Preparation and Assessment of Antimicrobial Effect of Strontium and Copper Co-substituted Hydroxyapatite Nanoparticle-Incorporated Orthodontic Composite: A Preliminary In Vitro Study

Background and aims Enamel demineralization and white spot lesions (WSLs) during orthodontic treatment have always been a challenge to orthodontists. The advancement of nanotechnology has paved the way for the incorporation of bioactive compounds in orthodontic materials especially orthodontic composites for prevention and management of WSLs. The present study aims to prepare, characterize, and then incorporate copper and strontium doped nanohydroxyapatite into orthodontic composite material and test its antibacterial efficacy. Materials and methods The present in vitro study involved the preparation of the strontium and copper co-substituted hydroxyapatite (SrCuHA) nanoparticles (Nps) using the sol-gel method. The prepared Nps were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX), and Fourier transform infrared spectroscopy (FTIR). The Nps were incorporated into a commercially available orthodontic composite. The antimicrobial properties of the SrCuHA Nps-incorporated composite were tested using the Agar well diffusion method against Staphylococcus aureus(S. aureus), Streptococcus mutans (S. mutans), and Escherichia coli (E. coli). Results The SrCuHA Nps were successfully prepared. EDAX, FTIR, and SEM analyses revealed the successful formation of the Nps. The SrCuHA-incorporated orthodontic composite at a higher concentration of 40 μl showed the maximum zone of inhibition (ZOI) against S. mutans. The control group showed the maximum ZOI against E. coli and the SrCuHA Nps-incorporated composite at 20 μl showed the maximum inhibition against S. aureus. Conclusion In the present study, successful preparation of SrCuHA Nps followed by incorporation in the orthodontic adhesive was done. The prepared nanoparticle was characterized and the SrCuHA Nps-incorporated orthodontic composite demonstrated comparable ZOI against S. mutans to the control.