LOCALIZED MECHANICS OF DENTIN SELF-ETCHING ADHESIVE SYSTEM

• Published in: Journal of applied oral science 2007-08, Vol.15 (4), p.321-326
• Main Authors: Anchieta, Rodolfo Bruniera, Rocha, Eduardo Passos, Ko, Ching-Chang, Sundfeld, Renato Herman, Martin, Manoel, Archangelo, Carlos Marcelo
• Format: Article
• Language: English
• Subjects: Original
• ISSN: 1678-7757; 1678-7765
• DOI: 10.1590/S1678-775720070004000015

The bond strength of composite resins (CRs) to dentin is influenced by the interfacial microstructure of the hybrid layer (HL) and the resin tags (TAG). The contemporary self-etching primer adhesive systems overcame the inconvenient of the etch-and-rinse protocol. Studies, however, have demonstrated that HL thickness and TAG length vary according to the wetting time and additional use of acid-etching prior to self-etching primers. This study investigated the localized stress distribution in the HL and the dentin/adhesive interface. Two HL thicknesses (3 or 6 μm), two TAG lengths (13 or 17 μm) and two loading conditions (perpendicular and oblique-25 o ) were investigated by the finite element (FE) analysis. Five two-dimensional FE models (M) of a dentin specimen restored with CR (38 x 64 μm) were constructed: Ml - no HL and no TAG; M2 - 3 μm of HL and 13 μm of TAG; M3 - 3 μm of HL and 17 μm of TAG; M4 - 6 μm of HL and 13 μm of TAG; and M5 - 6 μm of HL and 17 μm of TAG. Two distributed loadings (L) (20N) were applied on CR surface: L1 - perpendicular, and L2 - oblique (25°). Fixed interfacial conditions were assigned on the border of the dentin specimen. Ansys 10.0 (Ansys®, Houston, PA, USA) software was used to calculate the stress fields. The peak of von Mises (σ vM ) and maximum principal stress (σ max ) was higher in L2 than in L1. Microstructures (HL and TAG) had no effect on local stresses for L1. Decreasing HL decreased σ vM and σ max in all structures for L2, but the TAG length had influence only on the peributular dentin. The thickness of HL had more influence on the σ vM and σ max than TAG length. The peritubular dentin and its adjacent structures showed the highest σ vM and σ max , mainly in the oblique loading.