Comparison of Oral Microbial Profile Among Patients Undergoing Clear Aligner and Fixed Orthodontic Therapies for the Treatment of Malocclusions: An Updated Review.

: The present review aims to compare the oral microbial profile (OMP) of patients undergoing fixed orthodontic therapy (OT) versus clear aligner therapy (CAT) for the treatment of malocclusions. : Clinical studies were included. Case-reports/-series, letters to the editor, reviews, perspectives, and expert opinions were excluded. Indexed databases (MEDLINE/PubMed, Embase, Scopus, and Web of Science) were searched up to the end point of May 2025, without time and language barriers. The study was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The risk of bias (RoB) and quality of evidence were assessed. : Three randomized clinical trials (RCTs) and seven non-RCTs were included. In all RCTs and five non-RCTs, OMP was assessed using subgingival plaque samples. Periodontopathogenic bacteria and Gram-negative anaerobic microbes were more often identified in patients undergoing fixed OT than CAT. The biofilm mass was higher in patients undergoing fixed OT than CAT. In two RCTs, periodontopathogenic bacteria were dominant among patients undergoing fixed OT than CAT. All RCTs and two non-RCTs had a high RoB. The certainty of evidence was "moderate" in 70% of the studies. : Due to a high RoB, variability in study designs, and lack of power analysis, direct comparisons remain limited.