Effect of carbodiimide on the fatigue crack growth resistance of resin–dentin bonds

Abstract

Recent studies have shown that ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) inactivates endogenous dentin proteases, thereby preventing collagen degradation and improving the durability of adhesive bonds to dentin. Bond durability is routinely assessed by monotonic microtensile testing, which does not consider the cyclic nature of mastication. Objective to characterize the effect of an EDC pretreatment on the fatigue crack growth behavior of resin-dentin bonds. Methods Bonded interface Compact Tension (CT) specimens were prepared using a three-step etch-and-rinse adhesive and hybrid resin-composite. Adhesive bonding of the treated groups included a 1 min application of an experimental EDC conditioner to the acid-etched dentin. The control groups did not receive EDC treatment. The fatigue crack growth resistance was examined after storage in artificial saliva for 0, 3 and 6 months. Results There was no significant difference in the immediate fatigue crack growth resistance of the EDC-treated and control groups at 0 months. However, after the 3 and 6 months storage periods the EDC-treated groups exhibited significantly greater (p≤0.05) fatigue crack growth resistance than the control specimens. Significance Although the EDC treatment maintained the fatigue crack growth resistance of the dentin bonds through 6 months of storage, additional studies are needed to assess its effectiveness over longer periods and in relation to other cross-linking agents.

Fatigue resistance of dentin bonds prepared with two- vs. three-step adhesives: Effect of carbodiimide

“…There was no evidence of degradation or indications of changes in the mechanisms of fatigue crack growth. The fracture surface morphology for the specimens prepared with SBMP adhesive (not shown) were very consistent with the characteristics of the SB specimens and have been presented elsewhere [27]. …”

“…Detailed views of the SBMP samples were presented previously [27] and are very consistent with the SB results. Failure of the resin tags occurred consistently at the primary fracture plane without evidence of pullout, suggesting well-hybridized resin tags.…”

“…Although the resin adhesive of the control SBMP specimens did not exhibit signs of degradation (Figure 7b), the collagen fibrils extending to the tags were thinner. In our earlier study concerning the fatigue crack growth resistance of bonded interfaces prepared with SBMP [27], it was unclear if the fracture surfaces revealed degrading matrix or fibrils. However, with these additional results, it is now clearer that the reduction is associated with degrading collagen fibrils at the top of the hybrid layer.…”

“…Cyclic loading was continued until the specimen underwent complete fracture. These procedures have been used previously for evaluating the resin-dentin bonded interface [18, 27] and the fatigue crack growth resistance of dentin [29, 30]. …”

“…In comparison to other products it has the advantage of very low cytotoxicity, and an ability to preserve dentin bond strength within clinically acceptable treatment times [23–26]. The application of 0.5 M EDC for 1 min during dentin bonding reportedly reduced the degradation in fatigue crack growth resistance of bonds prepared with a three-step resin adhesive bonding system [27]. While promising, two-step adhesive systems generally exhibit lower durability and resistance to degradation with aging [15].…”