By the BossCE Editorial Team.
Key Points
- The European Society of Endodontology (ESE) S3-level guideline strongly recommends periapical radiography as the routine test for apical periodontitis, with CBCT as an additional measure only when the diagnosis is in doubt [1].
- A periapical radiograph can miss apical periodontitis that CBCT or histology would show, and no radiograph can tell a granuloma from a radicular cyst; histology remains the reference standard [2, 5].
- A radiolucency over a tooth that tests vital, especially in the anterior mandible, should prompt a rethink rather than a root canal: periapical cemento-osseous dysplasia is a classic mimic [6, 7].
Why Periapical Radiolucencies Are Easy to Misread
Apical periodontitis generally presents with an apical radiolucency, but it can also be symptomatic or asymptomatic, and it is principally caused by bacterial infection of the root canal system [1]. The radiograph is only one part of the diagnosis. A systematic review comparing imaging with histopathology found consistently low sensitivity and negative predictive value for periapical radiography, while CBCT agreed more closely with histology; both had high specificity [2]. In practice, that means a “clear” periapical film does not rule disease out, and a visible radiolucency still needs explaining.
The evidence base has limits. All seven studies in that review used cadaver material, and the authors caution that clinical relevance must be interpreted with care [2].
Start with History and Testing, Not the Image
The ESE guideline suggests cold testing, possibly supplemented by electric pulp testing, combined with pain history and clinical findings such as tenderness to percussion, to assess the pulp [1]. Before you decide what a radiolucency is, establish:
- Pulp status: cold and electric pulp tests on the suspect tooth and its neighbours.
- Periapical status: percussion, palpation, swelling and any sinus tract.
- Periodontal status: full probing around the tooth, looking specifically for a narrow, isolated deep pocket.
- History: previous trauma, restorations, root canal treatment and earlier radiographs for comparison.
The Differential Diagnosis Checklist
| Possibility | Clues that point towards it | What to do next |
|---|---|---|
| Apical periodontitis (granuloma or radicular cyst) | Non-vital pulp or root-filled tooth; radiolucency centred on the apex | Root canal treatment for a restorable tooth [1]. Granuloma and cyst both appear as radiolucencies; only histology separates them [5] |
| Periapical cemento-osseous dysplasia (PCOD) | Vital teeth, often several, mainly in the anterior mandible; lesion may become mixed or radiopaque over time [6] | Confirm vitality, avoid endodontic treatment, monitor clinically and radiographically [6, 7] |
| Vertical root fracture | Usually a root-filled or post-retained tooth; narrow deep pocket; halo-shaped radiolucency [8] | Limited field-of-view CBCT if clinical and 2D findings are inconclusive [3] |
| Superimposed anatomy | Mental foramen, incisive canal or sinus over the apex; intact lamina dura; vital tooth | A second view at a different horizontal angle |
| Other jaw cysts and tumours | Vital tooth, lesion not centred on the apex, expansion, root displacement or a lesion that does not fit an endodontic pattern | Refer for specialist assessment; do not start endodontic treatment |
The PCOD Trap
PCOD is a benign fibro-osseous condition that mainly affects the anterior mandible and involves one or more vital teeth [6]. It passes through an early radiolucent stage, a mixed radiolucent-radiopaque stage and a mature radiopaque stage, and the early stage looks very similar to apical periodontitis [6]. Published case reports describe asymptomatic lower anterior teeth referred for endodontic evaluation that tested normally to cold and electric pulp testing; the correct management was monitoring, not root canal treatment [7]. PCOD and apical periodontitis can also coexist in the same patient, so test every tooth individually [6].
Radiographic Features to Assess
- Continuity of the lamina dura around the apex
- Width of the apical periodontal ligament space compared with adjacent teeth
- Border: well defined or diffuse, corticated or not
- Internal structure: purely radiolucent or with radiopaque foci
- Relationship to the apex: centred on it, lateral to the root, or separate from it
- Quality of any root filling and coronal seal
- Change since previous radiographs
When Is CBCT Justified?
The ESE guideline advises that CBCT may be considered when there is doubt about the diagnosis, and notes that radiopaque materials in the canal or periapex can reduce CBCT accuracy [1]. The systematic review behind it likewise found CBCT less accurate in root-filled teeth [2]. The ESE has also published a separate position statement on CBCT in endodontics [4].
The AAE/AAOMR joint position statement (2015/2016 update) takes a similar line [3]:
- Intraoral radiographs are the imaging modality of choice for evaluating the endodontic patient.
- Limited field-of-view CBCT should be considered when clinical signs and symptoms are contradictory or nonspecific, when 2D findings are inconclusive for vertical root fracture, and when assessing non-healing after previous treatment.
- CBCT should not be used routinely for diagnosis or screening without clinical signs and symptoms. Follow ALARA: the smallest field of view and lowest exposure that answer the question.
An updated AAE/AAOMR statement was approved in 2025 [3]; check the current version before applying these points.
Where AI Fits
Dedicated detection software is improving, but performance depends heavily on the image. In one study of 49 patients, an AI tool detected periapical lesions with 78% sensitivity on CBCT but only 33% on panoramic radiographs, with specificity above 98% on both [9]. A missed lesion on a 2D image is therefore a real risk, whether the reader is human or software.
BossCE AI is a clinical reference assistant, not a validated detection tool. It can describe an anonymised radiograph you upload, walk through the checklist above, suggest differentials and confirmatory tests, and point you to guideline sources. It cannot reliably measure PDL width or lesion size, and it should never be the reason to start or withhold treatment.
Chairside Protocol
- Test first: cold and electric pulp testing, percussion, palpation and probing of the suspect tooth and its neighbours.
- Read the radiograph yourself using the feature list, and compare with previous images.
- Match the pattern: a non-vital tooth with an apical radiolucency fits apical periodontitis; a vital tooth does not.
- Escalate to limited field-of-view CBCT only when the diagnosis remains in doubt [1, 3].
- Refer any lesion that does not fit an endodontic or PCOD pattern.
- Review treated cases over a prolonged period, extending follow-up when healing is uncertain [1].
Ask BossCE AI
BossCE AI answers from guidelines and published evidence, with numbered sources under every answer. Try a periapical radiolucency case in BossCE AI, or browse the guidelines in the BossCE Library.
References
- Duncan HF, El-Karim I. Endodontic S3-level clinical practice guidelines: the European Society of Endodontology process and recommendations. British Dental Journal. 2025. doi:10.1038/s41415-025-8335-x (summarising Duncan HF et al. Treatment of pulpal and apical disease: the ESE S3-level clinical practice guideline. International Endodontic Journal. 2023. doi:10.1111/iej.13974)
- Hilmi A, Patel S, Mirza K, Galicia JC. Efficacy of imaging techniques for the diagnosis of apical periodontitis: a systematic review. International Endodontic Journal. 2023. doi:10.1111/iej.13921
- American Association of Endodontists and American Academy of Oral and Maxillofacial Radiology. Joint Position Statement: Use of Cone Beam Computed Tomography in Endodontics, 2015/2016 Update. aae.org. 2025 update: Journal of Endodontics. doi:10.1016/j.joen.2025.09.008
- Patel S, Brown J, Semper M, Abella F, Mannocci F. European Society of Endodontology position statement: use of cone beam computed tomography in endodontics. International Endodontic Journal. 2019. doi:10.1111/iej.13187
- Rios Osorio N, Jiménez Peña O, Contreras Ibarra M, Grajales M, Fernández Grisales R. Accuracy of ultrasound imaging in the differential diagnosis of inflammatory radicular cyst and periapical granuloma: a systematic review and meta-analysis. European Endodontic Journal. 2025. doi:10.14744/eej.2024.84755
- Ma Y, Fang D, Ji M. Periapical cemento-osseous dysplasia masquerading as asymptomatic chronic apical periodontitis in a Chinese woman: a case report. Clinical Case Reports. 2024. doi:10.1002/ccr3.9551
- Ucmak S, Faydali E. The vital illusion: CBCT-tracked evolution of periapical cemento-osseous dysplasia. Cureus. 2026. doi:10.7759/cureus.113758
- Scardini IL, Zamalloa SID, Paiva HC, et al. Diagnosis approaches and clinical management of suspected vertical root fractures: a questionnaire-based study. Journal of Clinical and Experimental Dentistry. 2025. doi:10.4317/jced.63012
- Kazimierczak W, Wajer R, Wajer A, et al. Periapical lesions in panoramic radiography and CBCT imaging: assessment of AI’s diagnostic accuracy. Journal of Clinical Medicine. 2024. doi:10.3390/jcm13092709
This article is for qualified healthcare professionals and is not a substitute for clinical judgement or the full guideline. Check the current version of each source before applying it.
