Conditioning dentinal collagen by glycation improves long-term bond strength

ObjectivesThis study examined methylglyoxal (MGO) as a collagen crosslinker to reinforce demineralized dentin, enhance its enzymatic resistance, and improve long-term durability of the resin-dentin bond. MethodsDemineralized dentinal collagen films were treated with 0.5, 1, or 3 M MGO and subsequently exposed to collagenase to assess their resistance to enzymatic degradation. MGO-induced crosslink formation was monitored using Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) spectroscopy by tracking the carbohydrate-associated band at 1180 cm-{superscript 1}. The apparent elastic modulus of the treated specimens was measured using a three-point bending test. For bond strength evaluation, resin-dentin beams were prepared and tested using microtensile bond strength (TBS) to assess the influence of MGO pretreatment on interfacial adhesion. ResultsThe ATR-FTIR spectra demonstrated increased intensity in the carbohydrate double bands (1000-1180 cm-{superscript 1}) in glycated samples compared to the control. Glycation with 3 M MGO exhibited the highest resistance to enzymatic degradation, persisting for up to 60 hours with a 78-fold increase in resistance factor compared to the control group (p < 0.05). Furthermore, glycation with 3 M MGO resulted in a 4-fold increase in elastic modulus compared with the control group. Notably, the functionalized dentin retained its improved mechanical properties even after collagenase exposure, whereas the control group experienced a significant 68.2% reduction in elastic modulus (p = 0.002). While MGO pretreatment did not influence resin infiltration or initial TBS ({approx}30-35 MPa), it maintained its original bond strength after one month of collagenase challenge. In contrast, the control group exhibited a significant reduction, decreasing to 17 {+/-} 5.5 MPa compared with its initial value (p < 0.01). ConclusionMGO demonstrated efficacy in enhancing the mechanical properties and enzymatic stability of collagen as well as improving the resistance of the bonded interface to enzymatic degradation. SignificanceMGO pretreatment maintains the long-term stability of the resin-dentin interface by protecting dentinal collagen from enzymatic degradation, without compromising initial bonding performance. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/701305v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@54ae32org.highwire.dtl.DTLVardef@1787fdforg.highwire.dtl.DTLVardef@130b40org.highwire.dtl.DTLVardef@47c5f9_HPS_FORMAT_FIGEXP M_FIG C_FIG