This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Down's syndrome is associated with all of the following except: 
Select and explain. 
A. Retrognathia, B. Periodontal disease, C. Premature exfoliation of teeth, D. Retained deciduous teeth
A: Retrognathia
Answer: A: Retrognathia 
Explanation: Skeletal ﬁnding is an underdeveloped mid-face, creating a prognathic occlusal relationship. 
Oral ﬁndings include mouth breathing, open bite, appearance of macroglossia, ﬁssured lips and tongue, angular cheilitis, delayed eruption times, missing and malformed teeth, oligodontia, small roots, microdontia, crowding, and a low level of caries. 
Children with Down syndrome experience a high incidence of rapid, destructive periodontal disease, which may be related to local factors such as tooth morphology, bruxism, malocclusion, and poor oral hygiene. 

Pediatric Dentistry / Shobha Tandon - 2nd Ed