Endodontics
Endodontics in NZDREX tests diagnosis and technical judgement together. You must name the pulpal and periapical diagnosis, justify treatment, then show safe access, canal negotiation, disinfection and obturation.
Core rules
- Diagnose before treatment: reversible versus irreversible pulpitis, asymptomatic versus symptomatic apical periodontitis, and whether the tooth is restorable and worth treating.
- Access must give straight-line entry to the canal orifices; remove all caries and old restorations from the pulp chamber roof and search for MB2, present in the majority of maxillary first molars.
- Establish working length with an electronic apex locator confirmed by a radiograph; create a glide path before rotary instrumentation.
- Irrigate with sodium hypochlorite (commonly 1-5.25%) using a side-vented needle kept 1-2 mm short of working length; use 17% EDTA to remove the smear layer and finish with a hypochlorite rinse.
- Obturate to 0.5-1 mm short of the radiographic apex and restore the coronal seal promptly.
Worked example
Tooth 36 has severe spontaneous pain, a cold response lingering 30 seconds, percussion tenderness and deep distal caries. Diagnosis: irreversible pulpitis with symptomatic apical periodontitis. An inferior alveolar nerve block gives only partial anaesthesia, which is common in irreversible pulpitis. Add a supplemental intraligamentary or intraosseous injection, then proceed with rubber dam, access, canal location and irrigation. Do not prescribe antibiotics for the pulpitis itself.
Traps
- Treating a cracked tooth as a straightforward endodontic case.
- Blocking a curved canal with a ledge, then losing working length.
- Overextending obturation material into the inferior alveolar canal.