Chitosan (CS) is a naturally occurring polysaccharide that is prepared by the deacetylation of chitin, which is mainly obtained from crab and shrimp shells. CS is generally regarded as non-toxic, biocompatible, biodegradable, and is intrinsically antibacterial in nature. In addition, CS has shown in different studies to prolong the residence time of drug-delivery systems at the site of drug absorption. In recent years, chitosan has been utilized widely in drug delivery and tissue engineering in the dental field. However, chitosan can only be dissolved when the pH is less than 6.5, which limits its antibacterial activity. Quaternized chitosan, which has quaternary amino groups introduced into the chitosan chain, is both a facile and effective method to render it soluble in water. Moreover, quaternized chitosan has cationic activity, bioadhesive properties, permeation enhancing effects, and high efficacy against bacteria and fungi even under neutral conditions. However, little research is available on the inhibition of quaternized chitosan against oral pathogens.