This study is the first large population based study of adult oral health in Sudan. There were some limitations that should be considered when interpreting the data presented in this study. Given the available infrastructure, it is not possible to conduct a randomly selected sample representative of the entire Sudanese population. Whereas it is possible to obtain some information on oral health issues from patients attending outpatient facilities of hospitals and dental health centres of Khartoum State, the findings may not be representative of the whole of Sudan. The sample was biased in that visits by the individuals attending these clinics were problem based. However, the sampling strategy employed ensures that the sample recruited from the country's most populated state is broadly representative of Sudan. Given the limited infrastructure for oral health services delivery in Khartoum, the prevalence rates of conditions reported in this paper are unlikely to be overestimated. Many people in Sudan do not receive regular dental care and have acute problems when seen by a dentist. In Sudan the dentist-to-patient ratio is 1:33,000 compared with approximately 1:2,000 in most industrialized countries [21
]. Relative to the size of the Sudanese population, there are very few dentists and this restricts access to regular dental care. Other factors which influence dental attendance in Sudan include the lack of public funding for oral healthcare and dental insurance schemes to ameliorate the cost of care. In that sense, the dental attendance experience of this sample is not untypical of the wider Sudanese context.
One of the most striking findings from the study is the apparent lack of restorative or preventive dental care, as shown by the filled component F (0.2%) and treatment is limited to pain relief or emergency care by tooth extraction. Dentists' attitudes toward dental treatment were shown greatly to influence tooth extractions in this study. It would appear that there are barriers to the provision of restorative dental care which are multifactorial in origin and worthy of further investigation.
There were relatively few participants aged ≥ 65 years, but this reflects the age distribution of the Sudanese population according to the population Census of Khartoum State 2007 [22
]. In Khartoum state, only 2% of the population are aged over 65 years. Also of interest is the observation that life expectancy at birth of Sudanese is 55-60 years according to United Nations [23
]. People from older age groups might also have lower expectations or less money available for dental treatment.
The low level of literacy observed in Khartoum (which is probably amplified in other Sudanese states) as well as low income level, could have had profound effects on the level of oral health observed in this study. The impact of socioeconomic status on oral health has been documented in other studies [24
In terms of accessing dental care, only 16.7% reported attending more frequently than every 2 years, which is much lower than reported elsewhere. For example, the Irish Oral Health Survey of adult oral health in 2000-02 reported that 44-57% visited the dentist more frequently than every 2 years.
Because nearly one fifth of subjects used tobacco in some form, the strong correlation between smoking habits, severity of periodontal disease, and tooth mortality, as established in various studies, should be considered [26
]. Smokeless tobacco "Toombak" has been linked to oral health hazards such as cancer in a few studies [28
The finding that just over half the population brushed their teeth twice daily is similar to the findings of the Irish National Oral Health Survey 2000-02 [20
], whose authors commented that people who brushed at least twice daily had a greater number of teeth and lower DMFT and were more likely to have ≥ 18 SUNT. Very few participants used additional methods of oral hygiene such as floss or mouthwashes, and this might be due to lack of awareness or inability to purchase them.
The prevalence of xerostomia in Khartoum at 3.5% was much lower than in other studies, where approximately one fifth of older people [30
], and 10% of subjects aged in their early 30s [31
] reported the condition. This might be due to more limited exposure of the Sudanese population to medications which reduce saliva flow. Further investigations using objective besides subjective measures for xerostomia are needed to observe whether any associations between medications or other factors such as medical condition and xerostomia exist; this is beyond the scope of the present study.
In this study, it was decided to use CPI to give an indication of the periodontal status of subjects. There are, however, some shortcomings to CPI such as it does not distinguish between gingival inflammation and periodontal destruction because of its hierarchical scoring principle. Furthermore, the use of index teeth instead of a full mouth recording has been shown to increase underestimation of the prevalence of periodontal pockets [32
]. However, the use of alternative indices would allow direct comparison with only a few other studies, which is the reason that we decided to use the CPI in this study. The results of CPI were very different to those of a study carried out in Sudan in by Ali in 1991 [33
] who included 126 adolescents and 138 adults from areas inside as well as around cities of Khartoum and El Obeid. In that study of adults aged 35-44 years, only 3% had calculus, 71.3% had probing pocket depth between 4 and 5 mm, and 25.7% ≥ 6 mm. These results revealed a much higher prevalence and severity of periodontal disease than our study, which could be due to a combination of factors such as differences in sample design. The more severe periodontal disease could also have resulted from a decreased awareness towards oral health at the time when Ali's study was carried out almost 20 years ago [33
]. Geographic region could have also played an important role because approximately half the population studied was from Obeid, which is outside Khartoum State. One could speculate that different methods of dental self-care might have been more common then, such as using the miswak (a teeth-cleaning twig of the Salvadora persica
tree) instead of toothbrush and fluoridated toothpaste. Our results show that there is a need for preventive programs to improve oral hygiene levels, bearing in mind that the ultimate goal is to prevent more severe periodontal disease prevalence, which is complex to treat.
The mean DMFT 8.7 (SD, 5.9) of our study according to WHO criteria can be considered as low in the 35-44-year age group when compared with same age groups with dental caries levels worldwide. In world map of dental caries prevalence published by the WHO [1
], a mean DMFT < 5.0 is considered very low, 5.0-8.9 low, 9.0-13.9 moderate, and > 13.9 high. Our results are slightly higher than other African countries such as Niger (mean DMFT = 5.7) and Uganda (mean DMFT = 3.4) [13
] but lower than Madagascar (mean DMFT = 13.1) [12
The mean number of missing teeth in the age group 35-44 years was 4.2 (SD, 4.1), which is in agreement with the study carried out in Madagascar (4.8) but much higher than Uganda (0.6) and Niger (0.4). The finding that the filled component of DMFT was only 0.2% in total population gives an indication of how little dental treatment is actually done, which has important implications for service planning and advocacy.
Virtually all community prevention programmes in Sudan target children and adolescents and as a result, decay among adults is more likely to remain untreated. The mean number of untreated decayed teeth among Sudanese adults in our study was about 9 times that among 12-year-old schoolchildren (DT, 0.4) [34
], underscoring the importance of initiating caries-prevention programs for adults.
Among adults aged ≥ 65 years, one third of exposed root surfaces had root caries lesions in the United Kingdom [6
], which is considerably higher than our results where those aged ≥ 65 years had caries on only 12% of exposed roots. One reason for this may be the increased life expectancy in the UK, which exposes teeth to the cumulative effect of dental disease for longer. The lower level of root caries may also be partly explained by the relatively low prevalence of wearing partial dentures (3%), which has been shown adversely to affect the remaining dentition through greater incidence of caries [35
Even though the percent exposed roots in our study was lower in younger adults, their exposed roots were more affected by decay. This may be because of differences such as diet with increased sugar consumption. Toothwear was recorded when it had progressed through tooth enamel into the dentine because considerable inter-examiner variability has been reported when trying to record wear confined to tooth enamel. Results similar to those of our study were obtained in the UK survey [6
], where two thirds of all adults had some wear into dentine on anterior teeth. Moderate wear (extensive involvement of dentine) occurred in 11% of adults and 1% had severe wear. Tooth wear has been considered a problem for individual patients rather than being community based. Albeit the trend that tooth wear is increasingly recognized as problematic, it is difficult to foresee who will be affected and true prevention is therefore difficult to accomplish. Presently, treatment is aimed at limiting further tooth wear in individuals already affected by this condition.
Considering the multivariate analysis, dental caries seems less prevalent in older than younger age groups, even after controlling for the effects of confounding variables. This might be because of the small numbers of people present in that category or that teeth presenting decay had already been extracted. The observation that southern tribes are more likely to present with decay than other tribes suggests a cultural dimension to the pattern of decay. The revelation that frequent attenders have higher odds of having decay could emanate from the implication that they experience more pain due to decay and are therefore more likely to seek treatment. Frequent attendance in this survey is not the same as regular checkups, because 91% of patients only went to the dentist when they experienced pain. Those who did go for regular dental checkups in this study were less likely to present with decay. The importance of regular checkups has also been highlighted by others [3
] who showed that patients who attended only when they had some trouble with their teeth had one less tooth on average, were twice as likely to have active decay, and six times more likely to have unrestorable caries than those who attended for regular checkups. The finding that people who were educated had lower caries rates is similar to observations made by other authors [25
]. Recording the number of ≥ 18 SUNT, which is an arbitrary cut off point, was previously used in adult national oral health surveys in the United Kingdom [7
] and Ireland [20
]. Western tribes were associated with having lower rates of ≥ 18 SUNT possibly because of some cultural differences or increased consumption of sugar. To clarify the cause further investigations would be necessary. Probands who reported occasional dry mouth also had lower rates of ≥ 18 SUNT. Having a dry mouth has been associated with more decay and tooth loss [36
], which might explain the decrease in SUNT observed in the present study.
Increasing age and being male were characteristics associated with periodontal pocketing of ≥ 4 mm. This is consistent with findings from other studies such as the US National Health and Nutrition Examination Survey, 1999-2004 in adults aged 20-64 years. Tobacco users were also more likely to present with periodontal pockets, which is in accordance with other studies by [20
] wherein smokers had a higher prevalence periodontitis, suggesting poorer periodontal health in these individuals.