Effect of a calcium chloride solution treatment on physical and mechanical properties of glass ionomer cements

Abstract

This paper details a novel method to improve wear resistance of dental glass ionomer cement (GIC) restorations. The purpose of this in vitro study was to evaluate the effect of a calcium chloride (CaCl) solution treatment on surface hardness, surface roughness, compressive strength, water sorption and solubility of three conventional glass ionomer cements (GICs). Additionally, the changes of the Ca composition and morphology of the surface of the tested GICs were also investigated. The experimental groups of the study were: Group 1 (control) specimens after mixing were left in the mold to set without any treatment for 5 min; Group 2 specimens were left in the mold to set for 5 min and then each specimen was immersed in 10 ml of 42.7 wt% CaCl solution for 60 s. Statistical analysis was performed using one-way ANOVA and Tukey post hoc tests (a = 0.05). Calcium chloride solution treatment increased surface hardness of the GICs compared to control groups (P < 0.05), while surface roughness and compressive strength did not change after the treatment (P > 0.05). Reduction in water sorption and solubility was detected but not in all CaCl solution-treatment groups. No alterations were observed in surface morphology of the GICs, while surface calcium composition was increased after the treatment (P < 0.05). The use of a CaCl solution immediately after initial setting of GICs may be advantageous for some properties of the materials and possibly leads to improved prognosis and wear resistance of their restorations.

Evaluation of Surface Hardness and Color Stability of Two Different Glass Ionomer Cements After Treatment with Calcium Chloride: An In-Vitro Study

“…By adopting an alpha (α) level of 0.05, a beta (β) of 0.2 (i.e. power=80%), and an effect size (d) of 1.32 calculated based on the results of a previous study [8] . The total sample size was 80 samples: 40 for Fuji IX group and 40 for Fuji II LC group.…”

“…For preparation of disk-shaped specimen measuring a specially designed custom-made split Teflon mold was fabricated with 7 mm diameter and 2 mm thickness with an external metallic ring. The assembled split Teflon mold within the metallic ring were placed over a polyester strip (0.05 mm thickness) on a glass slab [8] .…”

“…The mixed capsule was loaded onto the applicator and the material was dispensed slowly and directly into the mold. After filling the mold with GIC, the material was then covered by a polyester strip, then a glass slab was placed over it and pressed to provide a flat smooth surface and to remove excess material [8] .…”

Is it Possible to Improve the Clinical Behaviour of Glass Ionomer Cement Restorations?

“…The method of improving GIC setting reaction through the supply of Ca cations using a CaCl 2 solution is based on the fact that the main setting reaction of GICs is the cross-linking of the carboxylate groups of polyalkenoic acids with the Al 3+ and Ca 2+ ions released from glass particles. A significant increase in surface hardness of various GICs has been reported when this method is used [16,17,24,25]. Considering that surface hardness of a restorative material is important for its wear resistance, this increase may improve the longevity of the restoration in clinical conditions.…”

“…It has been found that surface hardness increase is significantly correlated with the concentration of Ca ions on the GIC's surface [17], the immersion time in the CaCl 2 solution [24] and the concentration of the solution [24]. A recent study [25] reported that immersion of GIC specimens into 10 ml of a 42.7 wt% CaCl 2 solution (saturated concentration of CaCl 2 solution at 20 o C) for 60 sec increased surface hardness (5.3 to 7%), and decreased water sorption (3.3-24.4%) and solubility (2.2-33.5%).…”