Traditionally, much of the attention placed on irrigation in endodontics has focused on smear layer removal. While the smear layer continues to be a relevant topic, other areas related to irrigation and irrigants have emerged that also require a more in‐depth analysis and understanding. This review starts with the smear layer, partially from a new angle, and expands into other topics such as uninstrumented root canal areas, and effect of irrigation in lateral canals and dentin canals. Advanced microbiological models for irrigation research will be presented and discussed. The effect of sodium hypochlorite and decalcifying solutions on dentin structure and dentin strength has become an important topic, which is related to the possible harmful effects of irrigation such as dentin erosion and even vertical root fracture. The impact of irrigant sequence and time of exposure will also be discussed, and recommendations for irrigation protocols will be made.