This article reported upon the prevalence of dental caries experience, dental pain, other oral problems and oral impacts on daily performances in a deprived population of 10–19-yr- olds attending primary school in Kilwa district, Tanzania, detailed the association of clinical- and self-reported oral health indicators with OIDP and examined which oral impacts on daily activities affected perceived dental treatment needs. In spite of a low prevalence of untreated dental caries (19.2%), dental pain, oral problems and oral impacts affected a significant part of the population studied. Moreover, whereas dental caries and reported oral problems were useful predictors of OIDP, OIDP, in turn predicted perceived dental treatment needs accounting for between 8% and 14% of its explainable variance. In presenting unweighted prevalence estimates, the present study is limited in that the sample was not self-weighted and thus differed in some aspects from the population of urban/rural schoolchildren considered. This should be taken into consideration when interpreting the findings pertaining to the urban and rural schoolchildren combined.
According to the present data, the 3 months period prevalence of dental pain (including tooth sensitivity) and reported oral problems of Kilwa students amounted to 30% and 48.5%, respectively. The corresponding prevalence rates in students with caries experience were 50% and 54%, respectively. Obviously, if toothache and tooth sensitivity had been assessed separately, the prevalence estimates of dental pain would have differed. Nevertheless, the present results are within the range of dental pain prevalence rates reported by Slade [9
] and accord with the 1-month period prevalence of dental pain observed among similar aged children and adolescents in Uganda, Pakistan, China, Greece, UK and Brazil [18
]. Comparing the present prevalence rates across young populations worldwide should be done with caution since various time frames and age groups are focused in the different studies. Using a relatively long recall period of 3 months might have led to a slight underestimation of the prevalence rates reported in this study. Evidently, however, experience from Tanzania have indicated that a recall period for up to 12 months does not affect the prevalence estimates when it comes to more serious experiences (e.g. toothache) [30
]. The causes of dental pain reported in this study should be investigated further although sequelae of caries are the most likely reason for dental pain. This is so since 99% of the students investigated were without treatment experience in terms of tooth fillings provided by dental therapist, dentist or traditional healers. Dental pain estimates are recognized indicators of the oral health status as well as a measure of quality of life [31
]. The present finding indicates that dental pain in primary schoolchildren could be avoided and thus their quality of life improved by strengthening preventive and therapeutic dental services in sparsely populated and remote areas of Tanzania.
Compared to the prevalence rate of Child-OIDP reported in 10–14-yr- old primary school children in Dar es Salaam (28%) [9
], a higher prevalence rate was observed in Kilwa students, amounting to 36%. Nevertheless, the prevalence of OIDP observed in this study was lower than those reported among similar age groups in other cultures and also lower than those observed in East African adults [8
]. Consistent with previous findings, the Child-OIDP index exhibited marked floor effect, amounting to 64%. Nevertheless, this inventory exhibited sufficient discriminative properties suggesting that it is suitable for detecting group differences in cross-sectional studies. The higher prevalence rate of oral impacts seen in urban students compared to their rural counterparts is in line with rural residents presenting a healthier profile in terms of self-reported pain and oral problems, although the level of parental education and family wealth was most favourable among urban residents (Table ). Thus, Kilwa students from urban areas and of higher socio-economic status presented with higher prevalence of OIDP than did their rural- and lower socio-economic status counterparts. Socio-economic disparities in OHRQoL of younger age groups have been reported previously, however with low-income children having severe oral disease being those experiencing the poorest OHRQoL scores [32
]. Eating and cleaning were the most frequently reported impairments in urban as well as rural areas, a finding that is consistent with those of other populations using the adult-and child versions of the OIDP instrument [33
Consistent with pervious studies and irrespective of socio-economic position and dental caries experience, students reporting dental pain and oral problems during the last 3 months were more likely than their counterparts without such problems to present with impaired OIDP across the 8 impacts investigated [34
]. As shown in table S2; additional file 2
, dental pain was most strongly related to problems sleeping and difficulty to perform schoolwork and least strongly related to problems speaking-, smiling- and emotional stability. Thus, in Kilwa students, toothache seems to have more serious consequences for social- than for the functional and psychological performances. Contrary, reported oral problems were most strongly related to problem eating and cleaning and more weakly associated with other impairments. Obviously, the characteristics of symptoms (type, frequency and severity) that an individual experience would have varying consequences on different aspects of daily performances. As discussed by Locker [31
], the psychosocial impacts of oral disorders tend to vary from individual to individual even though the severity of their clinical condition remains the same. Accordingly, Wong et al [37
] studying the association between toothache and oral impacts in a sample of Hong Kong adults found toothache to be a stronger predictor of sleep- than of eating disturbances.
Understanding dental need perceptions is important for the effective planning and implementation of oral health care services. Consistent with theory and empirical findings, impaired OHRQoL was positively associated with perceived need for dental care in Kilwa students, indicating that a full understanding of young people's need for dental care cannot be captured by clinical indicators alone. These findings are consistent with previous reports, suggesting that self-evaluations of oral health status rather than disease presence per se are the primary determinants of perceived dental treatment needs [13
]. Consistent with results of previous studies in older age groups, the present findings suggest that normatively assessed and perceived need for dental care differs among Tanzanian primary schoolchildren [38
]. The present results provide insight into what oral impacts guide Kilwa students' perceived need for dental care. As shown in Table , respondents who reported problem eating, problem cleaning and problem sleeping were those most likely to perceive a need for dental care. Jokovic and Locker [39
] found problems associated with chewing and appearance to be the impacts most strongly associated with perceived dental treatment need in adult populations. Future studies should compare the performance of various OHRQoL inventories for children in relation to reported dental pain and perceived need for dental care. Not everybody who perceived oral impacts reported need for dental treatment the latter being related to factors that predispose and enable individuals to express their needs. Thus, the least common discrepancy observed- in terms of reporting no treatment need whilst having impacts were most frequent in urban areas and among children in the less poor wealth categories. This indicates a social gradient in impairment coping- or impairment reducing behaviours, suggesting that urban children possess better ability to cope with adversity including impaired OHRQoL as compared to their rural counterparts. Hastie et al [40
] suggested that besides seeking professional treatment, an individual can choose other pain and impairment coping strategies such as self-care, seeking of social support and spiritual/religious coping.