Novel Antimicrobial and Bioactive Resin-Based Clear Aligner Attachment Orthodontic Materials

Heba Alqarni^1,2,3*Ibrahim Ba-Armah^1,2,4Nader Almutairi^1,2,5Mohammad Alenizy^1,2,6Dwayne D Arola⁷Thomas Oates⁸Jirun Sun⁹Michael D Weir^2*Hockin H K Xu^10,11,2*

• ¹Dental Biomedical Sciences PhD Program, Graduate School, University of Maryland, Baltimore, MD 21201, United States
• ²Department of Biomaterials and Regenerative Dental Medicine, University of Maryland School of Dentistry, Baltimore, MD 21201, USA., United States
• ³Department of Pediatric Dentistry and Orthodontics Sciences, College of Dentistry, King Khalid University, Abha 61421, Saudi Arabia
• ⁴Department of Restorative Dental Science, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam 31441, Saudi Arabia
• ⁵Department of Conservative Dental Sciences, College of Dentistry, Prince Sattam bin Abdulaziz University, Alkharj 16245, Saudi Arabia
• ⁶Department of Restorative Dental Sciences, University of Hail, Hail 55475,, Saudi Arabia
• ⁷Materials Science and Engineering (MSE), University of Washington, Seattle, WA 98195-2120, United States
• ⁸8 Department of Advanced Oral Sciences and Therapeutics, University of Maryland, School of Dentistry, Baltimore, MD 21201, USA, United States
• ⁹The ADA Forsyth Institute, Cambridge, MA 02142, United States
• ¹⁰Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA., United States
• ¹¹Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States

Clear aligner orthodontic treatment provides a hygienic and esthetic alternative to fixed appliances; however, the required resin attachments can promote plaque accumulation and increase the risk of white-spot lesions in enamel. This study aimed to develop a novel resinbased antibacterial and bioactive orthodontic clear aligner attachment and evaluate its mechanical and antibacterial properties. A resin matrix composed of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE) was modified with 3% dimethylaminododecyl methacrylate (DMADDM) for antibacterial effects and nanoamorphous calcium phosphate (NACP) to support remineralization. Transbond™ LV and Vitremer™ were selected as commercial controls. Mechanical properties (flexural strength, elastic modulus, microhardness, and shear bond strength), degree of conversion, and antibacterial performance against Streptococcus mutans (S. mutans) biofilms were assessed through colony forming units (CFU), biofilm metabolic activity (MTT), and lactic acid production. All experimental groups showed flexural strength of 100.6 -109.2 MPa, exceeding the ISO standard for resin-based materials. Degree of conversion in experimental groups ranged from (53.4 ± 2.3 to 69 ± 0.9) %, significantly exceeding (47.5 ± 0.1) % for Transbond control (p < 0.05). Hardness was (0.21 ± 0.03) GPa for Transbond control, statistically comparable to (0.20 ± 0.02) GPa for the 20% NACP + 45% glass group. All experimental groups achieved a 6-log reduction in biofilm CFU and 90% reduction in metabolic activity and lactic acid production versus controls (p < 0.01). This novel clear aligner attachment resin exhibits promising mechanical strength, high degree of conversion, potent antibacterial effects, and ion releases to potentially reduce white-spot lesions during clear aligner treatment.