Details

Autor(en) / Beteiligte

• Swearingen, Elizabeth Blake

Titel

The effects of SeLECT Defense™ orthodontic brackets on the formation, composition, and metabolism of oral microflora: An in vitro study

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2013

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• In orthodontic patients, persistent biofilm accumulation on fixed orthodontic appliances and enamel surfaces in the presence of dietary sugars results in the repeated acidification of the local environment leading to white spot lesion formation. Multiple strategies have been developed to reduce surface microbial colonization, as well as modify local factors to prevent or resist acid production, but enamel demineralization remains a persistent problem for patients being treated orthodontically. Objectives: In this study, we utilize a four-species biofilm model to assess the effects of selenium-coated orthodontic brackets on the formation, metabolism, and composition of acid-producing bacteria. Methods: A mixed-species biofilm composed of Streptococcus mutans, Veillonella dispar, Fusobacterium nucleatum, and Actinomyces odontolyticus was grown for seven days on lysine-coated glass coverslips with affixed orthodontic brackets composed of three distinct biomaterials: stainless steel, single crystal sapphire, or SeLECT Defense™ selenium-coated. Biofilms were labeled with BacLight Live/Dead™ fluorescent stain, and imaged at 4x and 10x magnification on upright and inverted microscopes, respectively. Images were quantified using ImageJ1.46r and fluorescence intensities were calculated for red and green channels, to assess total biofilm accumulation, ratios of live to dead cells, and zone of inhibition surrounding each bracket. ANOVA comparisons were performed between independent experiments in triplicate. Biofilm supernatants were collected and analyzed for acid production and for species composition. Results: Total biofilm mass accumulated and composition around each bracket-type was not significantly different. However, relative proportions of live/dead bacterial cells and accumulation were significantly different on the brackets themselves; the selenium-coated bracket having the highest dead and least accumulation. There was no zone of inhibition observed immediately surrounding the bracket footprints for any bracket-type, and the final biofilm composition was primarily Gram-positive and Gram-negative cocci. pH values in the supernatant were not significantly different between groups (Avg=5.1). Conclusion: During the 7-day experimental period, SeLECT Defense™ selenium-coated brackets did not inhibit metabolism or biofilm accumulation and composition at the bracket margin white spot lesion zone, but did significantly influence total bacterial viability and accumulation for the biofilm in direct contact with the bracket.