Biological and mechanical properties of an experimental glass-ionomer cement modified by partial replacement of CaO with MgO or ZnO

Abstract

Some weaknesses of conventional glass ionomer cement (GIC) as dental materials, for instance the lack of bioactive potential and poor mechanical properties, remain unsolved. Objective The purpose of this study was to investigate the effects of the partial replacement of CaO with MgO or ZnO on the mechanical and biological properties of the experimental glass ionomer cements.Material and Methods Calcium fluoro-alumino-silicate glass was prepared for an experimental glass ionomer cement by melt quenching technique. The glass composition was modified by partial replacement (10 mol%) of CaO with MgO or ZnO. Net setting time, compressive and flexural properties, and in vitro rat dental pulp stem cells (rDPSCs) viability were examined for the prepared GICs and compared to a commercial GIC.Results The experimental GICs set more slowly than the commercial product, but their extended setting times are still within the maximum limit (8 min) specified in ISO 9917-1. Compressive strength of the experimental GIC was not increased by the partial substitution of CaO with either MgO or ZnO, but was comparable to the commercial control. For flexural properties, although there was no significance between the base and the modified glass, all prepared GICs marked a statistically higher flexural strength (p<0.05) and comparable modulus to control. The modified cements showed increased cell viability for rDPSCs.Conclusions The experimental GICs modified with MgO or ZnO can be considered bioactive dental materials.

Incorporation of cellulose fiber in glass ionomer cement

“…With respect to incorporation of fiber in GIC powders, the aspect ratio (fiber length:diameter), chemical composition, reinforcing fiber fraction, composition of the GIC powder and liquid, and the powder:liquid mixing ratios employed were markedly different for the studies reporting fiber reinforcement of GICs, such that a direct comparison under controlled conditions was not possible. On the other hand, this study confirms that the mean fracture toughness and compressive strength values reported for the commercial GIC without reinforcement are within the range of data previously reported . However, studies have been published reporting higher values of compressive strength for commercial conventional GICs than those obtained in the present study .…”

Compressive strength of calcium silicate-based cement

“…It has been confirmed in our research, as well as by other researchers, that cement reaction continues after one day, because crosswise bonds are established in the cement matrix [3]. Shiowaza [17] pointed out that cement maturation (acid-base reaction) is continued in the first week that can be seen as an increase in compressive strength and it is then stable for the next 12 months.…”

“…Adding Zn has shown to have a stimulating effect on bone formation in in vitro and in vivo conditions, as well as antibacterial activity, similar to silver. Adding MgO increased cell proliferation [3]. Titanium oxide is added because it is chemically stable, biocompatible and has antibacterial properties, and has shown significant activity against Streotococcus mutans in nano-formulation [8].…”

“…GJC su razvijeni iz kombinacije dva različita cementa: silikatnih i cink-polikarboksilatnih [3]. Konvencionalni GJC nastaju acido-baznom reakcijom jona stakla sa vodenim rastvorom poliakrilne kiseline i u širokoj su upotrebi u kliničkoj praksi.…”

“…GIC are developed by combining two different cements: silicate and zinc polycarboxyilate cements [3]. Conventional GIC are made by an acid-base reaction of glass ions with a water solution of polyacrylic acid.…”