Bioactive Glass With Adsorbed Xylitol in a Bracket Adhesive: Shear Bond Strength
Objectives: Bioactive glass with adsorbed xylitol (BAG-X) has been shown to significantly reduce viable bacteria in vitro. This project used BAG-X as the filler in an orthodontic bracket bonding resin and measured its shear bond strength. Methods: Bioactive glass (BAG) (85mol %SiO2, 11mol %CaO, 4mol %P2O5) was synthesized in our laboratory, ground and micronized to a powder with a particle size <7um. Xylitol adsorption to the surface of the BAG created BAGX. BAGX was introduced (57wt%) into a mixture of resin monomers and light activating agents to create BAG-Bond-X.
Human maxillary right first pre-molars (N=14) were mounted in acrylic blocks. Seven were randomly selected for bonding brackets with Transbond XT, and the other seven had brackets bonded with BAG-Bond-X. Teeth were pumiced, rinsed, and air dried. They were treated with 37% phosphoric acid, rinsed and again air dried. Excite adhesive (Ivoclar Vivadent, Amherst, NY) was applied and light cured. Roth brackets (Henry Schein, Melville, N.Y) were bonded to the buccal surface by an experienced orthodontist using either Transbond XT or BAG-Bond-X. They were light cured for 10 seconds each from the mesial, occlusal and distal surfaces. Samples were stored for 24 hours in water.
Brackets underwent shear bond strength testing with an Instron E-3000 (Norwood, MA) using a crosshead speed of 0.5mm/min. The maximal loading forces were compared using a Student’s T-test with α=0.05. Results: Brackets bonded with BAG-Bond-X had an average shear bond strength of 7.79 MPa, while brackets bonded with Transbond XT had an average shear bond strength of 13.83 MPa. Conclusions: The difference in bond strength between BAG Bond X and Transbond XT is statistically significant, however, it is not clinically significant. Both materials provided clinically acceptable bond strengths (>6 MPa). BAG-Bond-X, however has been shown to provide antimicrobial ion-release and might therefore provide a reduction in deleterious white spot lesions.