Pyknodysostosis is an autosomal recessive disorder with a characteristic increase in bone density. Ten percent of patients have developmental delay and mild dwarfism (acromelic type). The nose is beaked and the jaw is hypoplastic with an obtuse mandibular angle, as shown above. Also characteristic are the hypoplastic terminal phalanges of the hand. Even with an increase in bone density, these patients are at risk for multiple fractures.
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Bathi RJ, Masur VN. Pyknodysostosis--a report
of two cases with a brief review of the literature. Int J Oral Maxillofac
Surg. 2000 Dec;29(6):439-42.