Photothermal-promoted multi-functional gallic acid grafted chitosan hydrogel containing tannic acid miniaturized particles for peri-implantitis.

Peri-implantitis, a leading cause of implant failure, currently lacks effective therapeutic strategies. Given that bacterial infection and reactive oxygen species overabundance serve as primary pathogenic and triggering factors, respectively, an adhesive hydrogel has been created for in-situ injection. The hydrogel is a gallic acid-grafted chitosan (CS-GA) hydrogel containing tannic acid miniaturized particles (TAMP). This provides antibacterial and antioxidant properties. Therefore, this study aims to evaluate the potential role of this hydrogel in preventing and treating peri-implantitis via several experiments. It undergoes rapid formation within a span of over 20 s via an oxidative crosslinking reaction catalyzed by horseradish peroxidase and hydrogen peroxide, demonstrating robust adhesion, superior cell compatibility, and a sealing effect. Furthermore, the incorporation of TAMP offer photothermal properties to the hydrogel, enabling it to enhance the viability, migration, and antioxidant activity of co-cultured human gingival fibroblasts when subjected 0.5 W/cm2 808 nm near-infrared (NIR) irradiation. At higher irradiation power, the hydrogel exhibits progressive improvements in its antibacterial efficacy against Porphyromonas gingivalis and Fusobacterium nucleatum. It attains rates of 83.11 ± 5.42 % and 83.48 ± 6.855 %, respectively, under 1 W/cm2 NIR irradiation. In summary, the NIR-controlled CS-GA/TAMP hydrogel, exhibiting antibacterial and antioxidant properties, represents a promising approach for the prophylaxis and management of peri-implantitis.

Physicochemical properties of bone marrow mesenchymal stem cells encapsulated in microcapsules combined with calcium phosphate cement and their ectopic bone formation.

Calcium phosphate bone cement (CPC) serves as an excellent scaffold material for bone tissue engineering owing to its good biocompatibility, injectability, self-setting property and three-dimensional porous structure. However, its clinical use is limited due to the cytotoxic effect of its setting reaction on cells and difficulties in degradation into bone. In this study, bone marrow mesenchymal stem cells (BMSCs) were encapsulated in alginate chitosan alginate (ACA) microcapsules and compounded with calcium phosphate bone cement. Changes in the compressive strength, porosity, injectability and collapsibility of CPC at different volume ratios of microcapsules were evaluated. At a 40% volume ratio of microcapsules, the composite scaffold displayed high porosity and injectability with good collapsibility and compressive strength. Cell live/dead double staining, Cell Counting Kit-8 (CCK-8) assays and scanning electron microscopy were used to detect the viability, proliferation and adhesion of cells after cell microcapsules were combined with CPC. The results revealed that cells protected by microcapsules proliferated and adhered better than those that were directly combined with CPC paste, and cell microcapsules could effectively form macropores in scaffold material. The composite was subsequently implanted subcutaneously on the backs of nude mice, and ectopic osteogenesis of the scaffold was detected via haematoxylin-eosin (H&E), Masson's trichrome and Goldner's trichrome staining. CPC clearly displayed better new bone formation function and degradability after addition of pure microcapsules and cell microcapsules. Furthermore, the cell microcapsule treatment group showed greater osteogenesis than the pure microcapsule group. Collectively, these results indicate that BMSCs encapsulated in ACA microcapsules combined with CPC composite scaffolds have good application prospects as bone tissue engineering materials.

Influence of proanthocyanidins combined with ethanol-wet bonding on the bonding quality of fibre posts to root dentine.

This study evaluated the influence of a bonding approach using proanthocyanidins (PAs) combined with ethanol-wet bonding (EWB) and a hydrophobic adhesive on the bonding quality of fibre posts. After endodontic treatment and post-space preparation, 72 single-rooted extracted human teeth were etched, thoroughly rinsed, and then treated using the following procedures (n = 24 teeth per group): group 1, no pretreatment; group 2, pretreatment with absolute ethanol three times, for 30 s each time; or group 3, pretreatment with absolute ethanol solution containing 5% PAs three times, for 30 s each time. Six teeth per group were dried according to a dry and a wet drying protocol and then observed using field emission-scanning electron microscopy. The remaining 18 teeth in each group were cemented with fibre posts: All-Bond 3 and Duo-Link cement were used for group 1; and hydrophobic adhesive and Duo-Link cement were used for groups 2 and 3. Push-out bond strength, failure mode, and nanoleakage were evaluated immediately and after collagenase treatment. Higher push-out bond strength and less nanoleakage were observed in the two ethanol-pretreatment groups, regardless of storage conditions. Teeth pretreated with PAs + ethanol exhibited significantly higher push-out bond strength after collagenase treatment than did teeth pretreated with ethanol alone. Within the limits of this study, the bonding approach of PAs combined with EWB and a hydrophobic adhesive synergistically improved the durability of fibre post bonds.

Effect of Crosslinked Chitosan Nanoparticles on the Bonding Quality of Fiber Posts in Root Canals.

PURPOSE: To investigate the effects of root-canal dentin pretreatment with the crosslinker EDC combined with chitosan nanoparticles (Csnp) on the bonding quality of fiber posts in root canals in terms of bond strength, nanoleakage, quantification of collagen degradation, and degree of conversion (DC) of adhesive. MATERIALS AND METHODS: Forty-eight single-rooted teeth were prepared endodontically and etched using UNI-ETCH (Bisco) as per the adhesive procedure for fiber posts. They were randomly divided into three groups before adhesive (All-Bond 3) application, according to different pretreatments: a. immersed in 2.5% glutaraldehyde for 24 h; b. treated with Csnp solution under ultrasonic agitation for 60 s and immersed in EDC crosslinker for 24 h; c. without treatment (control). Bond strength, nanoleakage, DC within the interface, and collagen fiber degradation were evaluated. RESULTS: The pretreatments had a significant influence on the bonding stability of fiber posts in root canals, but not on the degree of conversion (p = 0.552). Enzymatic degradation significantly influenced bond strength for all groups (p = 0.001), with the greatest effect found in group c. The amount of amino acids released from the adhesive interface differed significantly between groups after hydrolysis and enzymatic degradation (p = 0.000); group c released the highest amount of amino acids. CONCLUSIONS: Csnp binding to dentin in combination with EDC reduced degradation of dentinal collagen and improved the stability of the adhesive interface without jeopardizing adhesive polymerization.

Bonding Quality of Etch-and-Rinse Adhesives in Root Canals upon Different Pretreatments.

PURPOSE: To evaluate the effect of ethanol-wet/hydrophobic resin bonding (EWB) in a simplified dehydration protocol with ultrasonic agitation (UA) of etch-and-rinse adhesives on the bonding quality in root canals. MATERIALS AND METHODS: 56 extracted human maxillary central incisors were divided into 4 groups (n = 14) according to the procedures of bonding fiber posts in root canals: A: conventional etch-and-rinse adhesive as control (All-Bond 3, Bisco); B: EWB in a simplified dehydration protocol, ie, after 100% ethanol dehydration (30 s, 3 times), ethanol/hydrophobic resin (50% bis-GMA + TEG-DMA, 50% ethanol) was applied into the root canal as a primer, followed by applying pure co-monomer adhesive; C: EWB in a standard dehydration protocol, ie, ascending concentrations of ethanol (50%, 70%, 80%, 90%) for 30 s and 100% ethanol (30 s, 3 times) for dehydration, with the remaining procedure conducted as in group B; D: EWB in a simplified dehydration protocol under ultrasonic agitation (UA), ie, 100% ethanol under ultrasonic agitation for 30 s, ethanol/hydrophobic resin as a primer applied under UA for 60 s, followed by the application of pure co-monomer adhesive. All the specimens were cemented with Duo-Link (Bisco) and immersed in artificial saliva for 24 h or thermocycled for 10,000 times. Bond strength, failure mode, and nanoleakage were evaluated. Hybrid layer and resin tags were also observed with SEM. Data were analyzed with two-way ANOVA (bond strength) and Kruskal-Wallis analysis (nanoleakage, resin tag score) (α = 0.05). RESULTS: Significant differences existed in bond strength (p = 0.02) and nanoleakage (p = 0.02) among groups. After 24 h and after thermocycling, group D exhibited higher bond strengths than did group B (p = 0.02 after 24 h, p = 0.03 after aging) and group A (p = 0.06 after 24 h, p = 0.04 after aging). Bond strength and nanoleakage showed no significant difference after aging (p > 0.05). There was no significant difference in resin tag scores between any of the groups, but the apical third of the roots exhibited the lowest score (p = 0.001). CONCLUSION: The synergistic effects of the two pretreatment strategies (EWB in a simplified dehydration protocol and UA) improved the bonding quality. UA had a positive effect on the adhesion of the etch-and-rinse adhesives, when EWB in a simplified procedure was applied into the root canal.