Mechanical and chemical analysis of experimental adhesive containing drug-loaded mesoporous silica nanoparticles
Creators: name: Alkhazaleh, Ahmad Mohammad
Publisher: name: University of Iowa
Year: 2024
Subjects: adhesive
dentin
dynamic mechanical analysis
monomer conversion
nanoparticles
resin
Chemistry
public abstract

description: Objectives: Proanthocyanidins (PACs) are a naturally occurring bioflavonoid reported to enhance dentin stability and biomechanics. This study investigated the impact of PAC-containing mesoporous silica nanoparticles (MSNs) incorporation into experimental resin-based adhesives on its chemical and mechanical properties. Methods: Wormhole-type MSNs were synthesized, then functionalized with aminosilane (3-aminopropyltriethoxysilane, APTES) and loaded with PACs, in alternate orders, forming MSN-APTES-PAC, and MSN-PAC-APTES nanoparticles. PAC-encapsulation efficiency (EE) was calculated for MSN-APTES-PAC and MSN-PAC-APTES, indirectly, by estimating the residual PAC amount in the wash collected from the PAC loading process. This calculation was facilitated by ultraviolet-visible spectroscopy that was also used to calculate the cumulative PAC release after 30 days of aqueous incubation. Next, an experimental resin-based adhesive (RBA) was fabricated utilizing 70.0 wt% of Bis-GMA, 28.75 wt% of HEMA, 0.25 wt% of CQ, and 1.0 wt% of EDMAB. Four groups of experimental RBAs (n=3 per group) were then formulated depending on the type of nanoparticle incorporated; RBA Control (unfilled RBA), RBA MSN-APTES (RBA filled with 20% wt/vol MSN-APTES); RBA MSN-APTES-PAC (RBA filled with 20% wt/vol MSN-APTES-PAC); and RBA MSN-PAC-APTES (RBA filled with 20% wt/vol MSN-PAC-APTES). Degree of monomer conversion (DC) of photopolymerized films representing each of the adhesive types was calculated. Dynamic mechanical analysis (DMA) and Quasi-static tensile testing were also performed to collect information on the glass transition (Tg) temperature at tan delta, tensile modulus, ultimate stress, ultimate strain, and toughness. A two-sample t-test was conducted to determine the differences in EE and PAC cumulative release, and a one-way ANOVA with the Tukey’s HSD test was conducted to determine significant differences in DC among the four experimental groups. Furthermore, a one-way multivariate analysis of variance (MANOVA), followed by a one-way univariate ANOVA and post-hoc Tukey’s HSD test, was conducted to probe the effect of the experimental groups on the Tg, tensile modulus, ultimate stress, ultimate strain, and toughness. All tests employed a significance level of 0.05.
description: Results: MSN-PAC-APTES showed statistically significantly higher mean PAC EE (%) than MSN-APTES-PAC (60.05% vs. 43.13%, p=0.002). MSN-APTES-PAC, however, showed statistically significantly higher mean cumulative PAC release (mg) after 30 days (11.32 mg vs. 8.15 mg, p=0.012). Degree of conversion of the unfilled control (RBA Control) was not significantly different from any of the filled systems; however, RBA MSN-APTES-PAC, displayed a significantly higher mean DC than the other two filled adhesive types (p&lt;0.05). RBA MSN-APTES-PAC claimed similar tensile modulus to the RBA Control but that was higher than the other two groups (p&lt;0.05). RBA MSN-APTES-PAC showed a higher mean ultimate stress than RBA MSN-PAC-APTES, but both were lower than the RBA Control (p&lt;0.05). Both PAC-containing systems showed that there was no significant difference in toughness and ultimate strain among them.
description: Conclusion: While expected to promote dentin-adhesive interface stability, MSNs functionalized with amine terminal groups and loaded with PAC (MSN-APTES-PAC) do not seem to negatively impact the monomer degree of conversion or the overall mechanical properties of dental adhesives. RBA MSN-PAC-APTES however, obtained overall inferior monomer degree of conversion and mechanical properties as compared to its RBA MSN-APTES-PAC counterpart.