This is one of the first population based studies to systematically investigate correlates of ECC and sugar consumption among infants 6–36
months old residing in rural high fluoridated- and urban low fluoridated regions of Tanzania and Uganda. Thus, the present study provides information about age groups that have not been covered by the national oral health surveys in Tanzania and Uganda. Information about the prevalence of ECC in the general pediatric population of sub-Saharan Africa is scarce and the Kampala and Manyara region have been surveyed to a very limited extent [5
]. Many previous studies regarding determinants of ECC and sugar consumption have focused solely on individual factors studied by univariate analyses in relatively small samples [11
]. In contrast, this study included various potential risk indicators using multivariable models, young and well defined age groups and large samples from different regions of sub-Saharan Africa. A comparison of the Manyara study group with the pediatric population (0–4
yr) in Mbulu, Babati and Hanang districts on socio-demographic markers, revealed that the study participants was representative of 6–36
month olds resident in those areas. In Kampala, the sampling method might make the external validity more questionable. However, high response rates and a limited number of missing items in the interview suggest that the study group for whom there are complete data reflects caregiver/child pairs living in the catchment areas of the RCH clinics in Makindye and Nakawa districts.
The prevalence of ECC in Manyara (3.7%) and Kampala (17.6%), reflected neglect of infants’ oral health, suggesting that caries might be a public health problem in the two areas [8
]. Although evidence of a major benefit of fluoride consumption in infancy is limited, the discrepancy in caries experience between the study sites indicated that living in the high fluoride area of Manyara might be recognized as a caries protective factor [39
]. Consistent with previously reported geographical variations in ECC, the present one is most probably attributable to various fluoride levels in drinking water [40
]. Nevertheless, it is difficult to evaluate the global amount of fluoride (systemic and topical) to which children are exposed. Widespread use of fluoride toothpaste has been associated with a significant reduction of caries [6
], however, the affordability and availability of fluoride toothpaste in its bioactive form is still a main challenge in many areas of sub-Saharan Africa [41
]. Care should be exercised when directly comparing findings between Manyara and Kampala, considering possible confounding due to different time points of study conduct. Confounding is also possible due to differences between examiners for whom the inter-examiner consistency was not known, although both examiners were trained and calibrated according to the same rules at University of Bergen, Norway. In both study sites, decayed teeth were the only component contributing to the dmft scores, reflecting unmet treatment needs due to poor accessibility of oral health care services in both countries. The present findings accord with rates of ECC assessed in studies of similar age groups in Southern China, Sri Lanka and Nigeria [3
] and also with studies conducted in the Western world [39
]. Moreover, the prevalence of ECC documented here is consistent with that reported decades ago in Tanzanian children aged 1–4
], but slightly lower than the rate reported among 3–5
yr olds in South Africa and Uganda [2
]. The various diagnostic and epidemiological criteria employed across studies make it difficult to obtain a clear picture of ECC rate across time and separate regions of sub-Saharan Africa. A possibility of misclassification between ECC and dental fluorosis in Manyara should also be considered.
As depicted in Figures
, the caries lesions were not evenly distributed, being most prevalent in the upper maxillary anterior teeth and the lower molars for both boys and girls, thus reflecting the patterns of eruption. Similar caries patterns have been reported in previous surveys of the primary dentition [11
] and have been attributed to infant feeding practices; baby bottle filled with sweetened beverages and prolonged breastfeeding on demand [43
]. This study revealed an on average longer breastfeeding exposure among children with than without caries experience. Previous evidence suggests that prolonged breastfeeding beyond one year is associated with ECC [20
]. On the other hand, the prevalence of ECC recorded in the present study varied inversely with current breastfeeding status, being highest among children who were not breastfed across tooth types and study sites (Table ). Moreover, weaned children presented with higher sugar consumption than their breastfed counterparts, indicating a protective effect of breastfeeding on ECC, as reported previously [46
]. Nevertheless, breastfeeding status did not maintain its significant relationship with ECC in multiple variable analyses (Table ). Being associated with both sugar consumption and ECC, the effect of breastfeeding was probably hidden in the final regression model, mediated or confounded by sugar consumption or other variables.
Frequency distribution of caries experience according to Sex and tooth type in Kampala, Uganda (low fluoridated urban area).
Frequency distribution of caries experience according to Sex and tooth type in Manyara, Tanzania (high fluoridated rural area).
Consistent with a number of studies, but at odds with others, the present study revealed a positive association between sugar consumption and ECC in Manyara and Kampala [17
]. A previous study of 3-5- yr- old preschool children in Kampala did not identify a similar relationship [11
]. In Kampala, the rates of both ECC and sugar consumption increased significantly with increasing age suggesting children’s adoption of adverse dietary habits and cariogenic foods when growing older. Previous evidence suggests that caregivers of 0–23
months-old Ugandan infants add sugar to complementary foods and drinks more often than using oils and milk [27
]. Sugar intake of 6-36- month olds increased with increasing teething symptom status suggesting a higher caries risk in diseased children consuming medicinal syrups for a longer time as has been reported previously [48
]. Advertisements and marketing of sweets and sugary beverages have influenced caregivers towards feeding their children with sweets and snacks [26
]. In contrast, this study revealed that caregivers who received oral health information from health care workers were less likely to have children with high sugar consumption and ECC. A recent review has shown that children of less well informed and lower educated parents have higher sugar intake leading to higher levels of dental caries [14
]. These findings reflect important oral health consequences of early oral health information from health care workers provided to caregivers of 6–36
month old children in Tanzania and Uganda.
Poor oral hygiene practices have been found to be strongly associated with the prevalence of ECC [6
]. In Kampala but not in Manyara, children with visible plaque on anterior maxillary teeth, recognized as a proxy of poor tooth brushing frequency, were more likely to have ECC as compared to their plaque free counterparts. This study also documented enamel hypoplasia as a potential risk indicator of ECC among Kampala children [21
]. Enamel hypoplasia provides suitable sites for the adhesion and colonization of cariogenic bacteria. Evidently, ECC on such altered surfaces develop more rapidly than on sound tooth surface [21
]. A low prevalence of ECC in Manyara due to high fluoride in drinking water might explain the lack of statistical significant relationship with visible plaque and enamel hypoplasia. Moreover, there is a risk of misclassification between enamel hypoplasia and dental fluorosis.
Previous studies have shown that socio-demographic factors such as parental education and household income have a direct influence on ECC [2
]. Traebert et al. [51
] reported a positive relationship between low maternal schooling and severity of dental caries in Brazilian preschool children. No such relationship was identified in this study, although belonging to the poorest household quartile emerged as a risk indicator for higher sugar consumption in Manyara. It is well known that determination of social class is a challenge in developing countries where accepted criteria for social classification do not exist [37
]. Moreover, it should be considered that socio-demographic variables in line with the other self- reported variables utilized in this study might have been subject to recall and response biases [52