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.