Association between sickle cell anaemia and dental caries among children in Nigeria

Abstract

Background

Sickle cell disease is a major public health issue that is associated with caries and oral health problems. This study aimed to assess the association between dental caries experience and sickle cell anaemia.

Methods

This was a case-control study that recruited children aged 4 to 16 years old with sickle cell anaemia (SCA) and those with normal haemoglobin genotype attending the Paediatric outpatient clinic of the Obafemi Awolowo University Teaching Hospitals’ Complex. Data collected included confounders (age, sex, socio-economic status, frequency of toothbrushing, use of fluoridated toothpaste, frequency of consumption of refined carbohydrate in-between-meals daily, history of dental service utilization, and oral hygiene status), dependent (dental caries experience), and independent (SCD status) variables. Multiple logistic regression was conducted to determine the association between sickle cell disease and dental caries experience after adjusting for the confounding factors.

Results

There were 264 participants with a mean age of 9.41 ± 3.35 years. Thirty-nine children (14.8%) had dental caries: twenty-eight (13.5%) in the primary dentition and eleven (5.0%) in the permanent dentition. Although the differences were not statistically significant, the caries experience of children with sickle-cell anaemia was twice those without with normal haemoglobin genotype, both in the primary (17.9% vs. 8.9%, p = 0.058) and permanent (6.6% vs. 3.5%, p = 0.361) dentition. The presence of SCA and dental service utilization were significantly associated with dental caries (p = 0.04 and 0.001, respectively).

Conclusion

Sickle cell anaemia and dental service utilization were significantly associated with caries in the children. Children with SCA should be screened early for caries and preventive measures instituted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-025-07315-1.

Introduction

Sickle cell disease (SCD), an autosomal recessive genetic condition of the red blood cells, is a major public health problem. Children with SCD have reduced quality of life due to the great morbidity and mortality associated with the condition [1–4]. This haematological disorder is characterised by the presence of haemoglobin S (HbS), and another abnormal haemoglobin such as C, D-Punjab, E, O-Arab, thalassemia, or another S [5]. The latter condition, a homozygous state (HbSS), is known as sickle cell anaemia (SCA) [6–8], which occurs when an individual inherits sickle-cell genes from both parents [9]. While the medical conditions associated with SCD are well established, the oral health conditions relating to SCD remain unclear [4, 10, 11].

Nearly 90% of the world’s SCD population resides in Nigeria, the Democratic Republic of Congo, and India [6, 10, 12]. In these countries, about 2% of the population is affected, with a carrier rate of about 10–30% [6, 13]. The disease is associated with painful bone, abdominal, and joint crises, acute chest syndrome, anaemia, infection, reticulocytopenia, cerebrovascular accidents, and multi-organ failure [3, 14]. In addition, children with SCD have reduced psychological development and intellectual impairment, with a higher rate of school absenteeism and poor educational performance [11, 14].

The prevalence of dental caries in children with SCD is important because of the high risk for untreated dental caries and its sequelae of pulpitis, predisposing to vaso-occlusive or painful crises. There are few studies on the association between SCD and dental caries, and the results are inconsistent [15–18]. It is posited that individuals with SCD have low caries experience because of the effects of long-term antibiotic therapy on Streptococcus mutans [15, 19]. On the contrary, SCD may be associated with increased caries rates due to the inability to maintain good oral hygiene, coupled with a higher level of associated enamel defects [20–22]. A higher level of dental caries was reported in African-American children with SCD compared to those without the condition [21]. In contrast, lower dental caries prevalence had been documented among Nigerians [23]. and American [24]Children and young adults with SCD, and among Brazilian children with SCD [4]. In addition, a hospital-based cross-sectional study among children in Nigeria showed no significant difference in the rate of dental caries in children with and without SCD [22].

The results of the few studies on the prevalence of dental caries in children with sickle cell disease are conflicting [8, 23, 25–27]. Infections predispose individuals with SCD to crisis, which is often associated with pain, hospital admission, school absenteeism, and poor quality of life. Oral health conditions such as caries, gingivitis, and periodontitis could be a major source of infection in this group of individuals. The study aimed to determine the association between sickle cell anaemia and dental caries among children in Nigeria.

Methods

Methods

Ethical considerations

Ethical approval for this study was obtained from Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife Ethics and Research Committee (NHREC/27/02/2009a). Written informed consent was obtained from the parents/guardians of all prospective participants. Assent was also obtained from participants aged 12 to 16 years.

Study design and study site

The was a case-control study conducted in Ile-Ife and Ilesha, Osun State, Nigeria. Study participants were recruited from the Obafemi Awolowo University Teaching Hospitals’ Complex (OAUTHC), Ile-Ife, Osun State, Southwest, Nigeria. The OAUTHC is a tertiary health institution comprising two hospitals: Ife Hospital Unit (IHU), Ile-Ife, and Wesley Guild Hospital (WGH), located in Ilesha, which is a 20-minute drive to Ile-Ife. Participants were recruited from the Paediatric sickle cell clinic and the outpatient clinic of both units of the hospital (IHU and WGH).

Study population

The study population consisted of two groups (A and B) of patients aged 4 to 16 years. Group A (case-HbSS) included children with SCA. Group B (control-HbAA) included healthy individuals. Children in both groups were recruited from the Paediatrics outpatient clinic of OAUTHC (IHU and WGH).

Children who had other forms of haemoglobinopathies, such as β-thalassemias (HbE/Beta thalassemia), HbSC, and HbAS, were excluded from the study. In addition, children with newly diagnosed SCD, underlying medical conditions such as diabetes mellitus and hypertension, and patients with intellectual impairment were also excluded. In addition, those with painful crises at the time of examination, those who had dental prophylaxis in the last month, and those who had an emergency dental appointment in the last three months of the study were also excluded.

Sample size

The sample size was determined using the formula for calculating sample size for the comparison of means of two independent groups (case-HbSS and control-HbAA) [28]. An expected standard deviation of the DMFT between the two groups was 2.36 [29]. The determined sample size for each arm of the study was 129, which was rounded off to 130 for each arm of the study.

Sampling procedure

A convenience sampling technique was adopted in the selection of the participants who met the eligibility criteria for the study. The case group comprised every consecutive patient aged 4 to 16 years with HbSS who presented at the Paediatric Sickle Cell clinic of both units of the hospital (IHU and WGH). The control (HbAA) included healthy children of similar age and gender who attended the Paediatric Outpatient clinic of the same hospital (IHU and WGH). The recruitment of the participants was between March 2021 and December 2021. This was part of a major study on the oral health status of Nigerian children with SCA that included developmental enamel defects and quality of life.

Study procedure

A structured, interviewer-administered questionnaire was used to collect information on participants’ socio-demographic status, oral health behaviour, and dietary habits. The socio-demographic information included age, sex, and socio-economic status (parental education and occupation [30, 31]. Information obtained on oral health behaviours included tooth brushing frequency, use of fluoridated toothpaste, and dental service utilization. Dietary habits related to refined sugar intake between meals were captured using a three-day dietary chart (two weekdays and one weekend/public holiday), completed at home with parental assistance and returned at the next clinic visit or via follow-up calls. A telephone call was put through to the parent/guardian to remind them about filling out the dietary chart. The dietary chart was retrieved from the parent/guardian at the child’s next clinic visit. When this was not possible, the chart was reproduced by the research team by placing a phone call through to the parent/guardian to collect the dietary chart. One of the authors (JBA) administered the questionnaire. The questionnaire was validated in a study by Folayan et al. among Nigerian children in Ile-Ife in 2015 and is reliable [25].

Each participant also underwent a structured intra-oral examination in a well-lit setting using a sterile dental mirror and probe. Clinical findings were oral hygiene status and dental caries experience. Oral hygiene was assessed using the Simplified Oral Hygiene Index (OHI-S) [32, 33], and dental caries were determined using the WHO standard criteria [27].

Data collected

Confounding variables

Socio-demographic profile

The socio-economic status of each child was determined using a combination of the mother’s/father’s levels of education and the father’s/mother’s occupation [34]. Each child’s socio-economic status was obtained by adding the scores of the father’s occupation and the mother’s level of education. For children with a single parent, the socio-economic status was obtained using the status of the living parent, that is, the addition of the scores of the parent’s occupation and level of education [25]. For ease of analysis, the socio-economic statuses in this study were regrouped into three: high (upper and upper middle classes), middle (middle class), and low (lower middle and lower classes) status. This social classification system has been used in Nigeria and was found to be valid and reliable [30, 35].

Caries prevention practices

Information on the participants’ oral health practices/behavior was collected. This includes frequency of tooth brushing (once daily, twice daily, more than twice daily), use of fluoridated toothpaste (yes/no), frequency of consumption of refined carbohydrate in-between-meals (always, sometimes, rarely), and history of dental service utilization (has he/she been to the dental clinic before yes/). Information on the use of fluoridated toothpaste was collected by asking about the brand of toothpaste used. The brand was used as proxy data to determine if the toothpaste routinely used for tooth cleaning contained fluoridated toothpaste. Dental service utilisation was assessed by asking whether the child had previously visited a dental clinic, received any dental treatment, and the type of treatment received [36].

Information on the frequency of consumption of refined carbohydrates in-between-meals was determined with the aid of a dietary chart, which was given to each participant to take home after the intra-oral examination. The parent/guardian and child filled and supplied information on all foods, drinks, and drugs consumed for three consecutive days in a week (two days were weekdays and the third day, a weekend day/public holiday). A telephone call was put through to the parent/guardian to remind them about filling out the dietary chart. The dietary chart was retrieved from the parent/guardian at the child’s next clinic visit.

Ora hygiene status

The oral hygiene status of each participant was assessed using the oral hygiene index simplified (OHIS) [33]. OHI-S has two components, the debris index and the calculus index. The debris and calculus indices were used to assess the level of debris and calculus on the surfaces of selected fully erupted permanent (11, 16, 26, 31, 36, and 46) or primary (54, 61, 64, 75, 82, and 85) dentition [32]. If any of the index teeth were absent or missing, the remaining index teeth were used to calculate the OHI-S score. The OHI-S score was the addition of both the debris index and calculus index scores. The score ranges from 0 to 6: good oral hygiene is 0–1.2, fair, 1.3–3.0, and poor, 3.1 − 6.0.

Dependent variable

Dental caries assessment was based on visual examination only. Dental caries was assessed according to the WHO standard criteria [27]. The DMFT/dmft score of each child was recorded, where D/d- decayed tooth due to dental caries, M/m- missing tooth due to caries, and F/f- filled tooth due to caries. The DMFT/dmft score was the addition of the scores of the D/d, M/m, and F/f for each participant. The DMFT and dmft scores were for the permanent and primary teeth, respectively.

Independent variable

The SCA status was the dependent variable. Participants were either living with SCA or had a normal haemoglobin genotype. Children with SCA were diagnosed using alkaline cellulose acetate haemoglobin electrophoresis at the Haematology Laboratory of OAUTHC. Information on the diagnosis of SCA was obtained from the patient’s hospital case note of OAUTHC. In addition, the haemoglobin status of the children in group B was determined using the Hemo typeSC™ kit rapid diagnostic tool [26].

Calibration of the investigator

An intra-examiner and inter-examiner reliability tests were conducted to calibrate one of the investigators (JBA). The investigator and calibrator (EOO) examined 10 children who visited the Paediatric dental clinic for the management of dental caries. A week later, the investigator and calibrator re-examined the same group of children for dental caries. The scores were compared, and the inter- and intra-examiner calibrations were 0.82 and 0.87, respectively.

Data analysis

Data was analyzed using IBM SPSS Statistics version 23. Descriptive analysis was conducted for all the variables. Categorical variables were presented using frequency and percentage distribution. The mean DMFT/dmft score was determined for the different age cohorts, sex, socio-economic status, frequency of tooth cleaning, use of fluoridated toothpaste, dental service utilization, oral hygiene status, and frequency of refined sugar consumption between meals. Binomial logistic regression was used to determine the association between the independent variables (age, sex, socio-economic status, genotype, frequency of toothbrushing, fluoride in toothpaste, frequency of refined sugar consumption in-between meals, dental service utilization, and oral hygiene status) and the dependent variable (dental caries) after adjusting for the confounders. Statistical significance was inferred at p < 0.05.

Results

Two hundred and sixty-four children participated in the study with a mean age of 9.41 ± 3.35 years. Two hundred and fifty (94.7%) participants brushed once a day, 242 (91.7%) used fluoridated toothpaste, 107 (40.5%) consumed refined carbohydrates in-between-meals daily, 240 (92.4%) had not utilized the dental services, and 162 (61.4%) had fair oral hygiene. There were 39 (14.8%) children with dental caries: 28 (13.5%) in the primary dentition and 11(5.0%) in the permanent dentition.

The Supplemental Table S1 shows that although children without SCA who had caries in the primary dentition doubled the number of children with SCA who had dental caries, the difference was not statistically significant (8.9% vs. 17.9%; p = 0.054). The Supplemental Table S2 shows that although more children without SCA had caries in the permanent dentition than children with SCA, the difference was not statistically significant (3.5% vs. 6.6%; p = 0.361).

Table 1 , shows that after adjusting for the confounding variables, children with haemoglobin genotype SS (SCD) had significantly lower odds of having dental caries compared to those with haemoglobin genotype AA (OR = 0.46, p = 0.04, 95% CI: 0.21–0.97).

Table 1.

Binomial logistic regression to determine the association between sickle cell disease and dental caries (N = 264)

Variables	n (%)	Adjusted Odds Ratio	p-value	95% Confidence Interval
				Lower bound	Upper bound
Age group (years)
4–5	24 (54.5)
6–12	69 (42.3)	1.64	0.37	0.56	4.80
13–16	27 (47.4)	0.25	0.12	0.04	1.44
Sex
Male	120 (45.5)
Female	144 (54.5)	1.17	0.69	0.54	2.53
Socio-economic status
High	64 (45.4)
Middle	43 (50.6)	0.88	0.76	0.38	2.01
Low	13 (34.2)	0.36	0.15	0.09	1.44
Genotype group
AA	132 (50.0)
SS	132 (50.0)	0.46	0.04*	0.21	0.97
Frequency of tooth brushing
Once a day	250 (94.7)
≥Twice a day	14 (5.3)	4.56	0.07	0.91	22.8
Fluoride in toothpaste
Yes	242 (91.7)
No	22 (8.3)	1.47	0.55	0.42	5.19
Frequency of consumption of refined carbohydrates
Always	107 (40.5)
Sometimes	152 (57.6)	0.40	0.06	0.15	0.15
Rarely	5 (1.9)	0.88	0.78	0.35	2.19
Dental service utilization
No	244 (92.4)
Yes	20 (7.6)	6.70	0.001*	2.17	20.70
Oral hygiene status
Good	96 (36.4)
Fair	162 (61.4)	0.74	0.45	0.33	1.62
Poor	6 (2.3)	2.94	0.27	0.44	19.85
Cons		0.25	0.02	0.08	0.83

Discussion

This current study explored whether children living with SCA are more likely to develop dental caries compared to children without SCA. Overall, 1 in 7 children, 4 to 16 years old, had dental caries: 1 in 7 children with the primary dentition and 1 in 20 children with the permanent dentition. Although more children with SCA had dental caries than those without SCA in both the primary and permanent dentition, children with SCD had significantly lower odds of having dental caries compared to those with haemoglobin genotype AA.

The reason for the non-significant association between sickle cell anaemia and dental caries though not clear may be attributed to the following reasons. Individuals with sickle cell anaemia are encouraged to drink lots of water to prevent dehydration that can predispose them to painful crisis. Frequent consumption of water helps cleanse the oral cavity of food debris and bacteria, dilutes acid produced by cariogenic bacteria and, its fluoride content helps promote remineralization of demineralized enamel thus preventing caries. In addition, people with sickle cell anaemia are advised against the intake of high sugar drinks, a major factor in caries formation because it can worsen hydration status. Furthermore, the frequent use of antibiotics, especially penicillin in this group of individuals for the control of infection is associated with a reduction in Streptococcus mutans count, a major bacteria implicated the aetiology of dental caries [15]. Moreover, the caries prevalence among Nigerian children is low [25].

The study had several strengths. Data were carefully collected, and potential confounding factors were accounted for in the analysis. The study also ensured consistency in measurements through good examiner calibration and used laboratory-confirmed methods to determine SCA status. Furthermore, this is the first study among children in Nigeria with SCA that assessed the proportion of children with SCA who had dental caries, and adjusted for confounders in determining the rate of dental caries in the population.

However, the study also had some limitations. As a cross-sectional study, it cannot confirm whether SCA causes more cavities. The study’s hospital-based setting may limit how well the findings apply to the broader population, particularly those not attending clinics. A paradoxical finding emerged from the regression analysis: while descriptive data showed higher caries rates in children with SCA, the model suggested lower odds, indicating possible overadjustment or model limitations. In addition, the small number of children with dental caries limited the statistical power to detect differences in subgroups, and the convenience sampling based on clinic attendance may have introduced selection bias. The sampling procedure, however, ensured that all eligible children attending the clinics during the study period were given an equal opportunity to participate, thereby minimizing selection bias within the clinic-attending population. This method was deemed appropriate due to the logistical difficulty of identifying children with sickle cell disease in the general population outside of clinical settings. Furthermore, generating data from only two clinics in a specific geolocation limits the generalisability of the study findings. Also, children with newly diagnosed SCD were excluded as they are often clinically unstable at presentation, frequently experiencing painful crises or undergoing treatments like blood transfusions. While this exclusion was necessary for obtaining a stable study cohort, we acknowledge it may introduce a selection bias, as patients with established disease might have different oral hygiene practices due to prior medical counselling. Finally, cavity assessments were conducted visually, without the use of X-rays, which may have missed hidden lesions. Despite the limitations, the study had some important findings.

First, this study adds to the ongoing discourse on the relationship between sickle cell anaemia (SCA) and dental caries risk. Consistent with the present findings, previous studies have reported no significant difference in caries experience between children with and without SCA [22]. However, research conducted among children in India and Brazil has shown a higher prevalence of caries in those with SCA compared to their healthy peers [19, 29]. In contrast, another study from Brazil found a lower dental caries experience among children with SCA compared to those without the condition [4]. These conflicting results may be attributed to differences in study designs, as well as variations in the characteristics of the populations studied. Notably, a recent meta-analysis of nine studies examining the association between SCD and dental caries reported that both HbSS and HbSC genotypes are significantly associated with increased caries risk [37].

The study findings suggest that the relationship between SCA and dental caries is complex and not easily defined. This inconsistency in individual study outcomes can largely be attributed to methodological disparities and variations in the characteristics of the populations studied. Factors such as socio-economic status, access to dental care, and differences in study design often play a substantial role, potentially masking or amplifying the biological vulnerability posed by SCA itself. These findings emphasize the importance of context: the dental caries risk for a child with SCA is shaped by a multifaceted interaction of biological factors, disease genotype, medical management, nutrition, social determinants of health, and the availability of preventive dental services.

Given the evidence from the meta-analysis, it is prudent to approach children with SCA as potentially at higher risk for dental caries. This calls for a proactive and comprehensive dental prevention strategy that includes the use of fluoride, application of sealants, dietary counselling, proper oral hygiene instruction, and routine dental visits. The current high use of fluoride needs to be encouraged [38]. Importantly, future research should strive to better control for and disentangle the confounding influences that may obscure the true relationship between SCA and dental caries risk.

Second, the observed higher prevalence of dental caries in the primary dentition than in the permanent teeth of children with SCA may be due to the significantly higher prevalence of enamel hypoplasia and MIH observed in those with SCA [39], the earlier tooth emergence that extends exposure time [21, 40]. and the prolonged use of sweetened medication during the critical window of primary tooth development. In Nigeria, the high prevalence of untreated dental caries [41], driven by limited access to care, high costs, and a general lack of prioritization [42–44], turns the biological vulnerability of children with SCA into a serious health challenge. Dental pain can be severe, often indistinguishable from SCA-related vaso-occlusive pain [45], complicating diagnosis and pain management. Infections such as dental abscesses pose a high risk of bacteremia and potentially life-threatening complications, including osteomyelitis and septicemia, for children with SCA. It also increases the risk of hospitalisation [46, 47]. Moreover, painful dentition compromises nutrition, as affected children tend to avoid fibrous, nutrient-rich foods, relying instead on softer, often sugary options [48, 49], that perpetuate the cycle of caries and lead to nutritional deficiencies. This poor dietary intake can impair growth and may worsen the severity and complications of SCA.

The implications of this are profound. Oral health in children with SCA cannot be treated in isolation, as it directly affects their general health and disease outcomes. Addressing this requires an integrated, multidisciplinary approach involving hematologists, pediatricians, dentists, and caregivers. Key interventions include advocating for sugar-free medications [50]Implementing early preventive dental care programs, offering tailored nutritional counseling, improving access to dental services, and educating caregivers on the unique oral health needs of children with SCA. The risk of dental caries pain-induced crisis in SCA should make it critical for routine screening for dental caries in the population, and preventive measures instituted early to prevent its consequences/complications.

Conclusion

Sickle cell disease is not significantly associated with dental caries. Considering the limitations of this study, the findings should be interpreted with caution. Significant attention should be given to the oral health of children with sickle cell anaemia to prevent complications to their general health. Preventive dental care should be implemented for children with sickle cell anaemia. Further research to unravel the confounding factors that conceal the true relationship between sickle cell anaemia and dental caries is desirable.

Authors’ contributions

Author Contributions: Conceptualization, JBA, [EOO]1, SAA, OA, [EOO]2, and MOF; Methodology, JBA, [EOO]1, SAA, OA, [EOO]2, and MOF; Data collection, JBA; project supervision, [EOO]1, SAA, OA, [EOO]2, and MOF; formal analysis, JBA, [EOO]1; Writing—original draft preparation, JBA, [EOO]1, MOF; Writing—review, JBA, [EOO]1, SAA, OA, [EOO]2, and MOF. All authors have reviewed and approved the final manuscript.

Funding

This study was funded out of pocket.

Data availability

Available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Ethical approval for the study was obtained from the Obafemi Awolowo University Teaching Hospitals Complex Health Research Committee (NHREC/27/02/2009a). The study was conducted in line with the Declaration of Helsinki, university regulations governing research involving humans, and the National Code guiding the ethical conduct of research in Nigeria. Written informed consent was obtained from the parents/legal guardians of all the participants before their involvement in the study.

Consent for publication

Not applicable.

Competing interests

Morenike Oluwatoyin Folayan is a Senior Editorial Board Member of BMC Oral Health. The other authors have no competing interests to declare.