Poliklinik für Zahnärztliche Prothetik

Direktor: Prof. Dr. Gerhard Handel


Experimental composites made of electron beam irradiated fillers

Behr M, Hagenbuch K, Rosentritt M

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

Objectives: Veneer fracture or bond failure between framework/veneer are typical failures of fibre-reinforced inlay fixed partial dentures (FPD). This study investigated the fracture resistance of FPDs different framework designs by an eccentric load point on the pontic. The hypothesis was stated that better support of the veneer by the fibre-framework would increase the fracture resistance. Methods: Four groups of Vectris/Adoro were manufactured. Beams (25mm length) made of Vectris pontic (parallel aligned) with a) round (Ø3mm) and b) rectangular (3x3) sectional view were directly veneered using Adoro. c) Round beams like "a)" were modified by coating the beams on the upper side with two layers of the cross-sectioned fibre mat Vectris frame. d) Vectris Pontic fibres were "anatomically" placed in the pontic area and wrapped using Vectris frame. The frameworks were constructed in a vacuum pressure process. All FPDs were mounted in a restrained-end apparatus and thermally cycled and mechanically loaded (TCML: 6000x5°C/55°C; 1.2 Mio x 50N, 1.66Hz). After TCML the FPDs were loaded to fracture. Statistics: One-way ANOVA .

Results: The highest flexural strength was evaluated for type Bs filler after irradiation (30kGy). In comparison to annealed fillers it was shown that the effect was not due to increased temperature during radiation. Generally, wear was not significantly affected by the different treatment procedures.

Flexural strength [N/mm2]

Wear [m] 200,000 cycles

 

Un-treated

Annealed 90C

Irradiated

30 kGy

Irradiated

90kGy

Un-treated

Annealed 90C

Irradiated

30 kGy

Irradiated

90kGy

A

100.78

89.26.6

107.66.3

87.96

72.54

72.34

73.54

73.24

As

90.413

46.46.8

94.915

--

70.95

96.45

78.55

--

B

111.717

86.28.1

119.3155

96.96

107.37

114.46

113.06

113.86

Bs

99.918

49.1

133.17

93.015

114.7

122.89

109.99

113.38

Conclusions: Irradiation of fillers using 30kGy can increase the flexural strength but not the wear resistance of composites.


vort05-04.htm