Pathology · patient case question
What is the diagnosis for Patient C?
Patient case: Four developmental anomalies
Patient: Four patients
Chief Complaint: A: “One back tooth bleeds when I floss.” B: referred for orthodontic assessment. C: mother reports the child's teeth on one side “look different”. D: referred for root canal treatment.
Background: A, 45-year-old male: excellent plaque control, no periodontal disease elsewhere. B, 13-year-old female: no medical history. C, 8-year-old male: unremarkable medical and family history. D, 36-year-old female of East Asian ancestry.
Findings: A: an ISOLATED 8 mm furcation pocket on a molar in an otherwise healthy mouth, with a well-defined radiopaque nodule at the furcation. B: the maxillary canine and first premolar have exchanged positions in the arch. C: several ADJACENT teeth in one quadrant with markedly thin enamel and dentine, disproportionately large pulp chambers and poor contrast, with an abrupt cut-off at the midline. D: mandibular first molar in which the root outline appears unusually wide and the periodontal ligament outlines do not resolve into two roots.
Show answer and explanation
Correct answer: C. Regional odontodysplasia
- A. Amelogenesis imperfecta is GENERALISED, affecting all teeth in both dentitions. The ENAMEL is defective while the dentine is normal, so the contrast between the two on a radiograph is preserved or even exaggerated — the opposite of the poor contrast described here.
- B. Dentin dysplasia type I produces teeth with absent or extremely short roots and crescent-shaped pulpal remnants, with clinically normal crowns, and it too is generalised rather than confined to one quadrant.
- C. CORRECT. REGIONAL ODONTODYSPLASIA — the ‘GHOST TEETH’. The defining feature is that it is LOCALISED to a segment or quadrant, affecting several ADJACENT teeth with a characteristically abrupt cut-off at the midline, and involving both dentitions in the affected region. Enamel and dentine are both markedly thin and hypomineralised, so the teeth show poor radiographic contrast and appear faint or ghostly, with disproportionately large pulp chambers. Eruption is delayed or fails altogether, and affected teeth are prone to abscess formation even in the absence of caries. The cause is unknown and it is NOT inherited.
- D. Dentinogenesis imperfecta is also generalised, producing opalescent brown-blue teeth with bulbous crowns, cervical constriction and OBLITERATED pulp chambers. This patient has enlarged pulps, which is the reverse finding.
Note: The localisation IS the diagnosis. Anything GENERALISED and affecting both dentitions is a hereditary condition — amelogenesis imperfecta, dentinogenesis imperfecta, dentin dysplasia. Anything confined to one segment with a midline cut-off is regional odontodysplasia. Management is usually extraction of the affected teeth with prosthetic replacement, since they are neither restorable nor able to erupt reliably.