Venous Disease

Systematic markers, Periodontal disease & Cardiovascular disease: A possible link?

 Introduction

Periodontitis is a bacterially induced, localized, chronic inflammatory disease that destroys the connective tissue & the bone supporting the teeth.1 In fact; it is a prototype of low grade local infection associated with a moderate systemic inflammatory response. Periodontitis is characterized by a non-specific acute phase response with exhibition of strong acute phase reactants like C- reactive protein.2 It may also affect the cellular components of blood with several studies consistently reporting slight elevation in number of leukocytes in periodontitis compared to controls. These same systemic markers appear to be predictive of atherosclerosis, myocardial infarction, stroke & thrombosis.3

Epidemiological associations between periodontitis and cardiovascular disease (CVD) have been reported.4,5 Both conditions have complex etiologies, genetic and gender predispositions and might share similar pathogenic mechanisms as well as common risk factors.6 It is becoming increasingly clear that infections and chronic inflammatory conditions such as periodontitis may influence the atherosclerotic process.7

A recent joint consensus conference of the American Heart Association & the Center for Diseases Control has identified different risk categories based on serum CRP levels. Subjects with CRP concentrations less than 1mg/l are considered to be at low risk, whereas those with concentrations in the 1-3mg/l range are assigned a medium risk level and those with more than 3mg/l in serum CRP are considered to be at high risk for future CVD & events.8 A recent systematic review and meta-analysis drew upon the conclusion that there is convincing evidence that plasma CRP was elevated in periodontitis affected patients compared with controls.9 It has been hypothecated that any association between periodontitis and CVD could be attributed to the moderate increases in CRP reported in subjects with poor periodontal health.10

A number of epidemiological studies consistently have shown a significant relationship between white blood cell (WBC) count and the occurrence of CVD and stroke.11-13 Chronic periodontal infections are associated with increases in number of leukocytes 14 which modify the blood rheology thereby promoting hypercoagulation. 15 The crucial causal relation might be established by prospective treatment studies, which elucidate the connection between treatment of poor dental health & systemic inflammatory markers.5 

 The aim of this study was to determine whether serum concentrations of established risk markers of atherosclerosis such as CRP and peripheral blood markers like total & differential leukocyte count are elevated in periodontitis &their relation to severity of periodontal disease. 

Materials & Methods

Study population;A total of 20 systemically healthy untreated, chronic generalized periodontitis patients who reported to the Department of Periodontics, P.M.N.M Dental College & Hospital were selected randomly. An additional 10 healthy controls were also included in the study. The purpose of the study was explained to them and written informed consent was obtained. The study was approved by the ethical committee of the institution.

Individuals with no history of CVD or other acute/chronic systemic disorders were included in the study. Pregnant women and individuals with trauma or recent extractions, smoking habit or who had antimicrobials in preceding three months were excluded from the study.

All the subjects underwent a comprehensive periodontal examination for gingival index (GI) [Loe and Silness 1963], probing depth (PD) and clinical attachment loss (CAL). Both PD and CAL were measured by graduated William's periodontal probe on four sites of all present teeth except third molars. PD and CAL nearest to the lower values were considered. Depending upon the PD and CAL measurements, study subjects were divided into three groups:

Group I- moderate chronic periodontitis; PD=4-6mm, CAL=3-4mm

Group II- severe chronic periodontitis; PD>6mm, CAL≥5mm

Group III- control group; PD<3mm, CAL<3mm

 According to NHANES-III-1988-94, CAL is age-dependent variable with CAL< 3mm reported to be present in more than 50% of population.16 Hence, the subjects are considered as controls.

Analysis of Systemic Infection: A 5ml of non-fasting venous blood sample was collected to measure TLC & DLC, & serum CRP. Serum CRP levels were quantified using turbidimetric immunoassay. The reference range was 2-3mg/l.

Statistical analysis;The results were presented as mean and standard deviation. Overall differences among the three groups for all variables including GI, PD, CAL, CRP, TLC and neutrophils were determined by ANOVA. The pair-wise differences among the three groups were carried by Mann-Whitney U test and Newman-Keuls post hoc procedure. The p-Value<0.05 was considered statistically significant.

Results

This cross-sectional study consists of total of 30 patients divided into three groups. Group I consists of 7 males & 3 females with mean age of 44.0±5.83 years. Group II consists of 8 males and two females with mean age of 47.50±5.30 years. 6 males and 4 females formed group III with mean age of 34.40±4.58 years. (Table 1)

The inter-group comparison of periodontal parameters was carried out by ANOVA test. The values were highly significant (P value=0.000) in terms of GI scores, PD and CAL among the three groups. The mean GI scores were 1.79±0.43 in group I, 2.17±0.15 in group II and 0.82±0.30 in group III. The mean PD scores were 5.33±0.40mm, 7.11±0.65mm and 1.98±0.38mm for groups I, II and III respectively. The mean CAL values were 4.21±0.43mm for group I, 7.20±0.69mm for group II and 1.20±0.33mm for group III. (Table 2)

Pair-wise comparisons among the three groups resulted in following results. The mean GI score was statistically significant when group II was compared with group I (p value= 0.034). But, comparison of mean GI scores of group I and group II with that of group III was highly significant (p value=0.0002). Likewise, pair-wise comparisons of PD and CAL among the three groups were highly significant (p value=0.0001). (Tables 3, 4 & 5)

Mean CRP values in group I was 6.65±1.40 mg/l, in group II, it was 4.48±0.85mg/l while in group III it was 2.45 ±0.57mg/l. A significant difference in mean CRP serum level was observed over all study groups (p value =0.0000). The total leukocyte count (TLC) among the 3 groups was significantly different (p value=0.000). The severe periodontitis group had higher mean number of leukocytes compared to moderate periodontitis patients and control group (9090/cu.mm versus 7310/cu.mm and 5500/cu.mm respectively). While the other types of leukocytes did not vary significantly, a significant difference in number of neutrophils was observed over the 3 study groups. (Table 6) Pair-wise comparisons of mean CRP level and TLC among three groups were statistically significant (Tables 7 and 8). The comparison of mean neutrophil count was highly significant when group III was compared with groups I and II. However, pair-wise comparison of mean neutrophil score was not significant when group I was compared with group II (p value=0.2030, Table 9)Discussion

Cross-sectional as well as prospective studies have established that elevated peripheral blood levels of several systemic inflammatory markers including CRP, fibrinogen, IL-6 are associated with the pathogenesis of artherosclerosis and the risk of CVD.17--19 CRP in particular has been the focus of attention as a key marker of artherosclerosis and elevated level (≥2.1mg/l) constitute a risk predictor of CVD. 13, 20 In addition, leukocyte count is considered as a good predictor of ischemic heart disease.12

It has been proposed that these markers could be elevated in undiagnosed chronic infectious processes like periodontitis. It is conceivable that chronically, elevated systemic markers in blood exacerbate other ongoing inflammatory processes in other organ systems and this way perhaps increase the risk for atherosclerosis leading to cardiovascular and cerebrovascular events.21

In this respect, CRP represents the most sensitive marker used to evaluate the inflammatory status of an individual. 10 Chronic bacterial infections such as periodontitis are one of the established risk factors for moderate elevated CRP levels. 22

In the present study, we observed a significant association between periodontitis and CRP. Moreover, the results showed a positive correlation between the severity of periodontal disease and CRP level. The findings of the current study support previous studies which reported similar result.22-25 Noack et al. 24 observed statistically significant increases in CRP in subjects with moderate to severe periodontitis when compared to healthy controls after adjusting for potential confounding factors. The presence of periodontal pathogens including Porphromonas gingivalis, Prevotella intermedia, and Tanerella forsythensis from subgingival plaque samples was also positively associated with elevated CRP levels.

Elevated numbers of leukocytes in periodontitis have previously been observed.14 Fredriksson et al. reported slight elevation of leukocytes in periodontitis in comparison to controls, although not statistically significant.26 In the present study, the total leukocyte count was significantly increased in periodontitis as compared to healthy controls. This finding is in agreement with previous study.27 A significant increase in polymorphonuclear leukocytes was also observed. The increase in number of leukocytes in periodontitis has been suggested to be mainly due to an increase in the number of polymorphonuclear leukocytes.28 However, moderate and severe periodontitis groups did not differ significantly in number of neutrophils. Moderately elevated numbers of leukocytes have been associated with an increased risk for cardiovascular diseases20. Also, it has been suggested that the higher numbers of leukocytes increase the blood rheology thereby increasing the risk for CVD. 12However, the current study did not measure the role of confounding factors like age, gender, parameters of lipid metabolism like cholesterol, triglycerides, low-density lipoproteins, obesity which influence the CRP levels.

Conclusion

In summary, our study provides evidence that periodontitis may cause systemic aftermath: plasma levels of CRP and numbers of leukocytes and neutrophils are elevated in the blood which are positively correlated with the severity of periodontitis. Thus, periodontitis, a common chronic condition, predisposes affected patients to CVD by increasing the levels of systemic markers of inflammation which may contribute to the process of artherosclerosis. Therefore, periodontitis deserves serious consideration as a risk factor for cardiovascular diseases.

 References

1.      The American Journal of Cardiology and Journal of Periodontology Editors' Consensus: Periodontitis and Atherosclerotic Cardiovascular Disease. J Periodontol 2009;80:1021-1032.

2.      Ebersole JL, Cappelli D. Acute phase reactants in infections and inflammatory diseases. Periodontol 2000 2000;23:19-49.

3.      Loos BG. Systemic markers of inflammation in periodontitis. J Periodontol 2005;76:2106-2115

4.      Janket SJ et al. Meta-analysis of periodontal disease and risk of coronary heart disease and stroke. Oral surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics 2003;95:559-569

5.      Meurman JH, Sanz M, Janket SJ. Oral health, atherosclerosis, and cardiovascular disease. Critical Reviews in Oral Biology and Medicine 2004;15:403-413

6.      Kinane DF, Lowe GD. How periodontal disease may contribute to cardiovascular disease. Periodontol 2000 2000;23:121-126

7.      Danesh J, Collins R, Peto R. Chronic infections and coronary heart diseases:is there a link? Lancet 1997;350:430-436

8.      Pearson TA, Mensah GA, Alexander RW et al. Markers of inflammation and cardiovascular disease: application to clinical and public health practice: a statement for healthcare professionals from the Centers for Disease Control and Prevention and the American Heart Association. Circulation 2003;107:499-511

9.      Paraskevas S, Huizinga JD, Loos BG. A systematic review and meta-analyses on C-reactive protein in relation to periodontitis. J Clin Periodontol 2008;35:277-290

10.  D'Aiuto F, Ready D, Tonetti MS. Periodontal disease and C-reactive protein-associated cardiovascular risk. J Periodont Res 2004;39:236-241

11.  Kannel WB, Anderson K, Wilson PWF. White blood cell count and cardiovascular disease. Insights from the Framingham study. JAMA 1992;136:59-70

12.  Sweetnam PM et al. Total and differential leukocyte counts aspredictors of ischaemic heart disease: the Caerphilly and Speedwell studies. Am J Epidemiol 1997;145:416-421

13.  Danesh J, Collins R, Appleby P, Peto R. Association of fibrinogen, C-reactive protein, albumin, or leukocyte count with coronary heart disease. Meta-analyses of prospective studies. JAMA 1998; 279:1477-1482

14.  Kweider M et al. Dental disease, fibrinogen and white cell count: Links with myocardial infarction? Scot Med J 1993;38:73-74

15.  Beck JD, Slade G, Offenbacher S. Oral disease, cardiovascular disease and systemic inflammation. Periodontol 2000 2000;23:110–120

16.  Beck JD, Samuel JA Jr. Epidemiology of gingival and periodontal diseases. In: Newman MG et al. Carranza's Clinical Periodontology. 10th ed. Saunders 2006. p. 110-131

17.   Berk B, Weintraub W, Alexander R. Elevation of C-reactive protein in "active" coronary artery disease. Am J Cardiol 1990;65:168-172

18.  Biassucci L et al. Elevated levels of interleukin-6 in unstable angina. N Engl J Med 1994;331:417-424

19.  Toss H et al. Prognostic influence of increased fibrinogen and C-reactive protein levels in unstable coronary heart disease. Circulation 1997;96:4204-4210

20.  Ridker PM et al. Established and emerging plasma biomarkers in the prediction of first atherothrombotic events. Circulation 2004;109:IV6-IV19

21.  Libby P, Ridker PM, Maseri A. Inflammation and atherosclerosis. Circulation 2002;105:1135-1143

22.  Slade DG et al. Acute phase response to periodontal disease in the U.S population. J Dent Res 2000;79:49-57

23.  Slade DG et al. Relationship between periodontal disease and C-reactive protein among adults in the atherosclerosis risk in communities study. Archives of Internal Medicine 2003;163:1172-1179

24.  Noack B et al.Periodontal infections contribute to elevated systemic C-reactive protein level. J Periodontol 2001;72:1221-1227

25.  Pitiphat W, Savetsilp W, Wara-Aswapati N. C-reactive protein associated with periodontitis in a Thai population. J Clin Periodontol 2008;35:120-125

26.  Fredriksson M et al. Effect of periodontitis and smoking on blood leukocytes and acute phase protein. J Periodontol 1999;70:1355-60

27.  Loos et al. Elevation of systemic markers related to cardiovascular diseases in the peripheral blood of periodontitis patients. J Periodontol 2000;71:1528-1534

28.  Kowalik MJ et al. Systemic neutrophil response resulting from dental plaque accumulation. J Periodontol 2001;72:146-151

 Table 1

Characteristics

 

Group  I

(Moderate periodontitis, n=10)

 

Group II

(severe periodontitis, n=10)

Group III 

(control, n= 10)

 

Age

 

44.00 ±5.83

 

47.50 ±5.30

 

34.40 ±4.58

 

Male / female %

 

70/30

80/20

 

60/40

Table 2 

Periodontal parameters

 

Group  I

(Moderate periodontitis, n=10)

 

Group II

(severe periodontitis, n=10)

Group III

(control, n= 10)

P Value †

 

GI score

1.79±0.43

 

2.17±0.15

  

0.82±0.30

 

0.0000*

PD (mm)

5.33±0.40

 

7.11±0.65

 

1.98±0.38

 

0.0000*

CAL (mm)

4.21±0.43

 

7.20±0.69

 

1.20±0.33

 

0.0000*

 

 

 

 

 

 

Table 3  

Group III- Group I

P=0.0002*

Group III- Group II

P=0.0002*

Group I- Group II

P=0.0343*

Table 4

Group III- Group I

P=0.0001*

Group III- Group II

P=0.0001*

Group I- Group II

P=0.0001*

Table 5

Group III- Group I

P=0.0001*

Group III- Group II

P=0.0001*

Group I- Group II

P=0.0001*

Table 6

 

 

Group I

(severe periodontitis, n=10)

Group  II

(Moderate periodontitis, n=10)

 

Group I

(control,

 n= 10)

P Value †

CRP (mg/l)

6.6500±1.4026

  

4.4800±0.8548

2.4500 ±0.5759

0.0000*

Total leukocyte count (per cub mm)

9090±1530.03

 

7310±858.23

5500±778.89

0.0000*

Neutrophil count (%)

70.1±4.77

 

65.9±9.72

54.4±6.17

0.0001*

 

 

 

 

 

 

 

Table 7

Group III- Group I

P=0.0002*

Group III- Group II

P=0.0001*

Group I- Group II

P=0.0002*

Table 8

Group III- Group I

P=0.0012*

Group III- Group II

P=0.0001*

Group I- Group II

P=0.0014*

Table 9

Group III- Group I

P=0.0015*

Group III- Group II

P=0.0002*

Group I- Group II

                                  P=0.2030