All ETDs from UAB

Advisory Committee Chair

Amjad Javed

Advisory Committee Members

John Ruby

Christos Vlachos

Andre Ferreira

Document Type

Thesis

Date of Award

2011

Degree Name by School

Master of Science (MS) School of Dentistry

Abstract

Introduction: Fixed appliances make satisfactory oral hygiene a greater challenge for the orthodontic patient. Improper oral hygiene during orthodontic treatment can cause enamel demineralization resulting in unesthetic white spot lesions. A new approach to providing protection against demineralization during treatment has been to incorporate antimicrobial agents into elastomeric ligature ties. A recent elastomeric ligature tie uses the antimicrobial characteristic of silver to help prevent formation of white spot lesions. The purpose of this in vitro study is to determine the antimicrobial effectiveness of a silver-releasing elastomeric ligature tie (OrthoShield Safe-T-Tie) against Streptococcus mutans and compare its results with a selenium-containing elastomeric (SeLECT DefenseTM) and a traditional non-antimicrobial elastomeric ligature tie (AlastiKTM Easy-To-Tie Ligatures). Methods: Two methods were used to evaluate the antimicrobial effectiveness of the elastomerics, agar diffusion and spectrophotometry. For the agar diffusion test, elastomerics were placed on S. mutans streaked agar plates containing Todd Hewitt (TH) Broth in .3% (3g/l). Plates were incubated (10% H2, 10% CO2, 80% N¬2) at 37° C for a 24 hour period and then evaluated for zones of inhibition surrounding the elastomerics. For the spectrophotometer test, elastomerics were placed in test tubes containing 500 µl and 100 µl of S. mutans culture and incubated for six or eight hours. Optical densities of the S. mutans cultures were measured for each test tube by spectrophotometer (SmartSpec Plus Spectrophotometer) to determine bacterial cell densities following incubation. Bacterial cell densities between groups were statistically analyzed using a non-parametric Wilcoxon Test. Generation times were calculated from cell density readings. Results: For the agar diffusion test, there were no measurable or visibly detectable zones of inhibition around any of the elastomeric samples. For the spectrophotometer test, silver-releasing elastomerics showed a statistical difference from the traditional elastomeric group in the 100 µl test but not the 500µl test. None of the elastomerics tested effectively reduced the generation times for a S. mutans cell population. Conclusion: Neither the silver-releasing nor silver-containing elastomeric ligature ties were effective in inhibiting growth of Streptococcus mutans in-vitro.

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