Behr M.*, Rosentritt M., Faltermeier A., Handel G.
(Department of Prosthetic Dentistry, University of Regensburg, Germany)
Objectives: This study investigated the influence of electron beam irradiation on the fracture toughness (Kmax), fracture work (FW) and Vickers hardness (VH) of experimental composite blends compared to blends with non-irradiated fillers. Methods: Six experimental composite blends with (33kGy) and six without irradiated fillers were composed. A total of 120 rectangular specimens of 36x8x3 mm (l,w,h) were cured. Three subgroups were assigned: type I: 72w% silaneted inorganic fillers, SiO2-based; type II: 100w% organic fillers, UDMA-based , type III: mixed 60w% organic/ 40w% not-silaneted inorganic fillers; matrix for all groups was UDMA; initiator system: light-curing. Blends of 20 and 30 volume % fillers were mixed. Kmax; [MPa m-1/2]), FW; [J/m2]) and VH (no units) were determined. Statistical analysis: Mann-Whitney U test, mean, std. dev.
Results: Blends with irradiated inorganic fillers of type I had significantly increased Kmax (0.005) and FW (0.02 / 20 vol%; exception: 0.11 / 30 vol%,) values. VH remained unchanged. Type II irradiated organic fillers improved Kmax, FW and VH significantly (0.005). Type III blends showed only significantly higher VH (0.005). Different filler volume (20/30) had not influence.
|I-20||I-20 irr||I-30||I-30 irr||II-20||II-20 irr||II-30||II-30 irr||III-20||III-20 irr||III-30||III-30 irr|
|Kmax +/-||1.03 0.09||1.26 0.14||1.07 0.1||1.27 0.07||0.72 0.12||1.0 0.06||0.79 0.08||1.13 0.12||1.0 0.13||1.09 0.08||1.1 0.09||1.09 0.06|
|FW +/-||87.9 11.5.||126.6 35.5||100.5 21.7||119.1 22.3||70.2 22.1||99.3 19.7||73.5 15.4||115.1 19.0||107.9 21.9||92.9 15.7||108.7 26.1||105.5 18.8|
|VH +/-||16.7 0.8||16.5 1.3||16.7 0.5||17.2 0,4||15.9 0.6||17.7 0.5||15.7 0.4||17.9 0.4||15.7 0.4||17.1 0.3||15.9 0.5||18.0 0.5|
Conclusions: It was demonstrated that electron beam irradiation of inorganic/organic fillers has the potential to improve the mechanical properties of composites.