Accumulation of microorganisms on the tooth surfaces has always lead to dental caries. The accumulation does
not limit to tooth surfaces only but also to other surfaces that exist in the oral environment, commonly dental
restorative materials. The adhesions of the microbial cells to the surface texture play a major significant in the
accumulation of bacteria on intraoral solid surfaces. However, information on the mechanism and the force of
adhesion on different substrate specifically in nanofilled tooth coloured dental materials are scarcely available.
Furthermore, there are studies reported on the role of fluoride and their uneffectiveness in combating bacteria at
early periods of adhesion (Carlen et al, 2001, Montanaro et al. 2004, Mohamad et al, 2007, Auschill et al, 2002).
In previous work (Moharnad et al, 2007). it was found that the biofllm thickness was higher in the glass-ionomer
cement (GIG) compared to the resin composite after 8 and 24 hrs. Studies of biofilm usually evaluated by
confocal laser scanning microscopy (CLSM) but limited to thickness and topography of the bacteria only, but no
quantity measurement betl.veen the bacterial eel! and the substrate. Recently, Oh et al 2009 has reported effects
of substrates on biofilm formation observed by atomic force microscopy (AFM) and successfully obtained the
force of adhesion. Therefore, within !his study, AFM will be utilized to evaluate the force of adhesion of bacterial.
In generaL the objective of this study is to investigate on the effect of polished nanofilled GIG and resin
Project Leader Member
composite on the bacterial accumulation. In particular, the substrate morphological variation. force of adhesion and biofilm thickness will be evaluated. Analysis of gene expressions will also be evaluated by Real-time PCR
This study is importance in understanding the mechanism which potentia!fy can be used for prevention of
bacterial accumulation and thus reducing the secondary caries