Aim: The aim of the doctoral thesis was to evaluate the structural and chemical changes, in intracanal dentin, as well as roughness and wettability of dentin slices after root canal irrigation with sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) using additional activation with a novel Er:YAG Shock Wave‐Enhanced Emission Photoacoustic Streaming (SWEEPS), ultrasonic irrigation (UI), and Nd:YAG irradiation. Materials and methods: Root canals of extracted human premolars were instrumented with distilled water and distributed into groups according to the irrigation protocol used: Group 1: conventional needle irrigation (CI) with 3% NaOCl; group 2: CI with 15% EDTA; and group 3: CI with NaOCl+EDTA. In group 4, root canals were irrigated with NaOCl+EDTA+NaOCl using the following techniques: CI (group 4A), SWEEPS (group 4B), UI (group 4C). In group 4D, root canals were finally irradiated with Nd:YAG laser. After the irrigation, the intracanal dentin sample was collected and analyzed using a spectroscope with a Fourier transformation of the infrared spectrum in the Attenuated total reflection technique (FTIR‐ATR) to calculate the apatite/collagen ratio. Scanning electron microscopy (SEM) and energy dispersive x‐ray spectrometry (EDS) were used to determine its chemical composition of split root canals of premolars. Surface profilometry with a contacting stylus (Perthometer S8P, Mahr Perthen) was used to measure arithmetic roughness average (Ra) of polished dentine blocks. Drop shape analizer (DSA30S, Krüss GmbH, Germany) was used for contact angle measurements of dentin blocks extracted from coronal parts of extracted human molars. Results: FTIR‐ATR showed no significant difference in the phosphate/amid I ratio between the control and the experimental groups (p > 0.05). SWEEPS and UI of NaOCl+EDTA+NaOCl caused the most pronounced decrease of Ca and P (p < 0.05) value compared to CI and control group, and canal wall erosion. SWEEPS and UI of NaOCl+EDTA+NaOCl caused the most pronounced decrease of Ca and P value and significant canal wall erosion. However, no difference in phosphate/amide ratio was reported among groups. All experimental groups increased the surface the surface roughness significantly with UI of NaOCl+EDTA+NaOCl causing the most pronounced surface roughness increase. CI of NaOCl and UI significantly increased wettability, while CI of EDTA and NaOCl+EDTA+NaOCl and SWEEPS of NaOCl+EDTA+NaOCl resulted in significant decrease of dentin wettability. Conclusion: SWEEPS and UI of NaOCl+EDTA+NaOCl caused the most pronounced decrease of Ca and P values and significant canal wall erosion. There was no difference in phosphate/amide ratio among the irrigation protocols. All experimental groups increased the surface roughness significantly with UI of NaOCl+EDTA+NaOCl causing the most pronounced surface roughness increase. CI of NaOCl and UI significantly increased wettability, while CI of EDTA and NaOCl+EDTA+NaOCl and SWEEPS of NaOCl+EDTA+NaOCl resulted in significant decrease of dentin wettability.