Which diagnosis best fits a tooth with a periapical radiolucency and a fistula apical to the tooth?

• A. Chronic apical periodontitis with necrotic pulp
• B. Reversible pulpitis
• C. Normal apical tissues
• D. Acute apical abscess

Answer: (A)

The key idea is that a draining sinus tract (fistula) at the apex along with a periapical radiolucency indicates a chronic inflammatory lesion stemming from a non-vital pulp. The radiolucency shows bone loss around the tooth apex from long-standing infection, while the sinus tract demonstrates ongoing drainage of inflammatory material. This combination fits a necrotic pulp driving chronic apical periodontitis. Reversible pulpitis would not produce a periapical radiolucency or a fistula because the pulp remains vital and inflammation is limited. Normal apical tissues would show neither radiolucency nor a fistula, and an acute apical abscess typically presents with more acute symptoms and pain, even though a sinus tract can sometimes be seen. Thus, chronic apical periodontitis with a necrotic pulp best explains the findings.