive exposure of maxillary gingival tissue during a full smile, usually caused by excessive maxillary vertical height.

habit In dentistry a term applied in a negative sense to frequently repeated activity such as finger or lip sucking or tongue thrusting. Such activity may alter the normal development of the teeth or bones.

habit therapy Treatment designed to prevent potentially deforming finger, lip, or tongue habits and/or correct a malformation of the teeth or bones caused by a habit. Treatment might occur by counseling, appliance therapy, or both.

habitual occlusion Habitual occlusion is closure into maximum intercuspation or the “best fit of the teeth.” The “best fit of the teeth” may or may not be consistent with “correct fit of the teeth.” Both malocclusions and normal occlusions close into the “best fit of the teeth.” Habitual occlusion may or may not coincide with centric relation. When an incompatibility exists between the “best fit of the teeth” and the “best fit and function of the TM joints” the teeth and habitual occlusion are dominant, take precedence over normal TMJ and neuromuscular function, and the TM joints and masticatory muscle function suffer. The result is a temporomandibular disorder (TMD) and/or myofascial pain disorder (MPD). To put it simply, “When the teeth are not in their correct positions, they (the teeth) can force the jaw out of its correct position.” The result is TMD and/or MPD. The goal of treatment is to establish compatibility between teeth, joints, and muscles.

Hawley appliance A Hawley retainer modified to obtain minor orthodontic corrections.

Hawley retainer A passive removable acrylic and wire appliance generally used to stabilize teeth in their new position after orthodontic correction. See retainer.

headgear An apparatus that is used to deliver traction force to the teeth derived from anchorage outside the oral cavity. A headgear consists of three parts: a face bow, a head gear force module, and either a neck strap or a high-pull, occipital-pull, or cervical-pull head cap.

Herbst appliance A fixed or removable appliance designed to advance and center the mandible. The appliance postures the jaw forward to stimulate sagittal correction of retrognathic Class II skeletal malocclusions.

holding arch See lingual arch. A space maintainer designed to prevent forward drift of posterior teeth.
hooks Attachments soldered or welded to arch wires for the placement of elastics, headgear, or elastic chains.

hyperplasia Tissue enlargement through multiplication of cells, Hyperplasia is often a response to inflammation or drugs.

hypertrophy An increase in tissue bulk through an increase in size of the tissue elements.
hypoplasia Incomplete development of a tissue or structure.

ideal occlusion A theoretical placement of the teeth in the dental arches which maximizes esthetics, function, stability, and longevity of the dentition and supporting structures. No malocclusion is present.

idiopathic An adjective that connotes an unknown etiology or causation. Pain, disease, or disorder caused by unknown factors.

immobilization To fix in place so that no movement is possible. Usually used in regard to orthognathic (jaw) surgery.

impacted tooth A tooth that failed to erupt into the oral cavity. In orthodontics this often describes maxillary canines and third molars or “wisdom teeth” that occupy positions in which normal eruption is highly unlikely.

impaction, tooth A condition describing the total or partial lack of eruption of a tooth well after the normal age for eruption.

implant A prosthetic metallic root is surgically inserted into the jaw bone. When the metallic root is secure, a replacement crown resembling a natural tooth is attached to the implanted root.

impression A negative image of a tooth or dental arch. An impression is produced by placing an elastic compound like alginate in a preformed tray and inserting the tray into the mouth around the teeth until the compound stiffens. The impression is removed from the mouth and filled with plaster to produce an exact positive reproduction of the teeth or dental arch.

incisal Pertaining to the cutting edge or surface of the anterior teeth. The biting edge of the central and lateral incisors.

inclination The tilt of the long axis of a tooth in the buccolingual or faciolingual direction. Often called torque. Contrast this with angulation, the tilt or tip of the long axis of a tooth in a mesial or distal direction.

inclined plane An acrylic ledge or platform which is usually added to a maxillary Hawley retainer and is designed to intrude anterior teeth or to position the lower jaw forward.

indirect bonding A procedure for bonding orthodontic attachments to the teeth. A laboratory process is performed to position the attachments on plaster casts; the prepositioned attachments are then bonded to the teeth utilizing an elastic impression tray as a transfer device.

infection control An important aspect of any health service. Guidelines are set by the Communicable Disease Center (CDC), the Occupational Safety and Health Association (OSHA), and other local, state, and federal agencies.

informed consent An agreement by the patient or parent to proceed with or decline treatment after the potential benefits and risks of treatment have been presented.

infraocclusion (Also spelled infracclusion) A tooth or teeth positioned below the normal plane of occlusion.

intensifying screen A stiff sheet of plastic impregnated with a material which fluoresces when exposed to x-radiation. It is used in an x-ray cassette to intensify the x-ray image and reduce the patient’s exposure to radiation. See rare earth screen.

interceptive orthodontics An extension of preventive orthodontics that may include localized tooth movement in an otherwise normal dentition. Such treatment may occur in the primary or transitional dentition and may include such procedures as the redirection of ectopically erupting teeth, correction of isolated dental crossbite, or recovery of recent minor space loss where overall space is adequate. Early intervention can simplify or eliminate the need for later, more complicated treatment.

interdental spacing Spacing between the teeth.

interdigitation Intercuspation.

intermaxillary Between the upper and lower jaws.

intermaxillary anchorage Using one dental arch as anchorage to apply traction on the other dental arch.

intermaxillary elastic traction Use of elastics to apply traction between the upper and lower jaws.

intermittent force An orthodontic or orthopedic force that is applied occasionally or periodically as opposed to continuously.

internal derangement An anatomic displacement or malposition of the articular disk and/or condyle relative to the temporal fossa and articular eminence. Malposition of anatomic structures within the temporomandibular joints may be due to the occlusion or may be due to arthritis, fibrosis, tumors, trauma, condylosis, condylar hyperplasia, and other internal factors.

interocclusal clearance Synonymous with freeway space.

interocclusal bite registration Bite marks in a wax wafer which are used to see how the teeth come together.

interproximal Between adjacent teeth.

intramaxillary Within one dental arch.

intramaxillary anchorage A situation where a tooth or group of teeth provides anchorage to apply traction to other teeth within the same arch.

intraoral Inside or within the oral cavity.

intraoral anchorage Anchorage located inside the mouth.

intraoral force Force which is generated by orthodontic appliances in the oral cavity.

intrusion Movement of a tooth back into the bone. A translational form of tooth movement parallel to the long axis of the tooth and directed apically or toward the root tip.

jackscrew Synonymous with expansion screw.

jaw A common term for the maxilla, the upper jaw, and mandible, the lower jaw.

jaw relationship The position of the upper jaw in relationship to the lower jaw; an anteroposterior, transverse, or vertical assessment.

joint symptoms A general term referring to subjective evidence of a disease or disturbance of joint function. Clenching and grinding of teeth, microtrauma, macrotrauma internal joint derangement, or internal pathologic conditions may result in TM joint symptoms. Contrast subjective symptoms with objective signs of disorder.

jumping the bite The correction of a crossbite brought about by buccolingual movements of the posterior teeth and/or transverse movement of the jaws to their correct positions in the case of posterior crossbite; or labiolingual movement of anterior teeth and/or sagittal movement of the jaws in the case of anterior crossbite.

labial Of or pertaining to the lip. Identifies a surface facing the lips. The same as ‘facial’ in the anterior portion of the dentofacial complex. The tooth surface facing the lips.

labial arch or bow A wire that traverses the labial surfaces of the teeth.

labial root (lingual crown) torque The third-order couple of a force system applied to the crown(s) of a tooth or a dental segment having the potential for displacement resulting in labial movement of the root(s) and/or lingual movement of the crown(s).

labioversion General term indicating the deviation of a tooth toward the labial.

lateral cephalometric radiograph An x-ray taken according to cephalometric conventions with the x-ray source facing the right side of the face and perpendicular to the midsagittal plane. The x-ray film faces the left side of the face. This radiograph is used to measure and determine sagittal and vertical craniofacial relationships. See cephalometrics.

lateral excursion Movement of the lower jaw away from the middle position.

leeway space The difference between the combined widths of the three buccal primary teeth, the primary canine, and first and second primary molars, and their successors, the permanent canine, and permanent first and second premolars (bicuspids).

leveling The initial phase of comprehensive orthodontic treatment using fixed appliances designed to change the line of intercuspation from a curve to a straight line; to align the teeth in the same plane.

leveling wire Orthodontic wire, ordinarily round in cross-section and exhibiting low flexural stiffness, used in the leveling phase of treatment.

ligament, periodontal See periodontal ligament. The fibrous attachment of the cementum of the root to the supporting alveolar bone. The attachment is comprised of one-half mm radial fibers that extend from the cementum of the root to the alveolar bone.

ligating module A small elastomeric O-ring used to hold the arch wires in the brackets on braced teeth.

ligature A tie used to secure the arch wire to the brackets