According to the World Health Organization (WHO), dental caries is a localized post-eruptive pathological process of external origin, with a progressive, irreversible nature and insufficiently clear aetiology (1). It affects hard dental tissues where microorganisms act to cause their demineralization, which consequently leads to the development of cavity causing pain and, if not treated, tooth loss. Over the years, studies have shown that tooth decay can be prevented and controlled, but reliable epidemiological data on its distribution are a prerequisite which would allow the implementation of measures that could be used in caries prevention (2). Since 1938, the DMFT index has become a relevant tool in monitoring of distribution trends concerning dental caries; applied by the WHO in their assessment of oral health, reflecting the intensity or frequency of dental caries (3). Caries prevalence in the world has decreased in developed countries due to improved organization of dental health care, available fluoride products, improved oral hygiene and higher awareness concerning caries occurrence (2, 4). Western and Northern European countries have recorded a decrease in caries, but in the countries of Eastern and Central Europe caries has remained a public health problem (5, 6). The restructuring of organized dental health care, years of insufficient preventative actions and the lack of promotional oral health campaigns are the reasons why Croatia has been listed among countries with a high DMFT index. The transition of paediatric dentists into the system of polyvalent dental care practice has led to the downfall of the systematic oral health care, i.e., the monitoring and dental caries prevention in children in Croatia. Earlier studies, which were conducted in Croatia, relating to the epidemiology of dental caries were sporadic, covering various age groups in individual cities and regions of Croatia, indicating intensified expansion of dental caries with, however, inconsistent data. A uniform database of the DMFT/dmft index has not yet been developed in Croatia, while the DMFT/dmft data for Croatia presented by WHO have been based on the data obtained from published scientific papers (7).
The objective of this paper was to show the trends in the DMFT/dmft index in Croatia, based on the data collected and summarized relating to the epidemiology of dental caries, found in the literature published in the last thirty years and in comparison with other European countries. Plans and goals will be presented also, aiming at the implementation of caries prevention, the DMFT reduction and the improvement of oral health. Moreover, we will show the DMFT index related data, kept in the database of the Croatian Health Insurance Fund, collected in the period from 2013 to 2015.
METHODS AND MATERIALS
Data were collected through search in Pub Med and Google Scholar databases. The following key words were used in the electronic search: dental caries, prevalence, DMFT, Croatia. All search results were checked; papers and articles published relating to the searched data in the period from 1985 to 2015 were selected, giving the information on caries in children and caries in adults. Our intention was to select the children population of 5 to 6-year olds and of 12-year olds as recommended age groups used for oral health surveillance by WHO (8). For the period from 2013 to 2015, the DMFT index data for Croatia were obtained by retrieving dental status data collected during clinical examinations carried out by dental practitioners who had signed the contracts with the Croatian Health Insurance Fund (9). Clinical examinations and status of the teeth were recorded in the Central Health Information System of Croatia (CEZIH) and the data were published on the website of the Ministry of Health in July 2015. Regarding dental caries among children and presentation of searched data, the prevalence and severity of disease was reported in terms of the standard epidemiological indicators, DMFT (number of decayed, missing due to caries and filled teeth in the primary dentition) and dmft index (number of Decayed, Missing due to caries, and Filled Teeth in the permanent dentition) (8). The statistical analysis of the resulting data was made and presented via graphs in Microsoft Access 2.0.
Caries in 6-Year-Old Children
A review of the literature on the prevalence of dental caries among 6-year-old children has shown high DMFT/dmft index figures and a small proportion of children without caries. In the period from 1985 to 1992, as a result of the implementation of the preventative dental caries programme (twelve years experience; from 1980 to 1992) in kindergartens in the city of Zagreb, the percentage of 6-year-old caries-free children increased from 16 to 27%, while the value of the dmft index decreased from 5.9 to 4.4 (10). In the study conducted in 1994 also in Zagreb kindergartens, 9.4% of 6-year-old children without caries was recorded, which indicates the increasing prevalence of dental caries in comparison to previous years (11). In the survey conducted in 1997 in the town of Zabok, to assess the impact of war life circumstances on oral hygiene, the dmft index of 6-year-old children was 6 (12). In the following years, the trend of increasing dental caries prevalence continued, reflecting the absence of preventive dental care campaigns. In the period from 2008 to 2009, the data collected among 6 year-old school children in the Primorsko-Goranska County showed the dmft index of 4.68 and a significant proportion of children with caries (74.5%) (13). Clinical examinations of 6 year-old children in the city of Rijeka, carried out from September 2012 to May 2013, showed dmft of 3.68 and 22% of caries-free children (14) (Figure 1, Figure 2). The DMFT index in 6 year-old children registered in the Central Health Information System, for the period from 2013 to 2015, was 4.14. The lowest DMFT index was recorded in the Međimurje County (3.25) and the Virovitičko-Podravska County (3.10) and the highest in the Sisačko-Moslavačka County (5.77) and the Ličko-Senjska County (5.65) (15) (Table 1).
Caries in 12-Year-Old Children
In 1985, the DMFT index of 12-year-old children was 5.9 (16). Years of educational and oral health programmes, which were conducted in schools and kindergartens and regular tooth fluoridation resulted in an improved oral hygiene and decreased DMFT index through the years. From 1985, DMFT’s declining trend continued, in such a way that the 1986 survey conducted in the city of Zagreb showed it at 4.6 (17). By 1990, DMFT decreased to 3.4. The highest improvement results were achieved in 1991 when the DMFT index was 2.6 (16). In 1997, the high DMFT value (4.1) was noted in the study performed in the town of Zabok among 12 year-old children (12). In 1999, it amounted to 3.5 and it has been observed that changes in the health care system and the war period have led to the increase in the DMFT index (16). In the survey conducted in the Šibensko-kninska County in the 2003, the index was at 3.85 (18). From 2003 until 2015, the increase in caries prevalence could still be noted and the study conducted among school children in the city of Zagreb in the period from 2009 to 2010 showed it at 4.8 (19) (Figure 3). The study conducted among disabled and healthy children aged 3-17 years in the city of Rijeka showed the average DMFT index score of 6.39 for disabled children and 4.76 for healthy children (20).
Caries in Adults
According to the survey conducted in the city of Zagreb in 1986 among 35-44 year-old adults, the DMFT index was 16.2, while the DMFT value in the oldest age group (over 64 years) was 20 (17). In 2003, the sample of 35-44 year-old population of the Šibensko-Kninska County had the DMFT value of 21.7 while the elderly population (65-74) had it at 23.7 (18). The survey conducted among Croatian army recruits aged 19-27 years, showed the DMFT value of 7.76 (21). Another study, conducted in 2004, also among army recruits in four Croatian regions (18-28 years old) showed high DMFT value (8.6) (22). In 2010, the DMFT index of 18-65 years old subjects in the town of Knin was 17.3 (23). The assessment of oral health among institutionalised elderly subjects in the city of Zagreb, in the 58-99 years age group, showed the DMFT index value of 27 (24) (Table 2). According to the Central Health Information System, the average DMFT index for adult Croatian citizens was 12.5 (Table 1). In the female population, it had a higher value of 13.2 (15).
According to the WHO Report, dental caries affects 60-90% of schoolchildren and the vast majority of adults, indicating how massive the extent of this public health problem actually is so that it emerges in the majority of industrialized countries (25). Children population from 5 to 6 year-old are of interest in relation to caries levels in the primary dentition, which may exhibit changes over a shorter timespan than in the permanent dentition at ages. Twelve-year old children are a particularly important age group because reliable data are accessible and trackable through the school system. For these reasons, this age group has been chosen by WHO as a global indicator age group for the global tracking and monitoring of disease trends. The experience of Western European countries has shown that schools provide a significant platform for the control of oral health in children and relevant indicators for oral health promotion (5). Scandinavian countries are the example of a long-standing practice of dental care service in schools, for all the children and youth up to the age of 18 years (26). The preventive and curative dental health care program was introduced in Denmark back in 1911 and it was mainly carried out in school-based clinics. Since then initiatives and activities have been implemented with the focus on schools and families and school and community oriented health promotion (27). The systematic dental health care in the Scandinavian countries has in the end given low DMFT figures for 12-year-olds in Denmark (0.6), Sweden (0.8) and Norway (1.7). From 1985 to 1991, Croatia had a decreasing trend in DMFT of 12-year-old children, reaching one of the joint WHO and FDI objectives set in 1981 for the year 2000, for 12-year-old children, who should not have had more than 3 carious teeth, 3 extracted and 3 filled teeth (28). Since 1991 (to date) Croatia has remained far from the objectives set by WHO for 2020 as part of the "Health21 Policy" for Europe (on average no more than 1.5 DMFT should be observed in 12-year-olds and at least 80% of 6-year-olds should be caries free) (5, 29). Kunzel has followed caries trends in industrialized countries and has divided the countries of Europe in two European regions: the Western European region (low-risk countries), with the DMFT average of 1.7 and 40% caries-free 12-year-old children and the Eastern European region (high-risk countries) with 4.1 DMFT and 10% caries-free 12-year-old children (30). According to the mentioned division and the DMFT data, Croatia belongs to the countries with high caries prevalence. The data from the available oral health database kept by WHO also show high DMFT index values in many countries such as Bosnia and Herzegovina 4.2, Albania 3.7, Macedonia, 3.5, Poland 3.2 and Bulgaria 3.1 (7). Figure 4 shows a significant reduction in the prevalence of dental caries in 12 year-olds in west European countries and some improvements in Eastern European countries in the last thirty years, but Croatia ranks last on the list with a reversed DMFT index trend. It should be noted that it is not appropriate to make a direct comparison of the DMFT scores among individual European countries because of different methodologies and different periods used to obtain the data (31). In addition, the overall positive trend in the reduction of dental caries is concealed by considerable inequalities among certain countries. For example, Poland has experienced a slower rate of improvement, reflected also by other East European countries, which could be explained by changes in health systems as a result of economic and political changes in Eastern Europe (5, 32). The privatization in the health system has led to the diminished use of public dental care services among children and adults and the inability to pay private health care.
According to Silveira, the average DMFT index for the European region from 1973 to 2008 was 2.3, ranging from 0.7 to 7.8 (33). He also pointed out that the majority of Western European countries have a lower relative risk (RR) compared with the European region’s average, while 24 European countries have a rate of decay higher than the average for the region. Montenegro and Serbia are the first two countries with a relative risk of 3.4 and the last with a risk that is 1.9 times higher than the average. The countries with the lowest rates are United Kingdom, Germany and Denmark (0.3) (Figure 5).
The positive trend in the reduction of the dental caries prevalence recorded in the neighbouring Hungary and Slovenia has been achieved via introduction of preventive school programmes and oral health education programmes (34). From 1980 to 2001, Hungary reduced DMFT from 6.6 to 3.3, while the highest extent of decrease in caries prevalence was observed in Germany and in the Netherlands (35). In Slovenia, from 1987 to 1998, the percentage of caries free 12 year-old children was increased from 6 to 40% while DMFT decreased from 5.1 to 1.8 (36). Croatia, for a while, was a good example of reduced prevalence of dental caries, achieved through controlled teeth fluoridation and improved oral hygiene, but changes in the organization of primary health care and political circumstances contributed, unfortunately, to a disruption in the continuity of preventive activities. On the other hand, Slovenia, despite the changes, has managed to maintain and improve prevention through oral health care initiatives in schools. Countries in the Eastern European region, if compared to Western European countries, also show high percentages of preschool children with caries (5, 37). The Netherlands, through its national epidemiological studies programme, made the evaluation of the oral health education programme for the period from 1965 to 1980. The results showed a decrease of the DMFT index among 6 year-old children from 18 to 6 and from 9 to 4 among 12 years old children (38). The observed range of DMFT values from 3.25 to 5.65 in 6-year-old children in Croatia can be attributed to socio-economic conditions in individual parts of the country, such as level of education and family income as important factors for the development and progression of dental caries (39-41). In addition to reduced preventive measures and low socio-economic conditions, the new trends in the dietary children’s habits and the extremely high consumption of erosive drinks should not be neglected.
Many European countries have recorded a decrease in caries prevalence among adults. The adult population in Croatia was found to have high DMFT values with considerable variations according to the age group. In 2003-2004 a national survey conducted in Hungary showed variations in the value of DMFT index (11.79 in the youngest age group and 21.0 in elderly people) and it was noticed that M-component of the index had the highest value in all age groups (42). Marthaler mentioned a significant reduction in the prevalence of caries from 1970 to 1996, among 20 year-old army recruits in Switzerland, with the DMFT index decrease from 16.0 to 4.8 (6). It is well known that numerous socioeconomic and demographic factors have an impact on the oral status and dental caries prevalence such as age, gender, urbanization, economic conditions and other (43, 44). According to the results shown by Bonev and al. on the DMFT index of adults in Bulgaria (17.7), it is evident that DMFT values can vary significantly depending on age, gender and general health (45). Bego et al. have found the difference in the incidence of dental caries in adults and higher DMFT index values in women than in men, which corresponds to the current data in Croatia (18).
All the above-mentioned data show evidently that it is necessary to intensify actions of control and promotion of oral health in Croatia. In March 2015, the Ministry of Health adopted the “2015-2017 Strategy Plan for the Promotion and Protection of Oral Health” derived from the “2012-2020 National Strategy for Health” as a key document setting the priorities of dental health care. The national programme for caries prevention has been launched, setting in motion a great number of activities with the following objectives: to increase the percentage of healthy teeth in 5-6 year-old children to 60%, reduce the DMFT index of 12-year-old children to 3.5, increase the application of products for fluoridation and remineralisation and improve oral hygiene and dietary habits of the entire population (46). The monitoring and creation of DMFT databases in Croatia through CEZIH, based on primary health care data obtained in the past two years and efforts invested in improving the reliability and validity of data constitute a great progress oriented towards the development of consistent caries and oral health databases, contributing also to years of global research of the epidemiology of dental caries. Sweden, Norway and Denmark are examples of countries that have begun to collect DMFT data at national level through public dental health care programmes. They have developed and continue to develop valuable systems to improve the quality of data and identify indicators of quality in dental health care (47). Along these lines, Croatia also needs to continue and intensify efforts towards further development of the system of oral-health monitoring and protection, in compliance with appropriate quality standards, through cooperation of numerous participants such as the Ministry of Health, the Croatian Institute of Public Health, the Croatian Health Insurance Fund, the schools of dental medicine and providers of dental health care, all with the aim to achieve the anticipated results.
The DMFT index data in Croatia show that dental caries is still a public health problem indicating that actions must be taken at national and local level. The establishment of dental health and DMFT/dmft index databases and the appropriate understanding of factors that lead to occurrence of dental caries are important for objectives to be set and preventive programmes to be planned in the domain of oral health. The implementation of programmes and actions towards oral health promotion and dental caries prevention, started at national level, should lead to changes and demonstrate the importance of preventative approach, encouraging also the revitalization of the preventive dental health care among pre-school and school children.