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Comparative Study
. Fall 2001;3(3):227-36.

Shear Strength of Dentin and Dentin Bonded Composites

  • PMID: 11803710
Comparative Study

Shear Strength of Dentin and Dentin Bonded Composites

E Mondragon et al. J Adhes Dent. .


Purpose: The objective of this study was to compare the shear strength of dentin with the shear strength of dentin bonded composites, and to determine how variables such as composite strength and blade width used during shear testing influence shear strength values.

Materials and methods: Dentin test samples (n = 36) were made by milling the anatomical molar crowns to a shape similar to a composite rod bonded to a flat dentin surface. Dentin bonding was accomplished by bonding composites to flat dentin surfaces (n = 72) using Scotchbond MP and Z100 (n = 36) or Silux Plus (n = 36) composites. Shear testing was conducted using a guillotine-like device with a flat blade embracing half the dentin or composite cylinders. The blade thickness was either 0.25, 0.5, 0.75, 1.0, 1.25, or 1.50 mm. Six samples per material and blade thickness were tested. In addition to the above study, the bond strength of Z100 (n = 6) and Silux (n = 6) bonded with Scotchbond MP and tested with an orthodontic edgewire loop were also tested and compared with the bond strength of the Z100 and Silux samples tested with the 0.5 thick blade. All shear testing was done at a load rate of 0.5 mm/min. The results were analyzed using ANOVA and Duncan's multiple range test.

Results: The shear strength values when tested with the blades were: dentin = 39.7 +/- 13.0 MPa, Z100 = 29.3 +/- 7.2 MPa, and Silux = 21.1 +/- 4.9 MPa; each group had significantly different values (p < 0.05). The blade thickness had no significant effect on strength (p = 0.471). Comparing the 0.5-mm-wide blade with the edge wire (width = 0.45 mm) revealed a significant difference (p = 0.0014) favoring the blade. Z100 performed better than Silux (p = 0.0014).

Conclusion: The shear strength of the tested bonding agent is significantly lower than the shear strength of dentin. The shear strength depends on testing method (blade vs loop) and composite material.

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