Accademia Italiana di Conservativa - CONSEURO 2000 - Abstract - Initial And Fatigue Repair Bond Strength Of An Aged Resin Composite

Initial And Fatigue Repair Bond Strength Of An Aged Resin Composite

R. Frankenberger*, S. Kolpak, U. Lohbauer, N. Krämer, And A. Petschelt

(Policlinic For Operative Dentistry And Periodontology, University Of Erlangen-Nuremberg, Germany)

The dramiatically increased use of resin composites for posterior restorations makes it necessary to consider the repairability of restorations instead of a complete removal. The bond between the aged and the freshly applied resin composite, however, is estimated critically in the literature.

Therefore the aim of the present study was to evaluate the effect of different pre-treatments of aged resin composite specimens (Tetric Ceram ®, Vivadent, Liechtenstein) on both initial and fatigue shear bond strengths of the same resin composite. 120 resin composite disks (simulation of inlay; 16x3 mm) were produced in two separately light-cured (40s) layers of 1.5 mm, and afterwards secondary cured (Light Box®, Heraeus-Kulzer, Dormagen, Germany) for 360 s. The specimens were stored for 365 days in aqua dest and randomly assigned to four pre-tratment groups (n=30):

1) Roughening with a diamond bur + dentin bonding agent (Syntac Classic®, Vivadent; DB),
2) roughening with a silicium carbide bur + dentin bonding agent (SC),
3) roughening with a silicium carbide bur + dentin bonding agent + Tetric®Flow (SF), and
4) silica-coating with the CoJet® system (Espe, Seefeld, Germany) + dentin bonding agent (CO).

The disks were restored with resin composite cylinders. Bond strengths [MPa](S.D.) were as follows (initial = 24 h storage; Adhesive fatigue limit: After 5000 cycles of subcritical load according to the staircase methodology):

	n	DB	SC	SF	CO
Initial bond strength	10	12.9 (5.2) C	19.3 (8.7) B	26.7 (6.4) A	19.7 (8.4) B
Adhesive fatigue limit	20	10,0 (2,3)	14,4 (6,7)	15,6 (4,5)	14,1 (7,7)
Data with same letters are not significantly different (p>0.05)

Within the limits of this in vitro study we conclude, that roughening with a diamond bur produced the lowest both initial and fatigue composite bond strengths of the repair composite tested (p<0.05; Wilcoxon test).