Wall Shear Stress Effects of Different Endodontic Irrigation Techniques and Systems
Available online 19 April 2013
Abstract
Objectives
This
study examined débridement efficacy as a result of wall shear stresses
created by different irrigant delivery/agitation techniques in an
inaccessible recess of a curved root canal model
Methods
A
reusable, curved canal cavity containing a simulated canal fin was
milled into mirrored titanium blocks. Calcium hydroxide (Ca(OH)2)
paste was used as debris and loaded into the canal fin. The titanium
blocks were bolted together to provide a fluid-tight seal. Sodium
hypochlorite was delivered at a previously-determined flow rate of
1 mL/min that produced either negligible or no irrigant extrusion
pressure into the periapex for all the techniques examined. Nine
irrigation delivery/agitation techniques were examined: NaviTip passive
irrigation control, Max-i-Probe® side-vented needle passive
irrigation, manual dynamic agitation (MDA) using non-fitting and
well-fitting gutta-percha points, EndoActivator™ sonic agitation with
medium and large points, VPro™ EndoSafe™ irrigation system, VPro™
StreamClean™ continuous ultrasonic irrigation and EndoVac apical
negative pressure irrigation. Débridement efficacies were analysed with
Kruskal-Wallis ANOVA and Dunn's multiple comparisons tests (α = 0.05)
Results
EndoVac
was the only technique that removed more than 99% calcium hydroxide
debris from the canal fin at the predefined flow rate. This group was
significantly different (p < 0.05) from the other groups that
exhibited incomplete Ca(OH)2 removal
Conclusions
The
ability of the EndoVac system to significantly clean more debris from a
mechanically inaccessible recess of the model curved root canal may be
caused by robust bubble formation during irrigant delivery, creating
higher wall shear stresses by a two-phase air-liquid flow phenomenon
that is well known in other industrial débridement systems.
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