Characterization of Stickiness of Glass Ionomer Restoratives

Objectives: The handling properties of glass ionomer (GI) restoratives are highly important because they directly affect the outcome of the clinical procedure. Specifically, GI restoratives that stick to the instrument can cause the inclusion of air bubbles during placement and contouring, which, in turn, negatively affect the long-term performance of the restoration. As a consequence, a GI restorative material exhibiting low stickiness is desired. The aim of this study was to develop a method to quantify and compare the stickiness of various GI restorative materials.
Methods: Six commercially available GIs were tested (Table 1). Restoratives were activated and mixed according to manufacturers’ instructions and extruded into a heated cavity (36°C). A spatula was used to level the surface. Stickiness of GIs was evaluated (n=10) using a Texture Analyzer (TA.XTplus, Stable Micro Systems, UK) by measuring (load cell 10N) the displacement and withdrawal work (N*mm). 30s after mixing commenced, a metal ball plunger (4mm diameter) was lowered and embedded 2mm into the sample at a constant speed (3mm/s). The plunger was then withdrawn at the same speed. Height was calibrated between measurements. Stickiness was defined as the ratio of the withdrawal work to the displacement work and expressed as a percentage, with lower percentages indicating less stickiness. Data was analyzed using one-way ANOVA, with Tukey’s HSD for post-hoc tests.
Results: A statistically significant difference (p<0.05) in stickiness was found among the materials tested (Table 1).
Conclusions: A reproducible method was developed to quantify different degrees of stickiness of GI restorative materials. The stickiness of Ketac™ Universal Aplicap™ (3M ESPE) was significantly lower compared to all other materials tested. GIs with low stickiness improve ease of handling and help to achieve a predictable clinical outcome.