Effect of irrigation solutions on surface topograpy of various generations of ProTaper instruments

The primary objective of endodontic treatment is the shaping, effective cleaning and hermetic obturation of the root canal system. In the past, hand instruments which made from stainless stell and Gates Glidden drills were commonly used for canal shaping; however, today, nickel-titanium (NiTi) rotary instruments have become the standard. As a result of technological advancements, various rotary instruments with different manufacturing processes have been developed. Despite the numerous advantages offered by Ni-Ti instruments, unpredictable fractures may occasionally occur during clinical use. Such fractures have the potential to negatively affect the outcome of root canal treatment. In root canal treatment, shaping and effective irrigation are inseparable components. During mechanical preparation, NiTi instruments come into contact with irrigation solutions. The corrosive properties of these solutions may cause surface deformation on the files. Such corrosion can lead to unexpected premature fractures of the instruments. The aim of this study was to investigate the effect of NaOCl, EDTA, and a HEDP–NaOCl mixture on the surface roughness of different ProTaper files (ProTaper Universal, ProTaper Next, ProTaper Gold, and ProTaper Ultimate). From each file system, one new file taken directly from its package was designated as the control group. For each irrigation solution, three files from each group were immersed for 5 minutes. The surface topography of the samples was analyzed using atomic force microscopy (AFM). As a result of the analysis, Ra and RMS values as well as three-dimensional surface images of the files were obtained. The findings were further supported by SEM imaging. Exposure to irrigation solutions resulted in an increase in surface porosity of the files. The ProTaper Next system was found to be the most affected by the irrigation agents. The ProTaper Universal and ProTaper Ultimate files exhibited similar surface characteristics. Considering all these findings, it can be concluded that irrigation solutions cause corrosion on the surfaces of the files. Therefore, in order to prevent possible clinical complications, clinicians should carefully evaluate the factors that may lead to file deformation.