Endodontics
Two diagnoses are required for every endo question: pulpal and periapical. The thermal test that triggers a lingering response is the most diagnostic finding the exam asks about.
Pulpal & Periapical Diagnosis
Two questions, two diagnoses. The cold test answers the first. Percussion and palpation answer the second.
Pulp test → diagnosis
Pulpal diagnosis — quick reference
| Diagnosis | Cold test | Symptom | Treatment |
|---|---|---|---|
| Normal pulp | Brief response, resolves < 2 sec | None | None |
| Reversible pulpitis | Sharp brief response, resolves quickly | Pain only on stimulus, brief | Remove etiology (caries → restoration) |
| Symptomatic Irreversible Pulpitis (SIP) | Lingering > 30 sec, severe | Spontaneous · sharp · radiating · sleep-disturbing | RCT or extraction |
| Asymptomatic Irreversible Pulpitis | May or may not respond | None — found via deep caries / pulp exposure | RCT or extraction |
| Pulp Necrosis | No response · no EPT | None or dull discomfort | RCT or extraction |
| Previously Treated | No response (RCT done) | None unless complication | None |
| Previously Initiated | No response | Variable | Complete RCT or extract |
Periapical diagnosis
| Diagnosis | Percussion | Radiograph | Treatment |
|---|---|---|---|
| Normal apex | Negative | Normal PDL | None |
| Symptomatic Apical Periodontitis | Positive | ± Widened PDL | RCT |
| Asymptomatic Apical Periodontitis | Negative | PARL present | RCT |
| Acute Apical Abscess | Positive · swelling | ± Widened PDL or early PARL | I&D · RCT · ± antibiotic if systemic |
| Chronic Apical Abscess | Negative | PARL with sinus tract / fistula | RCT |
| Condensing Osteitis | Negative | Diffuse radiopacity at apex | RCT if pulp involved · monitor if not |
The 4 P's of Pulp Therapy
Treatment escalates with pulp involvement. Pick the least-invasive option that addresses the depth of injury.
Indirect Pulp Cap
Material: RMGI or CaOH on remaining dentin → restoration.
Vitality: reversible pulpitis or normal pulp.
Direct Pulp Cap
Material: MTA or Biodentine directly on exposure → glass ionomer base → restoration.
Vitality: normal or reversible pulpitis only.
Pulpotomy
Partial: remove 2-3 mm coronal pulp → MTA. Mature or immature.
Cervical: remove all coronal pulp → MTA. Primary teeth OR vital cervical pulp on immature permanent.
Pulpectomy / RCT
Full removal of coronal + radicular pulp · clean & shape · obturate.
Required for: SIP · necrosis · all non-vital permanent teeth.
Open Apex — Three Routes
Three options for an immature tooth, chosen by pulp vitality and treatment goal.
Apexogenesis
Pulp: vital · partially exposed.
Goal: continue normal root development (apex closes naturally).
Procedure: partial pulpotomy with MTA + restoration. Monitor.
Outcome: long, thick walls + closed apex.
Apexification
Pulp: non-vital, necrotic.
Goal: form an apical calcified barrier so RCT can be obturated.
Procedure: place MTA apical plug (4-5 mm) → backfill GP. (Older: long-term CaOH dressings.)
Outcome: closed apex but root walls remain thin → fracture risk.
Regenerative Endo
Pulp: non-vital with apical lesion (open apex).
Goal: restore vital tissue → continued root development.
Procedure: disinfect with TAP/CaOH → induce apical bleeding → MTA over blood clot → restoration.
Outcome: thicker walls + apical closure (often best long-term).
Analyzing Failed Endo
When an OSCE shows a radiograph of a treated tooth that's failing, run through this acronym.
Posts & Cores
Three numerical rules for post placement. The OSCE asks for the exact length and apical seal.
Post placement — three rules
Material choices
| Material | Indication |
|---|---|
| Fiber post (composite) | Most cases. Modulus close to dentin → fewer root fractures. |
| Cast post-and-core | Severely damaged tooth · narrow ovoid canal · heavy occlusal load. Higher root fracture risk. |
| Pre-fabricated metal post | Less commonly used; reserved for specific cases. |
| No post | Anterior teeth with adequate ferrule + ≥ 50% coronal tooth structure remaining. |