A photocrosslinkable
gelatin methacryloyl (GelMA) hydrogel has been widely examined in
regenerative engineering because of its good cell–tissue affinity
and degradability in the presence of matrix metalloproteinases. A
halloysite aluminosilicate nanotube (HNT) is a known reservoir for
the loading and sustained delivery of therapeutics. Here, we formulate
injectable chlorhexidine (CHX)-loaded nanotube-modified GelMA hydrogel
that is cytocompatible and biodegradable and provides sustained release
of CHX for infection ablation while displaying good biocompatibility.
The effects of HNTs and CHX on hydrogel degradability and mechanical
properties, as well as on the kinetics of CHX release, and on the
antimicrobial efficacy against oral pathogens were systematically
assessed. Cytocompatibility in stem cells from human exfoliated deciduous
teeth and inflammatory response in vivo using a subcutaneous
rat model were determined. Our hydrogel system, that is, (CHX)-loaded
nanotube-modified GelMA showed minimum localized inflammatory responses,
supporting its ability for drug delivery applications. Moreover, we
showed that the incorporation of CHX-loaded nanotubes reduces the
mechanical properties, increases the swelling ratio, and diminishes
the degradation rate of the hydrogels. Importantly, the presence of
CHX-loaded nanotubes inhibits bacterial growth with minimal cell toxicity.
Our findings provide a new strategy to modify GelMA hydrogel with
chlorhexidine-loaded nanotubes for clinical use as an injectable drug
delivery strategy for dental infection ablation.
Oral
bacterial infection represents the leading cause of the gradual
destruction of tooth and periodontal structures anchoring the teeth.
Lately, injectable hydrogels have gained increased attention as a
promising minimally invasive platform for localized delivery of personalized
therapeutics. Here, an injectable and photocrosslinkable gelatin methacryloyl
(GelMA) hydrogel is successfully engineered with ciprofloxacin (CIP)-eluting
short nanofibers for oral infection ablation. For this purpose, CIP
or its β-cyclodextrin (β-CD)-inclusion complex (CIP/β-CD-IC)
has been incorporated into polymeric electrospun fibers, which were
subsequently cut into short nanofibers, and then embedded in GelMA
to obtain an injectable hybrid antimicrobial hydrogel. Thanks to the
solubility enhancement of CIP by β-CD-IC and the tunable degradation
profile of GelMA, the hydrogels promote localized, sustained, and
yet effective cell-friendly antibiotic doses, as measured by a series
of bacterial assays that demonstrated efficacy in attenuating the
growth of Gram-positive Enterococcus faecalis. Altogether, we foresee significant potential in translating this
innovative hybrid hydrogel as an injectable platform technology that
may have broad applications in oral infection ablation, such as periodontal
disease and pulpal pathology.
This study evaluated the effect of different adhesive protocols on the shear bond strength (SBS) of bulk-fill resin composite repaired with bulk-fill or conventional composite. Cylindrical bulk-fill resin composite specimens were prepared and allocated into groups according to the bonding strategy: no treatment, Silane+Scotch Bond Multipurpose (S+SBMP), Tetric N Bond Universal, and Single Bond Universal. Following bonding strategy, bulk-fill or conventional composite buildups were performed. After 24 h of storage in distilled water at 37°C, shear force was applied to the interface using a universal testing machine. The data were analyzed by twoway ANOVA and Tukey test (α=0.05). SBS was influenced by the bonding strategy and the composite used (p<0.001). Irrespective of the composite used, the group S+SBMP yielded the highest SBS values (p<0.001). Repair bond strength of bulk-fill composites can be improved by using a silane coupling agent followed by a hydrophobic resin.
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