NEET-MDS key terms

A small pyramidal space below the apex of the orbit, bounded by the maxilla, palatine and sphenoid bones, transmitting the maxillary nerve, its branches and the maxillary artery to the nasal cavity, palate and orbit.

An irregular space beneath the base of the skull, deep to the mandibular ramus, containing the lateral pterygoid muscle, the mandibular division of the trigeminal nerve, the maxillary artery and the pterygoid venous plexus.

A subdivision of the anterior cervical triangle bounded by the sternocleidomastoid, posterior belly of digastric and superior belly of omohyoid, containing the carotid bifurcation, internal jugular vein and vagus nerve.

The shift of the oxyhaemoglobin dissociation curve to the right when carbon dioxide and hydrogen ion concentrations rise, so that haemoglobin releases oxygen more readily in actively metabolising tissues such as exercising muscle.

The substrate concentration at which an enzyme-catalysed reaction proceeds at half of its maximum velocity; a low value indicates high substrate affinity, while a high value indicates low affinity.

A reversible adaptive change in which one fully differentiated cell type is replaced by another type better able to withstand stress, such as columnar changing to squamous epithelium in the smoker's bronchus.

A compact focal collection of activated macrophages, many transformed into epithelioid cells, often surrounded by lymphocytes and sometimes multinucleated giant cells, formed in chronic inflammation such as tuberculosis.

Programmed, energy-dependent cell death in which the cell shrinks, chromatin condenses and fragments, and membrane-bound apoptotic bodies are cleared by phagocytes without provoking inflammation, in contrast with necrosis.

The lowest concentration of an antimicrobial agent that prevents visible growth of a standardised bacterial inoculum under defined laboratory conditions, used to guide susceptibility testing and resistance reporting.

The apparent volume of body fluid into which a drug dose would need to be diluted to produce the measured plasma concentration, reflecting how extensively a drug distributes into tissues.

The fundamental structural unit of enamel, a tightly packed bundle of hydroxyapatite crystallites running from the dentinoenamel junction towards the surface, whose orientation and decussation influence the strength of the tissue.

The fused layers of the enamel organ that remain over the crown after enamel formation is complete; it mediates eruption and can later give rise to a dentigerous cyst.

The line where the cementum covering the root meets the enamel of the crown, appearing as an overlap, a butt joint or a gap exposing dentine, and used as the reference for measuring attachment loss.

A developmental cyst of the jaws lined by uniform parakeratinised stratified squamous epithelium with a corrugated surface and palisaded basal cells, known for high recurrence and association with PTCH1 mutations.

Loss of cohesion between squamous epithelial cells because desmosomal attachments fail, producing rounded floating cells and suprabasal clefts, as seen in pemphigus vulgaris and some viral infections.

A predominantly white patch or plaque of the oral mucosa that cannot be rubbed off and cannot be clinically or pathologically classified as any other definable disease, requiring biopsy to exclude dysplasia.

A dental imaging technique in which a cone-shaped X-ray beam and flat panel detector produce three-dimensional volumetric data in a single rotation, giving fine bony detail at a lower dose than multidetector CT.

Radiographic examination of the salivary duct system after instillation of a radiopaque contrast medium, used to demonstrate ductal obstruction, stricture or the classical changes of Sjögren syndrome.

A horizontal surgical cut through the maxilla above the apices of the teeth that separates the tooth-bearing segment from the skull base, allowing advancement, impaction or repositioning in three planes.

Post-extraction pain caused by loss or dissolution of the blood clot from the socket, leaving bare bone, typically beginning two to four days after removal of a mandibular third molar.

The distance measured from the cementoenamel junction to the base of the gingival sulcus or pocket, representing the cumulative loss of periodontal support at a particular site.

A periodontal surgical technique in which a barrier membrane is placed over a debrided defect to exclude gingival epithelium and connective tissue, allowing slower-migrating periodontal ligament and bone cells to repopulate.

A structured, adherent community of bacteria embedded in a polysaccharide matrix on tooth and restoration surfaces, whose metabolic products drive both caries and periodontal inflammation.

A microcrystalline layer of cutting debris, dentine and bacterial remnants produced on instrumented root canal walls, which occludes dentinal tubules and can reduce penetration of irrigants and sealers.

The distance from a stable coronal reference point to the selected apical limit of preparation, usually the apical constriction, determined radiographically or with an electronic apex locator.

A prosthodontic guideline stating that the total periodontal ligament area of the abutment teeth supporting a fixed partial denture should equal or exceed that of the teeth being replaced.

The difference between the vertical dimension of the face when the mandible is at physiologic rest and when the teeth are in maximum intercuspation, usually about two to four millimetres.

In orthodontics, the resistance to unwanted tooth movement that must be controlled so that reactive forces do not displace the anchor unit while the desired teeth are being moved.

The angle formed between the A point–nasion and B point–nasion lines on a lateral cephalogram, indicating whether the maxilla and mandible are in skeletal Class I, II or III relation.

The presence of one or more decayed, missing or filled tooth surfaces in a child under six years, often starting on upper primary incisors and linked to frequent sugars and nocturnal bottle feeding.

Removal of the inflamed coronal pulp while preserving the vital radicular pulp, followed by placement of a medicament and a coronal seal, used in primary molars with reversible pulpitis.

A fixed or removable appliance placed after premature loss of a primary tooth to preserve arch length and guide the eruption of the permanent successor into its normal position.

A count of permanently decayed, missing because of caries, and filled teeth in an individual, used to express caries experience in a population at a given time.

Controlled adjustment of the fluoride concentration of a public water supply to the level optimal for caries prevention, usually about 0.7 to 1.0 milligram per litre, with monitoring to limit fluorosis.

The proportion of people without a disease who are correctly identified as disease-free by a screening test, reflecting the ability of the test to avoid false positive results.