Nutrition and Oral Medicine (Nutrition and Health)

Chapter 5 / Bidirectional Impact 71without other risk factors for elevated CRP. These results are supported by another studyexamining the Atherosclerosis Risk in Communities (ARIC) population (77). The ARICstudy was designed to investigate the etiology and natural history of atherosclerosis andclinical cardiovascular diseases in four US communities. In that investigation, subjectswith periodontal disease were twice as likely to have elevated CRP levels among thosepersons with a low BMI but not among those with a high BMI, suggesting that if CRPproduction is stimulated by other causes, the stimulation coming from periodontal diseasemay be influenced by other factors and not add a further increment in its values (77).At least one other study, however, failed to show increased CRP levels in subjects withperiodontal diseases (78), although methodological limitations may be responsible.Recent studies suggest that even modest elevations in CRP levels may increase the riskfactors for cardiovascular diseases. Periodontal disease-induced increases in CRP levelsmay be just enough to constitute a risk for cardiovascular diseases. Since other inflammatorymarkers have been found to be associated with cardiovascular disease, these arealso being investigated to determine a possible link between periodontal and cardiovasculardiseases.Numerous association studies have been conducted to examine the relationshipbetween periodontal disease and cardiovascular events. Some of these investigationshave suggested a clinically important relationship (79,80); however, other studies havenot found an association (81–83), thus questioning the causal effect of periodontaldisease in the pathogenesis of the cardiovascular diseases. These inconsistencies acrossstudies may result from the fact that both study populations and methodologicalapproaches varied by investigation. In addition, when the strength of the relationshipis in the slight to moderate range, it is expected that some studies would not show anyassociation. A recent meta-analysis of nine cohort studies found a relative risk of 1.19,a result consistent with a relatively weak relationship (84). Interestingly, several studiesincluding the meta-analysis found that in younger subjects the association betweenperiodontal disease and cardiovascular disease was greatest in younger individuals(83,85). These results are consistent with the suggestion that periodontal disease maybe an important risk factor for cardiovascular disease in some but not all individuals.Continued work is necessary to determine what factors in patients with periodontaldisease additionally predict risk for cardiovascular disease as well as alternate explanationsfor the observed association between periodontal and cardiovascular disease (86).Future studies should explore confounding factors (i.e., shared risk factors for periodontaland cardiovascular diseases) that could explain the observed associations betweenperiodontal and cardiovascular diseases. Additional prospective, case-controlled studiesare needed to clearly demonstrate that proposed associations are real and independent ofcommon risk factors.2.2.4. PREGNANCY AND PRETERM BIRTHAn estimated 10,000 babies are born each day in the United States. Of these babies,800 are born at low birth weight and 150 at very low birth weight (87,88); more than 50%will die, and a significant number will have permanent deficits. A growing body ofevidence has revealed an increased risk for premature birth in women with varyingdegrees of periodontal disease (89–92). As discussed in the preceding section on cardiovasculardisease, the cytokines and other inflammatory mediators produced in gingi-