**4. Results**

As mentioned in our previous paper, intra- and inter-observers errors must be taken into account, but although they have an impact on the results, those are always discussed with these biases (Garcin et al. 2010).

#### **4.1 Prevalence of dental caries**

44 Contemporary Approach to Dental Caries

in order to evaluate the role of enamel structure on caries development. All statistical procedures and calculations were carried out by using Statsoft® Statistica version 7.1 and

Fig. 5. Representation of the established groups from the dental mineralization sequences

As mentioned in our previous paper, intra- and inter-observers errors must be taken into account, but although they have an impact on the results, those are always discussed with

Microsoft® Office Excel 2007.

(adapted from Ubelaker, 1978)

these biases (Garcin et al. 2010).

**4. Results** 

Frequencies of caries in all observable teeth are presented in figure 6 & 7. The evaluated teeth are those observable in the oral cavity and/or in occlusion. This information is different for dental enamel hypoplasia, because tooth germs, when isolated, were also evaluated for this second dental trait.

As often mentioned, posterior teeth are more affected than anterior teeth, which confirm the differential susceptibility of the molars to be suffering from dental caries (Klein & Palmer, 1941; Oyamada et al., 2008; Saunders et al., 1997). But it is interesting to point out that some individuals are attained by carious lesions on anterior deciduous teeth in both area of Mikulčice. These lesions are often related to higher enamel susceptibility to develop dental caries, even on permanent teeth (Li & Wang, 2002; O'Sullivan & Tinanoff, 1993).

Fig. 6. Caries frequencies per tooth type in the three collections (deciduous dentition)

Fig. 7. Caries frequencies per tooth type in the three collections (permanent dentition)

Socioeconomic Influence on Caries Susceptibility in Juvenile Individuals

**4.2.1 Dental enamel hypoplasia on deciduous canines** 

with Limited Dental Care: Example from an Early Middle Age Population … 47

Dental enamel hypoplasia on deciduous teeth were observed on four individuals from Mikulčice Bazilika. Any other individual presents hypoplasia in the other collections. All the cases correspond to what is named "localised enamel hypoplasia of human deciduous canines" (Clarkson, 1989; Taji et al., 2000). The figure 8 shows some of the observed cases.

Fig. 8. Illustration of two localized enamel hypoplasia on deciduous lower canines

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

Part of the affected crown (beginning from the cervical region)

areas, and Prušánky (Table 3).

Frequency of individuals

affected (%)

Severity

Some discussions exist on the aetiology of this sort of enamel defect (Skinner & Hung, 1989; Sweeney et al., 1971): genotype or environment? This point will be taken back in the next part of the chapter. All defects are localized on lower canine and are bilateral on 50% of the cases. The two unilateral cases show less marked than the bilateral ones. These four cases give argument for the difference of enamel susceptibility following the socioeconomic status.

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

 Mikulčice Bazilika Mikulčice Kostelisko Prušánky Total prevalence **0.12** 0.18 0.16

1 0.63 0.52 **0.29**  2 0.32 0.47 **0.61**  3 0.05 0.01 0.10

Proximal third 0.21 0.29 0.34 Mesial third 0.59 0.55 0.57 Distal third 0.15 0.14 0.09 Whole height of the crown 0.04 0.02 0.00

between the three collections (statistically significant differences are in bold)

Table 3. Linear enamel hypoplasia prevalence and differences in defect descriptive features

10.59 **30.63** 17.91

In terms of global calibrated prevalence, there is a difference between the Mikulčice areas and Prušánky in the caries frequencies on both deciduous and permanent teeth. The frequency of dental caries in the deciduous and permanent teeth from Prušánky was statistically significantly lower (χ² = 4.49; p = 0.03 for permanent teeth and χ² = 9.08; p < 0.01 for deciduous teeth) than in those from the two other collections. Table 2 shows the prevalence and the comparisons between features in the three collections.


Table 2. Caries prevalence and differences in caries descriptive features between the three collections (statistically significant differences are in bold)

Concerning the lesions traits, the most common are the occlusal caries in all sites. Once again, the site of Prušánky differs from the others. Indeed, there are less interproximal lesions in this collection than in the others (χ² = 8.48; p < 0.03 for the crown and χ² = 8.70; p < 0.03). Furthermore, another significant difference is shown for the severity of the lesion. But this time, the trend is reversed. Individuals of Mikulčice Bazilika have less severe lesions (stage 3) than in the two other collections (χ² = 8.63; p < 0.03). The large caries are less frequent in Mikulčice Bazilika individuals. Prušánky's individual are the most affected. Is there a relationship between the severity of the lesions, the diet, and/or the dental care? This notion will be discussed later. Apart this last trait, we can observe that individuals from the two areas of Mikulčice have very similar features even if their socioeconomic status differs. The rural lifestyle seems to have more impact on dental health than socioeconomic status. The tooth development is also very important in the comprehension of the caries susceptibility. That is why dental enamel hypoplasia will give another type of information.

#### **4.2 Expression of the dental enamel hypoplasia**

Contrary to the caries, dental enamel hypoplasia have been observed on all permanent teeth, even tooth germs. They will give information on crown development. Before discussing the differences between the collections, a paragraph on hypoplasia on deciduous teeth summarizes the encountered cases.

#### **4.2.1 Dental enamel hypoplasia on deciduous canines**

46 Contemporary Approach to Dental Caries

In terms of global calibrated prevalence, there is a difference between the Mikulčice areas and Prušánky in the caries frequencies on both deciduous and permanent teeth. The frequency of dental caries in the deciduous and permanent teeth from Prušánky was statistically significantly lower (χ² = 4.49; p = 0.03 for permanent teeth and χ² = 9.08; p < 0.01 for deciduous teeth) than in those from the two other collections. Table 2 shows the

 Mikulčice Bazilika Mikulčice Kostelisko Prušánky Prevalence on deciduous teeth 0.03 0.03 **0.01**  Prevalence on permanent teeth 0.03 0.04 **0.02** 

Occlusal – crown 0.36 0.34 0.52 Interproximal – crown 0.24 0.15 **0.11**  Interproximal – crown & neck 0.25 0.19 **0.11** 

Other locations 0.13 0.23 0.11

1 0.51 0.57 0.40 2 0.45 0.34 0.44 3 0.04 0.09 **0.13**  Table 2. Caries prevalence and differences in caries descriptive features between the three

Concerning the lesions traits, the most common are the occlusal caries in all sites. Once again, the site of Prušánky differs from the others. Indeed, there are less interproximal lesions in this collection than in the others (χ² = 8.48; p < 0.03 for the crown and χ² = 8.70; p < 0.03). Furthermore, another significant difference is shown for the severity of the lesion. But this time, the trend is reversed. Individuals of Mikulčice Bazilika have less severe lesions (stage 3) than in the two other collections (χ² = 8.63; p < 0.03). The large caries are less frequent in Mikulčice Bazilika individuals. Prušánky's individual are the most affected. Is there a relationship between the severity of the lesions, the diet, and/or the dental care? This notion will be discussed later. Apart this last trait, we can observe that individuals from the two areas of Mikulčice have very similar features even if their socioeconomic status differs. The rural lifestyle seems to have more impact on dental health than socioeconomic status. The tooth development is also very important in the comprehension of the caries susceptibility. That is why dental enamel hypoplasia will give another type of information.

Contrary to the caries, dental enamel hypoplasia have been observed on all permanent teeth, even tooth germs. They will give information on crown development. Before discussing the differences between the collections, a paragraph on hypoplasia on deciduous teeth

collections (statistically significant differences are in bold)

**4.2 Expression of the dental enamel hypoplasia** 

summarizes the encountered cases.

**0.02** 0.09 0.15

prevalence and the comparisons between features in the three collections.

Location of the lesions

Severity of the lesions

(more than 2/3 of the tooth affected)

Large caries

Dental enamel hypoplasia on deciduous teeth were observed on four individuals from Mikulčice Bazilika. Any other individual presents hypoplasia in the other collections. All the cases correspond to what is named "localised enamel hypoplasia of human deciduous canines" (Clarkson, 1989; Taji et al., 2000). The figure 8 shows some of the observed cases.

Fig. 8. Illustration of two localized enamel hypoplasia on deciduous lower canines

Some discussions exist on the aetiology of this sort of enamel defect (Skinner & Hung, 1989; Sweeney et al., 1971): genotype or environment? This point will be taken back in the next part of the chapter. All defects are localized on lower canine and are bilateral on 50% of the cases. The two unilateral cases show less marked than the bilateral ones. These four cases give argument for the difference of enamel susceptibility following the socioeconomic status.
