Diagnosis
Diagnosis
The diagnosis combines history (nature and onset of pain), clinical examination, vitality testing (non-vital tooth expected), and radiographic examination. The combination of a non-vital tooth plus percussion sensitivity plus periapical radiolucency is virtually diagnostic.
Vitality testing with cold or EPT: non-response to cold (absent response) or no response to EPT is expected in apical periodontitis secondary to pulp necrosis. A vital response indicates traumatic apical periodontitis or early disease in a tooth with vital pulp undergoing acute exacerbation.
Periapical radiographs are essential. Early AAP may show only slight widening of the periodontal ligament space apically. Established AAP shows a periapical radiolucency (darkening) representing bone resorption. CBCT detects early cortical changes and 3D abscess extent not visible on 2D radiographs.
Selective palpation over the root apex (buccal and lingual) identifies tender areas and fluctuance indicating abscess formation and pus location. A non-fluctuant firm swelling is cellulitis (diffuse spreading infection); a fluctuant swelling contains pus and is ready for incision and drainage.
Differentiating acute periodontal abscess from acute apical abscess is clinically important: periodontal abscess involves a vital tooth with a deep periodontal pocket; apical abscess involves a non-vital tooth. Both produce swelling, percussion sensitivity, and periapical radiolucency but differ in vitality testing and pocket depth.