There's very little doubt that periodontal disease and several forms of heart disease have a causal relationship.
Infection anywhere in the body elicts certain "acute phase reactants", which need not be so "acute" in chronic disease, but might be sustained at abnormally high levels. Certain of these acute phase reactants promote groth of the muscular lining of the heart vessles into the lumen...channel..., creating a substrate for obstruction of blood flow. In addtion, other reactants contribute to the formation of plaque - arteriosclerosis - in the lumen of the vessel.
The most notorious relationship between poor dentition and the heart is endocarditis. Under normal circumstances, one's system is flooded by mouth pathogens on brushing the teeth. When there is a chronic infection in the mouth, such as periodontitis, the bulk and nature of these pathogens increases, and they may be released spontaneously or by manipulation of the teeth, to settle on...and erode...a heart valve. Conversely, a malformed or damaged heart valve invites organisms to establish themselves upon it...again causing acute endocarditis. Nortoriously difficult to treat medically, and prone to cause valve obstruction or insufficiency as the disease progresses, endocarditis often leads to replacement of the native valve by a prothetic one. BUT...priot to valve replacement...in either scenario... diseased dentition must be corrected. In advanced periodontal disease, this usually results in the extraction of all teeth, and the placing of dentures.