Purpose

To evaluate the effects of collagen crosslinking with riboflavin 0.1% and ultraviolet-A (UVA) 5.4 J on bond strength of total-etch or self-etch adhesives on caries-affected dentin.

Methods

Sixty human caries-affected molars were randomly divided into three groups: control (C), riboflavin (R), and riboflavin + 3 minutes of UVA (R+UVA). After each treatment, either total-etch or self-etch adhesives were applied following the manufacturer's instructions, and composite stubs were built up on the treated surfaces. They were de-bonded in tension to measure bond strength. Twelve extra molars were used for scanning electron microscope (SEM) analysis.

Results

We observed that R+UVA-treated group yielded significantly higher bond strengths for carious dentin when the total-etch adhesive was applied. For the self-etch adhesive, no statistical differences were observed between the three pretreated-groups.

Conclusion

Our results, for the first time, are suggesting that etching with phosphoric acid potentialized the benefits of R+UVA crosslinking on carious dentin. R+UVA dentinal collagen crosslinking improves bond strength for caries-affected dentin when using a total-etch adhesive, but did not affect it when using a self-etch adhesive.

Purpose

To determine the bond strength, nanoleakage and interfacial morphology of four self-etch adhesives bonded to superficial dentin.

Methods

Microtensile (MT) (n= 15) and single plane shear (SP) (n= 8) bond tests were performed using human dentin polished through 320-grit SiC paper. Clearfil Protect Bond (PB), Clearfil S3 Bond (S3), Prompt L-Pop (PLP) and G-Bond (GB) were used according to their manufacturers' instructions. Composite was applied as cylinders with a thickness of 4 mm with a 1 mm diameter and stored in water at 370C for 24 hours. Specimens were debonded with a testing machine at a cross-head speed of 1 mm/minute. Means and standard deviations of bond strength were calculated. Data were analyzed using ANOVA. Fisher's PLSD intervals were calculated at the 0.05 level of significance. Failure modes were determined at x100. The hybrid layer was revealed by treatment with 5N HC1/5% NaOCl or fractured perpendicular to the interface and sputter coated with gold. Specimens were viewed at x1,000, x2,500, and x5,000 in a field emission SEM at 15 kV. Teeth (n=2) sectioned into 0.9 mm-thick slabs were immersed in ammoniacal silver nitrate solution for 24 hours, rinsed and immersed in photo-developing solution for 8 hours. Specimens were sectioned (90 nm-thick) and observed under TEM.

Results

Means ranged from 25.0 to 73.1 MPa for MT and from 15.5 to 56.4 MPa for SP. MT values were greater than SP, but were highly correlated (R2 = 0.99, P= 0.003) and provided the same order for the systems studied. Fisher's PLSD intervals (P< 0.05) for bond strength techniques and adhesives results were 1.7 and 2.3 MPa, respectively. Failures sites were mixed. TEM showed that hybrid layers were -0.5 pm for PB, GB and S3 and approximately 5 microm for PLP. SEM showed morphologic differences among adhesives. Silver nitrate deposits were observed within the interfaces for all adhesive systems.