Objective To determine the adherence of dental providers to the 2007 American Heart Association (AHA) infective endocarditis prevention guidelines regarding antibiotic drug administration before invasive dental procedures. Patients and Methods The study included all adults (≥18 years old) with a moderate-risk (MR) or high-risk (HR) cardiac condition who received dental care at participating dental offices from January 1, 2005, through June 1, 2015, in Olmsted County, Minnesota. Data collected included the date and type of dental procedure performed and receipt of antibiotic prophylaxis (AP). Results A total of 1351 patients underwent 8854 dental visits at participating dental offices during the study period; 1236 patients had an MR cardiac condition and 115 had an HR condition. The percentage of visits in which antibiotic drugs were used for indicated dental procedures in the MR group declined from 64.6% before to 8.6% after publication of the 2007 AHA guidelines (P<.001); for the HR group, AP declined from 96.9% before to 81.3% after publication of the guidelines (P=.02). Conclusion In this historical cohort in Olmsted County there was a statistically significant reduction in AP in the MR group before invasive dental procedures. In addition, there was an unanticipated significant reduction in AP in the HR group after publication of the 2007 AHA guidelines. These findings can be used to provide feedback and education to medical and dental professionals who are involved in decision making regarding the use of dental prophylaxis for their patients.