A single well-conducted case-control study provides direct evidence for this recommendation.39 Case-control studies are appropriate to answer questions regarding risk factors or etiology. Study enrollment consisted of 339 patients with prosthetic hip or knee infections (cases) and 339 patients with hip or knee arthroplasties without infection (controls) hospitalized on an orthopaedic service during the same time period. The comparison between these groups was for differences in dental visits (exposure) in terms of high and low-risk dental procedures, with and without antibiotic prophylaxis. Results reported as odds ratios with 95% confidence interval, demonstrate no statistically significant differences between groups. Neither dental procedures nor antibiotic prophylaxis prior to dental procedures were associated with risk of prosthetic hip or knee infections. The authors performed a sample size calculation and withdrawals were low, minimizing attrition bias. The prospective nature of this study minimized recall bias. Additionally, blinding of the treatment group to those assessing outcomes limits detection bias.
Although this one study of direct evidence was of moderate quality, it did have limitations. The authors conducted covariate analysis on some subgroups of higher risk patients. The number of patients in these subgroups, however, was relatively small, and there is insufficient data to suggest that these patients are at higher risk of experiencing hematogenous infections.
There is high quality evidence that demonstrates the occurrence of bacteremia with dental procedures. Historically, there has been a suggestion that bacteremias can cause hematogenous seeding of total joint implants, both in the early postoperative period and for many years following implantation. It was felt that the most critical period was up to two years after joint placement. In addition, bacteremias may occur during normal daily activities such as chewing and tooth brushing. It is likely that these daily activities induce many more bacteremias than dental procedure associated bacteremias. While evidence supports a strong association between certain dental procedures and bacteremia, there is no evidence to demonstrate a direct link between dental procedure associated bacteremia and infection of prosthetic joints or other orthopaedic implants. Multiple studies of moderate and high quality evidence suggest that antibiotic prophylaxis decreases the risk of dental procedure associated bacteremias. However, dental procedure associated bacteremia is a surrogate outcome for prosthetic joint infection. Surrogate outcomes may or may not relate to a clinically relevant patient outcome. Of additional concern is a positive surrogate outcome (e.g. reduced bacteremias) that could mask a negative patient-centered outcome (e.g. implant infection).
This recommendation is limited to patients with hip and knee prostheses because the single study of direct evidence included only patients with these types of orthopaedic implants. There is no direct evidence that met our inclusion criteria for patients with other types of orthopaedic implants.