Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Operative Dentistry

This in-vitro study was designed to evaluate the Microleakage remains a problem with the commonly used restorative materials. The current study was conducted to investigate the microleakage of the nano hybrid resin composite indirect restoration (Grandiso) fabricated using flexible or stone die after 24 hours and 3 months. The dimensional changes of the die materials were also evaluated after the same time intervals. A total number of 44 sound non cavitated extracted human upper premolar teeth were used in this study. Teeth were randomly divided into two main groups with 22 specimens each according to the type of the die material (A) used, where (A1) represented stone die and (A2) represented flexible die. Then, each group was subdivided into two subgroups according to the period time (B) with 11specimens each, where (B1) represented after 24 hours storage, (B2) represented after 3 months storage. Teeth were mounted into acrylic blocks and a standardized MOD cavities were prepared with dimensions (3±0.5 x 4 mm), corresponding to bucco-lingual width and depth respectively using the CNC milling machine. Alginate impression was taken using a specially constructed mould and poured with either silicone material to obtain a flexible die or stone for a stone die. Nanofilled resin composite (Grandioso) was applied in increments, the first one was to restore the contact followed by two increments and light cured. Inlay restorations were cemented to the prepared cavities using Future dual cured universal adhesive and Bifix QM resin cement

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