They also reflect the varied microbiological meth- odologies used in these studies (eg, culture-based rather than molecular), with the recognition that many bacterial species clearly enter the bloodstream but are not cultivable and there- fore not recorded.44,49,57 Of greatest importance is the subset of bacterial species reported in blood cultures after dental proce- dures that are known to cause IE.66 Finally, the varied method- ologies and results make it impossible to differentiate among procedures with regard to their risk for causing bacteremia. The collective published data from adult and pediatric stud- ies suggest that the vast majority of dental office visits result in some degree of risk for bacteremia, and the emphasis has therefore changed from a focus on specific dental procedures to a focus on gingival manipulation of any kind.3 The role of duration of bacteremia as a risk factor for IE is uncertain. Older guidelines and some pediatric bacteremia studies reported positive blood cultures for only short peri- ods (10 15 minutes) after tooth extraction(s),56,67 but the vast majority of studies did not include blood draws beyond that time frame. A study of teenagers and adults demonstrated that blood cultures can remain positive for upwards of an hour after a dental procedure,48 and a pediatric study reported that blood cultures can remain positive for >45 minutes.46 The incidence of positive blood cultures drops sharply after the procedure such that the period of risk rarely exceeds 30 minutes. A few studies report the magnitude of bacteremia in chil- dren after dental procedures,43,44,47,49,56,57 often using cell lysis filtration or centrifugation rather than conventional broth- based methods. Cell lysis methods can be problematic, being time consuming, expensive, less sensitive for some oral bacte- rial species, and slower in detection, and having an increased risk of contamination. 