Pediatric Dentistry · patient case question
All of the following are ectomesenchymal in origin EXCEPT:
Patient case: A father who says his son has no teeth
demo: 6-year-old male, accompanied by his father
chief: The father is worried that his son still has almost no teeth.
history: Born at term. The father reports the boy overheats badly in summer and has to be cooled with wet towels; he rarely seems to sweat. He has never been seen by a specialist.
meds: None.
findings: Sparse fine scalp hair, prominent periorbital wrinkling with darkening around the eyes, frontal bossing, a depressed nasal bridge and everted lips. The skin is dry and scaly. Only two conical teeth are present in each arch.
Show answer and explanation
Correct answer: B. Oral mucosal epithelium
- A. Cementum arises from the dental follicle, another ectomesenchymal derivative, as do the periodontal ligament and alveolar bone proper.
- B. Correct, and this is the exception. Oral mucosal epithelium arises from surface ectoderm directly, not from ectomesenchyme. Enamel likewise comes from ectodermally derived ameloblasts of the enamel organ.
- C. Dentin is produced by odontoblasts, which differentiate from the dental papilla, an ectomesenchymal tissue derived from migrating neural crest cells.
- D. The dental pulp is the mature dental papilla and is therefore ectomesenchymal.
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