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                        Discussion 
                            Cross-sectional 
                          studies performed with convenience samples, such as 
                          this study, cannot be generalized to the entire population. 
                          However, they can identify as risk indicators those 
                          parameters that are significantly associated with the 
                          condition being investigated (in this case, CHD). Whether 
                          these risk indicators prove to be risk factors (that 
                          is, causally related) remains to be demonstrated in 
                          prospective studies performed with a more representative 
                          population.   
                          The results of this cross-sectional study confirmed 
                          those of previous studies conducted with younger subjects 
                          that showed a significant association between dental 
                          disease and CHD.1-6 
                          We found that the subjects with one to 14 teeth were 
                          most likely to have CHD, and observed this association 
                          in subjects in both independent living and dependent 
                          living circumstances.    Chronic 
                          infection hypothesis. The importance of having 
                          only a few teeth in these subjects seems to be related 
                          to the greater periodontal morbidity of their teeth�that 
                          is, a higher percentage of teeth with attachment loss�to 
                          poorer oral hygiene as assessed by higher plaque scores, 
                          and to less-frequent visits to the dentist (Table 
                          3). In the multivariate analysis, a high BANA test 
                          score was positively associated with CHD in both the 
                          all-subjects dentate model (Table 
                          4) and the independent living dentate model (Table 
                          5).   
                          The BANA test detects the presence of an enzyme(s) that 
                          hydrolyzes the synthetic trypsinlike substrate benzoyl-DL-arginine-naphthylamide, 
                          or BANA, in plaque samples.16 
                          Of more than 60 plaque bacterial species that have been 
                          tested, only P. gingivalis, Treponema denticola and 
                          Bacteroides forsythus always exhibit strong BANA activity, 
                          although some species, like the Capnocytophaga species, 
                          occasionally exhibit weak BANA activity.16 
                          The three strongly BANA-positive species are invariably 
                          elevated in plaque samples removed from teeth with periodontal 
                          pathology.17-20 
                          Thus, a higher plaque BANA score would indirectly indicate 
                          that these periodontopathic species are elevated on 
                          the tooth surfaces of subjects with CHD. This implies 
                          some degree of periodontal pathology, which was documented 
                          by the significantly higher PBS in the multivariate 
                          model of independent living dentate subjects (Table 
                          5).   
                          These BANA-positive species are gram-negative anaerobes, 
                          so that their elevation in the dental plaque would support 
                          the various hypotheses linking chronic bacterial infection 
                          to CHD via effects mediated by endotoxins or lipopolysaccharides, 
                          or LPS.21-23 
                          The confrontation of the varied host-defense mechanisms 
                          with these LPS-containing invaders may lead to the supplementation 
                          of serum cytokine levels with inflammatory mediators 
                          derived from this confrontation,24 
                          which could contribute to the chronic inflammatory process 
                          that leads to increased levels of C-reactive proteins 
                          in the serum.8 
                          LPS has long been known to promote atherosclerosis and 
                          thrombus formation.25  
                           
                          An additional factor in this process could be an exaggerated 
                          host response to LPS, mediated by the presence of hyperresponsive 
                          monocytic cells.6 
                          Certain patients with early-onset perio-dontitis, refractory 
                          periodontitis or insulin-dependent diabetes have peripheral 
                          blood monocytes that secrete threefold to 10-fold greater 
                          amounts of PGE2, IL-1b and TNFa when exposed to LPS 
                          in vitro. These people would react to the penetration 
                          of gram-negative bacteria, such as the BANA-positive 
                          species, from the subgingival plaque into the periodontium 
                          by the overproduction of cytokines that could leak from 
                          the gingival tissue into the general circulation and 
                          have an effect on distant organs.   
                          Other studies have proposed a chronic infection hypothesis 
                          involving dental disease as a possible risk factor for 
                          the development of a cardiovascular event.21,22 
                          In their prospective study, Mattila and colleagues3 
                          were able only to associate dental infections as measured 
                          by the TDI and a history of myocardial infarction with 
                          a subsequent acute myocardial infarction. They then 
                          showed that there are elevated levels of von Willebrand 
                          factor antigen in subjects with an elevated TDI,26 
                          which could reflect increased endothelial cell damage 
                          induced by the LPS derived from the gram-negative dental 
                          plaque flora. Grau and colleagues7 
                          have shown that the TDI may be associated with an increased 
                          risk of cerebral vascular ischemia.    Missing 
                          teeth. The number of missing teeth was independently 
                          associated with CHD in the two epidemiologic surveys 
                          that randomly selected their study populations,4,5 
                          but these studies did not distinguish between edentulous 
                          subjects and dentate subjects with many missing teeth. 
                          Our results indicate that in these elderly subjects, 
                          it is the presence of only a few teeth that is associated 
                          with CHD. When we divided our subjects into groups with 
                          one to 14 teeth and 15 to 28 teeth, the presence of 
                          one to 14 teeth was significantly associated with CHD 
                          in both the all-subjects and dentate subjects models 
                          (Table 4).  
                           
                          An indirect confirmation of the importance of having 
                          15 to 28 teeth in protecting against CHD was the relationship 
                          between the salivary levels of S. sanguis and CHD status. 
                          The significant negative association seen in all models 
                          (Table 4) 
                          can be explained by the fact that this organism is associated 
                          with teeth, and is among the best microbial colonizers 
                          on the tooth surface.27 
                               This 
                          organism is dominant in early plaque formation, so that 
                          people with good oral hygiene would have higher proportions 
                          of S. sanguis in the mouth. The more teeth in the mouth, 
                          the more likely that the salivary levels of S. sanguis 
                          would be higher. 
                          S. sanguis has been studied for its role in endocarditis,28,29 
                          and a platelet-aggregation-associated protein has been 
                          identified as a virulence factor because it interacts 
                          with platelets, promoting coagulation, or it may behave 
                          as a heat-shock protein, which, by causing an autoimmune 
                          response, could initiate the early atherosclerotic lesion.30 
                          Our findings do not support a role for S. sanguis in 
                          CHD in these older subjects, but it is possible that 
                          such interactions could have occurred earlier in their 
                          lives.   
                          Evidence in the literature suggests that edentulous 
                          people with and without dentures and dentate people 
                          with missing teeth change their eating habits after 
                          they lose their teeth.31,32 
                          They may avoid certain nutritious foods because of difficulty 
                          in chewing, and select high-calorie, high-fat foods 
                          whose consumption is recognized as a risk factor for 
                          cardiovascular disease.33 
                          But an additional feature of this dietary change that 
                          could be particularly relevant in those dentate subjects 
                          with one to 14 teeth is that dietary-induced elevation 
                          of serum low-density lipoprotein levels has been shown 
                          to increase monocytic responses to LPS.34 
                          These subjects would have both the dietary-induced sensitization 
                          of the monocytes and the plaque-laden teeth and gingivitis 
                          that could provide the LPS challenge to these cells.  
                           
                          The advanced age of our subjects might explain the absence 
                          of an association between edentulism and CHD in the 
                          logistic regression models, since people most susceptible 
                          to the linkage between edentulism and CHD may already 
                          be dead. This would be consistent with the National 
                          Health and Nutrition Examination Survey, or NHANES, 
                          data that showed that in males younger than 50 years 
                          of age, edentulism was 2.6 times more likely to be associated 
                          with death resulting from any cause.4  
                           
                          However, this explanation, as well as the chronic infection 
                          hypothesis involving dental infections, would not seem 
                          to explain why 53 percent of our edentulous subjects 
                          had CHD, unless these patients experienced their first 
                          heart attack while they had teeth. It is possible that 
                          by having had their teeth extracted, these people coincidentally 
                          had the tooth-related microbial challenge removed that 
                          had been a major contributor to the events leading to 
                          their heart attack. Edentulism in this sense would be 
                          protective, although in the younger subjects in the 
                          NHANES study, edentulism might have been a marker for 
                          rampant dental disease that could have predisposed them 
                          to CHD by the mechanisms described above.    Other 
                          significant findings. The possible protective 
                          role of daily alcohol consumption noted in the all-subjects 
                          model in this study has been observed by others.35 
                          The greater use of all types of medications was significantly 
                          associated with CHD in both the all-subjects and dentate 
                          subjects models. This was expected, as our subjects 
                          were taking many types of medications associated with 
                          old age and a diagnosis of cardiovascular and other 
                          diseases.36  
                           
                          It is not clear how a complaint of xerostomia could 
                          be such a powerful risk indicator for CHD. Xerostomia 
                          is a common complaint of older people,37 
                          and it has been associated with poor oral hygiene, the 
                          inability to chew and involuntary weight loss among 
                          both institutionalized38,39 
                          and independent older adults.38 
                          We have found that people with complaints of xero-stomia 
                          avoid crunchy (carrots), dry (bread) and sticky (peanut 
                          butter) foods, but not crumbly (cake) or chewy (red 
                          meat) foods.40 
                          This choice of foods could lead to the selection of 
                          the high-calorie, high-fat foods that are associated 
                          with obesity and CHD.33  
                           
                          The use of a convenience sample of older subjects for 
                          our analysis may explain why recognized risk factors, 
                          such as serum cholesterol levels, BMI, smoking status 
                          and diabetes, were not more prominent in the modeling 
                          procedure. The use of medications to control blood pressure 
                          or cholesterol levels was not included in our analysis; 
                          as these subjects were actively receiving treatment 
                          for CHD, this could explain why these risk factors were 
                          not associated with CHD.   
                          In other studies performed with convenience samples, 
                          the dental variables were significantly associated with 
                          CHD, whereas the classical risk factors such as cholesterol 
                          levels, alcohol consumption, BMI and hypertension were 
                          not.1-3,7 
                          Thus, our investigation, like others performed with 
                          convenience samples, cannot be generalized to the entire 
                          population, and because of the cross-sectional nature 
                          of our study, the oral health variables can at best 
                          be considered risk indicators. Despite these limitations, 
                          for this group of older veterans, our findings suggest 
                          that the oral health parameters may play an important 
                          role in the occurrence of CHD. We are following up these 
                          subjects to determine whether any of these dental parameters 
                          can be shown to be risk factors. | 
                       
                       
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                        | Results | 
                          Conclusion 
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