Review Article
Keywords: Metallic nanoparticles; Orthodontic materials; Antimicrobial; Biocompatibility; Durability; In vivo; Systematic review.
Year : 2025 | Volume : 16 | Issue : 4 | Page : 14-38
Antimicrobial, Biocompatibility, and Durability Outcomes of Nanoparticle-Coated Orthodontic Materials: A Systematic Review of In Vivo Evidence
Avula Samata1, Gowri Sankar Singaraju2, Prasad Mandava2, P V Sravya Silpa1
1-Postgraduate Resident, 2-Professor, Department of Orthodontics, Narayana Dental College, Nellore, Andhra Pradesh, India-524003
Address for Correspondence:
Dr. Prasad Mandava,
Professor and Head, Department of Orthodontics,
Narayana Dental College,
Nellore, Andhra Pradesh, India -524003.
Email ID: mandavabruno9@gmail.com
ABSTRACT
Objective: To systematically review available in vivo evidence from animal and human studies evaluating the antimicrobial efficacy, biocompatibility, and durability of metallic nanoparticle-coated orthodontic materials, excluding all in vitro research.
Methods: Electronic searches were performed in PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, Ovid, and ClinicalTrials.gov for studies published from January 2015 to August 2025, supplemented by manual and grey-literature searches. Eligible studies included in vivo animal or human investigations assessing surface coatings of orthodontic components—brackets, archwires, ligatures, elastomeric modules, or aligners—with metallic or metal-oxide nanoparticles (Ag, TiN, TiO₂, N-TiO₂, ZnO, Au). Primary outcomes were antimicrobial efficacy (CFU, qPCR, or biofilm indices); secondary outcomes included biocompatibility (ion release, cytotoxicity, mucosal response) and coating durability. Quality appraisal used SYRCLE, RoB 2, and ROBINS-I tools; evidence certainty was graded using GRADE. Registration: OSF (https://doi.org/10.17605/OSF.IO/5CZSG).
Results: Of 1,499 records, eight in vivo studies met the inclusion criteria—six human and two animal. Nanoparticles evaluated were Ag, TiN, TiO₂, N-TiO₂, ZnO, and Au. All demonstrated reduced Streptococcus mutans or related bacterial loads compared with uncoated controls. Silver coatings produced early antibacterial effects but released trace Ag⁺ (0.16–0.35 ppb). TiO₂ and TiN coatings reduced bacterial adhesion up to four weeks but showed partial delamination (~60%). N-doped TiO₂ extended efficacy to 60 days, while ZnO coatings-maintained suppression and enamel protection for 12 months despite early surface degradation. Gold nanoclusters exhibited short-term antibacterial and excellent biocompatibility in animal models. Biocompatibility was acceptable across studies, but durability and long-term stability were inconsistently assessed. Meta-analysis was precluded by heterogeneity of outcomes and timepoints. Overall risk of bias ranged from low to serious; certainty of evidence was low to moderate.
Conclusions: In vivo data indicate short-term antibacterial and biocompatible benefits of metallic nanoparticle coatings on orthodontic materials; however, evidence for coating durability and long-term safety is limited. Well-designed randomized clinical trials with standardized microbial, biocompatibility, and durability outcomes are essential for clinical translation.
Keywords: Metallic nanoparticles; Orthodontic materials; Antimicrobial; Biocompatibility; Durability; In vivo; Systematic review.
CONFLICT OF INTEREST
The authors have no conflict of interests to declare.
FUNDING
Nil.
How to cite this article: Avula Samata, Gowri Sankar Singaraju, Prasad Mandava, P V Sravya Silpa. Antimicrobial, Biocompatibility, and Durability Outcomes of Nanoparticle-Coated Orthodontic Materials: A Systematic Review of In Vivo Evidence. Int J Orthod Rehabil 2025; 16 (4): 14-38.