Positive and negative pressure irrigation in oval root canals with apical ramifications: a computational fluid dynamics evaluation in micro‐CT scanned real teeth

Abstract

Loroño G, Zaldivar JR, Arias A, Cisneros R, Dorado S, Jimenez-Octavio JR. Positive and negative pressure irrigation in oval root canals with apical ramifications: a computational fluid dynamics evaluation in micro-CT scanned real teeth. International Endodontic Journal, 53, 671-679, 2020.Aim To compare using computational fluid dynamics (CFD) the flow pattern, irrigant velocity, apical pressure and shear stress produced by negative (MiC) and positive pressure with different types of needles (sidevented (SV), front-vented (FV) and notched (N)) at two insertion depths in the apical ramification of oval root canals. Methodology The micro-CT of a mandibular molar with an oval root canal with an apical ramification was used for computational analysis after preparation and geometric reconstruction. Geometries with the needles in two positions (1 and 3 mm from WL) were created to run the simulations. Key parameters of irrigation were displayed with CFD and compared. Results The penetration depth of the needle in the root canal strongly influenced shear stress and apical pressure. The three needles revealed that the highest shear stress, velocity and apical pressure were 1 mm from the WL and generated medium velocities. In N simulations, the fluid flow did not reach the apical ramification and the lowest shear stress values for positive pressure needles were found. The predominant axial component for FV revealed a different pattern of irrigation with high shear stress values and higher apical pressures than those exerted by other needles. SV simulations had generalized fluid flow in most of the main canal, the highest shear stress values and lower apical pressure than the threshold determined for risk of extrusion. MiC was associated with low velocity, shear stress and apical pressure. Conclusion The SV needle demonstrated a combination of low positive pressure and high shear stress; while N had the lowest shear stress and FV the highest apical pressure. MiC generated fluid flow in part of the apical ramification with negative apical pressure values but low shear stress and velocity.

In Vitro Evaluation of Different Irrigation Protocols on Intracanal Smear Layer Removal in Teeth with or without Pre-Endodontic Proximal Wall Restoration

“…Indeed, the pre-endodontic restoration acts as a reservoir, continuously maintaining a substantial volume of irrigant into the access cavity. This may enhance fluid dynamics, especially the crown-down streaming of root canal irrigants [ 25 , 26 ] during activation and the possibility to have fresh irrigants at the apical third. At the middle level, concerning the subgroups irrigated using the conventional needle irrigation method, a significantly lower amount of smear layer was found in G2ctrl (control) rather than in G1ctrl.…”

Apical Pressure Generated Using Conventional Syringe Irrigation in Immature Teeth—An In Vitro Study

“…The apical tissue pressure, likely varying between individuals, remains unknown. It depends, moreover, on the clinical condition [ 19 ]. Data from animal experiments suggest that the tissue fluid pressure at the apical foramen is unstable.…”

“…It is, however, important to consider that previous studies used different pressure thresholds to investigate apical irrigant extrusion. Previously used pressure thresholds included the capillary pressure (25 mmHg), the interstitial pressure (20–30 mmHg), and the intraosseous blood pressure (30 mmHg) [ 16 , 17 , 18 , 19 , 25 ]. Using one of these thresholds instead of 7.64 mbar, the interpretation of data obtained in the present study is different.…”

“…5.58 mmHg (lower level of the central venous pressure), corresponding to 7.64 mbar, was therefore chosen as the critical value to investigate apical irrigant extrusion in previous studies [ 16 , 17 , 18 ]. However, the apical tissue pressure countering an extrusion is another important factor that varies among individuals and depends on the periapical status [ 19 ].…”

Examination of irrigant flow on a tooth with internal root resorption by using a Computational Fluid Dynamics model: A preliminary study

“…WSS is the coplanar stress that acts parallel to the material’s wall and is caused by the fluid flow. By estimating WSS values in the root canal walls, we can approximate the interaction between the irrigants and the tissue or the biofilms attached to the canal walls ( 18 ). The average and maximum WSS values were recorded for all six cases studied, as shown in Table 2 .…”