Sickle cell anemia in Brazil: personal, medical and endodontic patterns

Abstract

Sickle cell anemia (SCA) is the most prevalent genetic disease worldwide. Recurrent vaso-occlusive infarcts predispose SCA patients to infections, which are the primary causes of morbidly and mortality. This study aimed to evaluate the relationship between SCA and endodontic diseases. Personal information, medical data (hematological indices, virologic testing, blood transfusions, medications received, splenectomy) and information on the need for endodontic treatment were obtained from SCA patients who were registered and followed up by the Fundação Hemominas, Minas Gerais, Brazil.These data were compared with the need for root canal treatment in SCA patients. One hundred eight patients comprised the studied population, and the rate of the need for endodontic therapy was 10.2%. Among the medical data, a significant difference was observed for eosinophil (p = 0.045) counts and atypical lymphocyte counts (p = 0.036) when the groups (with and without the need for endodontic treatment) were compared. Statistical relevance was observed when comparing the patients with and without the need for root canal therapy concerned eosinophil counts and atypical lymphocyte counts. The differences in statistical medical data, observed between the groups suggest that both parameters are naturally connected to the stimulation of the immune system that can occur in the presence of root canal infections and that can be harmful to SCA individuals.

Anemia, Sickle Cell; Endodontics; Hemoglobinopathies

Introduction

Sickle cell anemia (SCA) is a heterogeneous clinical condition characterised by episodes of vaso-occlusion and infectious events.¹ SCA is the most prevalent genetic disease worldwide,² as well as in Brazil.³ This hemoglobinopathy is caused by a mutation in the beta globulin gene of the hemoglobin molecule, resulting in the production of abnormal hemoglobin, called hemoglobin S (HbS). The presence of hemoglobin S in homozygosis (HbSHbS) triggers the formation of polymers when it is deoxygenated, leading to erythrocyte rigidity, loosening of the biconcave discoid shape of erythrocytes and changing the cells’ shape into a sickle shape, followed by membrane damage and hemolysis. As a consequence of this occurrence, the sickle-shaped red blood cells obstruct the capillaries, restricting blood flow to organs, which results in ischemia, pain, and often tissue damage.¹ Vaso-occlusive events can lead to complications, such as avascular necrosis of the bones, osteopenia, osteoporosis, retinal infarction, stroke, pulmonary hypertension and skin ulcerations.⁴

Recurrent vaso-occlusive infarcts predispose SCA patients to infections, which are the most common complications and the primary causes of morbidly and mortality in SCA patients.^5,6,7,8 Studies have shown an association between hematological factors and pathologic alterations in SCA.^9,10 The elevated white blood cell counts in sickle cell disease have been reported as being able to predict morbid events in patients with the disease.¹¹ Moreover, during persistently low oxygen tension, these cells are recognised by the reticuloendothelial system and are destroyed. The red blood cells of individuals with normal hemoglobin (HbA) survive approximately 120 days, while the red blood cells of Hbs individuals survive only between 15 and 25 days.¹² The accumulation of these distorted cells is responsible for vaso-occlusion and most SCA-related disorders.

Oral complications have been described in SCA patients. Those that have been recorded include: mandibular osteomyelitis, anesthesia of the mandibular nerve, and asymptomatic pulpal necrosis. Osteomyelitis occurs several hundred times more frequently in SCA patients than in the rest of the population and that up to 29% of SCA patients experience at least one episode of osteomyelitis during their lifetime.^{13,14,15,16,17} Permanent neuropathies affecting the inferior dental nerve after an SCA have been reported and resulted in persistant anesthesia for up to 24 months.^18,19

The occurrence of asymptomatic pulp necrosis has been described in clinically intact permanent teeth in patients with SCA. It has been associated to vaso-occlusion of the pulp microcirculation.^12,20,21 In this regard, the prevalence of pulp necrosis was reported to be 8.33 times higher HbS individuals compared to HbA individuals.¹² Sickle cells have also been identified in teeth with a history of repeated episodes of pulpal pain.²⁰ This finding indicates that not only the mandibular bone structure is affected by the sickling crises, but the microcirculation of the pulp is compromised.²²

Knowing the benefits of a health policy on SCA population, especially on its oral conditions, might lead to the implementation of strategies to promote the health of SCA patients. The aim of this study was to compare the personal information and need for root canal treatment of SCA patients with their medical and hematological data at the time of initial dental presentation (first appointment).

Methodology

A descriptive and cross-sectional study was conducted from October 2010 to August 2012. Data were obtained from 108 evaluated patients with confirmed diagnoses of SCA (HbSS genotype), who were registered and followed up by the Fundação Hemominas, Regional Montes Claros, Minas Gerais, Brazil. Personal information (sex and age) and information on the need for endodontic treatment were obtained from the patients during dental appointments. Medical data (hematological indices, serologic testing, blood transfusions, medications received, splenectomy) were obtained from medical records. Patients were excluded from this study if they had taken antibiotics within the 3 months prior to the initiation of endodontic therapy.The criteria adopted to determine the need for endodontic treatment were based on clinical and radiographic analyses, along with pulp vitality tests (Vitality Scanner^TM, Sybron Endo, Orange, USA).²³ Correlations among the collected data were calculated. This study was approved by the Research Ethics Committees of the Fundação Hemominas (ETIC 283/10), Universidade Estadual de Montes Claros – UNIMONTES (ETIC 1848/10) and Universidade Federal de Minas Gerais – UFMG (ETIC 203/10).

Statistical analysis

After data collection, statistical analysis was performed using SPSS statistical software for Windows (SPSS Inc., version 17.0, Chicago, USA). Descriptive analyses were performed to verify the patients’ characteristics and the prevalence of oral and systemic conditions. Bivariate analysis was performed to examine the relationship between the needs for endodontic treatment and for blood cells. The significant differences between categorical variables were examined with the Chi-square test and with Fischer’s exact test. Statistical significance was defined as a p-value of 0.05 or less.

Results

Patient characteristics

One hundred eight patients (n = 108) were included in this study. A total of 61 female patients (56.5%) and 47 male patients (43.5%), 5 to 59 years old (median age, 32 years) comprised the eligible individuals. The patients who needed to receive endodontic care corresponded to 10.2% (n = 11) of the study subjects.

Blood transfusions

Among all of the patients, 68.5% received blood transfusions. Of the patients who required root canal therapy, 63.6% were submitted to blood transfusions, whereas 69.1% of the patients without the need for endodontic treatment were not transfused. When the two groups (with and without the need for endodontic therapy) were compared, no statistically significant differences were observed (p = 0.739).

Serologic testing

Of the eligible population, positive serologic test results for syphilis (0.9%), Chagas disease (3.7%), hepatitis (anti-HBc) (3.7%), hepatitis (anti-HCV) (2.8%) and HTLV I/II (0.9%) were detected. However, in the group of patients who needed root canal treatment, the HTLV I/II test results were negative (Table 1).

Table 1
Description of positive serologic testing in HbSS patients with and without the need for endodontic treatment.

Serologic testing	HbSS patients (%)	Endodontic treatment (%)
		Yes	No
Syphilis	0.9	9.0	0.00
Chagas disease	3.7	9.0	27.30
Hepatitis (Hbs Ag)	0.0	0.0	0.00
Hepatitis (Anti-HBc)	3.7	9.0	27.30
Hepatitis (Anti-HCV)	2.8	9.0	18.18
HIV 1	0.0	0.0	0.00
HIV 2	0.0	0.0	0.00
HTLV I/II	0.9	0.0	9.09

• HbSS: Homozygous sickle cell disease.

SCA regimen

Folic acid and hydroxyurea were the most commonly prescribed agents for the SCA patients in this study. Of the eligible population, 99.1% received folic acid therapy, and 21.3% received hydroxyurea therapy. All of the patients who required endodontic treatment received folic acid therapy, and in the same group, 9.1% received hydroxyurea therapy. When the two groups (with and without the need for endodontic treatment) were compared, no significant differences were observed for folic acid administration (p = 1.000) or hydroxyurea administration (p = 0.451). Table 2 shows the medications, including different drugs, according to the regimen and the proportion of patients who received each therapy.

Table 2
Percentage of patients according to each prescribed medication.

Percentage/Number		Medication
SCA suffers (n = 108)
71.3	77	Folic acid
18.5	20	Folic acid, hydroxyurea
0.9	1	Folic acid, captopril
0.9	1	Folic acid, caverdilol
0.9	1	Folic acid, captopril, caverdilol
0.9	1	Folic acid, captopril, furosemida
0.9	1	Folic acid, exjade
0.9	1	Folic acid, fenitoína
0.9	1	Folic acid, hidroxyurea, exjade
0.9	1	Folic acid, hidroxyurea, paracetamol
0.9	1	Folic acid, paracetamol
0.9	1	Folic acid, vitamin D
0.9	1	Carbamazepin, captopril, hidroxyurea

• SCA: Sickle cell anemia.

Splenectomy

Splenectomised patients represented 1.9% of the SCA patients included in this study. Of the patients who required root canal treatment, 0% was submitted to splenectomy, and 2.1% of the patients in the group without the need for root canal treatment were splenectomised. No significant difference was observed when these data were compared between the groups of patients with and without the need for root canal treatment (p = 1.000).

Hematological indices

In this study, 43.5% of all of the patients presented leucocyte (white blood cells) counts greater than 11,000 cells/mm³, whereas 56.5% presented leucocyte counts between 4,000 cells/mm³ and 11,000 cells/mm³. In addition, 99.1% of SCA patients presented basophil counts between 0 cells/mm³ and 200 cells/mm³ (Table 3). The eosinophil counts were greater than 500 cells/mm³ for 20.4% of the population and for 45.5% and 17.5% of the patients with and without the need for root canal therapy, respectively. The SCA patients presented banded neutrophil counts < 700 cells/mm³ (100%) and segmented neutrophils count between 1,800 cells/mm³ and 7,000 cells/mm³ (69.4%). In the groups that required and did not require endodontic therapy, 81.8% and 81.4% exhibited lymphocyte counts between 1,000 cells/mm³ and 4,500 cells/mm³, respectively. Concerning atypical lymphocyte counts, 45.5% and 16.5%, respectively, of the patients who required or did not require endodontic treatment presented counts > 1 cell/mm³. The percentages of SCA patients who presented metamyelocyte counts and myelocyte counts of 0 cells/mm³ were 98.1% and 100%, respectively. When the white blood cell counts were compared between the patients with and without the need for root canal therapy, a statistically significant difference was detected only for the eosinophil (p = 0.045) counts and atypical lymphocyte counts (p = 0.036).

Table 3
White blood cell scores in HbSS patients with and without the need for endodontic treatment.

White blood cells (cells/mm3)	Endodontic treatment
	Yes				No
	Mean	Median	SD	Min/Max	Mean	Median	SD	Min/Max
Basophil	82.82	69.00	119.765	0/402	49.98	0.00	73.856	0/348
Eosinophil	570.73	163.00	576.756	691/582	601.91	360.00	826.732	0/5989
Metamielocyte	0.00	0.00	0.000	0/0	0.00	0.00	0.000	0/0
Banded neutrophil	128.55	0.00	244.068	0/815	102.38	40.00	133.385	0/656
Segmented neutrophil	4251.18	3955.00	1492.078	1789/7335	5195.24	4880.00	2352.760	345/12672
Limphocyte	4543.45	4154.00	1480.140	2760/7342	4723.71	4715.00	1687.800	763/8855
Monocyte	635.64	472.00	361.384	180/1340	581.55	578.00	382.405	0/2132
Mielocyte	0.00	0.00	0.000	0/0	0.00	0.00	0.000	0/0
Atypical limphocyte	59.75	40.00	67.724	0/163	29.78	0.00	70.081	0/374

• SD: standard deviation; Min: minimum; Max: maximum.

Table 4 shows the erythrocytes counts: they were < 4.0 x 10⁶ cells/mm³ for female subjects and < 4.5 x 10⁶ cells/mm³ for male patients in all of the patients in the group requiring endodontic treatment and in 86.6% of the group not requiring endodontic care. Hemoglobin concentrations < 12.8 (g/dL) for male patients and < 11.6 (g/dL) for female patients was observed in 100% and 95.9% of the patients with and without the requirement for endodontic therapy, respectively. In this study, the mean corpuscular volume (MCV) levels were > 98% in 26.8% of the patients who did not require endodontic therapy and in 9.1% of the patients who required root canal treatment. Among all of the patients of this study, 19.4% showed mean corpuscular hemoglobin (MCH) less than 27 (pg). Of those patients who did not require endodontic treatment, 19.6% presented MCH less than 27 (pg), and 35.1% presented MCH greater 34 (pg). However, in 18.2% of patients with the need for root canal therapy, MCH was greater than 34 (pg). The mean corpuscular haemoglobin concentration (MCHC) was < 31.5 (g/dL) for 15.7% of the eligible patients. An MCHC < 31.5 (g/dL) was observed in 9.1% and 16.5% of the groups with and without the need for endodontic treatment, respectively. Herein, 96.3% of the patients presented reticulocyte counts > 2.3%. Regarding the need or not for endodontic treatment, 100% and 95.9% of these patients presented reticulocyte counts > 2.3%, respectively. The majority of the SCA patients (96.3%) presented hematocrit < 36% for female patients and < 38% for male patients. In the groups with and without the need for endodontic treatment, 100% and 95.9% of the patients, respectively, presented hematocrit < 36%. No significant differences were observed when comparing the groups with and without the need for endodontic treatment, taking into consideration the red blood cell counts (p > 0.05).

Table 4
Hematological scores in HbSS patients with and without the need for endodontic treatment.

Hematological data	Endodontic treatment
	Yes				No
	Mean	Median	SD	Min/Max	Mean	Median	SD	Min/Max
Erythrocyte (x 106/mm3)	2.448	2.600	0.4006	2.0/3.1	8.484	8.300	17.182	6.0/15.7
Hemoglobin (g/dL)	7.400	7.300	13.3870	5.2/9.2	25.779	24.800	59.009	16.5/47.0
Hematocrit (%)	22.545	22.400	32.2350	18.0/28.0	91.852	92.200	114.578	70.2/122.7
MCV (fL)	92.491	92.600	124.0370	74.6/122.0	30.733	31.200	51.010	20.4/44.2
MCH (pg)	31.000	31.800	49.6510	23.8/41.6	33.259	33.200	22.544	28.9/41.4
MCHC (g/dL)	33.482	33.500	15.1510	31.3/36.6	8.656	7.000	70.266	1.0/55.0
Reticulocyte (%)	9.318	10.000	33.3370	5.0/14.0	429.610	414.000	148.083	117.0/960.0
Platelet (x 103/mm3)	434.180	434.000	114.7070	204.0/620.0	8.484	8.300	17.182	6.0/15.7

• MCV: mean corpuscular volume; MCH: Mean corpuscular hemoglobin; MCHC: mean corpuscular hemoglobin concentration; SD: standard deviation; Min: minimum; Max: maximum.

Finally, platelet counts > 360 x 10³ cells/mm³ were observed in 72.7% and 62.9% of those patients who required and did not require root canal treatment, respectively. None (0%) of the patients with the need for endodontic treatment exhibited platelets counts < 140 x 10³ cells/mm³. No significant difference (p = 0.769) was observed when the two groups (with and without the need for endodontic treatment) were compared.

Discussion

A recent study attempted to assess the epidemiological aspects of root canal diseases, defining the prevalence of the need for endodontic care in a given population.²³ This study reported a rate of 14.5% of HIV-infected patients requiring endodontic treatment.²³

A previous study analyzed the Pulp sensitivity in a SCA Turkey population in an area with high prevalence of heterozygote patients with SCA. Overall, pulp necrosis occurred with pathoses in 6% of those teeth.²¹ In this study, we detected a rate of 10.2% of SCA patients requiring endodontic therapy. This rate could reflect lower budgets and less policy support for dental programs in public dental health services, which offer basic dental assistance mostly to lower socioeconomic groups in Brazil. Moreover, it is important to note that the true prevalence of the need for endodontic treatment in SCA patients in Brazil would only be possible to determine via multicentre studies performed in different states.

Sickle cell anemia affects between 0.1% and 0.3% of Afro-Brazilian-descended people.²⁴ In 2001 in the state of Minas Gerais, 87 of 128,326 newborns were carriers of hemoglobin S (HbS), 46 of whom had the disease.²⁵ The Fundação Hemominas, Regional Montes Claros, Minas Gerais, Brazil, is responsible for monitoring SCA patients referred from different cities, and this centre is located in northern of the state of Minas Gerais.

The prognosis of people living with SCA depends on the SCA regimen. Herein, the most commonly prescribed agents were folic acid and hydroxyurea. The hydroxyurea provides therapeutic benefit through multiple mechanisms of action.²⁶ The efficacy of hydroxyurea in the treatment of SCA-related disease has generally been attributed to its ability to increase fetal hemoglobin (α2γ2) and consequently to decrease hemoglobin S (Hbs) as a compensatory mechanism that prevents the polymerisation of intercellular hemoglobin. Hydroxyurea administration leads to greater survival of erythrocytes, resulting in a decrease in the frequency and severity of vaso-occlusive episodes and diminishing the severe course of SCA, thus bringing clinical benefits.²⁷ Folic acid reduces the risk of endothelial damage. Its prescription is justified by its improvement of the production and maturation of red blood cells.^28,29 All of the SCA patients in this study who required endodontic treatment were under folic acid regimens, but only one of them was taking hydroxyurea. When the two groups (with and without the need for endodontic treatment) were compared, no significant difference was observed for the two agents. Conversely, another study¹² reported that HbS individuals presented more pulp necrosis in clinically intact permanent tooth than HbA subjects, and this rate remained significant after folic acid prescriptions were taken into account.

Blood transfusions were required in 68.5% of the patients as an ordinary procedure in the management of the SCA.³⁰ Continual transfusions of red blood cells greatly decrease disease severity. Their use is supported by transfusions decreasing the percentage of HbS, suppressing HbS synthesis, and reducing hemolysis.^5,31 However, blood transfusions are considered a risk factor for infections.³⁰ Today, the exclusion of high-risk donors, along with increases in technology, has reduced during procedures of the risk of the transmission of diseases, such as viral hepatitis and human immunodeficiency viruses (HIV I and HIV II), in northern Europe and the United States.³¹ In this study, positive serology for syphilis, Chagas disease, hepatitis (anti-HBc), hepatitis (anti-HCV) and human lymphotropic virus (HTLV) was assayed for the eligible individuals. However, in the group of patients who required endodontic treatment, the latter test (HTLV I/II) was negative.

Neutrophilia is a useful marker of infection in many clinical settings, as well as in SCA,^7,8 because the prevalence and intensity of neutrophilia are higher in SCA patients with bacterial infections than in those without infections. Additionally, neutrophilia in SCA individuals can be accompanied by eosinopoenia.^7,8 Our findings showed that only one SCA patient presented with neutrophilia. Despite the significant difference (p = 0.045) observed in the eosinophil counts when the groups with and without the need for endodontic treatment were compared, eosinopoenia was not observed among the eligible patients.

Leucocytosis is a risk factor for hemorrhagic stroke in children and adults, as well as a risk factor for acute chest syndrome and early death. Increased white blood cell counts can predict morbid events in sickle cell disease.¹¹ Leucocytosis was observed in 43.5% of the SCA patients included in this study. Moreover, it was observed in 45.4% and 27.3% of the patients in the groups with and without the need for endodontic treatment, respectively.

In SCA patients, immune cells, such as monocytes, neutrophils and endothelial cells, are in a permanently activated status,¹¹ which result in the production of immune mediators as cytokines and chemokines. A recent study from our research group demonstrated that teeth with periapical lesions from SCA individuals presented prone proinflammatory ability, expressing IL-1, TNF-α, and IL-17A at a significantly higher level compared to healthy teeth from control patients.³²

In this study, 96.3% of the SCA patients presented hematocrit < 39% among male patients and < 36% among female patients. High hematocrit is a risk factor for vaso-occlusive crises, acute chest syndrome, and avascular necrosis,³⁰ and it has been suggested that hemoglobin level plays a role in the deformability of sickled cells.⁹ Accordingly to previous results in SCA patients,¹ 88% of eligible patients presented red blood cells < 4,500 (x 10⁶/mm³) cells and < 4,000 (x 10⁶/mm³) cells for male and female patients, respectively.

Platelets contribute to vascular inflammation by activating neutrophils in SCA patients, in addition to their pro-coagulant role.³³ Increased platelet count activation has been recognised in the vasculopathy of SCA disease.³⁴ Abnormalities in blood rheology and platelet dysfunction might play a role in the pathogenesis of multiple organ failure in septic patients by reducing microvascular blood flow.³⁵ Red blood cell aggregation properties are likely to be involved in the pathophysiology of sickle cell disease: the increased shear forces needed to disperse red blood cell aggregates may disturb blood flow, especially at the microcirculatory level, since red blood cell are only able to pass through narrow capillaries as single cells rather than as aggregates.³⁶ Platelet counts > 360 x 103 cells/mm³ were observed in 72.7% of those patients who required root canal treatment in the present study. The deleterious effect of reduced blood flow and perfusion in the capillary pulp microcirculation may have contributed to pulp necrosis.

Conclusion

This study assessed the need for endodontic treatment in a controlled population of SCA patients assisted at a public dental health service in Brazil, and it attempted to determine the relationships between SCA and endodontic diseases. Despite providing knowledge of the epidemiological root canal requirements of the SCA population, the unique statistical relevance observed when comparing the patients with and without the need for root canal therapy concerned eosinophil counts and atypical lymphocyte counts. Both parameters are naturally connected to the stimulation of the immune system that can occur in the presence of root canal infections and that can be harmful to SCA individuals. Hence, this study reinforces the necessity for government polices to improve dental health service for these individuals.

Acknowledgments

This work was supported by Fundação de Amparo à Pesquisa do Estado de Minas Gerais – FAPEMIG, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES and Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq. The authors wish to thank the post-graduate program at the School of Dentistry of Universidade Federal de Minas Gerais – UFMG. L.Q.V., H.M.J., and A.P.R.S. are CNPq fellows.

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Publication Dates

• Publication in this collection
  2016

History

• Received
  16 Aug 2015
• Accepted
  22 Nov 2015
• Reviewed
  24 Feb 2016