Pediatric Dentistry · patient case question
The same radiograph shows the root of a developing mandibular premolar bent at a sharp angle to its crown. What is this called?
Patient case: Seven-Year-Old with Down Syndrome
Patient: 7-year-old male
Chief Complaint: Mother: “He seems to be missing a lot of teeth.”
Background: Trisomy 21. Atrioventricular septal defect repaired at 8 months of age with no residual defect and no prosthetic material. Generalized hypotonia. Cleared by cardiology; no antibiotic prophylaxis required.
Medications: None
Vital Signs: BP 96/60 mmHg · HR 92 bpm · RR 20 · T 98.2°F
Findings: Class III tendency with midface hypoplasia, macroglossia relative to arch size, fissured tongue. Panoramic radiograph shows numerous absent permanent tooth germs and an abrupt angulation of the root of a developing premolar. Cooperative and pleasant at the initial visit.
Show answer and explanation
Correct answer: A. Dilaceration
- A. Correct. Dilaceration is an abrupt angular deviation between the crown and root, or within the root itself. It arises when the developing tooth germ is displaced — often after trauma to a predecessor — after part of the tooth has already mineralized.
- B. Incorrect. Dens invaginatus (dens in dente) is an infolding of enamel and dentin into the pulp space, seen radiographically as a tooth-within-a-tooth, most often in maxillary lateral incisors.
- C. Incorrect. Fusion is the union of two developing tooth germs involving dentin, producing a single large tooth and one fewer tooth in the arch. There is no crown union here.
- D. Incorrect. Concrescence is the union of two adjacent teeth by cementum only, after root formation is complete. The crowns remain separate and the roots are joined, which is not what is described.
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