Aim To compare penetration depths of endodontic irrigants into the dentinal tubules of extracted teeth when using several activation methods. Methodology The root canals of 90 extracted human teeth were prepared to size 40, .06 taper. The straight and round‐shaped root canals were distributed randomly into six groups, and final irrigation was performed with EDTA and sodium hypochlorite as follows: (I) manual dynamic activation, (II) Ultrasonic, (III) Sonic, (IV) PIPS (photon‐induced photoacoustic streaming, (V) SWEEPS (shock‐wave enhanced emission photoacoustic streaming) and (0) control without final irrigation or activation. Subsequently, methylene blue was inserted into the canals and activated according to the groups (I–V). Teeth were sectioned horizontally, imaged under a light microscope, and dye penetration depths were measured in six sections per tooth and 24 points on a virtual clock‐face per section. Data were analysed statistically by nonparametric tests for whole teeth and separately for coronal, middle and apical thirds. Results Penetration of dye into the dentinal tubules was lowest for the controls. Median penetration depths amounted to 700–900 μm for groups I–V with differences in the apical thirds between group I and the other test groups. Minimum penetration depths were significantly greater for PIPS in the apical thirds (P ≤ 0.046). Conclusions Greater penetration depths occurred in the apical thirds for ultrasonic, sonic and laser‐induced activation compared to manual dynamic activation. PIPS was associated with deeper penetration of irrigants. The novel SWEEPS mode did not increase irrigant penetration.

Lipopolysaccharide did not affect cell viability but interfered with odontoblast-like cell differentiation of DPSCs. Proteins from the dentine matrix may have a protective effect, attenuate the detrimental impact of LPS and thus play an important role during pulp repair.

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Cell homing for dental pulp tissue engineering has been advocated as a feasible approach to regenerate dental pulp in a clinical setting. In order to develop a translational protocol for clinical application, we wanted to determine the effects of disinfectants on the availability of growth factors from the root canal, the amount that can be obtained in this context, and whether they can be processed for use in tissue engineering procedures. The extraction of growth factors should also be confirmed in a clinical setting. Root canals were prepared in 36 extracted mature teeth, and the amount of TGF-β1 in solution was quantified after different irrigation protocols (sodium hypochlorite, chlorhexidine) and after intracanal medication (calcium hydroxide). Centrifugal filters with a cut-off of 10,000 Da and 3000 Da were used for efficient concentration, and volumes and amounts of retained TGF-β1 were measured at different time points. During conventional endodontic treatment, ethylenediaminotetraacetic acid (EDTA) solution was collected after ultrasonic activation from the root canals of mature teeth of 38 patients, and growth factor content was quantified via enzyme-linked immunosorbent assay (ELISA). Irrigation with sodium hypochlorite reduced TGF-β1 release into EDTA. This effect was partially reversed by canal enlargement after the use of sodium hypochlorite and by subsequent use of calcium hydroxide. A few minutes of centrifugation with a cut-off of 10,000 Da reduced the initial volume of the irrigant by 90% and led to a continuous increase in concentration to the same extent. Furthermore, TGF-β1 was obtained from root canals of mature teeth during endodontic treatment in quantities that have been shown to elicit desirable cellular responses in a subsequent clinical application. A mixture with a suitable scaffold material and injection into the root canal has the potential to promote dental pulp regeneration.