Effect of Canal Anastomosis on Periapical Fluid Pressure Build-up during Needle Irrigation in Single Roots with Double Canals using a Polycarbonate Model

Qi Huang,Jun-Qi Ling,Franklin R Tay,Lisiane F Susin,Li-Na Niu,G John Schoeffel,Candice Tay,Brian E Bergeron,Bing Fan,Jonathan B Barnes

doi:10.1038/s41598-017-01697-1

Abstract

Sodium hypochlorite is an effective irrigant for chemical debridement of root canals. However, increasing the intracanal pressure during irrigant delivery may result in irrigant extrusion into the bone and soft tissues surrounding the tooth. Because clinicians often encounter teeth with intracanal communications, the objective of the present study was to examine the effects of canal anastomosis on the generation of periapical fluid pressure at different fluid flow rates and insertion depths. Two similar polycarbonate models were used to simulate a single root with double canals, one containing, and the other without communicating channels between the canals. For both models, periapical pressure increased with increasing irrigant flow rates and insertion depths of a 30-gauge side-venting needle. In the presence of communicating channels, the magnitude of pressure build-up decreased by almost 90% irrespective of the fluid flow rate or needle insertion depth. Pressure reduction in anastomoses-containing roots provides an explanation why pressure generation in single roots is considerably higher. Nevertheless, it is still possible in teeth with canal anastomoses for pressure exceeding the intraosseous pressure to be generated when the fluid flow rate is sufficiently high and when the needle tip is close to the apical terminus.

Highlights

There is a subtle balance between efficacy and safety for needle-assisted irrigation of the apical canal space
The materials could not expand to accommodate the increase in fluid volume within the canal space. It was not readily apparent what accounted for the discrepancy in the magnitude of positive apical fluid pressure generated from those two studies, it is speculated that the two mesial canals prepared in the natural tooth utilised by Park et al could have been connected by canal anastomosis
Because clinicians often encounter teeth that contain single roots with multiple canals, which may contain an isthmus or other types of intracanal communication, the objective of the present study was to examine the effects of canal anastomosis on the generation of periapical fluid pressure at different fluid flow rates and needle insertion depths, using a polycarbonate model to simulate a single root with double canals

Summary

Introduction

There is a subtle balance between efficacy and safety for needle-assisted irrigation of the apical canal space. Due to the difference between intraosseous blood pressure and the central venous pressure (1–7 mm Hg, or 0.13–0.93 kPa), the NaOCl that enters bone sinusoids rapidly drains to the superficial facial venous vasculature where ecchymosis is manifested To address both fluid exchange efficacy and safety concerns, closed-end side-venting type needles have been recommended for canal debridement, by inserting the hypodermal needle in a non-binding manner to 1 mm short of the working length[2]. The materials (polycarbonate or root dentin) could not expand to accommodate the increase in fluid volume within the canal space It was not readily apparent what accounted for the discrepancy in the magnitude of positive apical fluid pressure generated from those two studies, it is speculated that the two mesial canals prepared in the natural tooth utilised by Park et al could have been connected by canal anastomosis. The null hypothesis tested was that canal anastomosis has no effect on the magnitude of periapical pressure build-up when a root canal irrigant is delivered at different fluid flow rates and needle insertion depths

Objectives

Methods

Results

Conclusion