One of the characteristics that can predict the cariostatic effect of dental pit and fissure
sealants is wear resistance of the material, and those for the expectation of the retention
rate is the bond strength to enamel. Although the Bis-GMA resin based sealants are
widely used, their mechanical properties are lower than those of composite filling resins
because of lower cross-linking of the material. After incorporation of filler to the resin
sealant, almost all the mechanical properties are improved except tensile strength.
Incorporation of various amount of filler to the same resin for sealant. The purpose of
this study was to determine the bond characteristics to enamel and the biaxial fracture
strength of dental pit and fissure sealants after incorporation of various amount of glass
fillers to the same unfilled resin sealant.
lignt cured pit and fissure sealants(CO and TM) were used as controls. Glass filler
was incorporated in the chemically cures resin sealant(HO) with the ratio of 10, 30 and
50 wt.%, and was used as experimental groups. Two types of fillers, silane-coated and
not coated, were used. For bonding test, flat enamel surface was made on sound
premolar tooth by grinding with #600 silicone carbide paper. This surface was etched
with 37% phosphoric acid for 30 second, and sealant filled gelatin capsule(3 mm
diameter) was attached to this surface. After immersion in 37℃ distilled water for 24
hours, shear bond properties were measured with a universal testing machine(Zwick 020,
Germany) with the cross-head speed of 1mm/min. From the load-deflection curve
obtained, shear bond strength, displacement at bond failure and elastic modulus ratio
was calculated. For biaxial fracture strength test, diameter of 10 mm and thickness of 2
mm specimens were made with the same materials as in bonding test. After immersion
in 37℃ distilled water for 24 hours, biaxial fracture properties were measured with a
universal testing machine(Zwick 020, Germany) with the cross-head speed of 0.5
mm/min. From this experiment, the following results were obtained.
1. The shear bond strength of unfilled HP to enamel surface was 13.870 MPa, and
those after filler incorporation were 18.956-19.684 MPa.
2. The shear bond strength to enamel surface increased significantly after incorporation
of filler with the ratio of 10, 30 and 50 wt.%(p<0.05), and the incorporation ratio did not
influence on the shear bond strength(p>0.05). Silane treatment of the filler did not
influenced on the shear bond strength(p>0.05).
3. The biaxial fracture strength of TM was 170.69 MPa, and this was significantly
higher than that of unfilled HP(p<0.05). Incorporation of the filler with the ratio of 10,
30 and 50 wt% resulted in significantly lower biaxial fracture strength compared with
that of unfilled HP(p<0.05).
4. In HP with the incorporation of filler 10 or 30 wt.% group, the biaxial fracture
strength of silane coated and not-coated filler group was significantly different(p<0.05).
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