PMC3518957_01
An intraoral clinical examination of the mandible did not reveal macroscopically detectable pathologies.
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PMC3518957_01_CRIM.DENTISTRY2012-453415.001.jpg
fig1
Upon clinical examination, the mandibular left first molar (tooth 36) (Figure 1), which had been satisfactorily restored with a conservative restoration, was tender to percussion.
Radiolucency image of tooth 36 showing a periapical radiolucency in the region of the mesial and distal root apices.
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PMC3518957_01_CRIM.DENTISTRY2012-453415.002.jpg
fig2
A single-tooth radiograph of tooth 36 revealed an enlarged periodontal space and a periapical radiolucency in the region of the distal root of tooth 36 (Figure 2). 
Root canal orifices after enlargement during endodontic treatment.
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PMC3518957_01_CRIM.DENTISTRY2012-453415.003.jpg
fig3
After access cavity preparation, pulp was removed and three root canals were exposed (Figure 3).