Rahman, Raihaniah Abd
(2016)
Adhesion of streptococcus mutans on tooth coloured restorative materials.
Masters thesis, Universiti Sains Malaysia.
Abstract
Currently, the application of nanotechnology has become broadly developed in
aesthetic dentistry due to its nanofiller particles size which offered numerous
excellent advantages such as capable in reducing the bacterial adhesion of cariogenic
oral bacteria mostly of early oral colonizers of S. mutans. This initial adhesion of S.
mutans on the surface of materials contributed to the biofilm formation, surface
deterioration of materials and may cause dental caries. In order to restore a carious
tooth, the use of composite resin and resin-modified glass ionomer cement (RMGIC)
in the restoration field has been increased due to the demand for aesthetic value.
Different filler sized materials such as nanofilled, microfilled and microhybrid were
used to compare and evaluate the adhesion of S. mutans on these materials at several
incubation times. Four materials were used in this study which were RMGICs;
KetacTM N100 (nanofilled) and Fuji IITM LC (microfilled) and composites resins;
FiltekTM Z350 (nanofilled) and FiltekTM Z250 (microhybrid). A microscopy study
was performed which include atomic force microscopy (AFM) for evaluation of
surface roughness of the incubation materials, confocal laser scanning microscopy
(CLSM) for evaluation of biofilm thickness and scanning electron microscopy
(SEM) for distribution observation of S. mutans on materials. Fluoride release
measurement was carried out for RMGIC materials to analyse the fluoride release of
the materials. In addition, bacteria growth was done to assess the growth activity of
S. mutans on the tested materials. Gene expression was also performed to determine
the gene expression levels of gtfB and gbpB genes. Data obtained were statistically
analyzed with either Independent T-test or One-way ANOVA at significance level of
p<0.05. From the result, Fuji II LC gave a significantly higher of fluoride release
compared to Ketac in both storage media (p≤0.001). Both nanofilled materials gave a
lower value of surface roughness while no significant difference of biofilm thickness
between nanofilled and microfilled materials was shown except on day 7. RMGIC
groups gave a lower S. mutans growth compared to composite resin group at all the
incubation times. Nanofilled RMGIC gave significantly lower of expression levels of
gtfB and gbpB gene compared to other materials p<0.05. From the results, surface
roughness and fluoride release by RMGIC materials were recognized as a significant
factor that affected the adhesion and accumulation of S. mutans on materials. In
general, both nanofilled materials has the capability in reducing the bacterial
adhesion of S. mutans compared to micron sized materials since most results in this
study proved that nanofilled gave lower surface roughness, less biofilm thickness and
low level of gene expression. Comparison between both nanofilled groups, Ketac
showed an excellent improvement in reducing S. mutans adhesion compared to Z350
due to its fluoride release ability. These finding suggested a nanofilled RMGIC as the
ideal material in reducing the accumulation of S. mutans, which could inhibit the
adhesion of S. mutans on the surface materials.
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