Primary failure of eruption – a review and case report

Failure of eruption of first and second molars is rare, with the prevalence estimated at 0.01% for first permanent molars and 0.06% for second permanent molars.^1,2 Eruption failure may result from a number of causes. These include mechanical interference with eruption or failure of the eruptive mechanism of the tooth so that the expected amount of eruption does not occur.³ Mechanical failure of eruption (MFE) is characterized by single tooth anklyosis, whereas primary failure of eruption (PFE) is a condition in which unimpeded, non-ankylosed teeth fail to erupt with an absence of systemic factors.³ Primary failure of eruption is diagnosed based on its clinical appearance, which is reported to include the seven features shown in Table 1.³ The last of these clinical features has been disputed. Advances in gene discovery and identification have been able to show a heritable basis of this dental phenotype,^4,5,6,7,8 and recently mutations in parathyroid hormone 1 receptor (PTH1R) have been identified in several familial cases of PFE.⁹