Objective: To test dental fiber-reinforced composite (FRC) substructure arrangements within a bi-layer beam on the load to initial (IF) and final failure (FF) in a modified mode II delamination test. Methods: Three groups of FRC and particulate reinforced composite (PRC) were tested: PE (Ultra high molecular weight polyethylene ribbon, Connect, and BelleGlass, Kerr), W (woven E-glass, Vectris Frame, and Targis, Ivoclar), and U (unidirectional R-glass, Vectris Pontic, and Targis, Ivoclar). Twelve specimens were fabricated by placing an FRC layer into a 25x6x0.75 mm3 mold. PRC (10x6x0.75 mm3) was added to the specimen center. The FRC was placed into unpolymerized PRC layer at 3 depths to the veneer surface: 0 % (750 mm), 50 % (300 mm), or 100 % (< 10 mm). After light-polymerization, the specimens were standardized and then stored 1 week in 37 °C water. Four specimens were randomly selected for sectioning/pre-test evaluation. The remaining 8 specimens (= n) were loaded in a static 4-point bend test (20 mm upper/ 10 mm lower spans) veneer side down until failure (recording IF and FF). A failure ratio (FR) was developed (IF/FF x 100). Means and standard deviations (SD) were calculated (ANOVA, Tukey post hoc, p < 0.05). Results: No position of PE fiber increased the load to elicit IF. For the woven E-glass and unidirectional R-glass, the 50 % fiber position increased the load to IF. Conclusion: Glass fiber positions with 50 % penetration into the PRC significantly increased the load to IF in a modified mode II delamination.

S.R. Dyer, L.V.J. Lassila, P.K. Vallittu  The effect of internal fiber arrangement on the delamination failure in hybrid composite dental prostheses // Физ. мезомех. - 2004. - Т. 7. - № Спец2. - С. 119-122