Structural stability of DHMAI antibacterial dental composite following in vitro biological aging.

Objective: To assess the impact of the quaternary ammonium antibacterial agent, Dimethyl-Hexadecyl-Methacryloxyethyl-Ammonium Iodide (DHMAI), on structural stability of an experimental resin composite after biological aging.

Methods: Experimental resin composites containing 7.5% of DHMAI were incubated in a biological medium in the presence of a Streptococcus Mutans (SM) strain during 3 months. The physicochemical, mechanical, and thermal properties, before and after 3 months of aging, were evaluated using: Degree of Conversion (DC), Residual Functions (RF), Vitreous Transition (Tg), Thermal Expansion Coefficient (CTE) and thermal degradation using Fourier Transform Infrared Spectroscopy Analysis (FTIRATR), Differential Scanning Calorimetry (DSC), Thermo Mechanical analyses (TMA) and Thermo Gravimetric Analysis (TG).

Results: Incorporation of DHAMI increased DC and decreased RF. After aging, DHMAI decreased and slowed RF release. Incorporation of 7.5% DHAMI provided significant modification of the thermal behavior (Tg and thermal degradation) but did not affect CTE. After aging, DHMAI enhanced the structural stability and improved resistance against biodegradation compared to the control composite.

Significance: The development of an antibacterial dental composite based on DHMAI improved its physical, mechanical, and thermal behaviors, possibly enhancing dental composite longevity. Results suggest that DHMAI could be used in the composition of other bioactive dental materials.