Clinical case review
Review the complete Dental case, its five progressive clues, the diagnosis, and the clinical reasoning behind the answer.
Want to test yourself first? Play the original case before reading the clues and explanation below.
WhatsTheDx publishes a new Dental case every day. Five clues, one diagnosis, and no account needed to play.
Play today's Dental caseThese are the case findings in their original reveal order, moving from the broader presentation to the most discriminating evidence.
Clue 1
A 52-year-old arrives for a second opinion she did not ask for. Her dentist took a radiograph before fitting a planned crown, saw something unexpected around the root of a lower left premolar, and sent her on. She is faintly baffled by the whole thing: that tooth has never given her a moment of trouble in her life — nothing spontaneous, nothing at night, no twinge with hot or cold — and left to herself she would never have known anything was there.
Clue 2
Clinically there is nothing to find, and that is not a throwaway observation — it is most of the differential being quietly closed off. There is no swelling and no sinus tract. The tooth is not tender to percussion, and pressing over the apex produces nothing. It has never been restored, there is no caries and no crack line anywhere on it, and probing depths are a normal 2 to 3 mm the whole way around. It is not mobile.
Clue 3
The single most useful test is also the simplest. On cold testing the tooth responds, and it responds within normal limits — the sensation appears and then goes, settling within a few seconds rather than dragging on past the half-minute that would mark an irreversibly inflamed pulp. Whatever is happening around this root, the pulp inside it is alive and behaving normally.
Clue 4
The radiograph shows what her dentist saw. The apical half of the root is enlarged and club-shaped, thickened into a bulbous form instead of tapering the way the roots on either side of it do. Crucially, the dense area is not a separate mass sitting against the tooth. It is continuous with the root — the same structure, simply more of it — with no radiolucent rim dividing one from the other.
Clue 5
One radiographic detail settles it. The periodontal ligament space does not stop at the enlargement or thicken around it — it runs uninterrupted the whole way round, holding its normal width and enveloping the swollen part of the root exactly as it envelops a normal one, with the lamina dura intact outside it. There is no radiolucency at the apex, and the surrounding bone is neither expanded nor perforated.
Diagnosis
This is a case about reading a radiograph rather than treating a patient, and it hinges on two findings that are easy to state and easy to miss. The first is the pulp test. The tooth responds to cold within normal limits and the response settles within seconds rather than dragging past the half-minute that marks irreversible inflammation, so the pulp is alive. That single result deletes the whole inflammatory half of the differential, because the chronic pattern at an apex is the mirror image of this one — a necrotic pulp giving no response at all, a tooth that is not tender, and a radiolucent lesion at the periapex. She has none of that: no radiolucency, a normal pulp, and no tenderness anywhere. The second finding is the one that actually names it, and it is a line rather than a shadow. The apical half of the root is enlarged into a club-shaped, bulbous form, and the dense area is continuous with the root itself instead of being a separate mass abutting it. Around that enlargement the periodontal ligament space runs uninterrupted at its normal width, enveloping the thickened root exactly as it envelops a normal one, with an intact lamina dura outside. That continuity is the diagnosis. What has been deposited is cementum, laid down on the outer surface of the root beyond its physiological limits, with no neoplastic character — which is why it behaves like part of the root, because it is. The two conditions that sit closest are separated on precisely these axes. Inflammatory sclerosis of the surrounding bone is poorly marginated, is not continuous with the tooth mass, usually sits on a non-vital tooth, and comes with a thickened rather than normal ligament space. The true neoplasm of cementum is also fused to the root and also spares vitality, but it carries a well-defined radiolucent rim and it expands the bone, sometimes perforating the cortex — and here the bone is neither expanded nor perforated. The practical consequence is deliberately unexciting: nothing needs treating today. It matters for later, because the altered root shape makes working length harder to determine and raises the risk of incomplete obturation if this tooth ever does need root canal treatment, and it makes extraction harder too. Management is stepwise, and for an asymptomatic tooth like hers the correct step is to record it, tell the dentist restoring it, and leave it alone.
The explanation and decisive case findings were checked against the source below.
Open the clinical referenceFor education and entertainment only. This fictional case is not medical advice and does not replace supervised clinical training, diagnosis, or treatment.
