The Comparison Of The Bonding Properties Between Resin-modified Glass Ionomer Cements And Root Canal Dentine

Due to the similar elastic modulus to that of dentin,fiber posts could allow more favorable stress distribution and lower risk of root fractures.Fiber post is superior to conventional metal post when hardness,aesthetic performance, erosion-resistance,fatigue-resistance,and biocompatibility are considered.The adhesion of fiber post to root canal is the problem concerned by many researchers.There are many kinds of resin cements in clinic,but the evaluations of the bonding strength are not coincident.Resin-modified glass ionomer cement is a new kind glass ionomer cement, and it has many properties that are superior to the traditional glass ionomer cement.With the promotion of the bonding strength,resin-modified glass ionomer cement is more and more popularly used in the clinic.In this research,a traditional glass ionomer cement(GC FujiⅠ),a resin-modified glass ionomer cement(GC FujiⅡLC )and a resin cements(Clearfil DC Core Automix)were used to bond fiber posts.Before bonding fiber post,the dentin of root canal wall are treated with different treatments including: a)control without treatment;b)etching with phosphoric acid and bonding directly;c)Etching with phosphoric acid and a dentinal bonding agent was applied before the post cemented.Push-out tests were used to evaluate the bonding strength of the three cements to root canal dentine before and after thermocycling.The microleakage between endodontically treated teeth canal dentin and the three cements after thermocycling were also evaluated.The main results are as follows:1.After different root canal wall treatments,the bonding strengths of three cements to root canal dentine were different.Clearfil DC Core Automix had the highest bonding strength(8.2510±0.7757Mp).With the same root canal wall treatment,the bonding strengths of resin-modified glass ionomer cement were higher than that of the traditional glass ionomer.The different root canal wall treatments affected the boding strengths between resin-modified glass ionomer cement and root canal dentin,and using adhesive agent can improve the bonding strength.2.After 1000 times thermal cycling,the bonding strengths of three cements(GC FujiⅠ,GC FujiⅡLC,Clearfil DC Core Automix) with different root canal wall treatments to root canal dentin were significant different.Clearfil DC Core Automix had the highest bonding strength(7.1410±0.9267Mp).The bonding strengths of RMGIC groups with etching and adhesive agent decreased apparently.After the thermal cycling,the bonding strengths of the GIC groups and the RMGIC group without etching were not significant difference.3.There were microleakages between endodontically treated teeth canal dentin and three cements(Clearfil DC Core Automix)after 1000 times thermal cycling.Specimens with Clearfil DC Core Automix showed the least microleakage compared to the others.There are no significant differences among the GIC groups with different treatments of root canal wall,and there are significant differences among RMGIC groups.The RMGIC groups show the lower microleakage compared to the GIC groups.