This study was conducted in 2017 alongside the fieldwork for the national CDHS.²² The research drew on two internationally accepted epidemiological methodologies including the World Health Organization (WHO) pathfinder survey method,²⁵ and the UK Adult Dental Health Survey (ADHS).²⁶

This study was conducted across all four regions (areas) of SL as follows: Northern (Makeni City and Libeisaygahun), Southern (Selenga, Kori and Bo Town), Eastern (Kenema City and Hangha village) and Western (Waterloo Lumpa and Regent).

The aim was to have at least 50 adults from each of the four regions of SL in line with the WHO sampling method,²⁵ described in an earlier paper.²² In summary, adults who were present at the school site on the day of the CDHS-SL were provided with a ‘pictorial information and consent’ (PIC) sheet regarding the study.²⁷ The PIC sheet informed participants about a basic oral examination with a trained dental professional, following a short self-completion questionnaire. Where necessary, this information was reiterated by an SL team member in their preferred local language (mainly in Krio, Mende or Temne).

Participants were provided with the self-completion questionnaire and assisted by a local SL team member, if required. The internal consistency of the self-completion questionnaire was evaluated using Cronbach’s alpha, yielding a coefficient of 0.827, indicating good reliability.

The oral examination was carried out by a trained and calibrated dentist supported by the local SL team members who acted as a recorder to capture data in a paper format.²² All examinations were conducted under natural daylight using a standardised portable chair, appropriate personal protection equipment (PPE) and disposable clinical instruments. Examinations were performed by a single calibrated examiner, with intra-rater reliability (kappa = 0.61) confirming substantial agreement. As a token of appreciation, each adult was provided with toothpaste following their participation in the study.

Data were analysed using STATA and Statistical Package for Social Sciences (SPSS).^29,30 Descriptive statistics were carried out to report the demographic characteristics of the sample. Frequencies and proportions were calculated for all questionnaire items. Bivariate analyses using chi-square tests were performed to explore associations between questionnaire items and demographic variables including sex, age groups (18–24 years, 25–34 years, 35–44 years and 45+ years), area (urban; rural) and region (east, north, south and west). For participants who underwent clinical examination, univariate and bivariate analyses were conducted using parametric tests (t-test, analysis of variance [ANOVA]) and non-parametric tests (Mann–Whitney U, Kruskal–Wallis) to assess associations between demographic factors and clinical indicators, including dental caries experience (DMFT), PUFA, oral mucosal lesions, tooth wear, dental fluorosis and denture status.

Ethical approval for the study was received from King’s Research Ethics Committee (HR-15/16-1951) and the Sierra Leone Ethics and Scientific Review Committee (RESCMR-16/17-1951). All procedures performed involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Participants were informed that taking part in the study was entirely voluntary, and there was no incentive on offer. If they agreed to participate, a signed consent (through ‘pictorial information and consent’ [PIC] sheet) 27 was obtained. Participants were informed that clinical examination would only be conducted at that site after the examination of school children had been completed. All data were anonymised using unique codes that ensured privacy and confidentiality of all participants. Data were securely stored, and access was restricted to the research team.

One hundred and sixty-one participants aged 19 years to 70 years (mean age = 35.6 years), predominately female (n = 95; 60%), completed the questionnaire survey, and 45 underwent a clinical epidemiological examination. Among participants who had a clinical examination, 64% (n = 29) were female. The proportion of participants from rural areas was 44% (n = 71) and most participants who provided information on ethnicity were from the ‘Mende’ tribe (26%; n = 41) (Table 1).

Three-quarters of participants had ‘never been to a dentist’ (75%; n = 121), and one in five (21%; n = 33) only had visited a dentist because of ‘problems with their teeth’. Routine check-up attendance was less commonly practised in this group and reported by only 1% (n = 2) of participants (Table 2). Access to dental care varied by age, with a borderline association (likelihood ratio [LR] = 17.70, p = 0.04); participants aged 35–44 years were least likely to report ‘never been to a dentist’ (Table 3).

Most participants reported using a toothbrush (97%; n = 156) and toothpaste (93%; n = 150), while a small proportion (1%; n = 3) used alternative tools such as toothpicks or chewing sticks (Table 2). Almost all participants (99%; n = 159) reported brushing their teeth daily, with over two-thirds (69%; n = 111) brushing at least twice a day. Brushing frequency varied significantly by region (LR = 19.26, p = 0.02), with participants from the Western region most likely to report brushing twice daily (Table 3).

More than nine out of 10 (92%; n = 145) participants reported consuming fruit at least once a day. Twenty per cent reported consuming fizzy drinks (n = 22) and cakes and/or biscuits (n = 23) along with 17% reported consuming sweets (n = 11) and fruits juice (n = 12) at least once a day, respectively (Table 2). Male participants were more likely to report frequent consumption of sweets compared to females (LR = 6.32, p = 0.04), whereas higher fruit intake was more commonly reported by females (LR = 7.82, p = 0.02). Fruit consumption also varied significantly by region (LR = 37.29, p = 0.01), with participants from the Western region reporting the highest frequency of intake (four or more times per day). Similarly, regional variation was observed in the consumption of cakes and biscuits (LR = 14.45, p = 0.03), with the highest frequency reported in the Southern region (Table 3).

Most participants reported no history of smoking (86%; n = 138) or alcohol consumption (83%; n = 133) (Table 2). However, male participants were significantly more likely than females to report both smoking (LR = 29.00, p = 0.01) and alcohol use (LR = 23.35, p = 0.01). Regional variation was evident in alcohol consumption (LR = 19.35, p = 0.01), with regular use of alcohol most commonly reported in the Southern region (Table 3).

Significant associations were observed between demographic factors and participants’ general health, dental health and OHRQoL (Table 3). Overall general health varied significantly by region (LR = 26.38, p = 0.01), with participants from the Southern region most likely to report ‘good’ or ‘very good’ health. In relation to dental health, participants residing in urban areas were more likely to report favourable ratings compared to those in rural areas (LR = 7.69, p = 0.02). Experience of recent dental problems also differed significantly by region (LR = 26.38, p = 0.01), with the highest proportions of reported ‘toothache’ found among participants from the Western and Eastern regions.

Several OHRQoL indicators were significantly associated with area (urban vs. rural). Participants from rural areas were significantly more likely to report negative impacts in items such as difficulty in speaking (LR = 8.75, p = 0.01), eating (LR = 7.05, p = 0.03), cleaning teeth (LR = 9.61, p = 0.01), relaxing or sleeping (LR = 6.64, p = 0.04), feeling upset or irritated (LR = 7.29, p = 0.03), smiling (LR = 7.73, p = 0.02), enjoying being with others (LR = 6.44, p = 0.04) and the overall perceived impact of dental conditions on daily life (LR = 7.59, p = 0.02).

Age-related differences were also observed across OHRQoL items. Difficulty in speaking was most frequently reported by participants aged 35–44 years (LR = 14.51, p = 0.02), while those aged 25–34 years were most likely to report difficulty in relaxing or sleeping (LR = 13.57, p = 0.04) and smiling (LR = 15.01, p = 0.02).

Just over one-quarter of the participants who completed the questionnaire (28%; n = 45) underwent a clinical examination with all having dental caries experience (D_2–6MT > 0) (Table 4). Almost four out of 10 of these participants had missing teeth, with an average of four missing teeth per adult.

Eighty-four per cent of examined participants had cavitated dental caries and visible dentine involvement (D_5–6MT) with an average of 5.2 affected teeth per adult. Although the mean number teeth having dental caries experience at different thresholds was slightly higher in males as compared to females, it was not found to be statistically significant (Table 4).

Dental caries experience (DMFT) was slightly higher in the 25–34 years and 35–44 year age groups compared to younger (18–24 years) and older (45+ years) participants, with a mild decreasing trend in the number of decayed teeth with age; however, these differences were not statistically significant.

The participants in urban areas had similar proportions of dental caries experience; however, the mean number of DMFT was slightly higher at D_2–6MT and D_3–6MT in those from urban areas while it was slightly higher in rural areas at D_4–6MT and above. Similarly, the mean number of DMFT was higher in the Western region at D_4–6MT and above threshold, along with the average missing number of teeth when compared to Eastern and Southern region (Table 4). These differences at area (urban or rural) and regional levels were not statistically significant (p > 0.05).

Half of the participants (51%, n = 23) who underwent clinical examination reported pain in their tooth/teeth. Forty-seven per cent (n = 21) had PUFA lesions, and all were of pulpal origin, with a mean of 1.2 teeth, which increased to 2.5 teeth in participants having PUFA score > 0.

Eighty-four per cent (n = 38) participants were found to have visible calculus in the oral cavity. Only two participants were seen to have suffered trauma to teeth involving pulp and reported to have a mucosal lesion (involving lips and buccal mucosa), respectively. Similarly, only two participants had upper dentures, and there was no fluorosis present in those who underwent oral examination.

Considering the dearth of oral health services in SL, it was not surprising that 75% participants reported that they had ‘never been to a dentist’, which was similar to findings reported through the CDHS-SL (over 66% of children).²² Similarly, most participants (> 90%) reported using a toothbrush and toothpaste, as also indicated by schoolchildren in SL (> 95%).²² Brushing twice daily was significantly more common in the Western region, likely due to better access to oral hygiene products and greater oral health awareness, supported by the presence of the country’s entire dental workforce.⁴ This contrasts with findings from other African contexts, such as Ethiopia, where between 12.2%³¹ and 19.3%³² of participants reported brushing twice daily, and Uganda,³³ where the proportion was 56.5%.

Although the clinical findings of the participants who underwent a clinical examination indicated a high proportion with visible calculus (84%), there are no recent published data available from SL. However, the study by Normark from 1991¹³ reported 94% (n = 100) of adults between the ages of 35–44 years having calculus and pockets (CPITN-index). In addition, the CDHS-SL also reported 85% of schoolchildren (aged 12 years and 15 years) having supragingival (visible) calculus.²² A study from a comparable setting in Tanzania showed a similar trend, with most adults (94.6%, n = 159) involved in the oral health survey reporting that they brushed their teeth using a toothbrush and toothpaste and consumed a diet high in sugar (85.1%, n = 143; three times a day).

The role of diet and sugar on oral health is well documented.^34,35,36 In this study, dietary and lifestyle behaviours varied significantly by sex and region. Females reported higher fruit intake, while males more frequently consumed sweets, smoked and used alcohol. Regional differences were also evident, with the Western region (which includes the capital Freetown) showing the highest fruit consumption and the Southern region reporting more frequent intake of cakes, biscuits and alcohol. Over two-thirds of participants (n = 82) reported consuming a sugary item at least once daily, in contrast to findings from Ethiopia, where only 10.7% of adults (n = 67) reported consuming sweets even once per week.³² The concern of easy availability and consumption of sugary diet in SL especially after civil war was reported by health professionals.⁴ The data from CDHS-SL showed 40% of schoolchildren consuming a sugary item at least once a day.²² Thus, the evidence suggests that while a high proportion of populations from sub-Saharan region report regular oral hygiene practices, other risk factors such as sugar, tobacco and alcohol are present and the burden of gingival and periodontal disease appears to be on the rise.^37,38

Significant sex and regional differences were also observed in risk behaviours, including smoking and alcohol use. Male participants were markedly more likely than females to report both behaviours, consistent with findings from other African contexts.³⁹ Alcohol use was significantly higher in the Southern region; however, the reasons for this pattern remain unclear. No notable environmental or infrastructural differences were observed between regions during fieldwork, suggesting other factors outside the scope of this study influencing it.

Considering OHRQoL, participants from urban areas reported more favourable dental health compared to their rural counterparts. Rural participants experienced a higher perceived burden on OHRQoL, with significant impacts related to difficulty in speaking, eating, cleaning teeth, sleeping, emotional well-being and social interactions. This is in line with findings from similar studies in other African settings, where rural participants experienced significantly higher proportion, intensity and extent of psychosocial impacts related to oral health conditions.⁴⁰ Age-related differences were also evident, with difficulty in speaking most commonly reported among participants aged 35–44 years, whereas difficulty in smiling and relaxing was reported among those aged 25–34 years. These patterns align with findings from other African contexts, where younger people report greater concern about the social and aesthetic impacts of oral health problems.^41,42

All participants (n = 45) who underwent a clinical examination had extensive dental caries experience in more than five teeth (mean D_5–6MFT = 5.2), just over half reported pain (51%, n = 23) and almost half had one or more PUFA lesions (47%, n = 21: pulpal origin). The proportion of missing teeth (M) was slightly higher in males (56%, n = 16) than females (34%, n = 29). In addition, 40% (n = 62) of all participants who responded through the survey reported to have experienced tooth decay in the past 3 months. These findings demonstrate the high burden of untreated dental caries experience, which was also highlighted in the qualitative study where Sierra Leonean dental professionals expressed their concern that people tend to neglect their oral health and often choose urgent treatments like extractions.⁴ Recently, a similarly high burden of dental caries experience was reported from amongst adults in Ethiopia.³² In addition, the CDHS-SL reported high levels (above 82%) of clinical dental caries experience (D_2–6MFT) in school-going children across all four regions of SL.²²

This study used the ICDAS epidemiological tool, currently referred to as the ‘International Caries Classification and Management System (ICCMS)’, which has the advantage of enabling comparisons with earlier surveys conducted using WHO methodology.^43,44,45 Based on ICDAS categories, the mean DMFT score could be described whether there is a ‘visual change in enamel’ (mean = 14.2, D_2–6MFT), or ‘distinct decay into dentine’ (mean = 5.2, D_5–6MFT), to ‘extensive decay into dentine’ (mean = 4, D₆MFT) (as depicted in Table 4). The challenge, however, is that the oral health (including DMFT) data from countries such as SL is very limited. The last caries experience data on adults aged 35–44 years from SL published through WHO reported an average score of 5.3.⁴⁶ Nevertheless, there is inadequate data from the WHO report to clarify the caries threshold. Various studies have focused on this challenge of establishing the caries threshold for comparison with ICDAS categories,^47,48,49 but there is no agreement, and this issue is open to debate unless thresholds are clearly measured and reported.

Given the large young population in SL and the practicality of conducting nationwide research, our main epidemiological survey concentrated on child oral health.²² Therefore, a convenience sample to explore perceived and normative needs in adults was preferred given its simplicity and cost-effectiveness, recognising that it may not be representative of adult population in SL. As the survey was conducted along with the CDHS-SL,²² most participants were either parents of schoolchildren participating in the CDHS-SL or were present at the school site or anticipated dental treatment as a part of participating in the survey. Therefore, it was important to secure appropriate informed consent, which was accomplished by using a simple ‘pictorial information and consent (PIC)’ sheet developed with an illustrator.²⁷ Moreover, the local SL team, who spoke all the main local languages, assisted in conveying information about the study to participants. In addition, given the dearth of recent adult oral health data,¹³ the research team deemed it a vital opportunity to look at adult oral health at least through the lens of a convenience sample.

Other possible limitation could be the low literacy levels, which could hinder participants to respond to a self-completion questionnaire in English. However, the local SL team proficient in local SL languages assisted any participants who requested support in completing the questionnaire. Nevertheless, there is a possibility of a bias as the participating adults could have been influenced either by other participating adults completing the survey or local SL team member assisting them. Furthermore, over 20% of cells in the chi-square tests had low expected counts (< 5), and although LR tests were used as an alternative, the results should be interpreted with caution. Additionally, as all participants who underwent clinical examination had some level of dental caries experience, it was not possible to assess associations based on caries presence versus absence. To address these limitations, future research should recruit larger and more demographically balanced samples to support robust comparisons informed by this study.

The unique strength of this study was showcasing the potential of ICDAS tool in a low-resource environment, allowing for the estimation and publication of oral health workforce requirements.¹¹ This is important for SL, which has a severe shortage of oral health workforce with the dental professional to population ratio at 1:375 000,¹¹ which is well short of the African regional average of 1:18 301.⁵⁰ The national schoolchildren oral health survey (CDHS-SL) used operational research to estimate the population’s oral health needs and the pragmatic workforce required to deliver appropriate care.^11,22 Therefore, it is vital for the future research to explore oral health needs of adults on a national level similar to CDHS-SL, which will not only validate the workforce needs projection for the general population but also inform realistic capacity-building as a part of the oral health strategy for SL.²¹