Methods: Sixty sound extracted human third molars were selected and the crowns were sectioned perpendicular to the long axis in order to obtain dentin slices to be bonded with one of the following adhesives: Syntac/Heliobond (Ivoclar-Vivadent) and Adper-Scottchbond-1XT (3M-ESPE). The adhesives were cured by using a LED-unit (Bluephase®, Ivoclar Vivadent) with three different curing times (10s, 20s and 30s) under two ceramics (IPS-e.max-Press,Ivoclar-Vivadent; IPS-Empress®CAD,Ivoclar-Vivadent) of different thicknesses (0mm,0.75mm,2mm) and a resin cement (VariolinkVeneer,Ivoclar-Vivadent) of 170 μm in thickness. Thirty groups were included, each containing 60 measurements. Micromechanical properties (Hardness,HV, Indentation Modulus,E and creep,Cr) of the adhesives were measured with an automatic microhardness indenter (Fisherscope H100C,Germany). Data were statistically analyzed by using one-way ANOVA and Tukey’s post-hoc test (SPSS 20.0).
Results: Significant differences were observed between the mechanical properties of the adhesives (p<0.05). The effect of included parameters on the mechanical properties with Eta- Squared values is given in the table. The ceramic type showed the highest effect on HV of the tested adhesives, while E and Cr were stronger influenced by the adhesive type. Ceramic thickness showed a very low effect on HV, and no effect on E and Cr.
Parameters |
Mechanical Properties |
Eta-Squared Values |
Adhesive |
HV E Cr |
0.046 0.275 0.194 |
Time |
HV E Cr |
0.095 0.106 0.073 |
Ceramic |
HV E Cr |
0.109 0.037 0.058 |
Ceramic thickness |
HV E* Cr* |
0.006 - - |
*No significant effect(p>0.05) |
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Conclusions: Dental adhesives used in this study exhibited a favorable mechanical properties under different thicknesses of the ceramics. The adhesive type was more effective on the mechanical properties of the adhesives when compared with the ceramic type and thickness.