Influence of voids in the hybrid layer based on self-etching adhesive systems: a 3-D FE analysis

Abstract

The presence of porosities at the dentin/adhesive interface has been observed with the use of new generation dentin bonding systems. These porosities tend to contradict the concept that etching and hybridization processes occur equally and simultaneously. Therefore, the aim of this study was to evaluate the micromechanical behavior of the hybrid layer (HL) with voids based on a self-etching adhesive system using 3-D finite element (FE) analysis. Material and Methods: Three Fe models (Mr) were built: Mr, dentin specimen (41x41x82 μm) with a regular and perfect (i.e. pore-free) HL based on a self-etching adhesive system, restored with composite resin; Mp, similar to M, but containing 25% (v/v) voids in the HL; Mpp, similar to Mr, but containing 50% (v/v) voids in the HL. A tensile load (0.03N) was applied on top of the composite resin. The stress field was obtained by using Ansys Workbench 10.0. The nodes of the base of the specimen were constrained in the x, y and z axes. The maximum principal stress (σmax) was obtained for all structures at the dentin/adhesive interface. Results: The Mpp showed the highest peak of σmax in the HL (32.2 MPa), followed by Mp (30 MPa) and Mr (28.4 MPa). The stress concentration in the peritubular dentin was high in all models (120 MPa). All other structures positioned far from voids showed similar increase of stress. Conclusion: Voids incorporated into the HL raised the σmax in this region by 13.5%. This behavior might be responsible for lower bond strengths of self-etching and single-bottle adhesives, as reported in the literature.

Influence of customized composite resin fibreglass posts on the mechanics of restored treated teeth

“…The maximum principal stress (σ max ) is appropriate for predicting failures in non‐ductile materials, such as dentine, as well as failures that could originate from small flaws (Anchieta et al. 2007, Martini et al. 2009).…”

“…The formation of bubbles or voids, representing areas of weakness within the Correspondence: Eduardo Passos Rocha and Rodolfo Bruniera Anchieta, Departamento de Materiais Odontológicos e Prótese, Faculdade de Odontologia de Araçatuba, UNESP, Rua Jose Bonifacio, 1193, Vila Mendonça, CEP 16015-000, Araçatuba-SP, Brasil (e-mails: eduardo_rocha@foa.unesp.br and rodol foanchieta@hotmail.com). doi:10.1111/j.1365-2591.01955.x International Endodontic Journal, 45, 146-155, 2012 ª 2011 International Endodontic Journal material, is less likely to occur in a thin and uniform layer of cement (Grandini et al 2005, D'Arcangelo et al 2007, Martini et al 2009). Furthermore, a thick cement layer may jeopardize the longevity of the restorations because adhesive failures are more common in a thick cement layer, because of the low mechanical properties of this layer (Tait et al 2005).…”

Mechanical Properties Comparing Composite Fiber Length to Amalgam

“…Also, dental students were found to produce class II failures 10x greater for composites than with amalgams with voids charted from X-rays as one of the common reasons for replacement at no cost [63]. Voids generally incorporate into the dentin hybrid layer as porosities at the gingival/adhesive interface as a possible reason for secondary decay acid-based deterioration adhesive error and loss of bond strength [64]. Further, voids in a class II cavity were found to be detrimental clinically for adhesive bond strength [65].…”

Effect of partially demineralized dentin beneath the hybrid layer on dentin–adhesive interface micromechanics

“…2) was built using solid modelling software (SolidWorks 2010; SolidWorks Corporation, Concord, MA, USA), in accordance with previously published data, with appropriate tensile loading (0.03 N), boundary conditions (Anchieta et al, 2007(Anchieta et al, , 2011Junior et al, 2012;Martini et al, 2009) and cross-sectional area ( Fig. 2) (Lin et al, 2011;Phrukkanon et al, 1998) taken into account.…”