Introduction

Over the past 15 years, there has been an increasing number of papers showing an association between oral health, especially the extent and severity of periodontal disease, and a variety of systemic conditions. A list of the systemic diseases associated with poor oral health is shown in Table 1. The nature of the association is variable, but two recent systematic reviews have suggested that periodontal disease is a risk for coronary heart disease and an adverse pregnancy outcome.1,2

Table 1 Systemic conditions that have been reported to be associated with poor oral health
Full size table

If periodontal disease is a significant risk factor for a variety of systemic conditions, it does raise the important question of whether failure to address poor oral health increases the risk of patients succumbing to the various conditions outlined in Table 1 and their sequelae. The converse argument can also apply – that is, what impact does improving oral health have on general health? In this paper, both aspects of this paradigm will be considered.

Two retrospective studies have investigated the impact of poor oral health on the development of further coronary events.3,4 In the first of these studies 214 patients with a history of a myocardial infarction underwent a dental examination to ascertain their oral health status. No dental interventions were carried out and the patients were followed up for a period of seven years. About 25% of these patients experienced further coronary events with 32 of them proving fatal. Poor oral health left untreated was identified as a significant risk factor for future coronary events (p = 0.007). The second study investigated the relationship between bone loss and death from coronary heart disease (CHD). From this cohort of patients, 162 died of coronary events and the findings showed that smoking and bone loss at baseline were significant risk factors for mortality from CHD (RR = 2.7).

These two studies do illustrate that ignoring poor oral health can increase the risk of further coronary events, especially in those patients with a history of CHD. When this information is considered together with the conclusion from the meta-analysis, which showed that the incidence and prevalence of CHD were significantly increased in patients with periodontal disease, and other interventions to improve oral health, then periodontal intervention does become an important priority in the CHD patients.

The second aspect to consider is what impact does periodontal therapy or other dental interventions have on general health? From this perspective, three areas have been studied, notably diabetes, adverse pregnancy outcomes and various aspects of coronary heart disease. The latter have included the impact of periodontal treatment on surrogate markers of CHD.

Diabetes control

Two meta-analyses have considered the efficacy of periodontal interventions on glycaemic control in diabetic patients.5,6Both analyses showed that periodontal treatment does result in significant reduction in HbA(1c) levels, with those patients suffering from type II diabetes benefiting more than the type I patients.

Adverse pregnancy outcomes

Five intervention studies have investigated the effectiveness of periodontal treatment in reducing the risk of adverse pregnancy outcomes.7,8,9,10,11 Four of these showed a significant benefit of periodontal treatment with up to a 50% reduction in the incidence of an adverse pregnancy outcome, with one study showing no benefit.7,8,9,10 The difference in findings may be related to the ethnicity of the population studied or the timing of the periodontal intervention.

Coronary heart disease

A variety of so-called 'surrogate measures' have been used to evaluate whether periodontal treatment reduces the risk of CHD. Most have focused on C-reactive protein (CRP), which is a biomarker of systemic inflammation. Raised levels of CRP (>2.1 mg/l) are considered a risk for CHD. Periodontal treatment does reduce CRP levels by approximately 0.5 mg/l.12 Similarly, removing periodontically compromised teeth also significantly reduces CRP levels.13,14 Although such reductions are encouraging, it has not been established whether such reductions in CRP levels are cardioprotective.

More recently the outcomes of the periodontitis and vascular events study (PAVE) have been published.15 CRP was used as the surrogate marker in this investigation and the six-month evaluation showed no reduction in CRP levels. Further analyses of the data showed that obesity nullified the periodontal treatment effects on CRP levels.

Cholesterol

Raised levels of low density lipoprotein (LDL) cholesterol are recognised risk factors for atheroma formation. Peridontitis has been shown to be associated with raised levels of cholesterol.16,17 One study has demonstrated that intensive periodontal treatment does significantly reduce cholesterol levels.18 Long-term benefits of the effects of periodontal treatment on cholesterol levels need to be determined.

Vascular markers and endothelial function

Inflammation is the common factor linking periodontal disease with CHD. Vascular changes are essential to this shared association and several markers of vascular and endothelial functions have been evaluated in response to periodontitis and its treatment.

It has been shown recently that periodontal intervention improves vascular function as assessed by brachial artery flow mediated dilatation.19 This improvement is sustained for up to 180 days post-treatment. The improvement in brachial artery flow mediated dilatation was matched by changes in other markers of inflammation and vascular functions. Again, it needs to be established whether such benefits to the vascular system reduces the risk of coronary events.

Conclusion

There is increasing evidence that poor oral health, especially the extent and severity of periodontal disease, does increase the risk of a variety of systemic conditions. Studies are now focusing on establishing causality.

There is increasing evidence that treating periodontal disease does have a systematic effect and the long-term benefits of such treatment in preventing CHD remain to be determined.

Certainly patients who present with CHD should be advised of the association, but more importantly of the potential benefits that may arise if there is an improvement in their oral health.