Influence of Short Fiber-Reinforced Composites on Fracture Resistance of Single-Structure Restorations

Objective: The aim was to determine the load-bearing capacity of anterior crowns prepared using two types of single-structure short fibre-reinforced composites (SFRCs). Furthermore, fracture toughness (FT), flexural strength (FS) and flexural modulus (FM) of tested composites were measured. Methods: Seven groups of composite crowns were designed for an upper central incisor (n=8/group). Two groups were CAD/CAM fabricated made of Cerasmart 270 and experimental single-structure SFRC blocks. Two groups were 3D-printed made of GC Temp PRINT and Pro3dure GR-17 composites. Two groups were made of conventional light-cured composites (Essentia and Gradia Plus). The last group was a single-structure SFRC made of commercial flowable SFRC (everX Flow). Crown restorations were loaded until fracture. Failure-modes were then visually examined. FT, FS and FM were determined for each tested composite OZ. The data were analysed using analysis of variance (p=.0.05) followed by Tukey's post-hoc test. Results: ANOVA revealed that crowns made of experimental SFRC blocks had significantly higher load-bearing capacities (1650 +/- 230 (p<0.05) among all the groups tested. Experimental SFRC blocks exhibited the highest FT (2.9 MPa m(1/2)) and FS (245.8 MPa) values (p<0.05) among tested composites. Conclusion: CAD/CAM fabricated restorations made of experimental SFRC blocks demonstrated encouraging performance related to their fracture-behaviour.