January 19, 2020
Arteagoitia I, Andres CR, Ramos E
Tooth extractions almost always cause bacteremia due to the large presence of bacteria in the oral cavity.4 The importance of this transient bacteremia in the pathogenesis of infectious endocarditis (IE) and prosthesis infection and whether it contributes to local infection after oral surgeries8 are controversial. Studies have shown that chlorhexidine mouthwash has a strong antimicrobial effect on saliva microflora3,5 and supragingival plaque.9
Chlorhexidine remains the gold standard to which other antiplaque and gingivitis agents are compared. Its effectiveness can be attributed to it bactericidal and bacteriostatic effects and its substantivity within the oral cavity. While other agents may possess one or more of these properties, few possess all three and perform so well.
The antimicrobial properties of chlorhexidine are attributed to its di-cationic structure, and this same property is the basis of its most common side effect, extrinsic tooth staining. By understanding the biochemical properties of chlorhexidine, an appreciation for the efficacy and use of chlorhexidine can be developed. It is only in such a way that the efficacy can be maximized and the side effects minimized, allowing chlorhexidine to remain the gold standard.7
One should assume that antimicrobial mouthwashes used by the patient before a dental procedure should decrease the number of microorganisms introduced into the patient's bloodstream. However, the scientific evidence is not clear.
The aim of this study was to test the null hypothesis that there would be no difference in the incidence of bacteremia following dental extractions in patients treated with or without chlorhexidine.
Scientific evidence is not clear regarding the use of antimicrobial mouth rinse before dental extraction to reduce bacteremia.
This meta-analysis combines data across studies to estimate antiseptic treatment effect with more precision than in a single study. Results showed that out of 18 studies, eight eligible trials with 523 participants were selected, 267 in the experimental group and 256 in the control group with a risk ratio of 0.882. The number needed to treat was 16.1
The main limitation of this meta-analysis is the small number of included studies and their small patient population, which could influence the results. More randomized trials would be required to increase the accuracy of the results. It should also be considered that only one of the primary studies11 reported a statistically significant result and that the overall result can only be generalized to populations with the same characteristics as the populations in the studies.
The quality of the included studies can also be a handicap in the results of the meta-analysis. The methodological quality of randomized controlled trials (RCTs) is commonly evaluated in order to assess the risk of biased estimates of treatment effects.
The treatment guidelines used in the different trials included in the meta-analysis differ slightly, although the use of a 0.20% chlorhexidine mouthwash for 1 minute prior to extraction is the most common recommendation. However, the time of blood sample extraction was different in each study. In some cases, there was only one sample, while in others, serial blood sample extractions were done post-extraction. These discrepancies should be taken into account when analyzing the results and were considered when the response variable had to be defined in our study.
Bacteremia follows an upward trend post-extraction, peaks at 1±5 minutes, and then drops for up to 15 minutes10,6, which indicates that the post-extraction time when the sample is taken is essential. Therefore, we decided to exclude the values of all measurements performed more than 10 minutes post-extraction.
Although it was not in the objective to analyze the bacteria involved in bacteremia, the metaanalysis confirmed that the bacteria most commonly isolated in the cultures was the viridians group streptococci, except for the trial performed by Ugwumba12 in which the most common bacteria was Staphylococcus aureus.
Over 700 types of bacteria have been identified in the oral cavity, and over 170 in post-extraction blood cultures; however, the bacteria directly related to IE pathogenesis is the viridans group streptococci.2 Therefore, any IE prevention protocol should be aimed at preventing infection by this streptococcus.
It is well-known that tooth extraction is associated with peaks of bacteremia, although most of these peaks do not progress to a clinical infection. It would be important to demonstrate that a disinfectant, possibly chlorhexidine, reduces the risk of clinical infection after dental extractions, but no articles have been published on this subject.
Antiseptics could reduce the incidence of bacteremia. Pre-extraction chlorhexidine treatment significantly reduces bacteremia cases by 12%. The number necessary to treat to prevent just 1 case of bacteremia is 16. Chlorhexidine is an economic and easy to use antiseptic with no evidence of adverse reactions.
The ultimate purpose of this revision is to help the clinician make a decision in daily practice. With the results obtained from combining the few quality studies available, we can state there is evidence to support the efficacy of using chlorhexidine pre-extraction to reduce bacteremia. More studies on this topic are required to achieve accurate conclusive results to enable decision making based on a sufficient number of quality clinical trials.