Reimagining bonding interfaces: UV photofunctionalization, a novel physicochemical approach, unlocks titanium and cement adhesive potential.

Objectives: Mechanical roughening and chemical priming are conventional techniques to improve material bonding, but they come with inherent limitations. This study aimed to investigate a novel physicochemical approach-UV photofunctionalization-to enhance bonding performance between titanium and glass ionomer cement.

Methods: Shear bond strength tests were conducted using Grade 4 commercially pure titanium and a resin-modified glass ionomer cement. Both smooth, machined titanium surfaces and gritblast-roughened surfaces were evaluated, with and without 1-min UV photofunctionalization.

Results: UV photofunctionalization reduced the surface carbon content of titanium from over 35 % to 20 % and transformed the surface wettability from hydrophobic to hydrophilic. This physicochemical alteration significantly enhanced bonding properties. On machined surfaces, UV treatment increased yield strength and elastic modulus by up to 4-fold, and interfacial energy by over 9-fold. The effect of UV treatment was comparable to, and in some aspects exceeded, the effect of grit-blasting. When UV photofunctionalization was applied to grit-blasted surfaces, further improvements were observed-yield strength and elastic modulus increased by 2-fold, and interfacial energy by approximately 3-fold. The synergistic application of both surface roughening and UV photofunctionalization resulted in a 7-fold increase in yield strength and up to a 19-fold increase in interfacial energy compared to the untreated machined surface. Post-shear analyses revealed significant cement remnants on the UV-treated titanium, indicating that actual interfacial bonding may have been even stronger than the measured values suggest.

Significance: UV photofunctionalization for a minute provides a powerful, non-invasive physicochemical surface modification method that significantly improves the bonding between titanium and resin-modified glass ionomer cement without altering surface morphology. This strategy represents a paradigm shift in resin-modified glass ionomer cement-titanium adhesion by enhancing interfacial compatibility and energy, offering a promising alternative to traditional mechanical or chemical surface modification techniques.