**4.2.3 Age influence and relationship between caries lesions and hypoplastic defects**

Two approaches were lead to evaluate the age influence on dental health and development:

 The first one is the representation of the mean age when the stress occurred (on lower permanent teeth). Figure 10 show these periods of stress for each collection. The data were calculated from those of Reid and Dean (2000) and Skinner & Goodman (1992). We also used the records on the affected third (table 3). Only the highest frequency is mentioned in order to leave the figure readable. This figure takes into account only the crown mineralization, thus the stress which is arisen during puberty is not mentioned.

Fig. 10. Frequency of enamel hypoplasia per tooth type in the three collections

Socioeconomic Influence on Caries Susceptibility in Juvenile Individuals

points will be discussed in the next part.

group (significant differences are in bold)

then, some trends to discuss appear.

**influence on dental health** 

**5. Discussion** 

with Limited Dental Care: Example from an Early Middle Age Population … 51

When we compare the three collections by age class, it is noteworthy to remark that the individuals of Mikulčice Bazilika differ from the others for the classes 10-14, and 15-19 years for the caries lesions and for the class 5-9 for the LEH. Frequencies are significantly different between sites (p < 0.05). For the dental caries, it should be an evidence of a better dental care in higher socioeconomic status populations. For LEH, less individuals are affected during the juvenile period, is the environment less stressing in higher socioeconomic status? These

The second approach compares the dental features according to the tooth mineralization sequences describe in the methods. It is another mean to precise the last results, without using age estimation but biological traits. Table 4 gives the comparison for both dental caries & LEH. These more biological data (we avoid age-at-death estimation) confirm precedent results, giving significant differences for the individuals of Mikulčice Bazilika in both dental caries and LEH. Indeed, the group 5 and 6 of Mikulčice Bazilika are significantly less affected by caries lesions than those of Mikulčice Kostelisko and Prušánky. The last graph gave a trend; here we have a reliable result. We also notice a difference in group 4 and 5 for the LEH. The arguments of dental care and attenuated stress for these stages of development are thus strengthened.

Group Mikulčice Bazilika Mikulčice Kostelisko Prušánky

1 0.00% 5.26% 0.00% 8.82% 0.00% 0.00% 2 7.14% 23.08% 4.17% 22.73% 10.52% 21.05% 3 27.27% 41.67% 31.82% 57.14% 27.27% 36.36% 4 20.00% **20.00%** 25.00% 90.90% 20.00% 80.00% 5 **11.11% 55.56%** 50.00% 78.13% 23.07% 78.57% 6 **0.00%** 62.46% 88.89% 73.68% 61.53% 61.53% Table 4. Frequency of dental caries, and linear enamel hypoplasia per dental mineralization

To sum up, few differences between the collections are highlighted: one on global prevalence of LEH, and two on location and severity of dental caries. However, if we compare more biological traits, related to tooth development and enamel susceptibility,

Three main topics will be discussed in this last part. The first one deals with the assets and the drawbacks of archaeological collections in a study of dental health. The second develops the influence of socioeconomic status on dental mineralization. And finally, we will discuss

**5.1 Archaeological collections: assets and drawbacks in the study of socioeconomic** 

There are many studies on the influence of lifestyle and/or socioeconomic status on dental health (Bodoriková et al., 2005; Duray, 1990; Kim & Durden, 2007; Vodanovic et al., 2005). However, they concern both living and past populations. Moreover, the protocol of

the differential enamel susceptibility to be affected from defects and lesions.

Caries LEH Caries LEH Caries LEH

 It is noticeable that few stress arose during the occlusal third mineralization (light grey), apart for the first incisor in Mikulčice Bazilika. The individuals were subjected to stress during infancy, and especially between 2 and 6 years, and the stress concerns mainly the mesial third of the crowns for all collections. These results can be transposed to upper teeth. There is no statistical difference between collections for these stress periods (p>0.05 for all statistical tests). Even if this approach is not very precise, it gives a good mean of comparison. Here, Mikulčice Bazilika seems to be different because the stress periods arose sooner in the mineralization stages than in the other collections. If we compare now the prevalence of dental lesions and defects in age classes, the frequencies are represented in figure 11.

Fig. 11. Frequency of dental caries, and linear enamel hypoplasia per age class

When we compare the three collections by age class, it is noteworthy to remark that the individuals of Mikulčice Bazilika differ from the others for the classes 10-14, and 15-19 years for the caries lesions and for the class 5-9 for the LEH. Frequencies are significantly different between sites (p < 0.05). For the dental caries, it should be an evidence of a better dental care in higher socioeconomic status populations. For LEH, less individuals are affected during the juvenile period, is the environment less stressing in higher socioeconomic status? These points will be discussed in the next part.

The second approach compares the dental features according to the tooth mineralization sequences describe in the methods. It is another mean to precise the last results, without using age estimation but biological traits. Table 4 gives the comparison for both dental caries & LEH.

These more biological data (we avoid age-at-death estimation) confirm precedent results, giving significant differences for the individuals of Mikulčice Bazilika in both dental caries and LEH. Indeed, the group 5 and 6 of Mikulčice Bazilika are significantly less affected by caries lesions than those of Mikulčice Kostelisko and Prušánky. The last graph gave a trend; here we have a reliable result. We also notice a difference in group 4 and 5 for the LEH. The arguments of dental care and attenuated stress for these stages of development are thus strengthened.


Table 4. Frequency of dental caries, and linear enamel hypoplasia per dental mineralization group (significant differences are in bold)

To sum up, few differences between the collections are highlighted: one on global prevalence of LEH, and two on location and severity of dental caries. However, if we compare more biological traits, related to tooth development and enamel susceptibility, then, some trends to discuss appear.
