Presentation Blocks: 03-23-2018 - Friday - 11:00 AM - 12:15 PM

Title: In vitro Evaluation of Antimicrobial Activity of Chlorhexidine Hexametaphosphate Nanoparticle Coatings on Orthodontic Elastomeric Chains


Karthikeyan Subramani (Presenter)
Roseman University of Health Sciences

Han Na Seo, Roseman University of Health Sciences
Joseph Dougherty, Roseman University of Health Sciences
Prashanti Bollu, Roseman University of Health Sciences
Kenneth Rosenthal, Roseman University of Health Sciences
Jian-Feng Zhang, Roseman University of Health Sciences


Objectives: The purpose of this in vitro study was to evaluate the release and antimicrobial activity of chlorhexidine (CHX) from orthodontic elastomeric chains (OEC) coated with chlorhexidine hexametaphosphate (CHX-HMP) nanoparticle (NP).

Methods: Test groups were divided into four groups: CHX-HMP-5 (5mM CHX-HMP), CHX-HMP-1 (1mM CHX-HMP), CHX-5 (5mM CHX) and CHX-1 (1mM CHX). Control group had no coating.
The release of CHX from coated groups was evaluated for a period of 28 days from samples collected on day 1, 2, 3, 5, 7, 14, 21 and 28 with a UV spectrophotometer (n=5/group).
The force decay of all 5 groups (n=20/group) was measured on day 0, 1, 7, 14, 21 and 28 with a digital force gauge.
Antimicrobial properties were tested for Streptococcus mutans (S. mutans) and lactobacilli by measuring the inhibition zone after 24 and 48 hours. S. mutans were cultured in Mitis Salivarius agar plate and lactobacilli were cultured in MRS agar plate. Microbiology evaluation was performed in triplicate.
Scanning electron microscope (SEM) was used to evaluate the surface characteristics of (1) uncoated and coated OECs, (2) before and after release of CHX, and (3) before and after microbiology evaluation.

Results: SEM analysis showed the presence of CHX-HMP nanoparticles on the CHX-HMP-5 and CHX-HMP-1 groups. No difference in surface characteristics was observed on CHX-5, CHX-1 and uncoated groups. CHX-HMP-5 group showed the highest amount of CHX release after Day 1 followed by CHX-HMP-1, CHX-5 and CHX-1with gradual decrease until day 28.

Conclusions: OECs can be succesfully coated with CHX-HMP nanoparticles. Gradual CHX release from the coatings is expected to exhibit antibacterial properties by the inhibition of growth of Streptococcus mutans (S. mutans) and lactobacill.