Influence of a Hydrophobic Coating Layer on GIC Longevity

Objectives: Glass Ionomer Cements (GIC) are materials of choice in different clinical situations. However, as resin composites, GIC are subjected to mechanical wear overtime. The aim of this in vitro study was to test the mechanical behaviour or two different GIC employed in molar I class cavities with or without the application of a hydrophobic coating on the surface. The null hypothesis tested was that coating was not able to improve 1) roughness of the surface and 2) to prevent wear of the material.
Methods: 16 intact molars were selected and a standardized cavity (2x3x2mm) was prepared on each specimen. Teeth were then divided into two groups according to the material employed for the restoration: G1) Iono Star Molar (Voco); G2) Dentsply Chemfil Rock Advanced Ionomer Restorative (Dentsply). Both materials were applied following manufacturer’s indications. Specimens of the two groups were divided into two subgroups according to the application of a coating protective layer: SG1) application of a thin layer of hydrophobic coating (Easy Glaze, Voco); SG2) no coating application. Restored specimens were then scanned with an oral scanner and surface roughness was evaluated before and after wear induced by in-vitro chewing simulation and thermocycling. Images obtained were compared to evaluate surface loss. Results were statistically analysed with Kruskal Wallis test and statistical significance was set for p<0.05.
Results: Statistics showed no differences among the groups (p>0,05). The application of a coating on the surface was not able to prevent GIC wear overtime. Further, roughness was only initially improved by the coating application, but not overtime.
Conclusions: GIC material mechanical properties were not modified by the application of a hydrophobic coating. However, further analyses are necessary to better investigate the implication of a coating layer application on the surface of a restoration.