The Study On Dissolution Rate And Dentinal Bond Strength Of Three Glass Ionomer Cements

Dental bonding is a new emerging professional science. Compared with the traditional single scientific field, dental adhesive is a complex and intercross science which combine multiple courses such as Endodontics, Prothodontics, Orthodontics etc. Dental bonding technique means the use of adhesive to link restoration and tooth structure. However, bonding materials directly affect the quality of clinical rehabilitation. Therefore, the study on bonding materials is of great interest. Nowadays, the glass ionomer cement has become one of the most focused dental adhesives because of its superior clinical performance.Glass ionomer cement (GIC) is composted of polyacrylic aicd aqueous solution and glass powder. It has the advantages such as strong bond strength to enamel, sustaining release of fluoride and dissolving lowly in intraoral.Compared with traditional zinc polucarboxylate cement, silica cement, and zinc phosphate cement, glass ionomer cement has advantages on fluoride release, bonding ability and little negative effect on teeth. However, the early glass ionomer cement is a liquid based powder. Since the quantity of powder and liquid and the technique of hand-mixing are hard to control, the clinical performance of glass inomer cement will be affected by the technique sensitivity.The purpose of this study is to evaluate the soluble rate and shear bond strength to dentin of a two-paste glass ionomer cement-GC glass ionomer cement (GC Fuji CEM) and two different types of traditional glass ionomer cements-3M resin reinforced glass ionomer cement (gouache formulations, RelyXTM Luting Cement), GC glass ionomer cement (gouache formaluation, GC Fuji PLUS) in a simulated oral environment. The micromorphology of the cement surfaces before and after dissolution test were also observed under SEM. The following results could be revealed:1. The dissolution rate between the three glass ionomer cements were as followed. The dissolution rate of GC Fuji CEM(0.0409%±0.0133%)was lower than GC Fuji PLUS(0.0683%±0.02152%).But,there was no significant difference between GC Fuji PLUS and RelyXTM Luting Cement(p>0.05).2. The SEM observation showed that the experimental group of glass ionomer cements (GC Fuji CEM, two-paste formulation) had only a small surface cracks and no exfoliation phenomenon occurs. In contrast, the RelyXTM Luting Cement and GC Fuji PLUS was observed in vary degrees of exfoliation phenomena, accompanied by a large number of cracks and pores.3. The shear bond strength to dentin of the three cements were as the following: 6.163±1.177 MPa (RelyXTM Luting Cement),8.004±0.962 MPa (GC Fuji PLUS) and 10.31±0.893 MPa (GC Fuji CEM),respectively.There was statistically significant difference between group GC Fuji PLUS and GC Fuji CEM (P< 0.05);and between group GC Fuji CEM and RelyXTM Luting Cement (P< 0.05).