an evaluation of the possible relationship between chronic periodontitis and hypertension

Abstract

Background

Periodontal diseases have been reported to have a form of reciprocal relationship with the general systemic health, in which case those with some systemic diseases such as hypertension have poorer periodontal health and vice versa. The issue of causal or casual relationship is however yet to be finally resolved.

Aim

The aim of this study was to determine any possible relationship between chronic periodontitis and cardiovascular risk factors.

Methodology

A cross-sectional assessment of cardiovascular risk factors such as blood pressure, body mass index, waist circumference and the carotid artery intima media thickness (CIMT) was done among 100 consecutive subjects in the echocardiogram unit of the University College Hospital, Ibadan, Nigeria over a period of six months. These cardiovascular risk factors were compared with periodontal parameters such as Simplified Oral Hygiene index (OHI-S), Gingival index (GI) and Community Periodontal Index (CPI).

Results

The systolic blood pressure (SBP) of the respondents ranged from 98 – 210 mm Hg with a mean of 133.1 ± 15 mm Hg, diastolic blood pressure (DBP) 60 – 136 mm Hg with a mean of 84.6 ± 6.4 mm Hg. There was a statistically significant relationship between the systolic blood pressure and oral hygiene index (P< 0.000), diastolic blood pressure and oral hygiene index (P < 0.010) and mean carotid artery intima media thickness and oral hygiene index (P< 0.012) among the respondents.

Conclusion

In view of the significant relationship between the blood pressure and the mean carotid artery intima media thickness, when compared with the oral hygiene status of respondents in this study, more emphasis should be laid on regular preventive dental visit as a way of decreasing cardiovascular health risk.

Introduction

William Hunter, a British physician, in 1900 proposed the focal infection theory, which linked the oral micro-organisms with a range of systemic diseases1. The theory led to an indiscriminate extraction of teeth with conditions such as caries, pulpal necrosis and periapical abscesses. These conditions, including gingivitis and periodontitis, were said to be foci of infection predisposing to systemic diseases. The theory fell into disrepute when extraction of teeth was found to be ineffective in the control of the systemic diseases for which patients sought relief. Although the focal infection theory1, as presented then, lacked sound scientific evidence to back it up, the theory is being revisited in periodontal medicine with the quest to answer the following questions:

1. Can bacterial infection of the periodontium commonly known as periodontitis, have an effect remote from the oral cavity?

2. Is periodontal infection a risk for systemic diseases or conditions that affect human health? 1

Many studies have since been done in order to either establish or disprove any link between periodontal and systemic diseases2^-6. D’Aiuto et al,4 carried out a longitudinal single blind pilot intervention trial with 6 months’ follow-up among 94 patients. The authors excluded patients known to have systemic diseases involving the cardiovascular, respiratory and renal systems. Medical history, standard clinical periodontal parameters, blood and microbial samples were collected at baseline, followed by a periodontal treatment phase done by a periodontist. The patients were re-examined 2 and 6 months after the completion of the treatment. The authors then concluded that effective control of periodontal infection reduced the serum inflammatory markers in the population under study, indicating that there was a causal link between periodontitis and the systemic inflammatory status 4.

Blum et al3 studied the effect of periodontal care on the endothelial function among 22 patients consisting of 12 women and 10 men. Baseline data obtained included the measurement of the periodontal health status and measurement of the arterial diameter in millimeter using pulsed Doppler. Then each of the participants was treated with scaling and root planing followed by the use of antibiotics for one week. The procedure for data collection was again repeated 6 months after the initial periodontal treatment. The authors reported that there was a significant improvement in the periodontal health of the subjects after 6 months of treatment. They concluded that periodontitis might be an insidious cause of endothelial dysfunction and future cardiovascular events. In addition, they indicated that treating periodontitis might improve endothelial function, reverse endothelial dysfunction in patients with severe periodontitis and prevent future cardiovascular disease3. There are some studies with contrary results that also assessed possible relationship between periodontal disease and cardiovascular risk factors using hypertension as the entry point. D’Auito et al, reported higher prevalence of hypertension among those with moderate periodontitis than those with the severe form of the disease7. Another study conducted among health professionals also reported that there was no statistically significant relationship between periodontal disease and hypertension8. Therefore, we carried out this study to determine possible relationship between periodontal disease, hypertension and arterial diameter.

Patients and Methods

A cross sectional study of 100 consecutive subjects that were referred for echocardiogram in the Department of Internal Medicine, University College Hospital, Ibadan, Nigeria were recruited for the study. The inclusion criterion was that each patient should have at least 20 teeth remaining in their mouth. Cigarette smokers and pregnant women were excluded from the study. They were grouped into their respective socio-economic classes according to the classification by Famuyiwa et al9. Ethical approval was obtained from the UI/UCH Institutional Review Committee before the commencement of the study.

Periodontal assessment

The oral hygiene status of the respondents was assessed using the Simplified Oral Hygiene Index [OHI-S]10, while the periodontal parameters and treatment needs were assessed using the Community Periodontal Index of Treatment Needs (CPITN)11.

Assessment of blood pressure

The blood pressure of each of the subjects was measured with the aid of a mercury sphygmomanometer and a stethoscope after the subject had been seated quietly on a chair for at least 5 minutes. The sitting position during the measurement was such that the feet of the subjects were comfortably on the floor, their backs rested on the chair and their right arm supported on a table. The blood pressure of the subjects was classified according to the recommendation by Chobanian et al12.

Body Mass Index

The height of each individual was measured without shoes on a stadometer in meters while the weight was measured in kilograms with a body weight scale. The body mass index was then calculated and the respondents classified according to the WHO criteria 11. The waist and hip circumferences were measured to the nearest centimetres with a tape rule.

Carotid Intima Media Thickness (CIMT) measurement

The carotid artery thickness in each subject was evaluated with high resolution B- and M-mode ultrasonography using Toshiba Xario (model UJUR-6608; Toshiba Medical System, Tokyo, Japan) ultrasound imaging system with a 7.5MHz linear array transducer. All images were acquired and read by a single trained and experienced ultrasonographer who was blinded to the subjects. This was conducted in the echocardiography suite of a teaching hospital under standardised conditions. The common carotid, carotid bulb and internal carotid were scanned bilaterally, in longitudinal and transverse projections to identify the far wall’s thickest carotid intimal media thickness (CIMT) and the average value was used for analysis. Using the automated edge detection tracing technique, the maximum intima media thickness from the leading edge of lumen-intima to the leading edge of media-adventitia was measured in still images at the end of diastole triggered by electrocardiographic recording. The mean IMT was computed as the average IMT on both sides.

Data Analysis

Data analysis was done using Statistical Package for Social Sciences (SPSS) version 14 for frequencies, cross-tabulation and calculation of mean values for variables. Statistical significance was inferred at p< 0.05.

Results

The study included 100 subjects made up of 45 (45.0%) males and 55 (55.0%) females with a male/female ratio of 1:1.2 and their age ranging from 20 – 88 years with a mean of 51.0 ± 13.6 years. Table 1 is the socio-economic classification of respondents, with 10(10%) of them classified as executives, 39(39%) civil servants and 5(5%) of them were students. In all, 6(6.0%) patients were diabetic while 70(70%) were hypertensive – all of them well controlled; 43(43%) patients indicated they were undergoing some stressful conditions while 57(57%) were not under any stress in their life during the study.

Table 1. SOCIO-ECONOMIC CLASSIFICATION OF RESPONDENTS*.

Socio-economic classes	Frequency (%)
Executives	10 (10)
Civil Servants	39 (39)
Semi-skilled	8 (8)
Unskilled	25 (25)
Retiree	13 (13)
Students	5 (5)
Total	100 (100)
*based on the classification of Famuyiwa et al9

Table 2 shows the periodontal status and treatment needs of respondents, with none of them having healthy gingiva (community periodontal index score of zero) or 1 (gingival bleeding) as their highest score, which translated to none of the subjects having treatment need of 1 (TN – 1); 15(15%) of them required complex periodontal care, while all of them needed prophylaxis. The systolic blood pressure of the subjects ranged from 98 – 210 mmHg (mean 133.1 ± 15.0) and 60 – 136 mmHg (mean 84.6 ± 6.4 mmHg) for diastolic blood pressure (DBP). Table 3 shows the mean blood pressure of respondents and an assessment of the systolic blood pressure (SBP) revealed that 13(13%) of the respondents had normal blood pressure while 16 (16%) had their readings within the stage 2 hypertension range. Assessment of the DBP revealed that 25(25%) had normal readings, while 15(15%) had readings in the range of stage 2 hypertension. Patients in the age group 20 – 30 years had a mean SBP of 113.1 ± 11.1 mmHg and mean DBP of 75.8 ± 7.2 mmHg and those older than 60 years of age having corresponding mean values of 147.8 ± 19.8 mmHg mean SBP and 90.0 ± 13.6 mmHg mean DBP respectively. Forty–nine (49%) of the subjects had poor oral hygiene, while the remaining 51(51%) had fair oral hygiene. Mild gingival inflammation was seen in 47(47%), 48(48%) had moderately severe gingival inflammation and 5(5%) had severe gingival inflammation.

Table 2. COMMUNITY PERIODONTAL INDEX (CPI)- PERIODONTAL DISEASE STATUS AND TREATMENT NEEDS OF RESPONDENTS.

		CPI CODES	SCORES
I	Percentage of persons who have as highest score	0	0
		1	0
		2	37
		3	48
		4	15
II	Mean number of sextants with	0	0.37
		1+2+3+4	0.50
		2+3+4	3.16
		3+4	1.59
		4	0.38
		X	Nil
III	Treatment Needs (TN)	Oral hygiene Instructions (TN 1)	0
		Prophylaxis (TN 2)	100
		Complex care (TN 3)	15

Table 3. MEAN DISTRIBUTION OF THE BLOOD PRESSURE OF RESPONDENTS ACCORDING TO THEIR AGE GROUPS.

		Frequency	%	Systolic B.P (mmHg)		Diastolic B.P (mmHg)
				Mean	SD	Mean	SD
Age group (Years)	20 – 30	9	9.0	113.1	11.1	75.8	7.2
	31 – 40	11	11.0	121.5	22.5	80.1	19.5
	41 – 50	27	27.0	139.2	19.4	90.6	14.4
	51 – 60	29	29.0	143.7	19.0	86.4	12.1
	> 60	24	24.0	147.8	19.8	90.0	13.6
		CIMT		Waist circumference		Hip circumference
		Mean	SD	Mean	SD	Mean	SD
Age group (Years)	20 – 30	0.527	± 0.145	83.22	± 6.89	89.87	± 13.73
	31 – 40	0.591	± 0.193	75.73	± 23.11	88.36	± 25.00
	41 – 50	0.758	± 0.281	87.61	± 24.26	94.70	± 23.97
	51 – 60	0.925	± 0.298	92.17	± 21.86	100.79	± 25.07
	> 60	1.060	± 0.280	88.92	± 21.17	95.83	± 21.51
			Frequency	%
Body Mass Index	< 18.5	Underweight	3	3.0
	18.5 – 24.9	Normal	37	37.0
	25.0 – 29.9	Overweight	35	35.0
	≥ 30.0	Obese	25	25.0

A Pearson correlation test was conducted to find the relationship between cardiovascular risk factors such as BMI, waist circumference, blood pressure and the mean CIMT and the periodontal parameters. This revealed that there was no statistically significant relationship between the worst community periodontal index (CPI) score and any of the cardiovascular risk factors that were assessed. There was a statistically significant relationship between waist circumference of respondents and their gingival index (P<0.005), while the systolic blood pressure was statistically related to both oral hygiene status (0.000) and the gingival index (0.002) of the respondents (Table 4). Furthermore, a multiple linear regression was performed to identify predictors of the cardiovascular risk factors among the periodontal parameters, and it was found out that adjusting for age, none of the periodontal parameters could significantly predict any of the cardiovascular risk factors that were considered.

Table 4. COMPARATIVE ANALYSIS OF CARDIOVASCULAR RISK FACTORS WITH PERIODONTAL PARAMETERS OF RESPONDENTS.

		PERIODONTAL PARAMETERS
		Simplified Oral Hygiene Index	Gingival Index	WORST CPITN SCORE
CARDIOVASCULAR RISK FACTORS
Body Mass Index	Pearson Correlationp-value	0.0640.526	-0.0030.980	0.1180.241
Waist Circumference	Pearson Correlationp-value	-0.0200.840	0.278**0.005	0.0330.743
Systolic Blood Pressure	Pearson Correlationp-value	0.389**0.000	0.312**0.002	0.1430.157
Diastolic Blood Pressure	Pearson Correlationp-value	0.256*0.010	0.247*0.013	0.0370.712
Mean CIMT	Pearson Correlationp-value	0.249*0.012	0.230*0.021	0.0980.333
** Correlation is significant at the 0.01 level (2-tailed)
* Correlation is significant at the 0.05 level (2-tailed)

Discussion

The relationship between chronic periodontitis and cardiovascular diseases is largely equivocal. Some authors strongly posit from their studies that a statistically significant relationship exists between these two conditions3,6,14^-16. Based on their findings, the link between the two diseases has been explained by the inflammatory mechanisms associated with periodontal lesions, locally or systemically, that will influence the initiation or propagation of atherosclerotic lesion. The lesion may be produced by systemic or locally produced inflammatory cytokines and chemotactic agents that may cause up-regulation of adhesion molecules, which promotes interaction with leucocytes. The leucocytes then migrate into the intimal layer of the artery17. The mean blood pressure tends to increase with the age of the subjects and this was statistically significantly related to their oral hygiene (P<0.000 for SBP) and gingival status (P<0.002 for SBP).

The current study found no statistically significant relationship between the worst community periodontal index (CPI) scores and any of the cardiovascular risk factors that were assessed (Table 4). It is important to note the limitation inherent in this observation-- the limited value of CPITN in measuring periodontal status. Despite the limitation, the finding corroborated previous reports. In a review of a vast database of over 10,000 participants from the Third National Health and Nutrition Examination Survey of 1988-1994, the authors concluded that “no consistent association between periodontal status and high density lipoprotein cholesterol was detectable ”18.

The current study found a significant relationship between waist circumference of respondents and their gingival index. The finding was consistent with a recent report of a significant relationship between gingival index, CPI, waist circumference and overall abdominal obesity 19,20. It is noteworthy however that the authors included a cautionary note, they agreed that the “positive association was consistent and coherent with a biologically plausible role for obesity in the development of periodontal disease.” They however cautioned that “with few quality longitudinal studies, there is an inability to distinguish the temporal ordering of events, thus limiting the evidence that obesity is a risk factor for periodontal disease or that periodontitis might increase the risk of weight gain”.

The relationship between both the blood pressure and CIMT with oral hygiene and gingival index was explored and found to be significant in the current study. The reason for the exploration is based on the premise that mediators of chronic inflammation in periodontitis support the initiation and propagation of artheromatous plaques.

The scientific argument involving the role of pro-inflammatoiry cytokines and the up-regulation of adhesion molecules as posited earlier support a possible mechanism and has been corroborated by several studies. However, this academic position of possible mechanisms of a causal link between chronic periodontitis and cardiovascular events failed to stand the scrutiny of an expert committee constituted at the instance of the American Heart Association. It is noteworthy that after the review of about 500 journals, the expert committee failed to establish a causal link between the two entities21.

The American Heart Association in conjunction with dentists and infectious disease experts issued a statement describing a cause and effect relationship between periodontal disease and cardiovascular disease, or claim that dental treatment may prevent heart attack or stroke were "unwarranted," at this time,” This position does not however preclude further research into this phenomenon which inform the rationale behind the current study.

What then is the position of the current study? Should all the findings be discarded in light of the position paper by the American Heart Association? May be not. It is however humbling to note that on adjusting for age in the current study, none of the periodontal parameters could significantly predict any of the cardiovascular risk factors that were considered.