How to Read Dental Radiographs: A Systematic Approach
Most missed findings on a dental X-ray are not subtle. They are outside the area the student was looking at.
Students miss findings on radiographs for one reason far more often than any other: they look at the tooth the patient complained about and stop. A systematic sweep — the same sweep, every single time — catches almost everything that matters.
Start with the film itself
Before you interpret anything, judge whether the radiograph is diagnostic:
- Coverage — is the apex visible? A periapical film that cuts off the apex cannot rule out a periapical lesion.
- Distortion — elongation or foreshortening from angulation error changes apparent root length and bone levels.
- Density and contrast — too dark or too light hides early caries.
- Overlap — overlapping contacts on a bitewing make interproximal caries undiagnosable.
A non-diagnostic film should be retaken, not squinted at. Reporting from a poor radiograph is how lesions get missed.
The sweep — in this order, every time
1. Crowns
Interproximal surfaces first — early caries appears as a triangular radiolucency below the contact point. Then occlusal surfaces, then existing restorations: look for recurrent caries at the margins, overhangs, and open margins.
2. Pulp chambers and canals
Chamber size relative to age (it narrows over time), pulp stones, internal or external resorption, and how close a restoration or lesion sits to the pulp.
3. Roots
Number, curvature, fractures, resorption. Note anatomy that will matter clinically — a sharply curved mesiobuccal root changes the difficulty of both extraction and endodontics.
4. Periapical region
Widened periodontal ligament space, loss of lamina dura, radiolucencies at the apex. Compare against the adjacent teeth as your control — the contralateral side is your best reference.
5. Alveolar bone
Crestal bone height relative to the cemento-enamel junction, the pattern of any loss (horizontal versus vertical), furcation involvement in multi-rooted teeth, and trabecular pattern.
6. Everything else on the film
This is the step that gets skipped and where the important incidental findings live: the maxillary sinus floor, the inferior alveolar canal, the mental foramen, unerupted or supernumerary teeth, cysts and any radiopacity that doesn't belong.
Know your normal anatomy — half of "lesions" aren't
Commonly mistaken for pathology: the mental foramen (a radiolucency at the premolar apex), the incisive foramen, the maxillary sinus floor overlying molar apices, the nutrient canals, and the submandibular fossa. Learn these as normal before you start hunting for abnormal.
Choosing the right view
- IOPA — the whole tooth including apex. Endodontics, periapical pathology, trauma.
- Bitewing — crowns and crestal bone of both arches. The best view for interproximal caries and early bone loss.
- OPG / panoramic — broad overview. Excellent for impactions, jaw pathology and general screening; poor for fine caries detection.
- CBCT — 3D. Implant planning, complex endodontics, impacted teeth near the inferior alveolar canal. Higher dose; use when it changes the plan.
Write it down in a fixed structure
Type of film and quality → teeth present → crowns and restorations → periapical findings → bone levels → other findings → impression. Examiners in viva are testing whether you have a system. So is the reality of clinical practice.
EnamDoc's study section includes radiograph practice cases and AI X-ray analysis for students to test their reading against — free on iOS and Android.
Frequently asked questions
What is the difference between IOPA, bitewing and OPG radiographs?
An IOPA shows the whole of a few teeth including the root apex and is used for endodontics and periapical pathology. A bitewing shows the crowns and crestal bone of both arches and is best for interproximal caries. An OPG gives a broad panoramic overview, useful for impactions and jaw pathology but poor for fine caries detection.
How do you identify caries on a dental X-ray?
Interproximal caries typically appears as a triangular radiolucency just below the contact point, with the base towards the outer surface. Compare the same surface on adjacent and contralateral teeth, and confirm that overlapping contacts are not obscuring the area before concluding it is sound.
What normal structures are commonly mistaken for pathology on dental radiographs?
The mental foramen near premolar apices, the incisive foramen between the upper central incisors, the maxillary sinus floor overlying molar roots, nutrient canals, and the submandibular fossa are all normal anatomy frequently misread as lesions by students.
