Nanomechanical properties of biochemically modified dentin bonded interfaces.

The effect of biomodification of dentin matrices using collagen cross-linkers, glutaraldehyde (GD) and grape seed extract (GSE), on the reduced modulus of elasticity (Er) and nanohardness (H) of the hybrid layer and underlying dentin was investigated at the dentin-resin bonded interface. The coronal dentin of nine molars were exposed and divided into groups: 5% GD, 6·5% GSE and control. Control samples were etched, bonded with Adper Single Bond Plus and Premise composite. GD and GSE were applied for 1 h prior to bonding procedures. After 24 h, samples were sectioned, and resin-dentin beams were either kept in distilled water or exposed to collagenase treatment for 24 h. Nano-indentations were performed at the hybrid layer and underlying dentin. GD and GSE treatment increased the Er and H of resin-dentin interface structures when compared to the control group (P<0·05), particularly the hybrid layer, and may be a promising novel approach to strengthen the dentin-resin bonded interface structures when using these adhesive system and resin-based composite.

Mechanical properties of tannic-acid-treated dentin matrix.

Dentin collagen is a major component of the hybrid layer, and its stability may have a great impact on the properties of adhesive interfaces. We tested the hypothesis that the use of tannic acid (TA), a collagen cross-linking agent, may affect the mechanical properties and stability of the dentin matrix. The present study evaluated the effects of different concentrations of TA on the modulus of elasticity and enzymatic degradation of dentin matrix. Hence, the effect of TA pre-treatment on resin-dentin bond strength was assessed with the use of two bonding systems. Sound human molars were used and prepared according to each experimental design. The use of TA affected the properties of demineralized dentin by increasing its stiffness. TA treatment inhibited the effect of collagenase digestion on dentin matrix, particularly for 10%TA and 20%TA. The TA-dentin matrix complex resulted in improved bond strength for both adhesive systems.

Interfacial ultramorphology of single-step adhesives: nanoleakage as a function of time.

The aim of this study was to examine the effectiveness of single-step self-etching adhesives in preventing nanoleakage over a 90-day water-storage period, and analyse the ultramorphological characteristics of resin-dentin interfaces. Three single-step self-etching adhesives were evaluated: Adper Prompt L-Pop - LP (3M ESPE), iBond - iB (Heraeus Kulzer), and Clearfil Tri-S Bond - S3 (Kuraray). Bonded specimens were sectioned into 0.9-mm thick slabs and stored in water for 1, 60 or 90 days. After the storage periods, a silver tracer solution was used to reveal nanometer-sized spaces and evidence of degradation within resin-dentin interfaces. Epoxy resin-embedded sections were prepared, and the interfaces observed with the TEM. Nanoleakage patterns were compared among adhesives and storage periods using image analysis software. Data were statistically analysed by two-way anova and Tukey test. Nanoleakage was observed in all resin-dentin interfaces produced by the single-step self-etching adhesives. Results showed that LP presented the lowest silver deposition means at 1 day. However, after 60 and 90 days, the area of silver deposition significantly increased for LP. iB presented intense silver deposition after 1 day and a small increase after 90 days. S3 presented the lowest silver deposition means after 60 and 90 days of water-storage.