Antibiofilm Activity of Directly Printed Orthodontic Clear Aligners with Incorporated Chitosan Nanoparticles (A Randomized Clinical Trial)

The use of orthodontic appliances and equipment has dramatically increased over the past few decades, mainly due to improvements in materials and manufacturing processes that have paved the way for improved treatments .

The preference for aligner treatment and the increase in its prevalence can be attributed to patient demand for "invisible" treatments and the limitations of conventional fixed orthodontics. Direct 3D printing offers the possibility of creating highly precise clear aligners with soft edges, digitally designed and identically reproduced for an entire set of treatment aligners. These provide a better fit, higher efficacy, and reproducibility.

Clear aligner treatment demonstrated promising results in terms of controlling plaque index, gingival health, and the prevalence of white spot lesions. Nevertheless, grooves, ridges, microcracks, and abrasions on the aligner surface provide a prime environment for bacterial adherence and the development of plaque biofilms. A combination of mechanical and chemical methods seem to be a successful approach for removing plaque biofilm from aligners whilst preventing pigment adsorption.

Orthodontic appliances change the ecological environment of the oral cavity, resulting in a significant increase in the number of cariogenic bacteria such as Streptococcus mutans (S. mutans). The imbalance in oral homeostasis can lead to enamel demineralization, periodontitis and other bacteria-related adverse effects of orthodontic treatment. According to evidence-based clinical assessments, once enamel demineralization is formed it is difficult to be fully reversed using currently available remineralizing agents. Thus, several antibacterial strategies have been used clinically to prevent enamel demineralization, including antibacterial mouthwashes and toothpastes. However, these conventional interventions are largely dependent on perfect compliance from the patients, which most of the times does not occur.

Chitosan nanoparticles have a wide range of applications and have long been employed with or without other substances and techniques to increase their functionality .