Effect of Biosilicate® Addition on Physical-Mechanical and Biological Properties of Dental Glass Ionomer Cements

Abstract

This study investigated the influence of incorporating Biosilicate^® on the physico-mechanical and biological properties of glass ionomer cement (GIC). This bioactive glass ceramic (23.75% Na₂O, 23.75% CaO, 48.5% SiO₂, and 4% P₂O₅) was incorporated by weight (5%, 10%, or 15%) into commercially available GICs (Maxxion R and Fuji IX GP). Surface characterization was made by SEM (n = 3), EDS (n = 3), and FTIR (n = 1). The setting and working (S/W time) times (n = 3) and compressive strength (CS) were analyzed (n = 10) according to ISO 9917-1:2007. The ion release (n = 6) was determined and quantified by ICP OES and by UV-Vis for Ca, Na, Al, Si, P, and F. To verify cell cytotoxicity, stem cells from the apical papilla (SCAP) were exposed to eluates (n = 3, at a ratio of 1.8 cm²/mL) and analyzed 24 h post-exposure. Antimicrobial activity against Streptococcus mutans (ATCC 25175, NCTC 10449) was analyzed by direct contact for 2 h (n = 5). The data were submitted for normality and lognormality testing. One-way ANOVA and Tukey's test were applied for the working and setting time, compressive strength, and ion release data. Data from cytotoxicity and antimicrobial activity were submitted for Kruskal-Wallis' testing and Dunn's post hoc test (α = 0.05). Among all experimental groups, only those with 5% (wt) of Biosilicate^® showed better surface quality. Only M5% showed a comparable W/S time to the original material (p = 0.7254 and p = 0.5912). CS was maintained for all Maxxion R groups (p > 0.0001) and declined for Fuji IX experimental groups (p < 0.0001). The Na, Si, P, and F ions released were significantly increased for all Maxxion R and Fuji IX groups (p < 0.0001). Cytotoxicity was increased only for Maxxion R with 5% and 10% of Biosilicate^®. A higher inhibition of S. mutans growth was observed for Maxxion R with 5% of Biosilicate^® (less than 100 CFU/mL), followed by Maxxion R with 10% of Biosilicate^® (p = 0.0053) and Maxxion R without the glass ceramic (p = 0.0093). Maxxion R and Fuji IX presented different behaviors regarding Biosilicate^® incorporation. The impacts on physico-mechanical and biological properties were different depending on the GIC, but therapeutic ion release was increased for both materials.

Keywords: Biosilicate®; antimicrobial; bioactivity; biocompatibility; glass ceramic; glass ionomer cement; ion release.

Figure 1

SEM analysis of GIC and Biosilicate^® powders. (A) Fuji IX GP, (B) Maxxion R, and (C) Biosilicate^®.

Figure 2

Representative SEM micrographs and EDS histogram of the main ions present on their internal surface (%wt) as determined by EDS. On M0% (A) white arrows indicate presence of pores. Unreacted small particle clustering is shown in (B,C), indicated by white arrows at M5% and M10%, respectively. These clusters increased with higher concentrations of Biosilicate^®, as observed in (D) at M15%.

Figure 3

Representative SEM micrographs from Fuji IX groups and EDS histogram of the main ions present on their internal surface (%wt) as determined by EDS. The white arrow in (A) indicates the presence of a pore on F0%. (B–D) point out unreacted small particle clustering at F5%, F10%, and F15%, respectively, as indicated by white arrows. The observed increase in clusters was associated with higher concentrations of Biosilicate^®, which was observed in F15%.

Figure 4

Data from the FTIR of Maxxion R (A–C) and Fuji IX groups (D–F) at 1, 5, and 60 min.

Figure 5

Working and setting times of Maxxion groups (A,B) and Fuji IX groups (C,D) respectively. Error bars represent standard deviations. One-way ANOVA and Tukey’s, performed separately for working and setting time. Different letters indicate significant differences between mean values of working and setting times (p < 0.0001).

Figure 6

Compressive strengths of GICs. (A) Maxxion without Biosilicate^® (M0%), M5%, M10%, and M15%. (B) Fuji IX without Biosilicate^® (F0%), F5%, F10%, and F15%. Error bars represent standard deviations. Different lowercase letters indicate significant differences among mean values of compressive strength (MPa) in groups (p < 0.0001).

Figure 7

Concentration of ions released in 24 h. Na, Al, Si, P, and Ca determinations on the eluates by ICP OES, and F by UV-Vis. Different letters indicate significant differences in the amount (ppm) of the ion released by each group (Maxxion R: (A–F); Fuji IX: (G–L)).

Figure 8

Cytotoxicity at 24 h for Maxxion groups (A) and Fuji IX groups (B). Percentage of cell death relative to the lysis buffer (100% of death) while the negative control cells were cultured only in α-MEM. Different letters represent statistical differences on the charts.

Figure 9

S. mutans remaining after 2 h of direct contact with Maxxion groups (A) and Fuji groups (B). Black diamond (◆) indicates less than 100 CFU/mL recovered (limit of detection). Different letters indicate significant differences among groups (p < 0.0001).

Figure 10

Percentage of survival of S. mutans compared to no disk group (only bacteria) for Maxxion groups (A) and Fuji groups (B). No disk was considered 100% survival. Different letters indicate significant differences among groups.