Influence of dentin extrafibrillar collagen demineralization on resin-dentin bond durability - An in vitro study

To enhance the longevity of adhesive restorations, dentin collagen collapse prevention and preservation of matrix molecules are crucial to arrest the matrix metalloproteinase activation.

The aim of this study was to assess the polymeric chelating conditioners' impact on the microtensile adhesive strength as well as resin-dentin interfacial durability.

Sixty extracted human mandibular molars were prepared with standardized mesial and distal Class II box cavities. The specimens were divided into four groups (n = 15 each): control (37% phosphoric acid), and test groups include glycol chitosan-ethylenediaminetetraacetic acid (GCE), phytic acid, and glycolic acid (GA). All samples were restored using Clearfil S3 Bond Universal adhesive and a nanohybrid composite. Half of the samples from each group were tested for immediate microtensile bond strength (μTBS), while the remaining underwent cyclic thermomechanical loading before bond strength testing. Failure modes were analyzed using scanning electron microscopy. Statistical analysis included one-way ANOVA with Tukey's post hoc test and Chi-square test (P ≤ 0.05).

Test groups demonstrated significantly higher immediate and postaging μTBS values than the control (P < 0.05). GA showed the highest immediate bond strength (P < 0.05). No significant differences in bond strength were found between GCE and phytic acid groups (P > 0.05). Adhesive failure was predominant across all groups, with no statistical differences in failure modes observed before (P = 0.992) and after thermomechanical cycling (P = 0.938).

Dentin conditioning with polymeric chelating agents has significantly improved the immediate and after aging adhesive strength of resin-dentin interface.