Fluorescent Orthodontic Adhesive With APTES-Modified ZnO Quantum Dots: Bond Strength, Cytocompatibility, and Clinical Feasibility.

INTRODUCTION: To develop a fluorescent adhesive by incorporating 3-aminopropyltriethoxysilane (APTES)-modified ZnO quantum dots (A-ZnOQDs) and to evaluate its bond strength, rheological properties, cytocompatibility, and removal performance. METHODS: ZnOQDs were modified with APTES and blended with commercial orthodontic adhesive to construct the fluorescent adhesive, which was divided into four groups (0, 2, 4, and 6 wt.%). Shear bond strength (SBS) was measured with a universal testing machine. Rheological properties were evaluated through a dynamic shear rheometer (DSR) test. Cytocompatibility was assessed with a CCK-8 kit. Bracket bonding and debonding procedures were performed on a head simulator. Adhesive removal effectiveness during bonding and debonding procedures was assessed. RESULTS: There was no significant difference in SBS among four groups (0%: 10.06 +/- 4.81 MPa, 2%: 8.98 +/- 3.70 MPa, 4%: 10.88 +/- 5.12 MPa, 6%: 8.09 +/- 3.43 MPa, p > 0.05). DSR displayed that the rheological curves of group-2% and group-4% were close to that of group-0%. CCK-8 assay indicated cell vitality did not differ among group-0%, group-2%, and group-4% (p > 0.05). Group-4% showed less excess adhesive area (0%: 1.81 +/- 1.58 mm(2), 4%: 0.95 +/- 1.33 mm(2), p = 0.0465), less remnant adhesive area (0%: 0.73 +/- 0.79 mm(2), 4%: 0.07 +/- 0.21 mm(2), p = 0.0002), more time taken in removing excess adhesive (0%: 40.76 +/- 6.44 s, 4%: 47.19 +/- 8.40 s, p = 0.0046), and similar time taken in removing remnant adhesive (0%: 40.04 +/- 10.05 s, 4%: 43.54 +/- 10.18 s, p = 0.2365). CONCLUSIONS: Fluorescent orthodontic adhesive containing 4 wt.% of A-ZnOQDs with reliable SBS, rheological properties, and cytocompatibility was successfully constructed, with proof that it can be recognised and removed efficiently.