**6. Conclusions**

A novel composite with remineralization and antibacterial properties was established by combining nCaF2+DMAHDM for the first time. Release of F and Ca ions from the composite was significantly achieved through the incorporation of nCaF2. The new composite exhibited strong antibacterial and ion release capabilities, prevented biofilm production of lactic acid, and decreased biofilm CFU by 4 log. This bioactive nanocomposite is promising to protect tooth structures, inhibit demineralization, and provide a reservoir for the release of calcium and fluoride ions. The combined effect of nCaF2+DMAHDM shows promise in a variety of dental applications where remineralization and prevention of recurrent caries is a priority.

**Author Contributions:** H.M. contributed to design, data acquisition, and analysis, and drafted the manuscript; A.A.B. contributed to data acquisition, and analysis; R.A. contributed to data acquisition and analysis; T.W.O. contributed to data interpretation and funding acquisition; M.A.S.M. contributed to data acquisition, analysis, and interpretation; H.H.K.X. contributed to conception, design, data interpretation and critically revised the manuscript; M.D.W. contributed to design, data acquisition, analysis, and interpretation, and critically revised the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding. **Acknowledgments:** We thank Quan Dai, Jianghong Gao, Maria Ibrahim, Bashayer Baras, Pei Feng, Nancy J. Lin, Jirun Sun, and Laurence C. Chow for discussions and assistance. We thank the technical support of the Core Imaging Facility of the University of Maryland Baltimore. We are grateful to Dentsply Sirona (Milford, DE) for the donation of the glass fillers. This work was supported by The University of Maryland School of Dentistry bridge fund (HX) and University of Maryland seed gran<sup>t</sup> (HX).

**Conflicts of Interest:** The authors declare no conflict of interest.
