Endodontic surgery causes a transient bacteremia, but this does not represent a problem in healthy patients because oral tissues are highly resistant to the invasion of micro-organisms. Infections after endodontic surgical procedures, as after periodontal surgery, are extremely rare, so antibiotic therapy is seldom required and cannot be justified as part of the routine postsurgical regimen. However, certain high-risk patients must have prophylactic antibiotic coverage following AHA recommendations. This group consists of patients with:
- prosthetic cardiac valves
- previous bacterial endocarditis
- cardiac transplantation with valvulopathy
- specific congenital heart disease: (a) unrepaired cyanotic conditions with or without palliative shunts/conduits, or other prosthe-ses; (b) within 6 months of repair using prosthetic material; (c) repair of any duration with residual adjacent defect or shunt.
Patients who no longer require prophylactic antibiotic are those with:
- mitral valve prolapse
- rheumatic heart disease
- bicuspid valve disease
- calcific aortic stenosis
- ventricular septal defect or atrial septal defect (except within 6 months of repair or with a residual peri-prosthetic defect)
- hypertropic cardiomyopathy
- intracoronary stents.
The organisms that produce oral infections most frequently are the normal flora of the oral cavity. According to Peterson, 70% of oral infections result from mixed aerobic-anaerobic flora, 25% from pure anaerobes, and 5% from aerobes only.
The rationale for initial therapy is to choose an antibiotic with the most specific and narrowest spectrum possible, yet sufficient to encompass the aerobes and anaerobes that usually cause dental postsurgical infections. Narrow-spectrum antibiotics are more effective against specific groups of susceptible micro-organisms than broad-spectrum types, and with less alteration of the normal microflora and thus lower potential for superinfections31.
Penicillin is the initial drug of choice because it is effective against Streptococci and Bacteroides. Cephalosporins are not substitutes for penicillin if these agents are effective, but they are indicated for infections that prove resistant to penicillin or in patients allergic to penicillin and amoxicillin. Clindamycin is especially effective against the anaerobic species of Bacteroides.
Amoxicillin and ampicillin have the disadvantage of broader spectrum of activity and less effectiveness against the specific organisms that most likely cause postsurgical infections; but nowadays, they are more used than penicillin.
Tetracyclines are also poor alternatives to penicillin because of limited activity against the primary target organisms, and they are most likely of all the antibiotics to cause superinfections with bacteria, fungi and yeasts3132.
Metronidazol is a specific antibiotic against anaerobes like Bacteroides.
Antibiotic oral regimens do not show clear clinic effects until the second or third day, and they must be continued for about 48 hours after resolution of infection signs and symptoms. When a faster effect is required, intramuscular administration can be used.