**6. Evidence of the efficacy of antibiotic prophylaxis**

Since the 1955 AHA statement, Ref. [2] antibiotic prophylaxis has been continuously recommended to clinicians for IE prevention among patients undergoing interventional medical procedures. Since that early paper, antibiotic prophylaxis for IE has been considered "good medical and dental practice" and it has been said that the "exact dosage and duration of therapy are somewhat empirical". Now, more than 50 years later, AHA experts continue to consider that the basis for the recommendations for IE prophylaxis are still not well established and that the quality of evidence is based on expert opinion, a few case-controlled studies, clinical experience and descriptive studies [11]. All these circumstances lead antibiotic prophylaxis against IE to be included in class C evidence (**Table 8**).


**Table 8.** Classification of the levels of evidence.

Despite this, intense research into this subject has been undertaken from three main perspectives:


*N* **%**

**Related to dental procedures (previous 3 months) 8 12** Tooth extraction 4 6 Scaling 1 1.5 Endodontics 1 1.5 No details 2 3 **Not related to dental procedures 60 88** Dental focus of infection (decay, fracture, trauma) 9 13.3 Dental focus of infection (no further details) 22 32.1 Periodontal disease 7 10.3 Endodontal and periodontal disease 12 17.5 Radiological dental infectious focus with no clinical lesion 9 13.3 Vigorous tooth brushing with frequent bleeding 1 1.5

**Table 7.** Infective endocarditis patients with identified oral and dental portals of entry (*n* = 68) [24].

sions than antibiotic prophylaxis on the incidence of IE of oral origin.

**6. Evidence of the efficacy of antibiotic prophylaxis**

prophylaxis against IE to be included in class C evidence (**Table 8**).

Level A Data derived from multiple randomised clinical trials or meta-analyses Level B Data derived from a single randomised trial or non-randomised studies

Level C Only expert consensus, case studies or standard of care

**Table 8.** Classification of the levels of evidence.

26 Contemporary Challenges in Endocarditis

These observations highlight the importance of maintaining oral hygiene in patients at highest risk of IE, and provide an important argument that dental care could have greater repercus-

Since the 1955 AHA statement, Ref. [2] antibiotic prophylaxis has been continuously recommended to clinicians for IE prevention among patients undergoing interventional medical procedures. Since that early paper, antibiotic prophylaxis for IE has been considered "good medical and dental practice" and it has been said that the "exact dosage and duration of therapy are somewhat empirical". Now, more than 50 years later, AHA experts continue to consider that the basis for the recommendations for IE prophylaxis are still not well established and that the quality of evidence is based on expert opinion, a few case-controlled studies, clinical experience and descriptive studies [11]. All these circumstances lead antibiotic
