Endodontics
This domain tests pulp and periapical diagnosis, root canal treatment principles, retreatment and endodontic emergencies. The exam often presents a symptom pattern and asks for the diagnosis or next step.
Diagnosis
- Pulp sensibility tests include cold and electric pulp testing; percussion and palpation assess the periapical tissues. Radiographs show anatomy and bone changes but not pulp vitality.
- Reversible pulpitis causes sharp pain that resolves quickly. Irreversible pulpitis causes lingering pain, often spontaneous or nocturnal. Necrosis gives no response; symptomatic apical periodontitis is painful on biting.
Treatment principles
- Access should be straight-line and remove all caries. Establish working length with an apex locator and radiograph, create a glide path, shape conservatively and irrigate.
- Sodium hypochlorite is the main irrigant; EDTA removes smear layer; chlorhexidine is an alternative with caution. Calcium hydroxide is a common intracanal medicament.
- Obturate with gutta-percha and sealer to the corrected working length, then restore with a coronal seal. A good restoration protects the root filling.
Worked example
A 30-year-old has deep caries, lingering cold pain for one minute, no periapical radiolucency and normal percussion. Reasoning: lingering pain indicates irreversible pulpitis; absence of apical change means no established apical periodontitis. The diagnosis is irreversible pulpitis and the treatment is root canal treatment, not just a filling.
Traps that cost marks
A cold test assesses sensibility, not vitality. No response does not always mean necrosis if the tooth is immature or recently traumatised. Do not express sodium hypochlorite beyond the apex or into the sinus. Do not confuse a sinus tract with a periodontal pocket. Incomplete coronal seal causes failure even after good obturation.