Differential diagnoses of enamel hypomineralisation in an archaeological context: A postmedieval skeletal collection reassessment

Developmental enamel defects (DDE) are often used as indicators of general health in past archaeological populations. DDE include three common types of lesions: hypoplasia, diffuse, and demarcated opacities. Molar incisor hypomineralisation (MIH) was defined in 2001 as a qualitative enamel defect affecting first permanent molars and often permanent incisors. The European Academy of Paediatric Dentistry established criteria to diagnose MIH in current populations as demarcated white or yellow‐brown opacities of enamel with or without posteruptive breakdown. MIH is prevalent in current populations (average 14.2%) and may cause important damage to first permanent molars. Aetiological factors are uncertain. The discovery of MIH in archaeological skeletal collections based on macroscopic examination has been reported previously, in particular by Ogden and colleagues (2008). If MIH exists in past populations, there are profound implications regarding current aetiological hypotheses. Aims of the present study were to (a) reassess the London postmedieval archaeological collection from which the first cases of MIH were reported and evaluate the reliability of MIH diagnosis criteria in past populations and (b) differentially diagnose developmental defects of enamel and post mortem discoloration in the teeth. Contrary to the reported prevalence in the original study (93.2%), among 47 subadult (>18 years) individuals, a low MIH prevalence was determined (27%). Reliability of MIH diagnosis was tested with three MIH experts who were also physical anthropologists. Our study highlighted that the reliability of a macroscopic diagnosis of MIH in past populations is fair (Cohen's kappa = 0.35 ± 0.11; Fleiss's kappa = 0.3). It could explain the large differential in prevalence values in studies performed in archaeological collections. Pathological and taphonomic agents can produce enamel modifications indistinguishable from one another, even to an “experienced eye.” Here, we