Effects Of Nano-diamond Filler On Mechanical Properties Of Pit And Fissure Sealants

Treating pit and fissure with resin sealants has been widely accepted as a preventive strategy. The mechanical properties of sealants are key factors that influence clinical effect and determined mainly by the filler used in the resin matrix. Various filler systems with instinct function have been employed in sealants to improve its mechanical properties. In the last 20 years, nanotechnology has brought great changes to medical materials, and it is a major trend to introduce nanotechnology into dental materials. However, there is little literature about nano-diamond as filler for sealants. In the present study, nano-diamond of different concentration was added into sealants and its effect on mechanical properties of sealants were evaluated, while 2% aerosol SiO2 was also introduced into sealants as control and unfilled sealants as blank control. The main part and results were listed below:1. Different proportion of nano-diamond was added to sealant and its dispersion was observed under TEM. The nano-diamond without pre-treatment was well dispersed in the resin matrix and the agglomerate particle was less than l00nm, and the agglomerate particle grew into 500nm after pre-treatment. 2% aerosol SiO2 was poorly dispersed and the size of aggregated particles were larger than .2. The wear-resistance and micro-hardness of sealants filled with different proportion of nano-diamond and 2% aerosol SiO2 were assessed. Comparedwith the blank control, the wear-resistance of groups filled with 4%, 2%, 1%, 0.5%, 0.1% (W/V) nano-diamond were increased significantly and so was the group of 2% aerosol SiO_?2?. But there was no difference existed between any group of nano-diamond and aerosol SiO_?2? (P>0.05). While micro-hardness of sealant filled with 4%, 2%, 1%, 0.5%, 0.1% nano-diamond were increased significantly (P<0.05), and groups of 4%, 2%, 1%, 0.5% nano-diamond showed a higher micro-hardness than that of 2% aerosol SiO_?2? (P<0.5). 3. The shearing bonding strength and penetration of sealants filled with different proportion of nano-diamond and 2% aerosol SiO_?2? were assessed. Groups of sealants of 4% nano-diamond and 2% aerosol SiO_?2? had a lower shearing bonding strength (P<0.01), while 2%, 1%, 0.5%, 0.1%, 0.05%, 0.01% nano diamond didn't show negative effects on shearing and bonding strength. The penetration of sealants filled with 2%, 1% nano-diamond didn't change (P>0.05), and SEM study can find resin tags penetrated into dematerialized enamel. But groups of2% aerosol SiO_?2? had a decreased the penetration (P<0.05), and SEM study showed insufficient penetration.