AbstractIntroduction: Oropharyngeal colonization with pathogenic organisms contributes to thedevelopment of ventilator-associated pneumonia (VAP) in intensive care units (ICUs). Oralhygiene care (OHC) is a very effective method for reducing the risk of VAP in these patients.This study aimed to evaluate recent OHC strategies to decrease VAP.Methods: Randomized clinical trials (RCTs) published in the PubMed, Scopus, Embase,Cochrane Library, and Web of Science databases from inception to September 10, 2020 werereviewed to compare the effects of selective oropharyngeal decontamination (SOD) on theincidence of VAP in adult patients requiring mechanical ventilation.Results: Out of a total of 1098 articles reviewed, 17 eligible studies were included for finalanalysis. The results showed that the use of chlorhexidine for oropharyngeal decontaminationreduces the incidence of VAP. However, it had a small effect on gram-negative resistant bacteria.Also, it was observed that the combined use of colistin and chlorhexidine was more effectivethan chlorhexidine alone in preventing VAP. The results of studies on the use of toothbrushes toreduce the incidence of pneumonia are unclear since they used chlorhexidine at the same time.However, tooth brushing is one of the best ways to maintain oral hygiene. Using povidoneiodine,Nanosil, and non-absorbable topical antibiotics reduced the incidence of VAP, whileIseganan did not show a significant effect in this regard.Conclusion: The prophylactic use of topical bactericidal agents in critically-ill patients is effectivein reducing the incidence of VAP. However, the use of non-absorbable topical antibiotics ismore effective than other methods in oropharyngeal decontamination.