In this study, the shear bond strengths and accompanying elastic modulus ratio, displacement at bond failure and work up to fracture of pit and fissure sealants to toothe enamel were analyzed by the following variables, those were acid etching, moistu...
In this study, the shear bond strengths and accompanying elastic modulus ratio, displacement at bond failure and work up to fracture of pit and fissure sealants to toothe enamel were analyzed by the following variables, those were acid etching, moisture content of the surface of enamel, dentin bonding agent(species and method), thermocycling, saliva contamination.
One kind of chemically cured resin based pit and fissure sealant, two kinds of light cured resin based pit and fissure sealants and one kind of glass ionomer based pit and fissure sealant, and two kinds of dentin bonding agents were studied. The buccal surface of extracted premolars were ground flat with # 600 silicone carbide papers, and the ground surface was treated depending on the experimental conditions. After each treatment, each pit and fissure sealant was filled into plastic tube of 3mm diameter, which were laid on the surface of ground enamel surface, and were cured. Sealant bonded teeth specimens were immersed in 37℃ distilled water form 24 hours. The shear bond strength of sealant to enamel surface was measured with Universal testing machine with the cross head speed of 1mm/min. From the obtained load-deflection curves, modulus ratio, bond strength, displacement at bond failure and work up to fracture were analyzed.
From this experiment, the following results were obtained :
1. Comparing the results of standard condition(i. e. acid etching, dry surface, no dentin bonding agent and 300 thermocyling), the elastic modulus ratio of chemically cured resinbased pit and fissure sealant was significantly higher than those of other materials(P<0.05), and the bond strength, displacement at bond failure and work up to fracture of glass ionomer based pit and fissure sealant were significantly lower than those of other materials(P<0.05).
2. The results of ANOVA with the variables of type of material, acid etching, moisture condition of the enamel surface, dentin bonding agents were as follows ; 1) variables showed significant main effect on the shear bond strength of pit and fissure sealant to enamel(P<0.01), 2) type of material, acid etching and moisture condition of enamel influenced the bond strength significantly(P<0.01), 3) type and application methods of dentin bonding agents influenced on the bond strength significantly(P<0.05).
3. There were statistically significant correlation between the work up to fracture and the bond strength, and between the work up to fracture and the displacement at bond failure(P<0.01), and in these cases the correlation coefficient was 0.87.