Aim A laboratory study to determine the apical pressure generated by seven canal irrigation methods in an anterior tooth with an open apex. Methodology Canal irrigation was performed on a 3D‐printed central maxillary incisor with an open apex (maximum diameter of 2.1 mm). Ultrasonically activated irrigation (UAI), sonic activation (EDDY), negative pressure irrigation (EndoVac), the self‐adjusting file (SAF) and the XP‐endo Finisher were employed at tooth length (TL), TL—1 mm, TL—2 mm and TL—3 mm. UAI was tested at three intensity levels additionally. Hydrodynamic irrigation with RinsEndo was performed in the pulp chamber, at the canal orifice, the coronal third, the middle of the canal and at TL. Er:YAG laser activation, at four frequency settings, was performed in the pulp chamber and at the orifice of the canal. The pressure of the fluid towards the canal terminus generated by activation was directly transferred to a pressure sensor with a range of 0 to 120 mmHg and a response time of ≤0.5 ms. The critical threshold for apical extrusion of the irrigant was set at 5.73 mmHg (lower limit of the central venous pressure: 5.88 ± 0.15 mmHg). Each experiment was repeated ten times. The tests were followed by descriptive analyses (maximum, mean, standard deviation, 95% confidence interval). Results EndoVac, the SAF, the XP‐endo Finisher, and UAI never exceeded the critical threshold at any insertion depth or intensity level. Er:YAG laser activation exceeded the critical threshold exclusively at frequency settings that varied from the manufacturer's recommendation. EDDY at TL and RinsEndo at any insertion depth exceeded the critical threshold in 100% of the measurements. EDDY at TL—1,—2, and—3 mm crossed the critical threshold in 30%, 10%, and 20% of the measurements, respectively. Conclusions In a simulated maxillary central incisor with an open apex, irrigation with EndoVac, Er:YAG laser activation, UAI, the SAF, and the XP‐endo Finisher generated apical pressures below the critical threshold of 5.73 mmHg. By contrast, using EDDY and RinsEndo for irrigation produced higher apical pressures that exceeded the critical threshold.

This in vitro study aimed to evaluate apical pressure during irrigant delivery with syringe irrigation in immature teeth with an open apical foramen. Conventional syringe irrigation was performed in a 3D-printed immature incisor. A 5 mL syringe combined with 25 G and 30 G cannulas was used. Open-ended and side-vented needle tip designs were assessed. Cannulas were placed at tooth length (TL), TL −1 mm, TL −2 mm, and TL −4 mm. The syringe plunger was moved with a force of 10 N, 20 N, 40 N, and 80 N to simulate clinical conditions. A pressure sensor measured periapical pressures during irrigation. Each experiment was repeated 10 times. Data were analyzed descriptively (maximum, mean, standard deviation, 95% CI) with the critical threshold indicative of extrusion set at 7.64 mbar. 30 G cannulas with both needle tip designs never exceeded the threshold at any TL with a plunger force of 10–40 N. At 80 N, 30 G open-ended cannulas exceeded the threshold in 10%, 30 G side-vented in 20–60% of the measurements. At any TL, 25 G open-ended cannulas and 25 G side-vented cannulas never crossed the threshold with forces of 10–20 N and 10 N, respectively. Consequently, 30 G cannulas with both designs can be recommended for irrigant delivery in immature teeth. 25 G cannulas ought to be used with caution.