Antibiofilm activity of chitosan nanoparticles incorporated into three-dimensional printed clear aligners on Streptococcus mutans after in vivo aging: A randomized clinical trial

Abstract

Background

To investigate if chitosan nanoparticles (ChNPs), incorporated into three-dimensional-printed clear aligners (CAs), retain their antibiofilm activity against Streptococcus mutans after extended use in the oral environment. Additionally, to measure the impact of the aligners on patient-reported outcomes.

Methods

Participants were randomly assigned to two groups: conventional CA and CA containing 3% ChNPs. They were instructed to wear their aligners for either one week (N = 16) or two weeks (N = 16) before CAs were retrieved. Clinical parameters, including plaque index (PI) and bleeding on probing (BOP), were measured, and the devices were weighed at baseline and at endpoints. A self-reported questionnaire was also completed. Samples from the retrieved devices underwent antibiofilm assays against S. mutans (American Type Culture Collection strain and a clinical isolate).

Results

After two weeks, the experimental group exhibited significantly lower PI and BOP scores compared to the control group (4.61 ± 1.22 vs 16.16 ± 5.26, and 3.83 ± 1.03 vs 5.35 ± 3.03, respectively). The number of colony-forming units was significantly reduced in the ChNPs-containing CAs (effect size > 0.9), with a greater effect against the American Type Culture Collection strain than the clinical isolate at both time points (effect size week 1: 0.953, week 2: 0.621). The ChNPs did not affect the device weight after in vivo aging, and the participants reported higher satisfaction levels.

Conclusions

Three-dimensional-printed CAs with ChNPs retained strong antibiofilm activity against S. mutans after two weeks of in vivo use. This was clinically reflected by lower PI and BOP scores and improved self-reported outcomes.