Masters Theses


"Although some progress has been made towards the chemical removal of dental plaque, it is generally removed by mechanical means. The current research is aimed to further that progress. Our hypothesis is that it is possible to remove dental plaque by aqueous two-phase systems (ATPS’) (due to an equilibrium distribution of cells and/or proteins between an adsorbed phase and a liquid/liquid interface). This investigation details the preliminary work for using ATPS’ to remove dental plaque. The prevention or degree of reduction of Streptococcus sanguis (S. sanguis) biofilm formation on hydroxyapatite discs in the presence of ATPS’ was investigated. The idea is that removal of plaque would be likely only if a great reduction in bacterial attachment in the presence of these systems could be achieved.

Dental plaque is a biofilm comprised of a diverse microbial community firmly attached to both root and enamel surfaces of teeth. Studies of in-vitro biofilms were performed using S. sanguis oral bacteria and hydroxyapatite discs (hydroxyapatite is a major mineral in human dental enamel so its use as the solid support is appropriate).

Recognizing the limitations of in-vitro studies, the experimental conditions were chosen such that they mimic those encountered in the oral cavity. Seven day biofilms were grown in various concentrations of yeast tryptone (YT) media, YT media with polymer, YT media with salt, and YT media with aqueous two-phase system. The biofilms were then characterized by scanning electron microscopy (SEM) and scintillation counting.

Two of the three ATPS’ investigated were found to reduce S. sanguis attachment to hydroxyapatite. The 10% YT media containing polyethylene glycol (PEG)/MgSO4 and all three concentrations of YT media containing PEG/Na2SO4 exhibited a reduction in bacterial attachment when compared to the systems containing the individual phase forming species and to the reference systems. These four systems can be further investigated for their effects on removal of young dental plaque"--Abstract, page iii.


Forciniti, Daniel

Committee Member(s)

Ybarra, Robert M.
Westenberg, David J.


Chemical and Biochemical Engineering

Degree Name

M.S. in Chemical Engineering


The author thanks the University of Missouri Research Board for providing the financial support to complete this work.


University of Missouri--Rolla

Publication Date

Spring 2001


viii, 60 pages

Note about bibliography

Includes bibliographical references (pages 50-59).


© 2001 Ondrea Bermudez, All rights reserved.

Document Type

Thesis - Restricted Access

File Type




Thesis Number

T 7933

Print OCLC #


Link to Catalog Record

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