NZDREX flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

C-factor

Ratio of bonded to unbonded surface area in a cavity preparation. High C-factor increases polymerisation shrinkage stress, so incremental layering and flowable liners are used to reduce stress in composite restorations.

Working length

Distance from a coronal reference point to the apical constriction, determined by apex locator and radiograph. Accurate working length prevents over- or under-instrumentation and improves endodontic success.

Ante's law

The root surface area of abutment teeth supporting a fixed partial denture should equal or exceed the root surface area of the missing teeth. Used to assess FPD feasibility and abutment selection.

Peri-implant mucositis

Reversible inflammation of the soft tissue around an implant without progressive bone loss. Managed by improved plaque control and professional maintenance; distinct from peri-implantitis, which involves bone loss.

Informed consent

A patient's voluntary agreement after disclosure of material risks, benefits, and alternatives, with capacity and understanding. Documented discussions support ethical and legal practice.

Apical periodontitis

Inflammation of the periapical tissues, classified as symptomatic (pain on percussion/biting) or asymptomatic (radiographic radiolucency without symptoms). Diagnosed with pulp tests, percussion, and radiographs.

Clinical attachment level

Distance from the cementoenamel junction to the base of the periodontal pocket, calculated as probing depth plus recession (or minus hyperplasia). A key measure for staging periodontitis.

Kennedy classification

Classifies partially edentulous arches: Class I bilateral posterior edentulous areas; Class II unilateral posterior; Class III unilateral bounded posterior; Class IV single anterior edentulous span crossing the midline.

Osseointegration

Direct structural and functional connection between living bone and implant surface without intervening soft tissue. Depends on primary stability, surface roughness, bone quality, and loading protocol.

Vita shade guide

A standard tool for shade matching using hue, value, and chroma under neutral daylight. Value (brightness) is the most important parameter for perceived tooth colour.

Autoclave sterilisation

Sterilisation using saturated steam under pressure, typically 134°C for 3 minutes or 121°C for 15 minutes. Validated with chemical indicators, biological spore tests, and regular maintenance.

Rubber dam isolation

A barrier that isolates teeth from oral fluids and soft tissues, protecting the airway and improving moisture control for adhesive and endodontic procedures. Standard of care for these treatments.

Sodium hypochlorite

Primary endodontic irrigant (0.5-5.25%) with antimicrobial and tissue-dissolving properties. Used with EDTA for smear layer removal; avoid direct mixing with chlorhexidine due to precipitate formation.

Pulp sensibility testing

Cold test and electric pulp test assess pulpal nerve response, not blood supply. Results are compared with contralateral and adjacent teeth; false positives/negatives occur with calcification or recent trauma.

Lekholm and Zarb

Classification of jawbone density: Type 1 dense cortical; Type 2 dense cortical with cancellous core; Type 3 thin cortical with dense cancellous; Type 4 thin cortical with low-density cancellous.

Mutually protected occlusion

An occlusal scheme where anterior teeth guide excursive movements and disclude posterior teeth, while posterior teeth protect anterior teeth in centric occlusion. Reduces lateral forces on posteriors.

Amalgam contraindications

Avoid in true mercury allergy and generally in visible anterior teeth. Requires mechanical retention and adequate resistance/retention form; no adhesive bonding to tooth structure.

Bleeding on probing

A clinical sign of gingival inflammation recorded during periodontal probing. Persistent BOP at maintenance visits indicates increased risk of periodontal disease progression.

Apex locator

An electronic device that determines working length by measuring impedance changes near the apical constriction. Reliable in the presence of blood and exudate but affected by metallic restorations.

Standard precautions

Treating all patients as potentially infectious using gloves, masks, eye protection, gowns, and hand hygiene. Fundamental to infection control in dental practice.

Caries risk assessment

A structured evaluation of lesion history, plaque, diet, fluoride exposure, saliva, and medical factors to categorise caries risk and set recall intervals and preventive strategies.

Vertical root fracture

A longitudinal fracture of the root, suggested by deep narrow pocketing, J-shaped radiolucency, and pain on biting. Usually managed by extraction or root resection, not retreatment.

Fluoride varnish

A 5% sodium fluoride preparation applied to teeth for caries prevention. Used for high-risk patients and children; complements fluoride toothpaste and dietary counselling.

Provisional restoration

A temporary restoration that protects prepared teeth, maintains occlusion and aesthetics, and allows assessment of vertical dimension and aesthetics before definitive treatment.

Supportive periodontal therapy

Regular maintenance visits (typically 3-6 months, risk-based) after active periodontal treatment. Reduces recurrence of periodontitis and tooth loss; includes reassessment and reinforcement of plaque control.

Peri-implantitis

Inflammation of peri-implant tissues with progressive bone loss. Risk factors include smoking, poor hygiene, history of periodontitis, and parafunction; managed by debridement and surgical/non-surgical therapy.

Polyvinyl siloxane

An addition silicone impression material with high accuracy and dimensional stability. Used for fixed and removable prosthodontic impressions; available in multiple viscosities for putty-wash techniques.

Lithium disilicate

A glass-ceramic with high strength and translucency, used for crowns, veneers, and onlays. Bonded to enamel for optimal strength; aesthetic alternative to zirconia in anterior regions.

Record retention

Clinical records must be accurate, contemporaneous, and legible, retained per jurisdictional requirements (commonly 7-10 years, longer for minors). Essential for continuity of care and legal defence.

ASA classification

A system grading systemic health: ASA I healthy; ASA II mild disease; ASA III severe but non-incapacitating; ASA IV incapacitating; ASA V moribund. ASA III+ often requires medical consultation.

EDTA irrigation

A 17% chelating agent used in endodontics to remove the smear layer and open dentinal tubules, improving disinfection and sealer adaptation. Used alternately with sodium hypochlorite.

Glickman furcation

A classification of furcation involvement (I-IV) based on horizontal and vertical bone loss. Guides treatment decisions such as furcation plasty, root resection, or extraction.