Fatigue of the resin–dentin interface: A new approach for evaluating the durability of dentin bonds

Abstract

There are concerns regarding the longevity of resin composite restorations and the clinical relevance of in vitro bond strength testing to the durability of dentin bonds in vivo. Objective The objectives of this investigation were to: 1) develop a new method of experimental evaluation for quantifying the durability of dentin bonds, 2) apply this method to characterize the interfacial strength of a selected commercial system under both monotonic and cyclic loading, and 3) distinguish mechanisms contributing to the interface degradation and failure. Methods A new method for fatigue testing the resin-dentin interface was developed based on a four-point flexure arrangement that includes two identical bonded interfaces. Cyclic loading of specimens comprised of coronal dentin bonded to a commercial resin composite and controls of resin composite was performed to failure within a hydrated environment. Scanning electron microscopy and nanoscopic dynamic mechanical analysis were used to evaluate failure mechanisms. Results The fatigue strength of the resin-dentin interface was significantly lower (p≤0.0001) than that of the resin composite and reported for dentin over the entire finite life regime. Defined at 1×107 cycles, the apparent endurance limit of the resin-dentin interface was 13 MPa, in comparison to 48 MPa and 44 MPa for the resin composite and dentin, respectively. The ratio of fully reversed endurance limit to ultimate strength of the interface (0.26) was the lowest of the three materials. Significance The proposed approach for characterizing the fatigue strength of resin-dentin bonds may offer new insights concerning durability of the bonded interface.

Synergistic degradation of dentin by cyclic stress and buffer agitation

“…Secondary caries are potentially facilitated by the localized high cyclic stresses at the interface and fatigue (Spencer et al, 2010; Pashley et al, 2011). Cyclic stress is detrimental to the durability of resin-dentin bonds (Mutluay et al, 2013a; 2013b). Resin composites also tend to accumulate more biofilm/plaque in the oral environment than other restoratives materials (Zalkind et al, 1998; Beyth et al, 2007).…”

Fatigue failure of dentin–composite disks subjected to cyclic diametral compression

“…However, as explained above, failure initiated by dentin fracture did not seem to have occurred in our fatigue tests. Compared to the results from the four-point flexure test [11], the disk in diametral compression produced lower bond strength and a slightly higher rate of reduction in fatigue life with increasing stress. These are reflected in the lower values for A and slightly higher absolute values for B in Equation (1), respectively.…”

“…Examples include micro-rotary fatigue test [13], cyclic shear and push-out tests [43], as well as cyclic four-point flexure test [11,14,44]. The present study proposed an alternative test method for assessing the fatigue resistance of the dentin-composite interface.…”

In-vivo Bond Degradation Resistance and In-vitro Degree of Conversion of Bulk Fill Versus Nano Filled Resin Composite Restoratives

“…In vitro laboratory studies reported decreases in dentin bond strength after long-term storage in water. Although in vivo long-term durability studies reported the degradation of hybrid layers over time, they are still limited with respect to number and adhesive type (9,10) .…”