Effects of N-vinylpyrrolidone containing polyelectrolytes on surface properties of GICs

Objectives: Due to the importance of surface properties on bond strength and adhesion of dental materials, this study investigates the effect of NVP containing terpolymers on the surface properties of GICs. In addition, the effect on NVP containing terpolymers as a conditioner on dentin was evaluated.

Methods: A terpolymer of acrylic acid (AA) - itaconic acid (IA) - (NVP) was synthesized by free radical polymerization and characterized using 1H-NMR, FTIR spectroscopy and viscometry. The experimental GIC samples were made from a 50% solution of the synthesized terpolymer with Fuji II powder in a 2.7: 1 P/L ratio. The wettability and work of adhesion of modified cements also were determined by contact angle measurements as a function of time (regarding Fowkes` law) and the bond strength of cement to dentin was evaluated and compared with the control group (Fuji II GIC).

Results: Results showed that NVP modified glass ionomer cements showed significantly lower contact angles (q= 47o) and higher work of adhesion (WA= 59.4 erg/cm2) in comparison to commercially available Fuji II GIC (q= 60o and WA= 50.3 erg/cm2, respectively). The wettability of dentin surfaces conditioned with NVP containing terpolymer was higher (q= 21o, WA= 74.2 erg/cm2) than dentin conditioned with Fuji conditioner (q= 30o, WA= 69). The experimental cement also showed higher but not statistically significant values for shear bond strength to dentin (7.6 MPa), when compared to control group (7.3 MPa).

Conclusions: It was concluded that NVP containing polyelectrolytes can enhance the surface properties of GICs and also increase their bond strength to the dentin.