ORE Part 1 key terms

The highly mineralised, acellular outer layer covering the crown of a tooth. It is about 96% inorganic by weight, cannot regenerate, and depends on saliva and fluoride for repair.

The hydrated, tubular hard tissue forming the bulk of a tooth, secreted by odontoblasts. It is softer than enamel, contains collagen, and its tubules transmit stimuli to the pulp.

Mineralised tissue covering the root surface, produced by cementoblasts. It anchors periodontal ligament fibres and can thicken with age or increased function.

Fibrous connective tissue lying between root cementum and alveolar bone. It attaches the tooth, transmits occlusal force, and contains vessels, nerves and proprioceptors.

Soft connective tissue in the central chamber of a tooth, containing odontoblasts, nerves and vessels. It forms dentine and mediates inflammatory and painful responses.

A structured community of bacteria embedded in a polysaccharide matrix on tooth surfaces. Metabolism of sugars within it produces acids that drive demineralisation.

The pH at which plaque fluid becomes unsaturated with respect to tooth mineral, roughly 5.5 for enamel. Below this value demineralisation outweighs remineralisation.

Explanation of dentine sensitivity: fluid movement within open dentinal tubules deforms nerve endings near the pulp, producing a sharp response to thermal, osmotic or mechanical stimuli.

Microscopic debris layer of cut collagen and mineral created by instrumenting dentine or root canal walls. It reduces permeability and can block tubules or interfere with adhesion and irrigation.

Adhesive restorative material based on fluoroaluminosilicate glass and a polyacid. It bonds chemically to tooth, releases fluoride, and is used for linings, luting and primary teeth.

Interdiffusion zone formed when resin infiltrates acid-etched, demineralised dentine and polymerises around exposed collagen. Its quality strongly influences bond durability.

Volume reduction occurring as resin composite monomers join into polymer chains. It creates stress at bonded interfaces and may cause marginal gaps, sensitivity or cuspal deflection.

Distance from a coronal reference point to the intended apical termination of root canal preparation, usually the apical constriction. It guides instrumentation and obturation.

The narrowest part of the root canal near the apex, where canal meets cementum. It is the preferred limit for cleaning and filling.

Irrigant used in root canal treatment. It dissolves necrotic tissue and collagen and is antimicrobial, but it does not remove the smear layer or decalcify dentine.

Three-dimensional filling of a cleaned and shaped root canal system with a core material, usually gutta-percha, and a sealer, to prevent bacterial re-entry.

A circumferential band of sound tooth structure, at least 1.5 to 2 mm high, retained by a crown or post-retained restoration. It resists lever forces and improves survival.

A maxillomandibular relationship in which the condyles sit against the deepest part of the articular fossae, independent of tooth contact. It is a repeatable reference for occlusal records.

The gap between upper and lower teeth when the mandible is in its resting posture, usually 2 to 4 mm at the premolars. It is used to judge occlusal vertical dimension.

Occlusal scheme for complete dentures in which contacts occur bilaterally and anteriorly and posteriorly during eccentric movements, helping to stabilise the denture bases.

Distance from the cementoenamel junction to the base of the periodontal pocket. It records historical periodontal destruction and is a key measure of periodontitis severity.

Surgical technique using a barrier membrane to exclude gingival epithelium and connective tissue from a periodontal defect, allowing slower-forming bone and ligament cells to repopulate the space.

Direct structural and functional connection between living bone and the surface of a load-bearing implant, without intervening soft tissue. It is the basis of implant stability.

Painful inflammation of a socket after extraction, caused by loss of the blood clot. It presents with severe throbbing pain and exposed bone, usually a few days after surgery.

Bone death in a previously irradiated area, typically the mandible, arising spontaneously or after trauma. Radiotherapy damages vessels and reduces the tissue's healing capacity.

A predominantly white patch or plaque of the oral mucosa that cannot be characterised clinically or pathologically as any other disease. It is potentially malignant and requires biopsy.

A developmental cyst of the jaws lined by parakeratinised epithelium with a corrugated surface. It grows along bone, recurs frequently, and may occur in a genetic syndrome.

Area on a radiograph where fewer X-rays are absorbed, so the image appears darker. It indicates reduced tissue density such as caries, cyst or soft tissue.

Curved image layer in panoramic radiography where structures are shown most sharply. Objects outside it appear blurred or magnified, and patient positioning determines its location.

Three-dimensional imaging using a cone-shaped X-ray beam and detector. It gives high-resolution views of teeth and bone at lower dose than medical CT, though soft tissue contrast is poor.

Eruption of a tooth in an abnormal position, such as a permanent first molar that resorbs the primary second molar. It may cause premature loss of the primary tooth.

Cementation of a preformed metal crown over a carious primary molar without local anaesthesia, tooth preparation or caries removal. It seals the lesion and arrests progression.

Removal of the coronal pulp while preserving the vital radicular pulp, used in primary or immature permanent teeth with reversible pulpitis. The remaining tissue is covered with a medicament.

Count of decayed, missing because of caries, and filled permanent teeth per person. It summarises caries experience at population level and is used in epidemiological surveys.

Controlled adjustment of fluoride concentration in public drinking water to a level that reduces caries. It benefits whole populations, especially children, and requires monitoring for fluorosis.

Cephalometric angle between point A, nasion and point B, describing the anteroposterior relationship of the jaws. It helps classify skeletal class I, II or III patterns.