Novel Metformin-Containing Antibacterial Composite for Root Caries Restorations

Altamimi, Ayman; Ba-Armah, Ibrahim; Alqarni, Heba; Almutairi, Nader; Altamimi, Yazeed; Alenizy, Mohammad; Schneider, Abraham; Sun, Jirun; Weir, Michael D.; Xu, Hockin H. K.

doi:10.3390/ma19142963

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Open AccessArticle

Novel Metformin-Containing Antibacterial Composite for Root Caries Restorations

by

Ayman Altamimi

^1,2,3

,

Ibrahim Ba-Armah

⁴

,

Heba Alqarni

^1,2,5,

Nader Almutairi

^1,2,6

,

Yazeed Altamimi

^1,2,3

,

Mohammad Alenizy

³,

Abraham Schneider

⁷

,

Jirun Sun

⁸

,

Michael D. Weir

^2,*

and

Hockin H. K. Xu

^2,9,10,*

¹

Dental Biomedical Sciences PhD Program, Graduate School, University of Maryland, Baltimore, MD 21201, USA

²

Department of Biomaterials and Regenerative Dental Medicine, University of Maryland School of Dentistry, Baltimore, MD 21201, USA

³

Department of Restorative Dental Sciences, College of Dentistry, University of Hail, Hail 55475, Saudi Arabia

⁴

Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam 31441, Saudi Arabia

⁵

Department of Pediatric Dentistry and Orthodontic Sciences, College of Dentistry, King Khalid University, Abha 61421, Saudi Arabia

⁶

Department of Conservative Dental Sciences, College of Dentistry, Prince Sattam bin Abdulaziz University, Alkharj 11942, Saudi Arabia

⁷

College of Dentistry, Ohio State University, Columbus, OH 43210, USA

⁸

ADA Forsyth Institute, Cambridge, MA 02142, USA

⁹

Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA

¹⁰

Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA

^*

Authors to whom correspondence should be addressed.

Materials 2026, 19(14), 2963; https://doi.org/10.3390/ma19142963

Submission received: 8 June 2026 / Revised: 2 July 2026 / Accepted: 8 July 2026 / Published: 9 July 2026

(This article belongs to the Section Biomaterials)

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Abstract

Background: Tooth root caries and periodontal tissue loss remain major challenges in elderly and periodontally compromised patients, while current restorative materials lack combined antibacterial and regenerative properties. Objective: The objective of this study was to develop a novel metformin-containing antibacterial composite for root cavity restorations to prevent recurrent caries and potentially promote periodontal tissue regeneration. Methods: Experimental composites contained 5% dimethylaminohexadecyl methacrylate (DMAHDM), varying metformin concentrations (2.5–15%), and glass fillers. Mechanical and antibacterial properties as well as cytocompatibility toward human periodontal ligament stem cells (hPDLSCs) were investigated. Results: The experimental composites achieved flexural strengths of 67.9 to 50.1 MPa (n = 6), significantly higher than (41.3 ± 3.4 MPa) of commercial control Vitremer (p < 0.05), while maintaining clinically acceptable elastic moduli of 3.7–3.1 GPa. Experimental composites achieved an 8-log reduction in Streptococcus mutans (S. mutans) biofilms and significantly reduced lactic acid production and metabolic activity compared to biofilms on commercial controls. The composite containing 15% metformin demonstrated acceptable cytocompatibility toward hPDLSCs under clinically relevant diluted conditions, matching commercial controls (p > 0.1). Conclusions: These findings suggest that this novel composite possesses potent antibacterial activity, acceptable cytocompatibility, and adequate mechanical properties, making it promising for multifunctional root caries restorations.

Keywords: metformin; hPDLSCs; DMAHDM; root caries; periodontal tissue regeneration; stem cells; antibacterial composite

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MDPI and ACS Style

Altamimi, A.; Ba-Armah, I.; Alqarni, H.; Almutairi, N.; Altamimi, Y.; Alenizy, M.; Schneider, A.; Sun, J.; Weir, M.D.; Xu, H.H.K. Novel Metformin-Containing Antibacterial Composite for Root Caries Restorations. Materials 2026, 19, 2963. https://doi.org/10.3390/ma19142963

AMA Style

Altamimi A, Ba-Armah I, Alqarni H, Almutairi N, Altamimi Y, Alenizy M, Schneider A, Sun J, Weir MD, Xu HHK. Novel Metformin-Containing Antibacterial Composite for Root Caries Restorations. Materials. 2026; 19(14):2963. https://doi.org/10.3390/ma19142963

Chicago/Turabian Style

Altamimi, Ayman, Ibrahim Ba-Armah, Heba Alqarni, Nader Almutairi, Yazeed Altamimi, Mohammad Alenizy, Abraham Schneider, Jirun Sun, Michael D. Weir, and Hockin H. K. Xu. 2026. "Novel Metformin-Containing Antibacterial Composite for Root Caries Restorations" Materials 19, no. 14: 2963. https://doi.org/10.3390/ma19142963

APA Style

Altamimi, A., Ba-Armah, I., Alqarni, H., Almutairi, N., Altamimi, Y., Alenizy, M., Schneider, A., Sun, J., Weir, M. D., & Xu, H. H. K. (2026). Novel Metformin-Containing Antibacterial Composite for Root Caries Restorations. Materials, 19(14), 2963. https://doi.org/10.3390/ma19142963

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