Effect Of Early Water Exposure On The Mini-flexural Strength Of Glass Ionomer Restoratives

Abstract

Glass ionomer cements have gained popularity in the last few years, combining the advantages of being aesthetic, adhesive, biocompatible, and an anticariogenic material. Poor mechanical properties of these materials have limited there use in many clinical situations and made them prone to failure under stress. Early moisture sensitivity is thought to be one of the reasons for physical and mechanical properties deterioration, among some of the undesirable properties poor surface roughness and low flexure strength. However, glass ionomer surface protection seemed to be one of the trials or promising solutions to limit these drawbacks. The present study aimed to investigate the effect of early water exposure on the mini-flexure strength of the two types of resin modified glass ionomer cement. A total of 60 specimens were used in this study. Specially constructed split stainless steel rod was used to produce specimens ( 12 mm length , 2 mm width , 2 mm thickness ). The rod was adapted to the glass slap by the aid of a double adhesive tape and surrounded by a polypropylene ring (24 mm width, 10 mm length), then the additional silicon rubber base material was injected to produce the specified mold. The specimens were divided into equal two main groups ( 30 each ). Each of the above main groups was divided into five equal subgroups (6 each) according to moisture exposure time after setting employed: control (not water exposure), immediate water exposure, 5 minutes after setting then water exposure, 10 minutes after setting then water exposure and 15 minutes after setting then water exposure. The specimens were measured using universal testing machine. Two Way ANOVA analysis of variance was used to test the effect of glass ionomer, exposure time to moisture after setting and their interaction on mini-flexure strength.