Occlusal molar surfaces in females with Turner's syndrome.

The aim of this study was to identify the molar occlusal features in 73 subjects with the Turner's syndrome (TS) and compared to a control group (CG) of 322 healthy females. The occlusal features were scored on dental plaster casts using the Scoring Procedures for Key Morphological Traits of the Permanent Dentition: The Arizona State University Dental Anthropology System (ASU). The results were analyzed through frequency, percentage and chi 2-test. TS subjects have more frequent reduction of cusp number, distolingual cusp on the upper molars and distal cusp on the lower molar, with the consequent reduction of the occlusal surface. Reduced size of occlusal surface and number cusps on upper molars resulted in the transformation of rhomboid occlusal shape into triangular, with the consequent loss of H-shaped groove system (in the upper right first molars H-shaped groove system was significantly less frequently found in TS (p < 0.05); in the upper left second molars H-shaped groove system was significantly less frequently found in TS (p < 0.01). The X-chromosome aneuploidy can cause a decrease in developmental homeostasis, which results in the alteration of apposition of the enamel and in consequently substantial changes of the molar occlusal morphological features.