NBDE Part II key terms

The distance from a stable coronal reference point to the planned apical endpoint of instrumentation, usually the apical constriction, determined by combining a radiograph with an electronic apex locator reading.

The narrowest portion of the canal near the cementodentinal junction, typically 0.5 to 1 mm short of the radiographic apex, marking the ideal limit for cleaning, shaping, and obturation.

A microcrystalline film of dentin debris, pulp remnants, and bacteria produced on canal walls and cut dentin by instrumentation; it can block irrigants and weaken bonding unless removed or modified.

Use of a chlorine-releasing solution to dissolve necrotic pulp tissue and kill microorganisms in the canal; it does not remove the smear layer and can severely injure tissue if extruded beyond the apex.

The resin-infiltrated zone formed where adhesive monomers penetrate demineralized dentin collagen, creating the main micromechanical bond between composite and tooth structure.

The ratio of bonded to unbonded surface area in a cavity preparation; higher values restrict resin flow and raise polymerization contraction stress at the bonded interface.

A tooth-colored restorative and luting material that sets by an acid-base reaction, releases fluoride over time, and bonds chemically to enamel and dentin, though it is moisture sensitive while setting.

Painful condition in which the blood clot in a recent extraction socket is lost or disintegrates, exposing bone, typically beginning two to four days after surgery without signs of suppuration.

An intraoral injection that deposits local anesthetic near the mandibular foramen to anesthetize the inferior alveolar nerve, providing pulpal and soft tissue anesthesia for mandibular teeth on that side.

Reduced ability to open the mouth, measured as decreased interincisal distance, caused by muscle spasm, inflammation, fibrosis, or nerve injury following surgery, infection, or trauma.

Resistance to unwanted tooth movement supplied by other teeth, bone, or appliances, allowing a clinician to move selected teeth without losing the planned positions of the anchoring units.

The size difference between the primary canine and primary molars and their permanent successors in one quadrant, roughly 1.5 mm per side in the maxilla and 2.5 mm in the mandible.

A fixed or removable appliance that preserves arch length after premature loss of a primary tooth until the successor erupts, limiting drifting, impaction, and later crowding.

Caries in children under six years, often starting on maxillary primary incisors and spreading rapidly, associated with frequent sugar exposure and prolonged bottle feeding or nighttime breastfeeding.

A system that describes occlusion by the anteroposterior relation of the first molars: Class I when normal, Class II when the lower molar sits distally, and Class III when it sits mesially.

The distance from the gingival margin to the base of the sulcus or pocket, measured with a periodontal probe; it reflects pocket depth but does not by itself show attachment loss.

The distance from the cementoenamel junction to the base of the pocket, expressing cumulative attachment loss; it is calculated by adding probing depth to recession or subtracting for gingival enlargement.

Loss of periodontal attachment into the space between the roots of a multirooted tooth, graded by severity and detected clinically with a furcation probe or on radiographs.

A surgical approach in which a barrier membrane excludes gingival connective tissue and epithelium from a defect so periodontal ligament and bone cells can repopulate it and regenerate attachment.

A maxillomandibular relationship in which the condyles rest against the thinnest avascular portion of their discs at the anterior-superior aspect of the articular eminences, independent of tooth contact.

The distance between selected facial or dental landmarks when the teeth are in maximum intercuspation; it guides facial appearance, speech, and the design of removable and fixed prostheses.

A direct structural and functional connection between living bone and a loaded implant surface with no intervening soft tissue, which is the biologic basis of implant success.

The line scribed on a cast by the surveying instrument that marks the height of contour of the teeth; it guides path of insertion, guide plane preparation, and clasp placement in partial denture design.

A ranked list of conditions that could explain a patient's signs and symptoms, progressively narrowed through history, examination, and laboratory or imaging tests before a final diagnosis is made.

A three-dimensional imaging method using a cone-shaped x-ray beam and flat detector to create volumetric data at lower dose than medical CT, used for implant, endodontic, and surgical planning.

A dark region on a radiograph where tissues absorb less x-ray and more photons reach the receptor, suggesting lower density such as caries, cysts, or soft tissue.

The fraction of an administered drug dose that reaches the systemic circulation unchanged; it is complete for intravenous dosing and lower for oral dosing because of absorption limits and first-pass effects.

Breakdown of a drug in the intestinal wall and liver before an oral dose reaches the general circulation, lowering bioavailability and sometimes requiring larger oral doses or a different route.

Antimicrobials given before a procedure to prevent infection, such as a single dose before invasive dental treatment for patients with specified cardiac conditions or severe immune compromise.

A predominantly white patch or plaque of oral mucosa that cannot be rubbed off and cannot be classified clinically or pathologically as any other lesion; it is a diagnosis of exclusion.

A developmental cyst lined by odontogenic epithelium with a corrugated parakeratinized surface, often multilocular in the posterior mandible, and known for a high rate of recurrence.

A benign but locally aggressive odontogenic epithelial tumor, most common in the posterior mandible, usually producing a multilocular soap-bubble radiolucency and treated by wide resection.

Disordered epithelial maturation with cytologic atypia, graded as mild, moderate, or severe, representing a precancerous change that raises the risk of progression to squamous cell carcinoma.

A patient's voluntary agreement to treatment after receiving and understanding the diagnosis, proposed procedure, expected benefits, material risks, reasonable alternatives, and consequences of refusing care.

A behavior guidance method in which the clinician explains a procedure in child-friendly language, demonstrates the steps, and then performs them, reducing fear and improving cooperation.

The proportion of a population that has a condition at a specified time, useful for estimating treatment need and planning services; it differs from incidence, which counts new cases.

A count of decayed, missing because of caries, and filled permanent teeth per person, used to summarize caries experience in a population; the primary dentition form is written dmft.

Adjusting the fluoride concentration of a public water supply to an optimal level so that caries is reduced across the whole population regardless of individual behavior or access to care.