Developmental disorders
Of the developmental disorders, congenital diseases of the enamel or dentine of teeth, problems related to the number, size and shape of teeth, and craniofacial birth defects such as cleft lip and/or palate (CL/P) are most important. The incidence of CL/P varies tremendously worldwide. Native Americans show the highest incidences at 3.74 per 1000 live births, whereas a fairly uniform incidence of 1:600 to 1:700 live births is reported among Europeans. The incidences appear high among Asians (0.82–4.04 per 1000 live births), intermediate in Caucasians (0.9–2.69 per 1000 live births) and low in Africans (0.18–1.67 per 1000 live births) (26). The causes of CL/P are complex involving numerous genetic and environmental risk factors. In particular, risk factors such as folic acid deficiency, maternal smoking and maternal age have been implicated in the formation of clefts