Endodontics · patient case question
The access outlines of the following teeth are broadly comparable EXCEPT one. Which is the EXCEPTION?
Patient case: An old root filling and a sharp cusp
Patient: Two patients
Chief Complaint: Patient A: “This tooth is tender and there is a bad taste.” Patient B: “I have had a sore on my tongue for two weeks.”
Background: Patient A, 48 years old: tooth #30 was root treated twenty-two years ago and obturated with SILVER POINTS. Patient B, 57 years old: the distolingual cusp of #32 fractured a fortnight ago and has not been treated.
Findings: Patient A: a periapical radiolucency at both roots of #30, a sinus tract on the buccal, tenderness to percussion, and a defective coronal restoration. The canals appear negotiable coronal to the points. Patient B: a sharp fractured cusp edge, and an ulcer with a slightly rolled margin on the lateral border of the tongue lying directly against it.
Show answer and explanation
Correct answer: B. Mandibular lateral incisor
- A. The maxillary canine has an OVAL access, its long axis labiopalatal, cut through the lingual surface. It has a single root with a single canal and the largest pulp chamber of the anterior teeth.
- B. CORRECT as the exception. The MANDIBULAR LATERAL INCISOR is the outlier in this group. Its crown is far narrower mesiodistally, the access is cut through the LINGUAL surface into a chamber that is ribbon-shaped buccolingually, and the outline must be extended incisally and lingually because a SECOND, LINGUAL CANAL is present in a substantial minority of mandibular incisors — commonly quoted around 40%. That second canal is missed precisely when a small conservative oval access is left as cut. Grouping it with the maxillary canine and the two maxillary premolars, which share a broad, straightforward buccopalatal oval, is what the question is testing.
- C. The maxillary second premolar has the same OVOID, buccopalatally oriented occlusal access. Usually a single root, with one or two canals.
- D. The maxillary first premolar has an OVOID access with its long axis buccopalatal, cut through the occlusal surface. Two canals in the great majority of cases, and two separate roots in roughly 60–70%.
Note: The outline shapes worth committing to memory. MAXILLARY: central triangular, lateral roughly ovoid, canine oval, both premolars ovoid, first and second molars triangular (rhomboidal for the first when MB2 is included). MANDIBULAR: incisors ovoid or elliptical, canine oval, both premolars ovoid, first molar rectangular or trapezoidal, second molar triangular. Whatever the shape, the principles do not change: straight-line access to the orifices, complete removal of the chamber ROOF, and preservation of the pulpal FLOOR with its developmental grooves.