Formulation and Characterization of Novel Fluoride-releasing Antibacterial Dental Composite

Objective: To formulate and characterize a new fluoride-releasing antibacterial experimental dental composite. Methods: A new cross-linking chelating monomer containing 3-hydroxy-2-pyridinones, its zirconium-fluoride complex (F-releasing monomer), and an antibacterial monomer containing a long-chain quaternary ammonium moiety were synthesized and used to formulate an experimental dental composite. The experimental and control composites and were formulated using 70 wt% silanized fluoroaluminosilicate filler (Caulk/Dentsply) and 30 wt% monomers (Control: BisGMA:EBPADMA:HDDMA 40:40:20, Experimental: BisGMA:EBPADMA:HDDMA:F-releasing-monomer 30:30:20:20). Fluoride release, fluoride recharge, compressive strength, flexural strength, flexure modulus, water sorption, and solubility were tested on the experimental and control composites. The data were analyzed using ANOVA and t-tests. Results: (mean ± SD)

Materials	Control	Experimental
Cumulative F-release in 44 days (µg/cm2, n = 5)	10.4 ± 1.7	33.9 ± 6.1
F-release in 3 days after recharge (µg/cm2, n = 5)	18.0 ±1.2	25.5 ± 2.7
Comprehensive strength (MPa, 24h; n = 10)	225 ±  46	237 ± 51
Flexural strength (MPa, 24h, n = 10)	104 ± 12	107 ± 9
Flexure Modulus (GPa, 24h, n = 10)	8.5 ± 0.3	8.1 ± 0.7
Water Sorption (µg/mm3, n = 5)	13.6 ± 1.5	16.3 ± 1.5
Solubility (µg/mm3, n = 5)	1.2 ± 0.9	1.6 ± 0.7

The experimental composite has significantly higher fluoride release and fluoride recharge capabilities than the controls (p < 0.01). Comprehensive strength, flexural strength, flexure modulus, and solubility of experimental composites are not statistically different from the controls (p > 0.05). Water sorption of experimental composite is slightly higher than control. Both the water sorption and solubility of experimental composites are well within the limit of the ISO Specification 4049.

Conclusion:  The novel F-releasing antibacterial dental composite has higher fluoride release and recharge capabilities while maintaining good physical and mechanical properties. Supported by NIH/NCRR-COBRE grant (P20RR020160).