Synergistic Effect of a Combined 10-MDP/γ-MPTS Primer on Glass-Ceramic Bonding: A Multimodal Study

Introduction and aims: This study investigated the synergistic effect of combining 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) and γ-methacryloxypropyl trimethoxysilane (γ-MPTS) in one primer on bonding to lithium disilicate ceramics. Methods: A 5% ethanol solution with 10-MDP and γ-MPTS (1:1 by volume) was prepared. The mixed solutions after 24 hours, 72 hours, 7 days, and 6 months storage were characterized by Fourier transform infrared spectroscopy (FTIR). Ultraviolet-visible (UV-Vis) spectrophotometric titration monitored the intermolecular interactions and their dynamics within 30 minutes of mixing. 84 IPS e.max CAD specimens were etched with 5% HF acid and assigned to four surface pretreatment groups: control, 10-MDP, γ-MPTS, and 10-MDP+γ-MPTS. After applying RelyX Ultimate resin cement, 1-mm composite resin cylinders were bonded and light-polymerized. The bonded assemblies were then stored in water for 24 hours or aged via 6 months storage plus 5000 thermocycles before micro-shear bond strength testing. The data were analysed using multivariate analysis of variance (P < .05). Six machine learning models including Logistic Regression, Decision Tree, Random Forest, Extra Trees, Gradient Boosting, and Extreme Gradient Boosting were employed to evaluate the feature importance influencing bond strength. Results: FTIR and UV-Vis analyses indicated that 10-MDP promoted the hydrolysis and siloxane condensation of γ-MPTS, forming a stable organic-inorganic hybrid network. The combined group showed the highest initial (24.22 MPa) and aged (16.07 MPa) bond strength, with more cohesive failures. Machine learning confirmed the combined primer as the most critical factor. Conclusions: The coexistence of 10-MDP and γ-MPTS in a single solvent environment provides a synergistic effect, significantly enhancing both the bonding strength and durability of glass-based ceramics. Clinical Relevance: A combined 10-MDP/γ-MPTS primer stabilizes the adhesive interface and increases the durability of ceramic restorations for better long-term success.