Evaluation of dental cements derived from mixtures of highly reactive ionomer glasses and bottle glass: Cement manipulation, mechanical, fluoride ion releasing, radiopaque and setting properties

Objectives

To evaluate the mechanical properties, fluoride release, radiopacity, and setting characteristics of dental cements derived from highly reactive ionomer glasses and bottle glass mixtures.

Methods

Two highly reactive glass series, LG99 and LG117, were synthesized, milled, sieved, and characterized using XRD and laser particle size analysis. These glasses were mixed with predetermined ratios of ground bottle glass, poly(acrylic acid), and aqueous tartaric acid to form glass ionomer cements. The cements' working time (WT), setting time (ST), fluoride release, radiopacity, compressive strength (CS), and elastic modulus (EM) were evaluated. Mean differences in CS were analyzed using multivariate ANOVA with Tukey’s post hoc test at p = 0.05.

Results

The WT and ST for both groups ranged from 1.5 to 2.5 min. LG99 series cements showed significantly higher CS (∼65 MPa) and EM (∼2 GPa) than LG117 series (p < 0.05). Both series showed similar fluoride release profiles, peaking at 1.2 mmol/L at 28 days. Radiopacity for LG99 ranged from 0.97 to 1.34, while LG117 ranged from 0.60 to 0.95. Solid state ²⁷Al magic-angle spinning-nuclear magnetic resonance (MAS NMR) confirmed the presence of Al(IV) and Al(VI), indicating setting completion by one day for both series. Bottle glass showed a chemical shift at 55.8 ppm, overlapping with LG99′s Al(IV) signal. The ¹⁹F MAS NMR spectra revealed Al-F and F-Sr(n) species in all glasses, with LG117 forming CaF₂ after one day in deionized water.

Conclusion

Mixtures of highly reactive ionomer glass and bottle glass produced cements with satisfactory properties for dental applications. Further research is needed to optimize their formulation and properties.