Determination and validation of criteria to define hypercementosis in two medieval samples from France (Sains-en-Gohelle, AD 7th–17th century; Jau-Dignac-et-Loirac, AD 7th–8th century)

• Hypercementosis is an excessive production of cementum which has rarely been studied.
• Our study establish for the first time reproductible criteria to define hypercementosis.
• Hypercementosis exist in different forms, diffuse and focal which can be moderate or marked.
• Hypercementosis is not a systematic major enlargement of the apical part of a root.
• Our definition criteria will provide a better assessment of hypercementosis frequency while it has the potential to be used to further investigate its aetiologies.

ObjectiveThe main aim of this article was to develop different visual criteria allowing for an objective definition of hypercementosis (cementum hyperplasia). This preliminary study must notably show how to better understand at a later stage the significance of its frequency as well as its aetiologies, especially in past populations.Materials and methodswe set up a study protocol (macroscopic and photographic observations) on material consisting of 2 medieval samples from France (1) Sains-en-Gohelle sample-SG (AD 7th–17th century; 407 individuals; 5756 teeth observed, 319 with hypercementosis) which was used to develop the different criteria for defining hypercementosis (2) Jau-Dignac-et-Loirac sample-JDL (AD 7th-8th century; 55 individuals; 709 teeth observed, 24 with hypercementosis) which was used to test the reproducibility of the criteria.ResultsFrom our observations we formulated different inclusion criteria with which to define hypercementosis objectively (k intraobserver ≥ 0.96; k interobserver ≥ 0.63). We were able to distinguish moderate (1m) and marked (1M) forms of diffuse hypercementosis, focal hypercementosis in the form of small knots (2m) or large nodules (2M), or excrescences in the form of ridges (3m) or spurs (3M). Different exclusion criteria were also determined.ConclusionThe definition that we propose in this study are based on various statistically validated inclusion and exclusion criteria. It is hoped that this will improve the significance of hypercementosis. More generally, this would also give a better understanding of the dynamics of cementum apposition.