On the fatigue behavior of resin–dentin bonds after degradation by biofilm

Abstract

The durability of resin-dentin bonds is a growing concern in the placement of composite restorations. Most reported evaluations concerning the mechanical behavior of the bonded interface are conducted using static loading to failure only. They also do not account for the acid production of biofilms, which is one of the most common contributors to interfacial failures in vivo. In this investigation resin-dentin bonded interface specimens were exposed to S. mutans for 14 days and then subjected to quasi-static or cyclic four-point flexure to failure. Control specimens (without biofilm) were evaluated after aging for one and fourteen days. While no significant difference in flexure strength resulted from the duration of water aging (66.2 MPa vs 56.9 MPa), biofilm exposure caused a significant reduction in strength (29.3 MPa; p≤0.000). After water aging for one and fourteen days the apparent endurance limits were 13.0 MPa and 13.1 MPa, respectively. Biofilm treatment caused a significant (p≤0.001) reduction in fatigue resistance of the interface, and the endurance limit was reduced to 9.9 MPa. Fatigue failure of the control specimens initiated within the resin composite adjacent to the interface, whereas failure of the biofilm treated specimens initiated within the hybrid layer and appeared attributed to the localized demineralization of dentin. Biofilm degradation is an important consideration in assessing the durability of resin-dentin bonds.

Bonding effectiveness of composite-dentin interfaces after mechanical loading with a new device (Rub&Roll)

“…In the present study, there was no statistical difference between groups and the mode of fracture, as the most prevalent fractures were apparently interfacial and mixed. This supports a study reporting that the mode of fracture may also be associated with the kind of gripping device 25) . The device used in this study was a K.U.Leuven-BIOMAT jig, which is a modified Geraldeli's microtensile testing jig 26) .…”

Biocompatibility and antibacterial activity of nitrogen-doped titanium dioxide nanoparticles for use in dental resin formulations

“…General instrument settings were as follows: microwave power, 10 mW; modulation amplitude, 1 G; receiver gain 1×10 5 ; time constant, 82 milliseconds; and time sweep, 42 seconds. Using the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), radical adducts were identified from dispersed particles in both aqueous and dimethyl sulfoxide (DMSO) solutions.…”

Effect of frequency on the fatigue strength of dentin bonds

“…Fatigue strength is the apparent strength of a material for a desired "life" (i.e., the number of loading cycles applied) (17). Degradation of the bonded interface can occur as a result of acid attack from oral bacteria (18), hydrolytic degradation of the adhesive (19), enzymatic degradation of the dentinal hybrid layer by MMP's (matrix metalloproteinases) (20), and fatigue of the adhesive resin (10,11). …”