Shear bond strength of Equia Forte with enamel and dentin of permanent immature teeth – in vitro study

Abstract

Introduction. Development of new glass-ionomer materials allows to treat deep caries lesions in a minimally invasive manner. Bioactive materials, which regenerate tooth tissue through their remineralising properties, are also used in practice. The Sylc preparation is an example of bioactive glass. Aim. The aim of this study was to evaluate the shear bond strength of glass-ionomer Equia Forte with enamel and dentine surfaces of permanent immature teeth. The effect of sandblasting with Sylc as well as thermal ageing on the quality of material adhesion in relation to tooth tissues was also analysed. Material and methods. The study was conducted on immature permanent teeth. Equia Forte (GC) was used as glass-ionomer filling material whereas the Sylc (GlaxoSmithKline) preparation served as bioactive glass. The subjects of the study were classified into eight study groups according to: the type of tooth tissue – enamel/dentin, cavity surface preparation: sandblasting/no sandblasting, thermal shocks including 500 thermocycles at a temperature ranging 5-55°C. The obtained results are shown as mean and standard deviation. The normality of data distribution, homogeneity of variations, significance of differences between two independent groups of discrete variables or variables deviating from normality were assessed. The probability of revealed differences between the given results was also determined by pure chance. Results. The mean values of shear bond stresses for individual tissues were 7.57 MPa ± 2.72 for enamel and 6.74 MPa ± 1.63 for dentin. After sandblasting the enamel and dentin surfaces with the Sylc preparation, the values were 7.53 MPa ± 1.88 and 5.74 MPa ± 2.03, respectively. Sanding with Sylc of the dentin surface of a permanent tooth with incomplete development statistically significantly weakened the strength of the bond of the Equia Forte glass ionomer material with this tissue under the conditions created by applying 500 thermocycles (6.91 MPa ± 1.94 vs. 4.34 MPa ± 2.00, P2-str. bootstrap < 0.004). Conclusions. The experimental study shows that sandblasting with the Sylc preparation weakens the shear bond strength of the Equia Forte material against enamel and dentin of permanent immature teeth. Thermal shocks weaken adhesion of the material to the surface of the studied tissues.