Antibacterial activity and bacterial microleakage resistance of endodontic materials
Date
2007
DOI
Authors
Sarkis, Ramzi
Version
OA Version
Citation
Abstract
Root canal therapy prevents and treats infection of the root canal system. The material used for obturating the root canal space has the primary goal of preventing bacterial invasion of the tissue surrounding the tooth. Over time biomaterials interact with their immediate environment and leach out products known as leachable components. The antibacterial activity of leachable components in the immediate vicinity of endodontic materials is highly desirable, as it could prevent bacterial infection or re-infection of the tooth.
Sections one and two of this project address the antibacterial activity of leachable components from aged endodontic materials:
The first section describes a new testing method named the Bacterial Survival Test (BST). Six MTA cylinders were placed in vials containing Phosphate-Buffered-Saline (PBS, 400mcl) (mcl = microliter) and allowed to leach out soluble components at 37[degrees]C for 11, 15, 21, 28, 59, and 98 days. Then they were tested using two techniques. In the Agar Diffusion Test, an overnight culture (OC) of Enterococcus faecalis was spread on Tryptic-Soy-Agar plate (TSA). A sterile filter disk was soaked with the liquid bathing the aged cylinder and placed on the plate. (+control: eugenol, -control: PBS). The zone of inhibition was noted at 24 and 48hrs of incubation. In the Bacterial Survival Test, an inoculum from an OC was placed in the vial and incubated (24hrs). A sample of the vial's content was transferred on a TSA plate. (+control: PBS+OC, -control: PBS). The plate was incubated (48hrs) and checked for bacterial growth. All experiments were performed in triplicate.
The second section of this research project used the Bacterial Survival Test to evaluate the antibacterial activity of MTA, Super Ethoxy Benzoic Acid (SEBA), and a modified MTA (MTAm1: mixture of MTA with 7%Si and 5.25%Ca by weight) against a strain of Enterococcus faecalis. The experiments were performed on days 11, 15, 21, 28, 59, 98.
The third section of the thesis focuses on an important property of the endodontic material used for Surgical Root Canal therapy (SRCT): the physical seal against bacterial progression.
An apparatus and method for testing the material seal were developed using a dual chamber bacterial leakage model and E faecalis as the challenging bacteria. The seals of MTA, SEBA, MTAm1, and MTA mixed with Phosphate Buffered Saline (MTAm2) were tested against the aggression of E faecalis.
A dual chamber model was developed using extracted human teeth. They were randomly divided into 4 groups of 12 samples each. Turbidity was monitored over 82 days and the day of leakage was noted. The mean day of leakage among the 4 groups was compared.
The results of three sections of this in vitro study were as follows: the Agar Diffusion Test showed no inhibition zone at all times while the Bacterial Survival Test showed bacterial growth at sampling day 12, then no-growth at sampling day 16 and onwards. Using the BST, SEBA showed no bacterial growth at all times while MTA showed growth at sampling day 12, then no-growth at sampling day 16 and onwards, and MTAm1 showed growth at all times.
During the first 20 days of bacterial leakage testing, MTA and MTAm1 performed significantly better than SEBA and MTAm2. But no significant difference was noted among the four groups when the results of the 82 days of testing were analyzed.
This in vitro study showed that the Bacterial Survival Test proved to be superior to the agar disk diffusion technique in detecting the antibacterial activity of leachable components from aged MTA against Enterococcus faecalis. When aged in PBS, SEBA had an early and continuous antibacterial activity (AA) of leachable components, while MTA had a delayed but persistent AA, and MTAm1 did not show any AA. Adding Si and Ca to MTA (MTAm1) affected MTA's antibacterial properties when aged in PBS but it did not affect MTA's long term sealing properties in resisting bacterial leakage. MTA's antibacterial and leakage resistance properties change over time. Therefore, MTA is a material that interacts with its environment. The Bacterial Survival Test and adding Si and Ca to MTA seem to be promising and require further testing.
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Thesis (MSD)--Boston University, Goldman School of Dental Medicine, 2007 (Dept. of Endodontics).
Includes bibliography: leaves 110-119.
Thesis (MSD)--Boston University, Goldman School of Dental Medicine, 2007 (Dept. of Endodontics).
Includes bibliography: leaves 110-119.
License
This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.