Anomalies of tooth formation and eruption

Both the primary and permanent dentitions may be affected by variations in the number, size, and form of the teeth, as well as the structure of the dental hard tissues. These variations may be exclusively genetically determined, brought about by either local or systemically acting environmental factors, or possibly a combination of both genetic and environmental factors acting together. The same interplay of influences may affect the eruption and exfoliation of primary teeth, as well as the eruption of permanent teeth. This chapter considers a range of conditions involving abnormalities of the number, size, form, and structure of teeth and their eruption. It is important to be aware of the psychosocial aspect when meeting children and families affected by these conditions. We have too often heard stories of social isolation of even very young children as a result of their missing or discoloured teeth. In the case of discoloured teeth, parents and children have told us that they have been told off or teased for not looking after their teeth when the discolouration was intrinsic and unavoidable. Society’s preoccupation with ‘the perfect smile’ seems to increase; hence children denied access to aesthetic dental treatment may be genuinely disadvantaged. Wherever possible, we try to avoid the use of the word ‘normal’ in our clinical care, although the word will be used in this text. The vast majority of children with these conditions want to become ‘one of the crowd’. Thus we would speak, when offering restorative treatment for example, of making a smile ‘ordinary’ or ‘boring’. While investigating inherited conditions, it is important to make enquiries of both sides of the family tree equally. Not only does this ensure that the investigation is complete, but also it may help to alleviate any sense of ‘guilt’ felt by an affected parent. We have been questioned repeatedly about the possibility of genetic treatment for some of these inherited conditions. We are not aware of any progress in this direction at present. Hypodontia is the term most often applied to a situation where a patient has up to six missing teeth (excluding third permanent molars) as a result of their failure to develop.