A positive trend of caries prevalence over a period 1994–2010 was observed both for national monitoring and smaller epidemiological studies. The two study series employed different methods of study sample selection (dental patients vs. subjects from a stratified national sample) and a different approach to examiner training (non-calibrated vs. calibrated examiners). Consistency observed in trends of individual parameters enhances the validity of the observed results. As it is evident from the data shown in Tables
and , the differences between the IHIS and IDR study results are generally small and they can be explained by methodological factors, e.g. by the differences between “patients” and “study subjects”. The study subjects recruited in the nurseries had higher proportion of intact teeth, but at the same time higher mean dmft and dt scores than patients examined in dental practices. This is probably related to the fact that the patients sought dental care predominantly not for preventive reasons, but because they were in need of dental treatment.
Detailed inspection of caries prevalence data shown in Tables
and reveals that the decline in caries prevalence happened mainly in 1990s and early 2000s. By the end of the investigated period, both series of studies suggest possible flattening of the trend. This observation is consistent with reports showing stopping or reversal of this declining trend in childhood caries in some other countries [6
]. Therefore, further surveys in the next few years would be needed to confirm whether this is a long-term trend or whether this was one-off event.
We can speculate on the reasons for the positive trend in caries experience. Over the recent years, there have been no systematic preventive initiatives against childhood caries implemented in the Czech Republic on a country- or regional level. Only isolated oral health programmes have been conducted in a few nurseries (such as oral hygiene training organized by dental students or programmes sponsored by dental companies). Dental prevention in preschool children has been conducted mostly only on individual level. Currently it has been a responsibility of parents to bring their child for dental check-up after the eruption of their first tooth; however, many of them neglect this responsibility. The underlying factors that might have influenced caries prevalence include children’s access to dental care and the availability of fluoride-containing products. These factors remained generally unchanged over the investigated period. As for the social and educational determinants influencing oral health, the standard of living (expressed by Gross Domestic Product per capita) and educational attainment of the Czech population (referring to the number of students in university education) were increasing steadily over this period, see Table [13
Selected social and educational determinants in the Czech Republic over the investigated period
Oral hearth surveillance issues
In 2006, due to a political decision, national oral health monitoring was terminated. The decision was probably guided by the cost-saving efforts of the government. In addition to that, at present, due to significant financial constraints on new research projects in the Czech Republic, no extensive regular oral health surveys can be planned. These factors significantly negatively influence national oral health surveillance.
The two presented study series both collected oral health data in a consistent way for more than a decade. Therefore they were chosen for the analysis of caries prevalence trend. Nevertheless, several potential sources of bias might have influenced their findings. IHIS studies recruited the subjects from patients who were actively seeking dental care. They involved non-calibrated examiners, but this was partially compensated by the fact that dental caries detection threshold was a cavitated lesion, and by large sample sizes. Nevertheless, limitations related to sample selection and non-calibrated examiners should not have influenced trends observed in the analysis, as the methods remained unchanged in all IHIS surveys; and thus the results from all 5 rounds were comparable with each other.
Inclusion of IDR study subjects based on parental informed consents interferes with random sample selection procedures. However, similarity of the results from both IHIS and IDR study series to some extent limits a possibility of differential bias related to response rates in IDR studies because response rates in IHIS were almost 100%.
In both IHIS and IDR studies, dental caries was detected using visual-tactile method at a cavity level as recommended by WHO. Choosing a cavitated carious lesion, i.e. a stricter criterion for the disease detection, reduces the incidence of false positive findings. However, it is currently generally accepted that such a detection threshold results in an increased number of false negative findings [15
]. In case oral health surveillance is re-initiated in the Czech Republic, dental caries should be recorded at a pre-cavitation level as has been a common practice in epidemiological studies lately [16
]. A geographically stratified national random sample used in IDR studies should be preferred to the sample recruited from dental patients.
In order to validly compare the ECC´s burden in different countries, it should be determined which definition better reflects the typical disease pattern, its severity and impacts. AAPD definition of ECC is significantly broad and sets no parameters for the disease severity. However, there is also a definition of severe ECC (S-ECC): ´in children younger than 3
years of age, any sign of smooth-surface caries is indicative of severe early childhood caries. From ages 3 through 5, 1 or more cavitated, missing (due to caries), or filled smooth surfaces in primary maxillary anterior teeth or a decayed, missing, or filled score of ≥4 (age 3), ≥5 (age 4), or ≥6 (age 5) surfaces constitutes S-ECC [20
]´. This definition probably better reflects typical clinical picture of rampant caries. Another issue that should be addressed is a reference age group, representative for the population suffering from this disease and well accessible for surveying. The disease impact is particularly severe in children aged less than 3
years, therefore ECC data on this age group would be especially valuable. Nevertheless, in the Czech Republic, children attending nurseries (which generally admit children from the age of 3 to 6
years) are best accessible for the oral health surveys. Collecting caries prevalence data in dental patients aged less than 3
years by calibrated general dental professionals is another option. However, even though it is generally recommended that regular dental check-ups should be established with the eruption of the first primary tooth, only a small proportion of parents, most likely non-representative, bring their children to the dentist at that age. Therefore, creating a nationally representative sample of children aged less than 3
years seems to be an issue.