Microstructure and Surface Characteristics of Short- Fiber Reinforced CAD/CAM Composite Blocks.

OBJECTIVE: The aim was to investigate certain surface properties and microstructure of an experimental short fiber-reinforced CAD/CAM composite block (SFRC) in comparison with different CAD/CAM, 3D-printing and manually-made commercial composites (Cerasmart 270, GC Temp PRINT, Pro3dure GR-17, Essentia U, Gradia Plus and everX Flow). METHODS: A wear-test was performed using a chewing-simulator with 15000 cycles. Wear depth (n=6) was assessed by 3D optical-profilometer. Surface roughness (SR) before and after wearing-test was evaluated. A Vickers-indenter was utilized for evaluating surface microhardness (VH) and glossmeter was utilized to measure the surface gloss at 60°. The surface microstructure of each composite was investigated with SEM. Data were statistically analyzed with analysis of variance ANOVA (p=0.05). RESULTS: Significant differences in the surface properties were found according to the type of composite (p⟨0.05). Cerasmart 270 exhibited the highest VH (94.8 V) and lowest SR (0.18 Ra) values (p⟨0.05) among the composites tested. The lowest wear depth measurement was located for GC Temp PRINT (19.3 µm) which was not significantly different (p⟩0.05) from Cerasmart 270 (20.7 µm). CONCLUSION: Incorporation of fibers to the composite of the CAD/CAM block did not negatively influence the surface characteristics of composite.

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 (n=8). 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 N) (p⟨0.05) among all the groups tested. Experimental SFRC blocks exhibited the highest FT (2.9 MPa m1/2) 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.

Romberg's syndrome: a case report.

A first case of Romberg's syndrome from Libya is reported. Romberg's syndrome is a rare disease causing progressive facial hemiatrophy. It was first described by Parry in 1825 and then by Romberg in 1846. Since then there have been sporadic case reports and reviews in the literature [1-5]. For the first time, we report a case from Libya.