In-vitro wear and hardness of new conventional glass ionomer cement coated with nano-filled resin

Abstract

Background: Since the introduction of glass ionomer cements (GICs) in the 1970s, many attempts have been made to improve them and expand their application in restorative dentistry. Recently, GC America introduced a new glass ionomer restorative system called EQUIA. The manufacturer claims that this material has improved wear resistance by coating the surface of high-strength GIC with a nano-filled resin coating. Objective: The objective of this study was to measure the wear resistance and hardness of EQUIA and to compare it to other current restorative materials. Materials and Methods: Four different materials were used in this study: EQUIA, Fuji IX GP Extra, Fuji II LC and Z-100. Six specimens of each material were made and then tested in a toothbrush abrasion machine for 20,400 cycles, after which the amount of volume loss was calculated. Eight specimens of each material were made and tested in a three-body Alabama wear testing machine under a load of 75 N for 400,000 cycles. Four surface profiles were obtained from each specimen and volume loss was calculated using computer software. Five specimens of each material were made and Knoop microhardness was determined by using the mean of the three values from the top surface of the specimen. Results of each test were collected and compared with the other materials using one-way analysis of variance (ANOVA) at a significance level of 0.05. Results: Wear-resistance results showed that EQUIA has wear-resistance values comparable to composite resin and higher values than those for the high-strength GIC. The results also showed that Fuji II LC had the highest wear among all tested materials. Microhardness results showed that EQUIA has significantly lower microhardness than Fuji IX GP Extra and Z-100. Conclusion: Based on the results of the present study, it can be concluded that coating the surface of glass ionomer restorations with a nano-filled resin coat results in increasing the wear resistance and decreasing the microhardness of the material. Within the limitations of this study, EQUIA has comparable wear resistance to composite resin.