Scanning electron microscopic evaluation of fiber post-resin core units built up with different resin composites

Purpose: To microscopically evaluate the structural characteristics of post-and-core units made of a fiber post and of different types of resin-based composites used as core materials. Methods: 55 endodontically treated human maxillary incisors were prepared for receiving a fiber post (,Esthetic Post Plus). One-Step and C&B resin cement were used for luting the post. Samples were randomly divided into 11 groups. Eleven different composite materials were selected to build-up the abutment. The materials on trial were: Group 1: Z100; Group 2: Light-Core; Group 3: Lumiglass; Group 4: Gradia Direct; Group 5: Build-It!; Group 6: Tetric Ceram; Group 7: Biscore self-curing; Group 8: Unifil Flow; Group 9: Definite Flow; Group 10: Tetric Flow; Group 11: AEliteFlo. All the post-and-core specimens were cut perpendicularly to their long axis and processed for SEM observations. The presence of voids/bubbles within the resin abutment and of defects at the interface between the post surface and the core material was scored. These aspects were quantified with reference to a predefined index. The differences among the scores were tested for statistical significance (P< 0.05). Results: Cores built up with flowable composites showed the highest integrity and the best adaptation onto the post.