## 4 Discussion
### Tooth Development and Why Tooth Anomalies of Number, Size and Structure Are Connected
In present-day populations, hypodontia is reportedly the most common dentofacial malformation in humans, with prevalence rates varying between 1.6-10.1%, while Europeans and Australians are more affected than North Americans [33; 40; 41]. Studies looking into the etiology of hypodontia over time have come up with different answers. For instance, [PERSON] et al. found that hypodontia had increased since 1957 [42], whereas [PERSON] et al. found that there was no increase of hypodontia of the third molar from the medieval period until present [43]. Of course, it has to be considered that differences between the different type of populations are probable, so the more specimens assessed, the wider database available, in order to have a clearer picture of the phenomenon. However, the scarcity of complete jaws and crania from archaeological records, makes it difficult to create relevant statistical records of dental pathology regarding different historical periods of time. In this view, we would like to emphasize the importance of acknowledging the presence of any supernumerary teeth in old crania, in order to create a database and compare their prevalence with present-day cases. Regarding geminated and fusioned teeth, there is a report of a 4000 year old mummy from ancient Egypt presenting with a fusioned right maxillary incisor and a geminated left maxillary incisor [44] as well as a few more recent findings [45]. Records of supernumerary teeth from all historical periods are available, but the prevalence of supernumeraries in the past is difficult to estimate because of the practical aspects associated with the uncovering of human remains, i.e., the lack of a large study sample and also the degradation and breakage to which skeletons are subjected to, while in the ground and while being uncovered. The oldest specimen cited in the literature is a 1.7 million year old Australopithecus robustus adult with a supernumerary tooth between the right first and second incisors [46]. Other remarkable reports of supernumerary teeth are that of a middle-aged Chalcolitic male with a supernumerary distomolar in the mandible [47] and that of a young adult woman from the Upper Paleolithic who presented with a right maxillary supernumerary molar [48]. Another study, concerning the CT scan of mummies from the Graeco-Roman Period, found two supernumerary teeth in the premaxillae region of a child [49]. Additionally, a syndromic individual from prehistoric Illinois, probably suffering from cleidocranial dysostosis, presenting with six supernumerary teeth, impacted teeth and dilacreated roots has been described in a study by [PERSON] [50]. Comparing the frequency of supernumerary teeth in ancient and present times would help to better understand this phenomenon and the phylogenetic process behind it and also gain more knowledge regarding the hypothesis that, with evolution, hypodonia becomes more frequent and that humans tend to have less teeth and smaller jaws. Considering the low prevalence in present-day populations, one can reasonably assume it was low in the past as well.