MDCG Dental Exam key terms

The portion of the maxilla or mandible that forms and supports the tooth sockets. It develops with the teeth and resorbs after tooth loss, which is why ridge height decreases in edentulous areas.

The line where the enamel of the crown meets the cementum of the root. In health the gingival margin lies near it; its position relative to the gingival margin helps define recession and attachment loss.

The fibrous connective tissue between root cementum and alveolar bone. It anchors the tooth, transmits occlusal force, contains proprioceptive nerve endings, and provides a route for lymphatic and vascular supply.

A thin, non-keratinized epithelial collar that attaches the gingiva to the tooth surface at the base of the sulcus. It forms the soft-tissue seal and is the first barrier breached in periodontal disease.

The distance from the cementoenamel junction to the base of the gingival sulcus or pocket, measured with a periodontal probe. It records cumulative attachment loss and does not change with simple gingival swelling.

A pathologically deepened gingival sulcus. It is termed suprabony or infrabony according to the relationship of its base to the underlying alveolar crest, and its depth alone does not prove active disease.

A postmitotic, columnar cell lining the pulp surface of dentin. It secretes predentin, which mineralizes into dentin, and its process remains within the dentinal tubule throughout the life of the tooth.

A microscopic channel running from the pulp to the dentinoenamel junction, occupied by an odontoblast process and fluid. Fluid movement within tubules is the basis of dentin hypersensitivity and a route for bacterial penetration.

The epithelial structure of the developing tooth germ that gives rise to ameloblasts and thus enamel. It passes through bud, cap, and bell stages, and its inner enamel epithelium differentiates into secretory ameloblasts.

An ectodermally derived cell that secretes enamel matrix and then matures and mineralizes it. Ameloblasts are lost after eruption, so human enamel cannot regenerate once destroyed.

Dentin in which tubules become obliterated by continued peritubular mineral deposition in response to slow, mild irritation. It is harder and less permeable and appears translucent, reducing sensitivity and bacterial access.

Tertiary dentin formed by surviving primary odontoblasts beneath a mild stimulus such as caries or attrition. It is deposited only at the affected site and differs from reparative dentin made by newly recruited odontoblast-like cells.

The fifth cranial nerve, which provides general sensation to the face, teeth, and oral mucosa through its ophthalmic, maxillary, and mandibular divisions. Its mandibular division also carries motor fibers to the muscles of mastication.

A branch of the mandibular division of the trigeminal nerve that enters the mandibular canal and supplies the mandibular teeth and chin. It is at risk during third molar surgery and implant placement in the posterior mandible.

A branch of the mandibular division of the trigeminal nerve that carries general sensation from the anterior tongue and lingual gingiva. It runs close to the lingual plate in the third molar region and is easily injured there.

The fascial space between the medial pterygoid muscle and the ramus of the mandible, containing the inferior alveolar and lingual nerves. It is the target of the classic inferior alveolar nerve block and a route for spreading infection.

A rapidly spreading bilateral cellulitis of the submandibular, sublingual, and submental spaces, usually of odontogenic origin. It can elevate and push back the tongue to obstruct the airway and is a surgical emergency.

Inflammation of bone and marrow, in the jaws usually following infection of a tooth or a fracture. Chronic mandibular disease may show patchy radiolucency with sequestra and requires prolonged antibiotic and surgical care.

Bone death after high-dose radiotherapy, most often in the mandible, presenting as exposed bone that fails to heal for months. It is precipitated by extraction or trauma in an irradiated field and is managed with conservative or surgical measures.

Exposed jaw bone persisting beyond eight weeks in a patient taking or previously taking antiresorptive drugs, with no history of jaw radiotherapy. It typically follows extraction and is managed by prevention, antibiotic control, and limited surgery.

A predominantly white patch or plaque of the oral mucosa that cannot be scraped off and cannot be classified clinically or pathologically as any other disease. It is a diagnosis of exclusion and carries malignant potential.

A fiery red patch of oral mucosa that cannot be attributed to any other recognizable condition. It is far less common than leukoplakia but has a much higher rate of severe dysplasia or invasive carcinoma.

Disordered maturation and architectural change of epithelium, graded mild, moderate, or severe by the extent of atypia. Severe dysplasia and carcinoma in situ are treated as high-risk lesions requiring excision or close surveillance.

A multifactorial, biofilm-driven destruction of dental hard tissue in which fermentable carbohydrate is converted to acid that demineralizes enamel and dentin. It is managed by risk assessment, fluoride, dietary control, and restoration when cavitated.

A structured, adherent microbial biofilm on tooth and other oral surfaces, embedded in a polymer matrix. Its composition shifts toward acidogenic and aciduric species with frequent sugar exposure, driving demineralization.

The destruction or removal of all microorganisms, including bacterial spores, from an object. In dentistry it is achieved for reusable instruments by autoclaving, and it is distinguished from disinfection, which does not reliably kill spores.

Infection-control measures applied to every patient regardless of known diagnosis, including hand hygiene, gloves, masks, eye protection, and safe sharps handling. They replaced the earlier strategy of treating only known infectious patients differently.

Treatment given after occupational exposure to a pathogen to reduce the risk of established infection, such as antiretroviral drugs after needlestick exposure to HIV. It must be started promptly and is guided by the source status and local protocol.

The lowest concentration of an antimicrobial that prevents visible growth of a standard bacterial inoculum. It quantifies susceptibility and, with pharmacokinetic data, guides whether a chosen dose is likely to be effective.

Administration of an antibiotic before a procedure to prevent infection in a susceptible patient, such as those with certain cardiac conditions or prosthetic joints. It is not a substitute for aseptic technique or for treating established infection.

The upper limit of local anesthetic, usually expressed in milligrams per kilogram, that may be given to limit systemic toxicity. It is calculated from the patient's weight and the drug concentration in the cartridge.

The distance from a coronal reference point to the intended apical limit of root canal preparation, usually the apical constriction. It is established radiographically and confirmed with an electronic apex locator before shaping and obturation.

The narrowest part of the root canal near the apical foramen, where the canal meets the pulp-periodontal junction. It is the preferred apical limit for instrumentation and filling to avoid overextension and extrusion of material.

The occlusion of opposing teeth when the mandible is closed in maximum intercuspation, which may or may not coincide with centric relation. Discrepancy between the two is assessed during prosthodontic and occlusal diagnosis.

A clinically determined, reproducible maxillomandibular relationship in which the condyles sit in their most anterior-superior position against the articular eminences, independent of tooth contact. It is a reference position used in complete denture and occlusal reconstruction.

The vertical distance between the maxilla and mandible when the teeth or occlusion rims are in contact. It is reduced by wear and tooth loss and is restored only after careful assessment of freeway space.

A volumetric X-ray technique producing three-dimensional images of bone and teeth with a lower dose than medical CT. It is used for implant planning, impacted teeth, and endodontic anatomy, and requires justification under radiation-protection principles.

A radiation-protection quantity, expressed in sieverts, that weights absorbed dose by tissue sensitivity to estimate overall stochastic risk. It allows comparison of different examinations, such as a panoramic film versus cone beam CT.

An intraoral image showing a few teeth and their surrounding bone, used to detect caries, periapical disease, and root morphology. It gives higher resolution than panoramic imaging but covers only a small region.

A patient's voluntary agreement to a procedure after receiving and understanding information about its nature, risks, benefits, alternatives, and the consequences of refusal. It is a process, not merely a signed form, and must be documented.

A legal duty to notify authorities of specified events, such as suspected child abuse or certain communicable diseases, even without patient permission. Confidentiality yields to this statutory obligation, and failure to report can itself be an offence.