Enhancing elemental release and antibacterial properties of resin-based dental sealants with calcium phosphate, bioactive glass, and polylysine

Abstract

Background: This study aimed to develop ion-releasing and antibacterial resin-based dental sealants comprising 3 to 6 wt% monocalcium phosphate monohydrate (MCPM, M), 3 to 6 wt% bioactive glass (BAG, B), and 3 to 6 wt% polylysine (PLS, P). The physical properties, mechanical performance, cytotoxicity, and inhibition of S. mutans biofilm by these materials were subsequently evaluated.

Methods: Five experimental dental sealants were formulated as follows: F1 (M6B6P6), F2 (M6B6P3), F3 (M3B3P6), F4 (M3B3P3), and F5 (M0B0P0, serving as the control). ClinproXT (CP, 3 M, Saint Paul, MN, USA) was used for commercial comparison. The degree of monomer conversion (DC) was determined using attenuated total reflectance-Fourier transform infrared spectroscopy (n = 5). The biaxial flexural strength (n = 6) and Vickers surface microhardness (n = 5) of the materials were evaluated after a 24-hour immersion in water. The element release over 4 weeks was measured using inductively coupled plasma-optical emission spectrometry (ICP-OES) (n = 3). The cell viability of mouse fibrosarcoma cells exposed to the extract was assessed via an MTT assay (n = 3). Additionally, the inhibition of S. mutans biofilm was tested (n = 3). Statistical analysis was conducted using one-way ANOVA and the Tukey HSD test.

Results: The lowest DC among experimental sealants was obtained from F1 (66 ± 4%), which was significantly higher than CP (54 ± 2%, p < 0.001). The lowest biaxial flexural strength was obtained from F3 (131 ± 47 MPa). This was comparable to that of CP (140 ± 58 MPa, p = 0.992). The lowest surface microhardness among experimental materials was detected with F2 (19 ± 2 Vickers hardness number), which was higher than that of CP (12 ± 1 Vickers hardness number, p = 0.003). Furthermore, high cell viability of > 90% after exposure to extracts from the experimental materials was detected, which was similar to that observed with CP. Additionally, the experimental materials exhibited higher Ca and P release compared to CP and showed a potential trend for reducing S. mutans biofilm formation. Increasing additive concentrations exhibited minimal effects on material properties, except for enhanced elemental release and a slight reduction in BFM with higher PLS content.

Conclusion: The experimental sealants provided sufficient physical and mechanical strength and maintained cell viability and bacterial inhibition with higher elemental release than the commercial product.

Keywords: Biaxial flexural strength; Bioactive glass; Calcium phosphate; Degree of monomer conversion; Polylysine; Resin sealant.

Fig. 1

Figure demonstrating the experimental design in the current study. Created in BioRender. Panpisut, P. (2024) BioRender.com/q26d152

Fig. 2

The degree of monomer conversion was measured after 40 s of light-curing. Error bars represent the standard deviation (n = 5), and same letters indicate no significant difference (p > 0.05)

Fig. 3

(A) Biaxial flexural strength and (B) biaxial flexural modulus of materials after being immersed in deionized water for 24 h. Identical letters indicate no significant difference with p > 0.05. Error bars represent the standard deviation (n = 6)

Fig. 4

SEM image and EDX analysis from the fracture surface of a representative specimen after biaxial flexural strength testing. The arrows indicate the presence of fillers on the fractured surface of the experimental resin sealants

Fig. 5

Vickers surface microhardness (VHN) of materials after immersion in deionized water for 24 h. The same letters indicate p > 0.05. Error bars are SD (n = 5)