Palatal and dental arch morphology in Down syndrome.

The analysis of palatal vault morphology and maxillary dental arch shape was carried out in the sample of 42 Down syndrome (DS) patients with trisomy 21. The data were compared to those of healthy controls from the same population matched for age and sex. Palatal morphology and upper dental arch shape were studied on hard plaster casts of the patients and controls. No sexual dimorphism in palatal and dental arch shape was observed in DS and controls. Normal palatal shape was more frequent in controls than in DS subjects (52.38% vs. 28.57%; p < 0.05). DS patients displayed significantly higher frequency of shelf-like or "stair palate" (38.1%) than controls (11.9%) (p < 0.02). The younger age group (3-14 year) showed much higher frequency of "stair palate" than controls (26.19% vs. 2.38%; c2 = 9.72; p = 0.003). The older group of DS patients did not show increased frequency of such shape of the palatal vault. There was no significant difference in dental arch shape between DS patients and controls. High frequency of shelf-like palate in DS subjects is decreasing by age. The obtained results indicate that palatal vault morphology is subjected to the age related changes. These changes can be attributed to the growth of caraniofacial structures and increased tonus of tongue and other orofacial muscles.