Effect of sodium hypochlorite, isopropyl alcohol and chlorhexidine on the epoxy sealant penetration into the dentinal tubules.

BACKGROUND: The sealer penetration into the dentinal tubules might be beneficial, especially in necrotic endodontic cases, as it provides the obstruction of the contaminated tubules. OBJECTIVES: To determine the effect of 3 final irrigants (sodium hypochlorite (NaOCl), alcohol and chlorhexidine (CHX)) on the penetration of an epoxy sealer into the dentinal tubules. MATERIAL AND METHODS: The study was carried out on 60 single-canal human teeth with straight roots. The root canals were prepared to the ISO 40/04 size, using the Reciproc® instruments. The teeth were divided into 4 groups (n = 15). The canals in each group were irrigated according to the following scheme: group 1 (control) - 5.25% NaOCl; group 2 - smear layer removal (40% citric acid (CA) and 5.25% NaOCl) and 5.25% NaOCl; group 3 - smear layer removal (as in group 2), and 40% CA, water and 98% isopropyl alcohol; and group 4 - smear layer removal (as in group 2), and 40% CA, water and 2% CHX. The root canals were filled using the vertical condensation technique with gutta-percha and the porphyrin-labeled AH Plus™ sealer. After 3 days, 1-milimeter-thick cross-section slices were cut from the roots at a distance of 2 mm, 5 mm and 8 mm from the apex. The sections were imaged under a confocal microscope and the sealant penetration depth into the dentinal tubules was measured. RESULTS: The longest resin tags in all parts of the roots were found in group 4 (CHX), and the shortest in group 1 (control). The mean depth of the sealer penetration (in micrometers) was as follows: 21, 22 and 23 (group 1); 201, 231 and 374 (group 2); 170, 232 and 280 (group 3); and 330, 408 and 638 (group 4) in the apical, middle and coronal parts, respectively. CONCLUSIONS: The final irrigation with CHX resulted in the deepest penetration of the epoxy sealer into the tubules. Isopropyl alcohol had the most negative impact on the sealer penetration into the tubules.

The impact of irrigation protocols on epoxy sealer penetration depth in dentinal tubules. Study involving laser confocal microscopy.

The aim was to assess the impact of irrigation protocols ended with ethanol or chlorhexidine on AH Plus penetration into dentinal tubules. 45 root canals were prepared to ISO 40/04, divided into three groups and irrigated with three protocols: Group 1 (control): 5.25% NaOCl; Group 2: 40% CA (citric acid), 5.25% NaOCl, 40% CA, water, ethanol; Group 3: 40% CA, 5.25% NaOCl, 40% CA, water, 2% chlorhexidine. Canals were filled using vertical condensation technique with gutta-percha and fluorescein-stained AH Plus sealer. After 72 h, 1 mm thick cross-sections were cut at 2, 5, 8 mm from the apex. Confocal laser microscope was used to measure the sealer penetration into dentinal tubules. Mean depth of sealer penetration (in micrometres) was 107, 131, 170 (Group 1); 146, 233, 317 (Group 2); 185, 301, 542 (Group 3); in apical, middle and coronal parts, respectively. Irrigation protocol ended with chlorhexidine resulted in the deeper sealer penetration compared with alcohol.

Encapsulation of Curcumin in Polystyrene-Based Nanoparticles-Drug Loading Capacity and Cytotoxicity.

Nanoparticles made of amphiphilic block copolymers are commonly used in the preparation of nano-sized drug delivery systems. Poly(styrene)-block -poly(acrylic acid) (PS-PAA) copolymers have been proposed for drug delivery purposes; however, the drug loading capacity and cytotoxicity of PS-PAA nanoparticles are still not fully recognized. Herein, we investigated the accumulation of a model hydrophobic drug, curcumin, and its spatial distribution inside the PS-PAA nanoparticles. Experimental methods and atomistic molecular dynamics simulations were used to understand the molecular structure of the PS core and how curcumin molecules interact and organize within the PS matrix. The hydrophobic core of the PS-PAA nanoparticles consists of adhering individually coiled polymeric chains and is compact enough to prevent post-incorporation of curcumin. However, the drug has a good affinity for the PS matrix and can be efficiently enclosed in the PS-PAA nanoparticles at the formation stage. At low concentrations, curcumin is evenly distributed in the PS core, while its aggregates were observed above ca. 2 wt %. The nanoparticles were found to have relatively low cytotoxicity to human skin fibroblasts, and the presence of curcumin further increased their biocompatibility. Our work provides a detailed description of the interactions between a hydrophobic drug and PS-PAA nanoparticles and information on the biocompatibility of these anionic nanostructures which may be relevant to the development of amphiphilic copolymer-based drug delivery systems.

Drug-loading capacity of polylactide-based micro- and nanoparticles - Experimental and molecular modeling study.

Micro- and nanostructures prepared from biodegradable homopolymers and amphiphilic block copolymers (AmBCs) have found application as drug-delivery systems (DDSs). The ability to accumulate a drug is a very important parameter characterizing a given DDS. This work focuses on the impact of DDS size, the packing of polymer chains in the DDS, and drug - polymer matrix compatibility on the hydrophobic drug - loading capacity (DLC) of nano/microcarriers prepared from a biodegradable polymer or its copolymer. Using experimental measurements in combination with atomistic molecular dynamics simulations, an analysis of curcumin encapsulation in microspheres (MSs) from polylactide (PLA) homopolymer and nanoparticles (NPs) from PLA-block-poly(2-methacryloyloxyethylphosphorylcholine) AmBC was performed. The results show that curcumin has good affinity for the PLA matrix due to its hydrophobic nature. However, the DLC value is limited by the fact that curcumin only accumulates in the peripheral part of these structures. Such uneven drug distribution in the PLA matrix results from the non-homogeneous density of MSs (non-uniform packing of the polymer chains in the coil). The results also indicate that the MSs can retain a greater amount of hydrophobic drug compared to the NPs, which is associated with the formation of drug aggregates inside the PLA microparticles.

Murine cellular model of mucopolysaccharidosis, type IIIB (MPS IIIB) - A preliminary study with particular emphasis on the non-oxidative l-cysteine metabolism.

The lack of the N-alpha-glucosaminidase (Naglu) is responsible for the incidence of a rare disease - mucopolysaccharidosis, type IIIB (MPS IIIB). To date, studies have been conducted based on cells derived from patients suffering from MPS or using in vivo MPS mouse models. These limitations have allowed for defining our research goal - to create and characterize the first in vitro murine cellular MPS IIIB model. In the current work we present a new, stable cell line with confirmed accumulation of glycosaminoglycans. The line stability was achieved by immortalization using a lentivirus carrying the T-antigens of SV40. The Naglu-/- cells were confirmed to produce no Naglu enzyme. To confirm the proper functioning of the in vitro MPS IIIB model, we determined the activity and expression of cystathionine γ-lyase, rhodanese and 3-mercaptopyruvate sulfurtransferase, as well as the level of low molecular-weight thiols (reduced and oxidized glutathione, cysteine and cystine). The results were referred to our earlier findings originating from the studies on the tissues of the Naglu-/- mice that were used to create the lines. The results obtained in the Naglu-/- cells were in accordance with the results found in the mouse model of MPS IIIB. It suggests that the presented murine Naglu-/- cell lines might be a convenient in vitro model of MPS IIIB.