Research methodology
Caries diagnostic systems usually consist of one-digit codes and computer programmes for analysing the data exist. ICDAS II consists of a two-digit codes system and thus a new programme is required for analysis of the aspects of caries experience derived from many combinations of codes. In this investigation, many combinations had been diagnosed, as a consequence of the population caries load, and it was necessary to report the prevalence and mean scores of these combinations. This scenario led to a long list of figures (Table
3) whose relevance towards understanding the caries situation in a population group may be questioned. Guidelines on how to analyze the data obtained through ICDAS II were not found, which forced us to make a few decisions based on the manner of analysing epidemiological data from previous studies. We converted the two-digit system into the one-digit system and used the DMF index to accommodate the combination scores. In view of the time and money spent in diagnosing carious lesion progression in detail, as requested by ICDAS II, it was deemed a clear deficiency of the system that it was not immediately possible to report these observations in an easily understandable and pragmatic manner.
As explained in the section on statistical analyses, we experienced difficulties in how to handle fillings at tooth level when they were observed on the same surface in the presence of one or more enamel or dentine carious lesions. This difficulty is absent when the DMF index is used because the decision, whether a condition will be counted as a filling or as a carious lesion, can be made at the time of the examination. We tried to solve this problem with ICDAS II by creating a f2/F2, a f3/F3 and a f_icdas/F_ICDAS-component. We are of the opinion that the need for inclusion of these components in future reports should not be necessary as they complicate the reading of such reports. Our conversion exercise showed that ICDAS II is sensitive to interpretation and use of codes, which is unwanted for a caries diagnostic system that is meant to be used internationally.
We had to purchase two portable compressors in order to use ICDAS II in the examination of all schoolchildren since only two of the six schools had a dental unit with compressed air. Regarding the ease of the examination, no difference between the schools with dental units and those with portable equipment was reported by the examiners. However, the need for compressed air will hinder the use of ICDAS II in developing countries. The real necessity of using compressed air in epidemiological surveys should, moreover, be discussed. According to the ICDAS II manual [
16], the use of compressed air is essential for detecting caries codes 1 and 3, while caries codes 2, 4, 5 and 6 can be assessed if the tooth is viewed while wet. Considering that both codes 1 and 2 relate to enamel carious lesions with a slight difference in the level of mineral loss [
17], which requires the same type of preventive measure [
18], the importance of detecting code 1 in epidemiological surveys can be questioned. For caries code 3 (cavity confined to the enamel), the ICDAS II manual reports that this type of lesion is detected after drying the tooth, but, in case of doubt, the WHO probe can be used gently across the surface to confirm the visual assessment. This means that, even without compressed air, code 3 can be detected by sliding the ball end of the WHO probe along the suspect area. Therefore, in order to facilitate the execution of epidemiological surveys, a more practical approach might be not assessing ICDAS II code 1 and using only the WHO probe to diagnose ICDAS II code 3, which would eliminate the need for compressed air. In addition, it was observed that in studies which used the ICDAS II, although enamel carious lesions were being scored separately, the researchers tended to collapse the codes into one when reporting the results [
19,
20], in order to facilitate understanding of the outcomes.
ICDAS II was developed because the ‘old’ DMF index was considered obsolete, as early enamel lesions were not part of the DMF index. With the decrease in caries prevalence, there was a need to diagnose non-cavitated lesions [
7]. For that reason, ICDAS II was proposed as an alternative to the DMF index. Nevertheless, researchers have encountered problems in reporting the data, necessitating conversion of ICDAS II codes into DMF components [
19,
21] or, as an alternative, to produce a table with a long list of possible combinations of the two digits of the system (Table
3) [
19]. This is not straightforward and may make the discussions with policymakers difficult. It would be close to impossible for a public health planner to understand the various caries related prevalence scores as it would be for the oral epidemiologist to explain these. Consequently, the elaboration of oral health programmes as well as the establishment of goals, which are the main reasons for conducting an epidemiological survey, would be compromised. Therefore, the usefulness of ICDAS II in epidemiological surveys should be reconsidered on the grounds that while data is collected in such a detailed manner, it cannot be reported in an easily comprehensible way. Moreover, the description of caries experience restricted to ICDAS II codes does not permit comparison with extensive studies that have used the DMF index.
Another aspect that needs to be addressed is the time required to complete the caries assessment when using ICDAS II in a caries-active mixed-dentition population like the present one. Even after a calibration period of 2 weeks, the first examinations took a long time to complete. The need to score the combination of the two-digit coding system and the need for drying one tooth surface at a time were found to be the most time-consuming activities. The final diagnosis was reached only after observing the wet surface and then the dried surface, as proposed by the ICDAS Committee [
16]. According to a previous study [
22], ICDAS II examination took twice as long as examination based on the WHO caries index. In epidemiological surveys with big samples, use of ICDAS II may become a costly undertaking.
In addition to the kappa coefficient, the percentage of correctly observed judgements (P
obs) was used to complement the reliability measurement because the kappa statistic is unreliable in low prevalence populations and when only a few number of scores are present for a code, as occurred a few times in the present study. As all P
obs readings and most of the kappa coefficients were high, it was concluded that the quality of the data obtained was high.
Considering the kappa coefficients for intra- and inter-examiner consistency in using ICDAS II, the reliability of the results regarding caries experience is considered high. This finding may be attributed to the lengthy and stringent training and calibration exercises that the examiners had undergone.
Main findings
The prevalence of caries in the primary dentition of this young child population, including enamel and dentine lesions (95.6%), is considered extremely high. Children from deprived areas are known to be at high-risk regarding caries [
23,
24], which could partly explain the high percentage of children affected with dental caries. Other epidemiological surveys using ICDAS II in similarly aged children in deprived communities revealed a caries prevalence of 81% [
25] and 100% [
26], which is in line with that obtained in the present survey. A somewhat lower caries prevalence (74.7%) was reported in low-income Colombian children, aged 2.5 to 4 years, using ICDAS II [
27]. The Colombian children were younger than those in the present study, which would be an obvious reason for the lower caries prevalence percentage. Another reason for the difference in caries prevalence between the Colombian and Brazilian children may have been the absence of ICDAS II code 1 recording in the Colombia study. In the present survey, code 1 was the most prevalent caries code in the primary dentition. The fact that the prevalence of dental caries, diagnosed according to the ICDAS II, was already very high in young children showed the low discriminating power of that system in identifying the level of seriousness of the disease. The fact that the very early sign of dental caries in enamel (code 1) is included in the system appears to be the reason. Although one never knows exactly if ICDAS II code 1 will progress, it has been demonstrated [
28] that a considerable number of those lesions will not progress. It is, therefore, very likely that including very early signs of enamel carious lesions in a caries assessment system will overestimate the severity of dental caries. The profession should be asked if they want to communicate to other health professionals and members of society in this manner. Using ICDAS II, an almost 100% prevalence of dental caries in primary teeth was observed at a young age in the present study. The same situation was applicable to caries prevalence in permanent teeth. Already at an age of 6 to 7 years, 63.7% of the children were affected by dental caries. This figure should be considered high, considering the fact that the permanent teeth had been erupted for about 1 year only.
Herein, a mean d
3mf
3-t of 3.2 ± 3.4 was observed, which is in line with the studies conducted among 6-year-old Brazilian children in the last decade. Mean dmf-t scores ranging from 2.4 to 3.1 had been described in the literature [
29‐
31]. It was not possible to compare our results with those published by the Brazilian Health Ministry in 2003 [
32] as children aged 6 to 7 years old were not included in their epidemiological survey. In general, the caries status of the sample was higher than expected and did not achieve the goal proposed by WHO for the year 2000, which was 50% of caries-free 6-year-old children, according to the DMF index [
33]. Only 32.8% of our children presented a mean d
3mf
3-t score of 0.
The findings confirmed the lack of a system capable of offering curative care for schoolchildren in Paranoá. The m- and f-components were extremely low in comparison to the d-component. Only a few children had received treatment in the primary dentition. For the permanent dentition, practically no treatment was carried out.
In the present survey, girls did not show a higher caries experience than boys, which is common [
34]. Only an age effect for D
2MF
2-S was observed. Despite the 1-year age difference, 7-year-old children had more carious lesions in permanent teeth than children aged 6. This finding showed once more that erupting and just-erupted permanent molars are vulnerable to carious lesion development [
35].
In summary, a high prevalence of dental caries in both primary and permanent teeth was found, with enamel carious lesions being the most frequent condition detected, showing that using ICDAS II can lead to overvaluation of the seriousness of dental caries experience. Prevalence of dentine carious lesions in the primary dentition was high, but low in the permanent dentition. Extractions due to caries, and restorations were seldom found, indicating the lack of access to oral health care services among schoolchildren in Paranoá.