Scoping Review of Antibacterial and Antibiofilm Surface Coatings for Fixed Orthodontic Brackets: Materials, Models, and Knowledge Gaps

Fixed orthodontic brackets promote biofilm formation, increasing the risk of enamel demineralization and caries. Nanotechnology-based antimicrobial coatings present a promising strategy to mitigate these risks, yet comprehensive synthesis across experimental models is lacking. This scoping review systematically maps the landscape of antibacterial and antibiofilm surface coatings for fixed orthodontic brackets, classifies materials and methods, and identifies critical knowledge gaps to guide future research and clinical translation. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines, 29 English peer-reviewed studies were identified from major databases up to April 2025. Data on coating types (e.g., silver nanoparticle, zinc oxide, and titanium dioxide), deposition techniques (e.g., physical vapor deposition, sol-gel dip-coating), antimicrobial efficacy, biocompatibility, durability, and experimental models were extracted and synthesized. Predominantly in vitro studies demonstrated > 90% reduction in Streptococcus mutans and Lactobacillus acidophilus colony-forming units sustained for up to 3 months, with hybrid coatings enhancing efficacy. However, in vivo and clinical data remain scarce, with limited evaluation of long-term durability and comprehensive biocompatibility. Nanocoatings exhibit robust antimicrobial potential for orthodontic applications, but strategic advancement requires standardized testing protocols, thorough safety assessments, and randomized clinical trials to validate long-term performance. Integrating such coatings into clinical workflows aligns with preventive dentistry goals by reducing biofilm-associated complications and improving patient outcomes.