v
Dr Nek Daraz, DR Usman Ali Younis, Dr Muhammad Amer Khan
Objectives: The aim of this study was to evaluate the effect of immediate placement of different restorative materials in comparison with a temporary restoration on the surface micro hardness of mineral trioxide aggregate (MTA). Materials and Methods: Access cavities were prepared in 40 extracted human molars, and a 3-mm layer of MTA was placed in the pulp chamber. The samples were divided into eight groups (n=5). Ten minutes after the MTA placement, two groups were restored with Zonalin temporary restoration, while the other six groups were restored with glass-ionomer cement (GIC), resin-modified glass-ionomer (RMGI), or resin-based composite. In each group, the Vickers micro hardness (VMH) of MTA was determined after 7 and 21 days Results: The type of restorative materials had a statistically significant effect on the micro hardness of MTA (P=0.002). However, the micro hardness of MTA was neither significantly influenced by the timing of final restoration (P=0.246) nor by the time-material interaction (P=0.116). Conclusions: Based on the results of the present study and by considering the limitations of laboratory studies, it is recommended to postpone the placement of final restorations until the underlying MTA is completely set. Otherwise, in the clinical conditions in which early covering of MTA is recommended, sufficient moist-curing and hydration should be guaranteed by selecting a restorative material with the lowest hydrophilic interaction energy. Keywords: Dental Restoration, Mineral Trioxide Aggregate, Composite Resins, Glass Ionomer Cements