Dental Caries

Dr Ratilal Lalloo
Department of Community Oral Health, Faculty of Dentistry and WHO Collaborating Centre
University of the Western Cape, South Africa

Introduction
The macro-economic changes imposed by the International Monetary Fund (IMF) and World Bank have increased the prevalence of malnutrition, especially amongst children.1,2 Malnutrition has been shown to affect the development of teeth and adversely affect the prognosis of dental caries and periodontal conditions.3,4,5 Malnutrition furthermore depletes the defence mechanisms which intensify conditions such as Acute Necrotising Ulcerative Gingivitis and its often fatal complication known as Cancrum Oris or Noma.6 Reduced coverage of immunisation programmes further exacerbates the already precarious situation in which many children find themselves. Oral health status studies in east African countries generally show that the prevalence is low but widespread and possibly increasing due to increasing exposure to the determinants of caries.7,8 This paper presents baseline dental caries data of a longitudinal study designed to assess the possible impact of Structural Adjustment Programmes (SAPs) on the oral helth status of 5-7 year old children in 3 districts in Tanzania, Uganda and Mozambique.

Method
During August and September of 1997, a longitudinal study was commenced in Tanzania, Uganda and Mozambique to assess the impact of Structural Adjustment Programmes (SAPs) on oral health. In year one (1997) of the study the oral health status of a cohort of 5-7 year old children was assessed. This cohort will be followed up in 1998 and 1999. The study was carried out in the districts of Maputo (Mozambique), Tanga (Tanzania) and Kampala (Uganda). In each country 3 different locations were selected for the study. These included:
1. A developed urban formal residential area.
2. A newly established urban informal settlement.
3. A rural village.
The developed urban formal location chosen was a well-established one, with formal housing and individual basic services such as piped water supplies and sewage. Shops, schools and health services were easily accessible through clinics and private medical and dental practitioners. The newly established urban informal location was under-developed, had communal piped or well water
supplies, a lack of sewage and a health post within a radius of five kilometres. The rural village had similar characteristics to the urban informal settlement but was well established. In each location 2 to 3 schools were randomly selected for the study from a school registry. Approximately 100 5-7 year old children were for the study in each location. In most locations all the 5-7 year old children at the schools selected were included in the study.

The WHO Basic Oral Health Survey diagnostic criteria of 19979 was used for the examination of the children. The data capturing form was modified to include data dental caries by tooth and surface. All the children dwere examined in daylight at the schools by 6 calibrated and standardised examiners (2 in each country). Prior to the study there was an 85% agreement on dental caries diagnosis (the inter-examiner and intra-examiner reproducibility for dental caries was 82% and 89% respectively).In kthe determination of the dmft, the m-component was recorded only for the canines and molars. For the dmfs index, 4 (canines) and 5 (molars) surfaces were counted for extracted teeth. Data on the permanent dentition are not presented because there were very few children with decayed or missing permanent teeth. The mean DMFT score for the entire sample was 0.088 with 4% of the sample experiencing decay of the permanent dentition. The ethics committees of Medical Research Council (South Africa), Faculty of Dentistry of University of the Western Cape as well as the relevant health authorities and research units in Tanzania, Uganda and Mozambique approved the project protocol. The consent of the school authorities was obtained.

Results
A total of 910 children were examined in the 3 countries. Table 1 shows that caries-free status (dmft=0) differs between countries and locations. The overall caries-free percentage of the total sample was 39%. In Tanzania the caries-free percentage was highest in the formal urban children (42%). In Uganda it was highest in the rural location (53%). In Mozambique it was high in all 3 locations, with again the rural population being the highest of all (55%). The overall dmft for the entire sample was 2.4 (SD 2.8), with the decayed component being 2.0 and the missing component 0.4. Only 3 children had filled teeth.

Table 1
Percentage Caries-Freeby Country and Location

Tanzania Uganda Mozambique
Formal urban 32 42 44
Informal urban 34 30 53
Rural 30 53 55
Overall 35 41 50

Table 2 shows that the overall dmft was significantly higher (p-value<0.05) in Tanzania and Uganda compared to Mozambique. The missing component in Uganda was significantly higher. This was due to the significantly higher number of missing primary canine teeth, especially in the informal urban children. In Uganda 17% of the sample had one or more missing primary canine teeth. In Tanzania and Mozambique this figure was 2% and 1% respectively. The overall mean dmft in Uganda decreased to 2.2 (from 2.8) when children with missing primary canines were excluded from the analysis. The missing component in the urban informal sample decleased to 0.3 (from 1.2). The decrease in the other 2 countries was not significant.

Table 2
Mean dmft Scores
by Country and Location
(standard deviation)

Tanzania Uganda Mozambique
dmft
Formal urban 2.4 1.9 2.2
Informal urban 2.9 3.3 1.3
Rural 2.5 3.3 1.0
Overall 2.6(3.0) 2.8(3.1) 1.6(2.3)
decayed
Formal urban 2.3 1.1 2.1
Informal urban 2.7 2.1 1.3
Rural 2.3 2.6 0.8
Overall 2.5(2.9) 2.0(2.4) 1.5(2.3)
missing
Formal urban 0.08 0.8 0.1
Informal urban 0.2 1.2 0.02
Rural 0.2 0.6 0.1
Overall 0.15(0.5) 0.8(1.5) 0.08(0.4)

Table 3 shows significant differences between locations in Uganda and Mozambique. The highest mean dmft scores were found in the informal urban and rural locations in Uganda (3.3). The lowest mean dmft scores were found in rural (1.0) and informal urban (1.3) locations in Mozambique. The decayed component constituted the major proportion of the dmft in all the locations and countries. The overall mean dmfs score for the entire sample was 5.1, with decayed component being 3.4, and the missing component 1.7. Table 3 shows the mean dmfs, decayed and missing scores by country and location. The highest mean dmfs score was found in Uganda, with the urban informal location being the worst off. The overall mean dmfs in Uganda decreases to 5.2 (in the urban informal location it decreases to 4.6) if the children with one or more missing canines are excluded from the Analysis. There were significant (p-value<0.05) differences between mean dmfs scores by country and location.The teeth most commonly affected by decay are the mandibular 1st and 2nd
molars and the maxillary central incisors. The teeth least affected are the mandibular incisors and the upper and lower canines. Of the teeth decayed, the majority needed to be extracted with fewer needing 1 and 2-surface fillings. The molar teeth (especially the mandibular) were the most common teeth needing extractions.

Table 3
Mean dmft Scores by Location & Country
Tanzania Uganda Mozambique
dmft
Urban formal 3.8 5.5 4.2
Urban informal 5.4 9.2 2.8
Rural 4.1 8.0 2.3
Overall 4.4 7.9 3.2
decayed
Urban formal 3.3 1.8 3.7
Urban informal 4.4 3.9 2.6
Rural 3.4 5.0 1.7
Overall 3.7 3.6 2.8
missing
Urban formal 0.5 3.5 0.5
Urban informal 1.0 5.2 0.2
Rural 0.7 2.9 0.6
Overall 0.7 3.8 0.4


Discussion
This study provides valuable comparative information on the oral health status of 5-7 year old children in the 3 districts in these countries. The uniform diagnostic criteria utilised makes comparison of the data across the countries and locations valid. The results of this study clearly shows that there are variations in the prevalence of dental caries between countries and locations within and between the countries participating in the study. National averages of dental caries prevalence will not always highlight areas that have high prevalence of dental caries. Generally the urban informal children have the highest levels of dental caries, except in Mozambique. The higher prevalence of dental caries in the urban informal children may be due to the increasing exposure to sugar and sugar-containing products with access to fluoride and oral healthcare remaining poor. The traditional practice of removing 'nylon teeth' (primary canine tooth buds) for diarrhoea and a range of childhood diseases continues to occur, particularly in Uganda.10 There is thus an urgent need to discourage this unnecessary, and potentially dangerous, traditional practice, as a number of deaths from haemorrhage and septicaemia have been reported.

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