Background
Dental caries continues to be one of the most widespread diseases in the world [
1]. In particular, children are predisposed to the development of carious lesions, and their treatment is not just a problem in low- and middle-income countries [
2,
3]. Even in economically developed countries such as the United Kingdom, France, Germany, and the United States, the treatment of decayed primary teeth remains an on-going public health challenge [
4‐
7].
Severely decayed teeth have an important impact on children’s general health, nutrition, growth and body weight [
8‐
10] by causing discomfort, pain, sleeping problems, learning disorders and absence from school [
11‐
13]. Furthermore, odontogenic infections as a consequence of untreated dental caries are the most frequent reason for the hospitalisation of young children [
6,
14]. Therefore, oral health fundamentally influences children’s general health and quality of life [
15‐
17].
The early onset of dental caries is of exceptional concern since it represents an indicator for missed opportunities for preventive care and endangers the general health of a child. Wyne classified dental caries in children aged younger than 6 years as early childhood caries (ECC) by three types of severity [
18]. Type I has been defined as the existence of isolated carious lesion(s) on molars and/or incisors, type II as labiolingual carious lesions on maxillary incisors and type III as carious lesions on almost all teeth, including lower incisors [
18]. The American Academy of Pediatric Dentistry (AAPD) defines ECC as the presence of one or more decayed (non-cavitated or cavitated lesions), missing (due to caries), or filled tooth surfaces in any primary tooth in a child under the age of six [
19].
Most epidemiological studies performed in children have used the dmft index, which provides information on the caries experience and restorative and surgical treatment, but fails to contribute data on the consequences of untreated caries. The diagnosis ‘
teeth indicated for extraction’ is a WHO criterion for treatment needs [
20], but does not give detailed information about the severity of advanced caries lesions and is rarely used in the literature.
In 2010, Monse et al. [
21] introduced a new clinical index characterising the consequences of untreated dental caries in primary and permanent teeth: the pufa/PUFA index. It is calculated as sum of teeth with four diagnoses concerning different kinds of odontogenic infections ([p] pulpal involvement, [u] ulceration, [f] fistula, [a] abscess). Thus, the pufa index complements the dmft index by displaying the severity of dental decay and quantifying odontogenic infections of the pulp and surrounding tissues due to untreated caries.
Recently, the pufa index was used particularly in low- and middle-income countries to display the severity of oral health neglect (Table
1). The pufa prevalence varies from 24 % in Brazilian 6- to 7-year-olds [
22] up to 85 % in 6-year-old children from the Philippines [
21], indicating a huge dental need. Although Germany is a high-income country, the treatment of dental decay in the primary dentition of pre-school children is insufficient. The last representative study amongst 6- to 7-year-old German children revealed that almost half of all carious primary teeth (47.4 %) are untreated [
7]. This situation has been nearly unchanged for more than 10 years [
23]. Until now, the consequences of untreated dental caries—odontogenic infections—had not been quantified in German children with the pufa index. Therefore, the aim of this cross-sectional study was to assess the prevalence and experience of caries and odontogenic infections in primary teeth of 5- and 8-year-old German children from the Westphalian Ennepe-Ruhr District (EN District). The null hypotheses tested were as follows: 1) there is no difference in the prevalence and experience of odontogenic infections between 5- and 8-year-old German children; 2) untreated dental caries does not correlate with odontogenic infections; 3) odontogenic infections in 8-year-olds do not correlate with caries experience in permanent teeth.
Table 1
Pufa prevalence and mean pufa index in the primary dentition of children—overview from the literature
Mehta A., Bhalla S. | 2014/2014 | N = 603/ Indian | 5–6 years | 69.5 | not reported | 38.6 | 0.9 ± 1.93 pufa |
0.84 ± 1.5 p |
0.001 ± 0.05 u |
0.01 ± 0.08 f |
0.5 ± 0.3 a |
Baginska J., et al. | 2013/2011 | N = 215/ Poland | 5 years | 85.9 | 5.56 ± 4.45 dmft | 43.0 | 2.20 ± 3.43 pufa |
4.90 ± 4.26 dt | 2.13 ± 3.35 p |
0.19 ± 0.83 mt | 0.00 u |
0.46 ± 1.16 ft | 0.07 ± 0.33 f |
0.00 a |
7 years | 94.8 | 6.69 ± 3.14 dmft | 72.0 | 2.44 ± 2.22 pufa |
5.22 ± 3.25 dt | 2.31 ± 2.14 p |
0.86 ± 1.33 mt | 0.01 ± 0.09 u |
0.61 ± 1.24 ft | 0.12 ± 0.35 f |
0.00 a |
Thekiso, M., et al. | 2012/2010 | N = 800/South Africa | 4–5 years | 49 | :2.4 dmft | 33.0 | 2.9 ± 2.4 pufa |
2.0 dt | 1.8 ± 1.9 p |
0.2 mt | 0.7 ± 0.4 u |
0.2 ft | 0.0 f |
0.4 ± 0.1 a |
6–8 years | 46 | 2.4 dmft | 41.0 | 3.4 ± 3.9 pufa |
2.0 dt | 2.9 ± 2.6 p |
0.3 mt | 0.3 ± 0.6 u |
0.1 ft | 0.1 ± 0.4 f |
0.1 ± 0.3 a |
Figueiredo M.J., et al. | 2011/2009 | N = 835/ Brazil | 6–7 years | not reported | not reported | 23.7 | 0.4 ± 0.9 pufa |
0.3 ± 0.7 p |
0.001 ± 0.03 u |
0.08 ± 0.3 f |
0.01 ± 0.1 a |
Monse B., et al. | 2012/2006 | N = 2030/ Philippines | 6 years | 96.8 | 8.4 ± 4.2 dmft | 85.0 | 3.4 ± 2.6 pufa |
8.0 dt | 2.9 ± 2.4 p |
0.4 mt | 0.3 ± 1.0 u |
0.0 ft | 0.1 ± 0.4 f |
0.1 ± 0.3 a |
Discussion
In recent years, epidemiological caries research in high-income countries like Germany focussed on the development of more sensitive diagnostic methods to enable the assessment of initial caries lesions like the International Caries Detection and Assessment System (ICDAS II) [
28,
29]. This trend results from the decline of cavitated caries lesions and the development of non-invasive and preventive interventions requiring a distinction between different stages of initial caries lesions. In contrast, the remaining decay is concentrated in a small group of children with high caries levels and a huge need for treatment [
27]. Epidemiological studies have indicated that socio-economic conditions are important risk factors for caries during childhood [
30,
31]. Thus, high caries prevalence and experience in low-income countries [
32] and in socio-economically disadvantaged groups [
33,
34] have been documented. That polarisation phenomenon is also present in German children [
35‐
37]. Our findings display the inequality of caries distribution by the Lorenz curve (Fig.
1), confirmed by the Gini coefficient. In 5-year-olds, 90 % of the whole caries burden was concentrated in 20 % of the children, showing a strong polarisation of ECC. Unfortunately, no data on the children’s ethnical or socio-economic background were collected in the examination, which is a limitation of this survey.
Untreated caries may affect seriously the quality of children’s life because of pain and discomfort, which could lead to acute and chronic infections, oral mucosal conditions and altered eating and sleeping habits [
38,
39]. Furthermore, untreated caries in primary teeth can have a lasting detrimental impact on the permanent dentition by causing high caries risk [
40] or developmental defects of the permanent successor tooth [
41]. This was demonstrated in the present study population by the fact that 41.7 % of 8-year-olds with dental decay in the permanent dentition (DMFT > 0) also presented pufa scores in the primary dentition (pufa > 0). With this fact the third null hypothesis that there is no correlation of odontogenic infections and caries in the permanent dentition of 8-year-olds was rejected (Table
3). Thus, children with pufa scores should be characterized to be at high caries risk for early caries onset in permanent teeth. Presenting only dmft data to decision makers leaves them unaware of the severity and associated consequences of untreated caries on general and dental health [
10,
42]. Therefore, for the first time, our study gathered data on odontogenic infections as consequences of untreated dental caries in 5- and 8-year-old German children by using the pufa index.
About one-third to one-half of Westphalian 5- to 8-year-olds suffered from caries in primary teeth, which is in the same range (47.3 %) estimated for 6- to 7-year-olds in the last representative epidemiological German study in 2009 [
7]. About one third of all decay was restored (5y: 29.7 %; 8y: 39.3 %), leaving the teeth to development of pulpal involvement and odontogenic infections. This reflects the fact, that many German dentists perceive dental treatment of children as stressful [
43]. Commonly, dental school graduates are insufficiently qualified because of the limited university education in paediatric dentistry. Furthermore, for most dentists, it is not attractive to attend a postgraduate paediatric curriculum, due to inadequate reimbursement for restorative treatment in small and pre-school children with limited or lacking capability to cooperate [
43]. But the risk of young children experiencing pain and sepsis increases with higher caries experience [
4]. Therefore, children at high caries risk would benefit most from early dental care. On average, every twentieth 5-year-old child (4.4 %) and every sixth 8-year-old child (16.6 %) had odontogenic infections. Thus, the first the null hypothesis that there is no difference in the prevalence and experience of odontogenic infections between 5- and 8-year-old German children was rejected. In 5-year-olds, nearly all odontogenic infections (89 %) were concentrated in 20 % of the children displaying the highest dmft scores. This is emphasised by the correlation of untreated dental caries and odontogenic infections (
ρ = 0.399,
p < 0.001). Hence, the second null hypothesis that untreated dental caries does not correlate with odontogenic infections was rejected.
Taking into account the different socio-economic background of the population examined, comparisons with other countries may be limited. The pufa prevalence of our population was considerably low (5y: 4.4 %, 8y: 16.6 %) compared to Filipino 6-year-olds (85 %) [
21], Brazilian 6- to 7-year-olds (23.7 %) [
22], South African 4- to 5-year-olds (33 %) and 6- to 8-year-olds (41 %) [
44], Polish 5-year- (43 %) and 7-year-olds (72 %) [
45], and Indian 5- to 6-year-olds (38.6 %) [
46]. Solely, the pufa prevalence in 8-year-old German boys (21.2 %) was in the same range as reported for Brazilian children [
22] since 40 % of the caries lesions had progressed to the pulp. Knowing the impact of severe consequences of untreated dental caries on children’s general health, these findings should lead to the development of programs for German children at high caries risk.
Consistent with the studies mentioned, pulp involvement (p) was the diagnosis most frequently recorded, followed by ulceration (u) especially in 8-year-olds. This is in contrast to the findings of Figueiredo et al. [
22] and Baginska et al. [
45], revealing different patterns of odontogenic infections in different countries. The fact that primary molars were the teeth most affected by pulp involvement is consistent with their high caries susceptibility [
45‐
47]. Possible causes for children showing more odontogenic infections in first primary molars are their earlier eruption compared to the seconds which leads to a longer oral cariogenic exposure and the potential of lesions development between eruption and examination time. Furthermore the faster lesion progression from enamel surface to the dental pulp due to the lower enamel-dentin-thickness is related to larger pulp chambers compared to second primary and permanent molars [
48,
49]. Additionally, the early age of the child at eruption of first primary molars as well as their posterior position at the dental arches may contribute to more difficult and less efficient tooth brushing by parents or care givers. However, there is no consistent evidence that the first primary molars are more often carious affected [
46,
50] than the second primary molars [
51-
54].
Frigueiro et al. [
22] and Murthy et al. [
55] suggest that the codes ‘f’ and ‘a’ of the pufa index could be grouped together since they refer to the same inflammatory process of the jaw bone and are only different stages of inflammation. Furthermore, the necessity to score these codes separately was questioned, as the treatment requested will be the same: endodontic treatment or extraction [
56,
57]. In this context, it should be considered that the pufa index was not designed to serve as a treatment need index, but rather as an index to quantify the severity of untreated dental caries and to assess the presence of odontogenic infections [
58].
The use of only the dmft/DMFT index may be misleading the interpretation of caries epidemiological data. That was shown by the national oral health survey of the Philippines [
21] reporting 2.9 DMFT in 12-year-olds, which fulfils the WHO/ FDI goal of 3 DMFT for this age group in 2000 [
59]. However, in reality, 41 % of the decay component had progressed to odontogenic infections assessed by the PUFA index, indicating the huge severity of untreated tooth decay. The dmft/DMFT index fails to provide information on the clinical consequences of untreated dental caries, which may be more serious than the caries lesions themselves. The more meticulous caries classification system, ICDAS II enables the recording of different caries progression stages from sound to extensive decay compared to the dmft/DMFT [
26]. However, scoring of odontogenic infections (pufa/PUFA index) is only optionally recommended. Until now, German public oral health services prefer using dmft/DMFT index, considering ICDAS II too complicated and time consuming. The new caries assessment spectrum and treatment (CAST)-index was developed combining elements of the ICDAS II and the pufa/PUFA index with the m- and f-components of the dmft/DMFT index [
60]. It covers the total spectrum of carious lesion progression, including the advanced stages of carious lesion progression in the pulpal and tooth surrounding tissue. De Souza et al. compared the assessment of dental caries using the CAST instrument and the DMFT index showing no difference between the recorded caries prevalence, caries experience and time spent for examination [
61]. Still there is a need to validate the CAST index more closely before trying to replace any other index.
Dental caries is a multifactorial chronic disease with the interplay of individual, cultural, social and socio-economic risk factors. The lack of data regarding these factors is a limitation of the present cross-sectional study. Nevertheless, using the pufa index provides a more comprehensive view on caries pattern in primary teeth of German children. However, there is a lack of other studies performed in high-income countries to compare the findings.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
RHW and IMSCH conceptualised the paper and reviewed the paper for content, including the final version of the manuscript. RHW, IMSCH and IG developed the study design. IG organised and conducted the clinical examination. KG collected the data, performed the statistical analysis, conducted the literature review and authored the major portion of the manuscript. IMSCH and TL contributed towards statistical analysis and data handling. All authors have read and approved the manuscript.