Clear aligner interface properties, oral microbial ecology, and strategies for biofilm control and caries-risk mitigation: a scoping review

Abstract

Background Clear aligners create an aligner–tooth interface that may retain saliva, microorganisms, and dietary substrates. Evidence linking interface properties, oral microecological responses, and preventive interventions remains fragmented. Objective To map and synthesize evidence on clear aligner interface properties and microbial adhesion, oral microbial ecology during clear aligner wear, and strategies for biofilm control and caries-risk mitigation. Methods Following Joanna Briggs Institute methodology and PRISMA-ScR guidance, PubMed, Embase, and Web of Science Core Collection were searched from inception to August 31, 2026, without language restrictions. Backward and forward citation searching supplemented database searches. Original clinical, in vitro , and ex vivo studies involving active clear aligner treatment, associated materials or interfaces, or clear-aligner-specific interventions were eligible when they reported microbial, biofilm, microbiome, metabolomic, caries-related, or mineral outcomes. Two reviewers independently screened records; two authors charted and verified data. Findings were synthesized descriptively within three evidence domains. Results Of 988 records, 132 reports were included. Because reports could contribute to more than one domain, 62 informed interface properties and microbial adhesion, 47 oral microbial ecology during wear, and 76 biofilm control and caries-risk mitigation. No single polymer, manufacturing method, or surface parameter consistently predicted microbial adhesion or biofilm formation. Outcomes reflected interactions among material characteristics, local topography, salivary conditioning, aging and exposure, microbial species, and experimental models. Clinical microbial responses were compartment- and time-dependent. Salivary and tooth-associated communities often remained relatively stable at the community level, whereas the inner aligner surface sometimes exhibited localized taxonomic, functional, metabolic, and pH-related changes. Investigated interventions included cleaning, antimicrobial and antifouling interface modifications, anticaries and remineralizing approaches, probiotics, and environment-responsive systems. Although many strategies reduced microbial burden, biofilm-related outcomes, acidogenicity, or mineral loss under tested conditions, evidence was predominantly short-term and preclinical. Assessments of durability, material performance, and safety were heterogeneous. Conclusions Clear aligner–microbiota interactions appear context-dependent rather than uniformly favorable or unfavorable. Evidence neither establishes causal relationships between interface or microecological changes and clinical disease nor identifies a universally superior intervention. More standardized, clinically representative evidence may clarify their clinical relevance and inform preventive management during clear aligner treatment.

The authors' abstract, as published at the source. Frontiers in Cellular and Infection Microbiology, 2026 · DOI ↗