Biomechanical Effects of Collagen Cross-linking Agents on Demineralized Dentin

Objectives: A consequence of the dentin acid conditioning, the collagen fibrils are exposed to degradation and are susceptible to cyclic fatigue rupture after being subjected to repetitive loads during function. The elastic modulus decrease, increases the stress concentration in the exposed-collagen layer. The dentin biomodification through the use of collagen cross-linking agents (CCA), seeks to increase the resistance to the enzymatic degradation and structural stability of the dentinal collagen matrix. The aim of this study is to compare the effect on the biomechanical properties of the dentinal substrate based on the flexural strength and the tangent elastic modulus (E) of demineralized dentin with the use of CCA.
Methods: Dentin beams (n=90) were obtained from healthy human third molars, conditioned with phosphoric acid (10%) for 5h, and randomly divided according to dentin treatment. Control group: mineralized dentin (DM) and experimental groups: demineralized dentin (DD), 100% ethanol (ET), 1% glutaraldehyde (GA), 6.5% proanthocyanidin (PAC) and experimental cross-linking substance (ECS). The samples were tested to the three-point bending test on the Shimadzu A-GIS 5kN® universal testing machine (Shimadzu, Tokyo, Japan) (0.5mm/min). Data were statistically analyzed through ANOVA and a post-hoc Tukey test (p<0.05).
Results: The flexural strength of DM was significantly reduced by acid conditioning (p=0.001). ET as ECS solvent, did not show any effect on the DCM. The ECS application in DD recovered the flexural strength values compared to DM, in a similar percentage obtained with the application of GA and PAC. There were differences in behavior regard to strain and E, GA and PAC showed an elastic behavior, without significant differences between two groups (p>0.05); while ECS demonstrated a viscoelastic behavior, suitable for the strain under flexural loads.

Conclusions: CCA application demonstrated the ability of dentinal substrate biomodification, by recovery of flexural properties and strain behavior, improving the stability and durability of the dentin-resin interface.