Insights into molar-incisor hypomineralisation in past populations: A call to anthropologists

Molar incisor hypomineralisation (MIH) is a developmental defect of enamel affecting the first permanent molars and often the incisors and affecting approximately 13% of the current population worldwide. Here, we aim to highlight potential differential diagnoses of MIH in archaeological collections (taphonomic discoloration, amelogenesis imperfecta, fluorosis, rachitic teeth, etc.).

Causative factors of dental discolourations are identified through a literature review.

In an archaeological context, the sediments contained in the burial soil can lead to tooth discoloration. Taphonomic staining of the dentition may have a similar appearance to enamel hypomineralisation, and thus is a confounding factor that has the potential to cause miscalculation of the true prevalence of MIH within archaeological collections. Some rare medieval cases are reported in the modern literature but without microanalysis, misdiagnosis is possible. The aetiological factors of MIH are unknown but probably follow the multifactorial model involving systemic medical and genetic factors.

Systematic detection and diagnosis of MIH during anthropological studies is therefore of great interest.

The hypotheses that only contemporary agents are causative factors of MIH could be refuted by the discovery of individuals living before medication or pollutants. The identification of MIH in a group of individuals also provides information regarding the health status of a population and reflects stress occurring during the period of mineralisation of the first permanent molars after secretion of the enamel matrix.

Taphonomic alterations of archaeological remains prevent MIH diagnosis.

MIH diagnosis can be difficult in archaeological series and further non-destructive methods (microtomography, elemental analyses, etc.) are required.