Pathogenesis and prevention of native valve infective endocarditis in elderly dental patients.

Elderly dental patients are at risk of developing infective endocarditis. Increased longevity is associated with an increased prevalence of cardiac valvular disease and impairment of the immune system. Aortic stenosis commonly occurs in persons between 60 and 75 years of age. Degenerative calcification of the mitral valve ring leading to valve incompetency often develops in those over age 70 years. Men over the age of 60 years with mitral valve prolapse and systolic hypertension are at risk of infective endocarditis because the excessive haemodynamic load placed upon the abnormal valve causes extensive stretching of cusps and loss of valve surface endothelium. Dental procedures, that result in mucosal or gingival bleeding (most notably dental extractions, periodontal probing, scaling and surgery, endodontics and restorative procedures which extend below the gingival line), frequently produce a bacteraemia. Anaerobic strains of bacteria are isolated twice as frequently as aerobic strains. Antibiotic prophylaxis decreases the level of bacteraemia, prevents adherence of bacteria to the damaged valvular epithelium and suppresses the growth of those microbes that manage to adhere to the valve. The standard prophylactic regimen consists of amoxicillin 3g 1 hour before the dental procedure, then 1.5g 6 hours after the initial dose. Erythromycin is a good alternative for penicillin-allergic patients. Topical chlorhexidine 5 minutes before initiating dental therapy reduces the bacterial inoculum and the likelihood of endocarditis.