Interfacial and mechanical effects of methylglyoxal on etched dentin: An in vitro study.

OBJECTIVES

This study evaluated methylglyoxal (MGO) pretreatment of demineralized dentin with respect to (1) reinforcement of the dentin matrix, (2) resistance to enzymatic degradation, and (3) Stability of the resin-dentin bond under enzymatic challenge.

METHODS

Demineralized dentin was treated with 0.5, 1, or 3 M MGO and examined using attenuated total reflectance-Fourier transform infrared spectroscopy, collagenase degradation assays, and apparent elastic modulus before and after enzymatic exposure. Resin-dentin specimens were bonded using an etch-and-rinse adhesive, and microtensile bond strength (µTBS) was assessed after 24 h and following 30 days of collagenase aging.

RESULTS

MGO treatment increased carbohydrate-associated FTIR bands (1000-1180 cm⁻¹), consistent with glycation, with the largest effect at 3 M. Resistance to enzymatic degradation increased in a concentration-dependent manner, with the onset of degradation rising from 28 ± 2 min in controls to 35.9 ± 0.6 h in the 3 M group (p < 0.0001). The apparent elastic modulus increased from 1.07 ± 0.47 MPa (control) to 4.01 ± 0.97 MPa (3 M; p < 0.0001). After enzymatic challenge, the modulus of untreated dentin decreased to 0.34 ± 0.38 MPa (p = 0.013), whereas MGO-treated dentin retained significantly higher stiffness (p < 0.05). Immediate µTBS values did not differ among groups (p = 0.64). After 30 days of enzymatic aging, µTBS declined in controls (30.9 ± 6.0 to 17.3 ± 5.5 MPa; p = 0.027), while all MGO groups maintained significantly higher aged bond strength than controls (p < 0.01).

CONCLUSIONS

MGO pretreatment reinforced demineralized dentinal collagen and increased resistance to enzymatic degradation without affecting immediate bond strength, while preserving bond performance after proteolytic exposure.

CLINICAL SIGNIFICANCE: Reinforcing exposed dentin collagen through controlled glycation may help limit enzymatic degradation, which reduces the longevity of adhesive restorations.