COMPARISION OF EIGHTH-GENERATION BONDING AGENT MODIFIED WITH BIO ACTIVE POLYMER FOR EVALUATION OF DIFFERENT TYPES OF PROPERTIES: AN IN VITRO STUDY

Abstract

In operational dentistry, degradation of the hybrid layer—the resin-dentin interface—rather than composite fracture is the primary cause of restoration failure. Activated by the acid-etching process, endogenous matrix metalloproteinases (MMPs) and cysteine cathepsins gradually break down exposed collagen fibrils that are not completely shielded by resin infiltration. This gradual enzymatic attrition is now acknowledged as the single greatest threat to the long-term survival of bonded restorations. Bioactive polymers — chitosan and L-arginine among them — have been proposed as additive modifiers capable of inhibiting this degradation while simultaneously offering antibacterial benefit. This article reports an in vitro comparative evaluation of G-Premio Bond (GC Corporation), an eighth-generation universal adhesive, in its unmodified form and after modification with 7 wt.% L-arginine or 0.5 wt.% chitosan. Two outcome measures were assessed: micro tensile bond strength (µTBS) to human dentin (n = 17 per group) and degree of conversion (DC%) by FTIR spectroscopy (n = 17 per group). Both modifiers significantly increased µTBS relative to the unmodified control — arginine by 25.7% (32.89 ± 0.86 MPa) and chitosan by 11.2% (29.09 ± 0.73 MPa), both p < 0.0001 — while DC% fell modestly with arginine (76.36 ± 0.74%, a statistically significant but practically small 1.16-point drop) and substantially with chitosan (67.36 ± 0.81%, a 10.17-point drop), though both modified formulations remained comfortably above the clinically accepted minimum DC threshold of 55–60%. These results imply that bioactive modification is a mechanically and biologically promising approach to enhancing adhesive performance; however, the particular modifier selection carries clear trade-offs between bond-strength gain and polymerization efficiency, which should guide future formulation efforts.