Crown heights in the permanent teeth of 45,X/46,XX females

Objectives: The aim of the present study was to determine permanent tooth crown heights in 45,X/46,XX females (mosaics) or individuals with a lack of sex chromosome material to obtain additional information about their oral growth. Earlier studies in 45,X/46,XX females compared to normal women have shown smaller mesio-distal dimension of the permanent tooth crowns and similar sized labio-lingual dimensions. Their tooth enamel layer is definitely thinner, the thickness of mesio-distal dentin layer is close to that in normal women, and root length is clearly shorter. Results on tooth crown heights of normal men and women have shown larger values for men. Methods: The study groups were 15 45,X/46,XX females, 10 female relatives, and 45 female population controls from L. Alvesalo's Kvantti research project. Metric tooth crown height measurements were performed from panoramic radiographs on each measurable tooth by a digital calliper according to the defined procedure. Results: The measurements showed that permanent tooth crown heights of 45,X/46,XX females were similar in size with those of normal women, although there appeared a trend for smaller crown height in mosaic females. In comparison to female relatives 45,X/46,XX females showed generally smaller crown heights. Conclusion: Present results on tooth crown height and earlier results on labio-lingual crown dimension in 45,X/46,XX females relative to normal women are parallel, which is contrary to the reduction in mesio-distal crown dimension and root length. However, a clear trend for smaller crown height for 45,X/46,XX females appeared in comparison to their female relatives. Kvantti research project has been supported by the Emil Aaltonen Foundation, the University of Turku Foundation and the Academy of Finland. This study has been supported by the Tyyne Tani Foundation, the Finnish Dental Society and the Orthodontic Section of the Finnish Dental Society.