MOH Oral and Dental Health Licensure Exam (Jordan) key terms

The basic structural unit of enamel; a tightly packed bundle of hydroxyapatite crystallites that runs from the dentinoenamel junction toward the tooth surface. Rod orientation affects caries spread and preparation design.

The scalloped interface where enamel and dentin meet. It is the site of initiation of dentinal caries and a landmark for judging excavation depth; its scalloping increases enamel-dentin bond area and crack resistance.

A post-mitotic, columnar cell lining the pulp periphery that secretes dentin matrix and later maintains it. Odontoblast processes extend into dentinal tubules, and their injury triggers tertiary dentin formation.

A double layer of epithelial cells derived from the cervical loop of the enamel organ. It maps root shape and induces odontoblast differentiation, and its remnants persist as epithelial rests of Malassez in the periodontal ligament.

A predominantly white patch of oral mucosa that cannot be characterised clinically or pathologically as any other condition. It is a diagnosis of exclusion and carries a variable risk of malignant transformation, so biopsy is advised.

A chronic immune-mediated mucocutaneous condition producing bilateral white striae, erosions or plaques, most often on the buccal mucosa. It is managed with topical corticosteroids; malignant transformation is debated but monitoring is recommended.

A developmental odontogenic cyst lined by parakeratinised stratified squamous epithelium with a corrugated surface. It grows along marrow spaces, recurs frequently, and may be a feature of the naevoid basal cell carcinoma syndrome.

A benign but locally aggressive odontogenic epithelial tumour, most common in the posterior mandible, typically presenting as a multilocular radiolucency. Treatment ranges from enucleation with adjunctive measures to resection, with long-term follow-up for recurrence.

A common condition of recurrent, painful, shallow oral ulcers with a yellow fibrin centre and erythematous halo, arising on non-keratinised mucosa. Diagnosis is clinical; management is symptomatic and involves topical corticosteroids and attention to triggers.

The distance from a coronal reference point to the apical constriction, determined radiographically and with an electronic apex locator. Accurate working length prevents short or over-extended instrumentation and obturation.

Deliberate, gentle passage of a small file through the apical constriction to maintain canal openness and prevent blockage by debris. It is performed with a file one to two sizes smaller than the apical master file.

A microcrystalline layer of dentine debris and organic material created on canal and cavity walls by cutting instruments. In root canals it harbours bacteria and must be removed with chelators; in operative dentistry its retention affects bonding.

The main irrigant in root canal treatment, used at 0.5 to 5.25 percent to dissolve organic tissue, kill microorganisms and flush debris. It must be kept within the canal because extrusion can cause severe tissue injury.

A device that measures electrical impedance between the file and the periodontium to locate the apical constriction. It improves working length accuracy, especially when the apex is not clearly visible radiographically.

The distance from the cementoenamel junction to the base of the periodontal pocket, measured clinically with a probe. It is the principal indicator of past periodontal destruction and is used in staging periodontitis.

Loss of periodontal attachment into the bifurcation or trifurcation of a multirooted tooth, graded I to III or IV. It complicates plaque control and treatment planning and worsens the prognosis of the affected tooth.

Non-surgical periodontal therapy that removes supra- and subgingival plaque, calculus and contaminated cementum from root surfaces. It reduces inflammation and probing depth, and is the initial treatment for periodontitis.

The combined supracrestal attachment of junctional epithelium and connective tissue, about two millimetres in health. Restorative margins encroaching on it provoke inflammation and bone loss, so a minimum distance from the bone crest is needed.

A maxillomandibular relationship in which the condyles sit in their most anterior, superior position against the articular eminence, independent of tooth contact. It is a reproducible reference for recording jaw relations and designing occlusal schemes.

The distance between the maxilla and mandible when the teeth are in maximal intercuspation, usually recorded as facial or incisal height. It guides complete denture construction and full-mouth rehabilitation, where excessive change causes discomfort.

Two or more parallel axial surfaces on abutment teeth that direct a removable partial denture along its path of insertion and provide stability against horizontal forces. They are prepared during mouth preparation for the framework.

A painful postoperative complication after extraction in which the blood clot disintegrates or is lost, exposing bare bone. It occurs most often in mandibular third molar sites and is managed by irrigation and dressing, not antibiotics routinely.

An abnormal opening between the oral cavity and maxillary sinus, most often after extraction of maxillary posterior teeth. Small defects may heal spontaneously; larger ones require surgical closure to prevent sinusitis and fistula formation.

A horizontal surgical division of the maxilla above the tooth apices that allows the maxilla to be repositioned in three dimensions. It is used to correct skeletal Class III, vertical excess and asymmetry, usually with rigid internal fixation.

In orthodontics, the resistance to unwanted tooth movement provided by other teeth, the palate or extraoral structures. Adequate anchorage planning determines whether space closure and incisor retraction succeed without losing posterior support.

Measurement of skeletal and dental relationships on a standardised lateral skull radiograph using defined landmarks, planes and angles. It supports diagnosis, treatment planning, growth assessment and evaluation of orthodontic or surgical change.

Removal of the coronal pulp while preserving the vital radicular pulp, usually in a primary or young permanent molar with reversible pulpitis. Success depends on haemostasis and a reliable dressing such as mineral trioxide aggregate.

A fixed or removable appliance that preserves arch length after premature loss of a primary tooth until the successor erupts. The band-and-loop is typical for a lost primary molar; failure to maintain space can cause impaction and crowding.

A paediatric technique in which a preformed metal crown is cemented over a primary molar with caries, without local anaesthesia or tooth preparation. It seals the lesion and is well accepted, though occlusion may alter temporarily.

Contraction of resin composite as monomer converts to polymer, creating stress at the tooth-restoration interface. It can cause marginal gaps, postoperative sensitivity and cuspal deflection; incremental placement and stress-relieving strategies reduce it.

A dental cement formed by the acid-base reaction of fluoroaluminosilicate glass powder with polyalkenoic acid. It bonds chemically to tooth structure, releases fluoride and is used for liners, luting and atraumatic restorative treatment.

Adrenaline or felypressin added to local anaesthetic solutions to constrict vessels, slow systemic absorption, prolong anaesthesia and reduce bleeding. Adrenaline is limited in severe cardiovascular disease and with non-selective beta-blockade.

The count of decayed, missing because of caries, and filled permanent teeth per person. It summarises caries experience in a population and is used for epidemiological comparison and planning of preventive services.

Adjustment of the fluoride concentration of a public water supply to an optimal level, usually about 0.7 milligrams per litre, to prevent dental caries. It is population-wide, equity-promoting, and requires monitoring and fluorosis surveillance.

A process that destroys all microorganisms, including bacterial spores, on reusable instruments. In dentistry it is achieved by autoclaving, validated with physical, chemical and biological indicators, and must follow cleaning and packaging.

A pressure vessel that sterilises instruments with saturated steam under pressure, typically at 121 degrees Celsius for 15 minutes or 134 degrees Celsius for 3 minutes. Correct loading and cycle monitoring are essential for effectiveness.

A patient's voluntary agreement to a proposed investigation or treatment after receiving understandable information about benefits, risks, alternatives and consequences of refusal. It is a process, documented in the record, and central to ethical and lawful practice.

The legal and ethical obligation of a clinician to act in the patient's best interests and to a reasonable standard. Breach of this duty, causing harm, may establish negligence; scope of practice defines its limits.