Fig 1.
Structural formulas of antibacterial NPs.
a–Silica particle with tertiary amine bearing two t-cial groups. b–Silica particle with dimethyl-octyl ammonium functional group. c–Quaternary ammonium polyethyleneimine particle.
Fig 2.
A- a resin material samples allowed to polymerize onto microtite’s well sidewalls, followed by applying of bacteria suspension. B-Evaporation of suspension liquid. C- addition of growing media to agitate proliferation of survived bacteria. D- OD650 measured as indication for survived bacteria growth.
Fig 3.
Polymerized samples of modified resin material were first rinsed during 7 days. Then, samples of each one of the test groups were divided into 3 subgroups for three different biofilm models. The biofilm tests were performed using MDFR.
Fig 4.
Comparison of maximal stress at rupture and the youngs modulus.
Unmodified resin material served as control. As can be seen, the SiCial particles did not lead to a significant reduction in maximal stress or modulus. Addition of any of the quaternary ammonium-containing particles resulted in lower mechanical properties, QPEI particles causing complete destruction of the resin material.
Fig 5.
Degree of monomer conversion calculated from the data measured with infrared spectroscopy data.
%DC values are expressed as mean with standard deviation. Quaternary ammonium iodide-containing particles caused a reduction in the degree of monomer conversion vs the base material. The SiCial particles preserved the %DC of the unmodified resin material.
Fig 6.
Representative FT-IR curves for DC calculation.
Infrared spectra area focusing on characteristic peaks related to double carbon-carbon acrylic bonds (~1637nm) and carbon-oxygen double bond (~1720nm) used as normalization peaks of uncured resin material (red) and after 10 minutes of curing (blue).
Fig 7.
Color changes in resin material modified with antibacterial nanoparticles.
Duplicates of all the test samples were compared with the unmodified control material. Changes in the color of the test samples are evident upon comparison of the unmodified material (control) with samples with incorporated quaternary ammonium iodide salt particles (i.e. QPEI and QASi). A relatively mild change in color is seen in samples with SiCial particles.
Fig 8.
Contact angle measurements arranged in increasing order of hydrophobicity.
A (unmodified, control): 59.4(±5.6)°; B (QPEI): 74.3(±5.1)°; C (QASi): 74.6(±1.9)° and D (SiCial): 111.2(±0.6)°.
Fig 9.
Antibacterial activity against S. mutans of unmodified acrylic material and with incorporated 8% QPEI, 8% QASi or 8% SiCial.
Fig 10.
Each error bar was constructed according to 1 standard error from the mean OD values for each microbiological model. The different datasets were normalized for viable biofilm formation on the reference material,(polystyrene) of tissue-culture treated multiwall plates.
Table 1.
Verification of assumptions of normality and homoscedasticity.
Table 2.
Biofilm formation on the surfaces of the test materials for each microbiological model.