Poliklinik für Zahnärztliche Prothetik

Direktor: Prof. Dr. Gerhard Handel


Electron irradiation of fiber reinforced composites: fracture strength, elongation and shear bond strength.

Kolbeck C.*, Rosentritt M., Behr M., Schneider S., Handel G.

(Department of Prosthetic Dentistry, University of Regensburg, Germany)

Objectives: Failures of fiber reinforced fixed partial dentures are often due to low fracture strength and high bending tendencies of the frameworks. Therefor we investigated the influence of electrone irradiation on the fracture and elongation behaviour of different fiber reinforced composites. Methods: 32 rectangular beams (25x3x3mm) were made per material (Construct: Girrbach Dental, Pforzheim, Germany; FibreKor: Jeneric Pentron, Wallingford/Ct, USA; StickNet: StickTech, Turku, Finland) and divided into four groups of 8 specimens respectively. Every group was treated with different amounts of electrone irradiation (0kGy, 15kGy, 33kGy, 100kGy) in an electrone beam accelerator (Rodotron: BETA GAMMA Services, Saal a. d. Donau, Germany). Afterwards fracture force [N] and breaking elongation [%] of the beams was determined by loading them to failure in the Universal-testing-machine 1446 (Zwick, Ulm, Germany) in a three-point bending design with fixed bearings. Medians and 25%-/75%-percentiles were calculated and Mann-Whitney-U-Test was carried out (pŁ0.05).

Results: Irradiation caused a dose dependent material specific increase of fracture resistance for all materials. For the elongation values Construct showed a significant decrease, FibreKor a significant increase and EverStick no significant changes.

 

Fracture force [N] (Median+25%/75%percentiles)

Elongation [%] (Median+25%/75%percentiles)

 

0kGy

15kGy

33kGy

100kGy

0kGy

15kGy

33kGy

100kGy

Construct

41(32/45)

46(43/49)

43(42/52)

84(79/104)

445(322/515)

424(403/437)

359(337/384)

322(263/333)

EverStick

67(48/74)

142(125/162)

130(113/155)

128(68/180)

128(109/174)

141(110/150)

111(96/131)

96(64/122)

FibreKor

74(71/86)

134(130/141)

153(147/158)

231(218/237)

87(85/101)

96(92/102)

113(101/121)

113(94/128)

Conclusions: A significant decrease of fracture elongation and thus possible problem with embrittlement only occured with Construct. Electrone irradiation seems to be a possibility to increase fracture resistance of fiber reinforced composite restorations.


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