Case Overview
A maxillary premolar presented with persistent biting discomfort despite the absence of caries or restorations. Clinical examination revealed intact enamel with no visible cavitation. Periapical radiography demonstrated a subtle widening of the periodontal ligament space, raising suspicion of crack tooth syndrome. Given the patient’s symptoms and radiographic findings, endodontic intervention was indicated.
During access cavity preparation under magnification and rubber dam isolation, an unusual three-canal configuration was identified: buccal, middle, and palatal canals. This anatomical variation is rarely encountered in premolars and requires meticulous exploration to avoid missed anatomy.
Clinical Protocol
All procedures were performed under strict rubber dam isolation to ensure asepsis and optimal visual control. Access was refined conservatively, preserving pericervical dentin to maintain structural integrity. Magnification allowed precise identification of the additional middle canal, which would have been easily overlooked without enhanced visual aids.
Working length was established using an electronic apex locator and confirmed radiographically. Chemomechanical preparation was carried out using a conservative shaping philosophy to respect remaining tooth structure. Copious irrigation protocols were followed to ensure adequate disinfection, particularly critical in anatomically complex canal systems.
Obturation was completed after confirming canal cleanliness and patency, achieving dense, three-dimensional sealing. Given the diagnosis of crack tooth syndrome, emphasis was placed on cuspal protection to minimise propagation of the crack and improve long-term prognosis.
Step-by-step with image explanations
Image 1: Pre-op occlusal view (intact tooth)
What to highlight:
- No obvious caries or restorations, yet patient has sharp pain on biting or release.
- This is classic for crack tooth syndrome where symptoms can be strong even when the tooth looks “clean”.
- Mention targeted biting test (Tooth Slooth) and transillumination (if you did it).
Key line: “Symptoms > surface appearance. A ‘sound’ tooth can still be cracked.”
Image 2: Rubber dam isolation + access outline
What to highlight:
- Full isolation is non-negotiable for diagnosis + predictable disinfection.
- Access is conservative but strategic: preserve pericervical dentin while gaining straight-line entry.
- If you used magnification, mention it here because this case is about finding anatomy others miss.
Clinical note: “Crack cases demand controlled access to avoid propagating existing microfractures.”
Image 3: Access cavity opened (pulp chamber visible)
What to highlight:
- You’re looking for anatomic “clues”: developmental grooves, darker dentine tracks, pulpal floor map.
- Emphasise that this stage is where missed canals happen if you rush.
Tip: Use DG16 + micro-openers + ultrasonics for troughing along grooves (light touch, not aggressive).
Image 4: Orifice location showing rare anatomy (Buccal + Middle + Palatal)
What to highlight:
- The key educational moment: three canals in a premolar.
- Describe the layout clearly:
- Buccal canal (often easiest)
- Middle canal (rare, easily missed, often between B and P line)
- Palatal canal (usually more centred/palatal)
Pro tip: “If the file paths aren’t symmetrical, assume there’s more anatomy.”
Image 5: Scouting and glide path (small hand files)
What to highlight:
- Start with small K-files (#08/#10) to negotiate, confirm patency gently.
- Establish a reproducible glide path before rotary/reciprocation.
- Mention lubricant + watch-winding + balanced force style.
Crack tooth angle: Keep instrumentation conservative to reduce further weakening.
Image 6: Working length radiograph (WL)
What to highlight:
- WL confirmed with apex locator + radiograph.
- If the canals are close/superimposed, mention angled radiographs to separate them.
- Briefly describe lengths without overdoing numbers (unless you want).
Key point: “Three canals can look like two on a straight PA. Angles matter.”
Image 7: Shaping protocol (master cone or file sequence reference image)
What to highlight:
- Conservative shaping philosophy.
- Keep coronal enlargement controlled.
- Respect canal curvature and avoid over-flaring (especially in premolars).
If you want to sound top-end: “Shaping done primarily to facilitate irrigation, not to ‘create space’.”
Image 8: Irrigation / activation image (needle/ultrasonic tip)
What to highlight:
- Irrigation is the disinfection engine, especially in complex anatomy.
- Mention your sequence (example): NaOCl throughout, final EDTA, final NaOCl rinse.
- Activation (ultrasonic/sonic) is where you show “evidence-based detail”.
Short explanation: “Activation improves irrigant penetration and debridement in fins/isthmuses.”
Image 9: Obturation radiograph (post-op)
What to highlight:
- 3 canals sealed with dense fills to WL.
- Show that anatomy is respected (no overextension, no voids).
- Mention sealer type briefly (bioceramic if used).
Crack tooth angle: “A clean endo isn’t enough. The long-term success depends on cuspal protection.”
Image 10: Post-endo build-up / cuspal coverage plan
What to highlight:
- Crack tooth syndrome is a structural diagnosis. Restoration is part of treatment.
- Mention immediate bonded build-up and the plan for onlay/crown depending on remaining tooth structure and occlusion.
Why this case matters
- Crack tooth syndrome can present with no caries, and a subtle PDL widening can be the only radiographic hint.
- Maxillary premolars can occasionally present with three canals, and missing one canal is a common reason for persistent symptoms.
- Magnification, rubber dam isolation, angled radiographs, and systematic scouting are what make these cases predictable.
References (you can keep these at the bottom)
- Abbott PV. Cracked teeth: A review of the literature. Aust Dent J. 2017.
- Kahler B, et al. Cracked tooth syndrome: Aetiology, diagnosis and management. Int Endod J. 2018.
- Cleghorn BM, et al. Maxillary first premolar root canal morphology review. J Endod. 2007.
- Vertucci FJ. Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol. 1984.
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