Date Approved

8-30-2023

Graduate Degree Type

Thesis

Degree Name

Engineering (M.S.E.)

Degree Program

School of Engineering

First Advisor

Dr. Sanjivan Manoharan

Second Advisor

Dr. Shabbir Choudhuri

Third Advisor

Prof. Tikran Kocharian

Academic Year

2023/2024

Abstract

This numerical study investigates the flow characteristics within a root canal during a manual endodontic treatment. To underscore the difference in root canal geometry, a simplified root canal (frustum of a cone) and a more complex (realistic) root canal geometry were considered. The needle utilized in all simulations is a side-vented 30G KerrHaweIrrigation Probe, KerrHawe SA, Bioggio, Switzerland. For both root canal geometries, the effect of variation of fluid inlet velocity, needle insertion depth, and needle tilt angle on flow characteristics was examined via velocity contours, turbulent intensity, wall shear stress, and streamline and vector plots. The fluid was Sodium Hypochlorite, and fluid inlet velocities of 6 m/s, 8.6 m/s and 12 m/s were considered. Needle insertion depths of 1 mm, 2 mm, and 3 mm from the working length, and needle tilt angles of 1o and 2o (both clockwise and counterclockwise) were considered. The complex geometry showed better flow penetration, significantly lower apical pressures, and almost half the shear stress as flow velocity increased when compared to the simplified model. For the complex geometry, as the needle insertion depth increased the apical pressures were almost four times smaller, better flow penetration was seen, differences in turbulent intensity patterns right above the apical third were witnessed, and wall shear stresses were almost half when compared to the simplified geometry. Finally, with respect to tilt angle, clockwise rotation had better flow penetration, wall shear stresses were more than halved, and apical pressure was highest at 2o counterclockwise rotation for complex geometry. Interestingly, for the simplified model, apical pressure was highest for 1o clockwise tilt. The optimum combination of input parameters includes fluid inlet velocity of 8.6 m/s, needle insertion depth of 2 mm, and 1o clockwise rotation of needle. Subsequently, the side vented needle was redesigned using fundamental fluid mechanics principles to enhance flow characteristics, especially at the apical third of the realistic root canal geometry.

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