**4.2.2 Results on dental enamel hypoplasia on permanent teeth**

We took into account only linear enamel hypoplasia (LEH), because pitting defects were defeated (less than 2% in each collection, 0% at Mikulčice Bazilika). The comparison of LEH global prevalences between collections show a significant difference between Mikulčice's areas, and Prušánky (Table 3).


Table 3. Linear enamel hypoplasia prevalence and differences in defect descriptive features between the three collections (statistically significant differences are in bold)

Socioeconomic Influence on Caries Susceptibility in Juvenile Individuals

place in the crown formation, and its relationship with age-at-death.

expression.

mentioned.

with Limited Dental Care: Example from an Early Middle Age Population … 49

Concerning the other features, the severity of the defects are obviously the same in the two areas of Mikulčice. The trend is inverted for Prušánky. There are more medium defects (stage 2) than slight defects (stage 1) in this collection (χ² = 14.16; p < 0.01 & χ² = 20.15; p < 0.01). Once again, the lifestyle seems to be more expressed by dental stress than the socioeconomic status. But what is more surprising is that this is the only feature which differs from the others. On the whole, the three collections present the same trend in LEH

The last information given by table 3, is that the part of the affected crown does not show any statistical difference (p > 0.05 for all statistical tests). This means that there is globally no difference on the period when the biological stress arose. The specific study with age estimation gives other information. Few individuals present teeth with all the crown height affected by multiple LEH. The stress period are thus isolated and occurred seldom more than two times during the crown formation. The next part presents when this stress took

**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

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

The whole prevalence (taking into account all observed teeth) is significantly lower in Mikulčice Bazilika (χ² = 8.61; p < 0.03). If we consider the frequency of individuals affected, the greatest frequency is at Mikulčice Kostelisko with more than 30% of individuals (χ² = 9.81; p < 0.01). If we consider the prevalence per tooth type, the results are given by the figure 9.

Fig. 9. Frequency of enamel hypoplasia per tooth type in the three collections

These graphs clearly show that there is a differential susceptibility in tooth type for developing LEH (Goodman & Armelagos, 1985; Palubeckaité et al., 2002; Wright, 1997). Anterior teeth (incisors & canines) are more affected by the defect than posterior teeth (premolars & molars). On the whole, canines are the most affected. Even if differences between sites could be shown, they are not statistically significant (number of teeth per tooth type differs, thus graphic results are misleading). We can see that posterior teeth are also affected, demonstrated that these individuals suffered from non specific stress during late infancy period, that is to say during the time of formation of posterior tooth crowns. This point is important for the next paragraph concerning the relationship between the lesions, the defects, and the age-at-death.

The whole prevalence (taking into account all observed teeth) is significantly lower in Mikulčice Bazilika (χ² = 8.61; p < 0.03). If we consider the frequency of individuals affected, the greatest frequency is at Mikulčice Kostelisko with more than 30% of individuals (χ² = 9.81; p < 0.01). If we consider the prevalence per tooth type, the results are given by the

18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 28

**Tooth type (upper teeth)**

48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38

**Tooth type (lower teeth)**

MkB MkK Pk

These graphs clearly show that there is a differential susceptibility in tooth type for developing LEH (Goodman & Armelagos, 1985; Palubeckaité et al., 2002; Wright, 1997). Anterior teeth (incisors & canines) are more affected by the defect than posterior teeth (premolars & molars). On the whole, canines are the most affected. Even if differences between sites could be shown, they are not statistically significant (number of teeth per tooth type differs, thus graphic results are misleading). We can see that posterior teeth are also affected, demonstrated that these individuals suffered from non specific stress during late infancy period, that is to say during the time of formation of posterior tooth crowns. This point is important for the next paragraph concerning the relationship between the

Fig. 9. Frequency of enamel hypoplasia per tooth type in the three collections

MkB MkK Pk

figure 9.

0,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00 40,00 45,00

> 0,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00 40,00 45,00 50,00

lesions, the defects, and the age-at-death.

**Frequency of affected teeth (%)**

**Frequency of affected teeth (%)** 

Concerning the other features, the severity of the defects are obviously the same in the two areas of Mikulčice. The trend is inverted for Prušánky. There are more medium defects (stage 2) than slight defects (stage 1) in this collection (χ² = 14.16; p < 0.01 & χ² = 20.15; p < 0.01). Once again, the lifestyle seems to be more expressed by dental stress than the socioeconomic status. But what is more surprising is that this is the only feature which differs from the others. On the whole, the three collections present the same trend in LEH expression.

The last information given by table 3, is that the part of the affected crown does not show any statistical difference (p > 0.05 for all statistical tests). This means that there is globally no difference on the period when the biological stress arose. The specific study with age estimation gives other information. Few individuals present teeth with all the crown height affected by multiple LEH. The stress period are thus isolated and occurred seldom more than two times during the crown formation. The next part presents when this stress took place in the crown formation, and its relationship with age-at-death.
