NZDREX cheat sheet

Pulp sensibility testing: cold test (refrigerant spray) is the primary vitality test; electric pulp test (EPT) thresholds vary between teeth and patients, so compare with contralateral and adjacent teeth rather than absolute numbers.

Percussion tenderness indicates apical periodontitis (symptomatic apical periodontitis if acute); palpation and mobility assess extent of apical and periodontal involvement.

Radiographic interpretation: periapical radiographs show bone loss only after significant mineral loss; CBCT is indicated when 2D imaging is inconclusive (e.g., suspected vertical root fracture, extra canals, complex anatomy).

Caries risk assessment (e.g., CAMBRA-style) categorises patients as low/moderate/high/extreme based on lesion history, plaque, diet, fluoride exposure, saliva flow, and medical factors; recall interval is set by risk category.

ASA physical status classification: ASA I healthy; ASA II mild systemic disease; ASA III severe systemic disease not incapacitating; ASA IV incapacitating threat to life; ASA V moribund. ASA III+ usually warrants medical consultation before elective care.

Antibiotic prophylaxis is not routinely indicated for infective endocarditis prevention in most patients; NZ guidelines restrict prophylaxis to highest-risk cardiac groups (e.g., prosthetic valve, previous IE, certain congenital heart disease) before invasive dental procedures.

Differential diagnosis of orofacial pain: odontogenic (pulpal, periapical, periodontal) vs. non-odontogenic (TMD, neuropathic, sinus, referred cardiac); key discriminators include response to local anaesthetic testing, thermal provocation, and pain on function.

Treatment planning sequence: emergency/acute relief → disease control (caries, periodontal, endodontic) → reassessment → definitive restorative/prosthetic/implant care → maintenance.

Cavity classification (G.V. Black): Class I pits/fissures; Class II proximal of posterior teeth; Class III proximal of anterior teeth without incisal edge involvement; Class IV includes incisal edge; Class V cervical third (gingival).

Amalgam is contraindicated in patients with true mercury allergy and generally avoided in visible anterior teeth; it requires mechanical retention and adequate resistance/retention form.

Composite resin bonding: total-etch (phosphoric acid 30-40% on enamel, 15s; dentine 15s) vs. self-etch; enamel bond strength is highest with phosphoric acid etch. Avoid over-drying dentine (collapse of collagen network).

C-factor = bonded surface area ÷ unbonded surface area; high C-factor in Class I cavities increases polymerisation shrinkage stress; use incremental layering (≤2 mm) and flowable liners to reduce stress.

Rubber dam isolation is standard for adhesive and endodontic procedures; it protects the airway, retracts soft tissue, and improves moisture control for bonding.

Shade selection should be made before dehydration of teeth, under neutral lighting, with the tooth moist; composite shades shift after curing, so use manufacturer shade guides for composites.

Finishing and polishing of composites: coarse to fine sequence with water coolant; immediate finishing reduces surface roughness and plaque accumulation compared with delayed finishing.

Glass ionomer cements release fluoride and bond chemically to tooth structure; resin-modified GIC has improved strength and is useful for cervical lesions and paediatric restorations.

Working length determination: apex locator combined with periapical radiograph; electronic apex locators are reliable in the presence of blood and exudate but may be affected by metallic restorations or very dry canals.

Irrigation: sodium hypochlorite (0.5-5.25%) is the primary antimicrobial and tissue-dissolving irrigant; EDTA (17%) is used as a chelator to remove smear layer; do not mix NaOCl and chlorhexidine directly (precipitate).

Root canal morphology: maxillary first molar typically has MB1 and MB2 canals; mandibular first molar typically has two mesial and one distal canal; mandibular premolars may have complex anatomy.

Pulpal diagnosis categories: normal, reversible pulpitis, symptomatic irreversible pulpitis, asymptomatic irreversible pulpitis, necrosis, previously treated, previously initiated therapy.

Apical periodontitis diagnosis: symptomatic apical periodontitis (pain on biting/percussion), asymptomatic apical periodontitis (radiographic periapical radiolucency without symptoms), acute apical abscess, chronic apical abscess.

Endodontic access principles: straight-line access to canal orifices, complete deroofing of pulp chamber, removal of all caries and defective restorations, and conservation of tooth structure.

Single-visit vs. multi-visit endodontics: multi-visit with calcium hydroxide intracanal medicament is preferred when there is persistent exudate, infection, or time constraints; single-visit is acceptable when canals are dry and infection controlled.

Vertical root fracture is suspected with deep, narrow pocketing, J-shaped radiolucency, and pain on biting; usually managed by extraction or root resection, not by endodontic retreatment.

Periodontal diagnosis requires probing depths, clinical attachment level (CAL), bleeding on probing (BOP), plaque scores, and radiographs; CAL = probing depth + recession (or minus hyperplasia).

2018 classification: periodontitis staged I-IV by severity (CAL, bone loss, tooth loss) and graded A-C by rate of progression (bone loss/age ratio, smoking, diabetes).

Gingivitis is reversible inflammation confined to gingiva; periodontitis involves attachment loss and alveolar bone loss.

Non-surgical periodontal therapy (scaling and root planing) is the initial treatment for periodontitis; re-evaluation at 6-8 weeks determines need for further therapy or referral.

Risk factors: smoking, poorly controlled diabetes, plaque accumulation, certain medications (e.g., phenytoin, ciclosporin, nifedipine causing gingival overgrowth), and genetic susceptibility.

Antibiotic adjuncts (e.g., amoxicillin + metronidazole) may be considered for aggressive/grade C periodontitis but are not a substitute for mechanical debridement.

Furcation involvement is classified Glickman I-IV or Hamp I-III; treatment options include furcation plasty, root resection, tunnel preparation, or extraction depending on severity.

Supportive periodontal therapy (maintenance) at intervals determined by risk (typically 3-6 months) reduces recurrence and tooth loss.

Tooth preparation for full veneer crowns: occlusal reduction 1.5-2.0 mm, axial reduction 1.0-1.5 mm, finish line (chamfer or shoulder) 0.8-1.2 mm, and adequate path of insertion with ≤10-15° convergence.

Fixed partial denture (FPD) design: abutment selection based on crown-root ratio, periodontal support (Ante's law: root surface area of abutments ≥ root surface area of missing teeth), and span length.

Removable partial denture (RPD) components: major connector, minor connectors, rests, direct retainers (clasps), indirect retainers, and denture base; Kennedy classification describes edentulous spans.

Complete denture principles: adequate border seal, balanced occlusion, centric relation record, and proper vertical dimension of occlusion (VDO); loss of VDO can cause angular cheilitis and reduced masticatory efficiency.

Occlusal schemes: mutually protected occlusion (anterior guidance in excursive movements, posterior disclusion) vs. group function; canine guidance reduces lateral forces on posterior teeth.

Impression materials: addition silicone (polyvinyl siloxane) for accuracy and dimensional stability; alginate for study casts; polyether for rigid, hydrophilic impressions.

Provisional restorations protect prepared teeth, maintain occlusion and aesthetics, and allow assessment of VDO and aesthetics before definitive restoration.

Occlusal vertical dimension and centric relation records are essential before extensive rehabilitation; use facebow and interocclusal records for accurate articulation.

Implant success criteria (Albrektsson): immobile implant, no peri-implant radiolucency, bone loss <0.2 mm/year after first year, no persistent pain, and satisfactory aesthetics/function.

Osseointegration depends on primary stability, implant surface (roughness), bone quality/quantity, surgical technique, and loading protocol.

Peri-implant mucositis is reversible inflammation of soft tissue without bone loss; peri-implantitis involves inflammation with progressive bone loss.

Risk factors for implant failure: smoking, uncontrolled diabetes, poor oral hygiene, history of periodontitis, inadequate bone volume, and parafunction.

Implant placement timing: immediate (same visit as extraction), early (2-8 weeks), or delayed (>3 months); immediate placement requires intact socket walls and absence of acute infection.

Bone density classification (Lekholm & Zarb): 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.

Sinus lift: lateral window approach for significant bone augmentation; osteotome (crestal) approach for minor augmentation; assess residual bone height and sinus anatomy on CBCT.

Peri-implant maintenance includes probing (light force), radiographs, plaque control, and regular recall; implant survival ≠ success, so assess function and aesthetics.

Shade matching: use Vita classical or 3D Master shade guides under neutral daylight (5500 K); assess hue, value, and chroma; value is most important for perceived brightness.

Composite resin: microhybrid and nanohybrid composites balance polish retention and strength; flowable composites have lower filler content and higher shrinkage.

Ceramic materials: lithium disilicate (e.max) has high strength and translucency; zirconia has high flexural strength but lower translucency; porcelain veneers require enamel bonding for optimal strength.

Bonding to enamel is more predictable than to dentine; enamel etching with 37% phosphoric acid creates microporosity for micromechanical retention.

Dental amalgam: high compressive strength, technique-sensitive, no adhesive bonding; composite: adhesive, aesthetic, but polymerisation shrinkage and lower wear resistance in large posterior restorations.

Colour stability: composites can discolour over time; polishing and avoiding staining agents (coffee, tea, smoking) help; ceramics are generally more colour-stable.

Fluoride varnish (5% NaF) and fluoride toothpaste (1000-1500 ppm) are evidence-based for caries prevention; high-concentration fluoride (5000 ppm) for high-risk patients.

Whitening: carbamide peroxide (10-22% at home) or hydrogen peroxide (in-office); common side effects include transient sensitivity and gingival irritation.

Informed consent requires capacity, disclosure of material risks/benefits/alternatives, understanding, and voluntary decision; document discussions and patient questions.

Confidentiality: patient information must not be disclosed without consent except where required by law (e.g., mandatory reporting of child abuse, court order, public health requirements).

Scope of practice: dentists must practise within their competence and refer when a procedure exceeds their training or experience; continuing professional development is required for registration.

Infection control standard precautions: treat all patients as potentially infectious; use gloves, masks, eye protection, and gowns; hand hygiene before and after patient contact.

Sterilisation: autoclave (134°C for 3 minutes or 121°C for 15 minutes) is standard; monitor with chemical indicators, biological indicators (spore tests), and regular validation.

Sharps safety: never recap needles by hand; use sharps containers; report needlestick injuries immediately and follow post-exposure prophylaxis protocols.

Surface disinfection and barrier protection: use intermediate-level disinfectants (e.g., chlorine-based, alcohol) for surfaces; barriers for frequently touched items.

Record keeping: accurate, contemporaneous, and legible clinical records are a professional and legal obligation; retain records per jurisdiction requirements (commonly 7-10 years, longer for minors).