B

Randomized trials and meta-analyses show that adding chlorhexidine antiseptic to routine oral care significantly lowers the incidence of ventilator-associated pneumonia, whereas tooth-brushing alone (manual or powered) or povidone-iodine rinses do not offer the same benefit [Koeman, 2008, PMID 18461894; Carvajal, 2010, PMID 20557902].