Root canal preparation must serve the goals of supporting debridement while exerting the least amount of structural damage. Toward those goals, several recent trends for innovation are noted: some changes in instrument design, several of them substantial, whereas others are rather discrete. In vitro testing is ongoing and, because of the lack of consistent methodology, gives only some guidelines for clinical use. Lastly, clinical outcome data are lacking for many current instruments; therefore, it is not clear if improvements in flexibility and resistance to fatigue will translate to better outcomes.