Characterization of the cell penetrating properties of a human salivary proline-rich peptide

Saliva contains hundreds of small proline-rich peptides most of which derive from the post-translational and post-secretory processing of the acidic and basic salivary proline-rich proteins. Among these peptides we found that a 20 residue proline-rich peptide (p1932), commonly present in human saliva and patented for its antiviral activity, was internalized within cells of the oral mucosa. The cell-penetrating properties of p1932 have been studied in a primary gingival fibroblast cell line and in a squamous cancer cell line, and compared to its retro-inverso form. We observed by mass-spectrometry, flow cytometry and confocal microscopy that both peptides were internalized in the two cell lines on a time scale of minutes, being the natural form more efficient than the retro-inverso one. The cytosolic localization was dependent on the cell type: both peptide forms were able to localize within nuclei of tumoral cells, but not in the nuclei of gingival fibroblasts. The uptake was shown to be dependent on the culture conditions used: peptide internalization was indeed effective in a complete medium than in a serum-free one allowing the hypothesis that the internalization could be dependent on the cell cycle. Both peptides were internalized likely by a lipid raft-mediated endocytosis mechanism as suggested by the reduced uptake in the presence of methyl-ß-cyclodextrin. These results suggest that the natural peptide may play a role within the cells of the oral mucosa after its secretion and subsequent internalization. Furthermore, lack of cytotoxicity of both peptide forms highlights their possible application as novel drug delivery agents.

Comparison of cytotoxicity of various concentrations origanum extract solution with 2% chlorhexidine gluconate and 5.25% sodium hypochlorite

Objective:

The purpose of this in vitro study was to compare the cytotoxicity of 0.5–4.5 origanum extract solution (OES), 2% chlorhexidine gluconate (CHX) and 5.25% sodium hypochlorite (NaOCl) with WST-1 test on human periodontal ligament (hPDL) fibroblasts.

Materials and Methods:

About 0.5–4.5% OES, 2% CHX and 5.25% NaOCl solutions cytotoxicity was evaluated with cell culture test using PDL fibroblasts. Viability of hPDL cells was evaluated with WST-1 (Cell Proliferation Reagent WST-1 Roche) test at 1, 24 and 72^nd h. hPDL cells were plated at 20 × 10³ cells per well in 96-well plates. Absorbance values were read in optical density 480 nm by ELISA plate reader spectrophotometer. The statistical differences between various groups were evaluated using one-way ANOVA, post-hoc Duncan's Multiple Range test using SAS software. Statistically, a significant difference was considered at P < 0.001.

Results:

According to the 1-h cytotoxicity results, 0.5% OES showed the least cytotoxic effect in test groups. There were not found any statistical significance between 1% OES and 2% CHX. About 5.25% NaOCl showed more cytotoxic effect than 1% OES and 2% CHX. In 24 and 72 h, different concentrations of OES, 5.25% NaOCl, 2% CHX solutions showed similar cytotoxic effect.

Conclusions:

Based on these results, 1% OES and 2% CHX showed similar results and less cytotoxic effect than 5.25% NaOCl. It could be considered as a favorable solution concentration when OES was used as root canal irrigation solution.

Fabrication and characterization of polymer composites for endodontic use

AIM

To develop a low-density polyethylene-hydroxyapatite (HA-PE) composite with properties tailored to function as a potential root canal filling material.

METHODOLOGY

Hydroxyapatite and polyethylene mixed with strontium oxide as a radiopacifier were extruded from a single screw extruder fitted with an appropriate die to form fibres. The composition of the composite was optimized with clinical handling and placement in the canal being the prime consideration. The fibres were characterized using infrared spectroscopy (FTIR), and their thermal properties determined using differential scanning calorimetry (DSC). The tensile strength and elastic modulus of the composite fibres and gutta-percha were compared, dry and after 1 month storage in simulated body fluid (SBF), using a universal testing machine. The radiopacity of the fibres was determined using digital radiography. The interaction of the composites with eugenol was evaluated and compared with gutta-percha. Data of the tensile test were submitted to two-way anova and Bonferroni tests (P < 0.05).

RESULTS

The endothermic peaks obtained from the DSC studies showed that the melting point of the HA/PE composites ranged between 110.5 and 111.2 °C, whereas gutta-percha exhibited a melting point at 52 °C. The tensile strength and elastic modulus of the silanated HA/PE composites were significantly higher than those of gutta-percha (P < 0.0001) under dry conditions and 1 month storage in SBF. The gutta-percha in eugenol showed a significant increase in the polymer molar mass, whereas the silanated HA/PE composites were unchanged. Radiological evaluations demonstrated that silanated HA/PE fibres were sufficiently radiopaque.

CONCLUSION

Promising materials for endodontic applications have been developed, offering relevant benefits over the traditional materials in terms of mechanical and chemical properties.

Biocompatibility of RealSeal, its primer and AH Plus implanted in subcutaneous connective tissue of rats

OBJECTIVE

This study tested rat connective tissue response to RealSeal, RealSeal primer or AH Plus after 7, 15, 30, 60 and 90 days of implantation.

MATERIAL AND METHODS

Thirty Wistar rats had subcutaneous sockets created on their back and received four implants each of polyethylene tubes containing one of the materials tested according to the groups: AH (AH Plus Sealer); RS (RealSeal Sealer); RP (RealSeal Primer); CG (control group - empty tube). After histological processing, sections were analyzed to identify the presence of neutrophils, lymphocytes and plasma cells, eosinophils, macrophages and giant cells, as well as fibrous capsule and abscesses, by an examiner using light microscope. Kruskal-Wallis and multiple-comparisons test were used for statistical analysis. Significance level was set at 5%.

RESULTS

Lymphoplasmacytic infiltrate scores significantly higher than those of the control group were observed at 14 and 60 days in AH group, and at 90 days in RS group (p<0.05). There were no differences in terms of presence of macrophages, giant cells, eosinophils, neutrophils or fibrosis. AH Plus group scored higher for abscesses at 7 days than after any other period (p=0.031). RP group scored higher for lymphoplasmacytic infiltrate at 14 days than at 90 days (p=0.04).

CONCLUSION

The main contribution of this study was to demonstrate that issues involved with tissue tolerance of a Resilon-containing sealer, RealSeal Sealer, cannot be attributed to its primer content.

In vitro Evaluation of the Cytotoxicity of Different Root Canal Filling Materials

OBJECTIVE

Aim of the present study was to evaluate the cytotoxicity of Real Seal 1 compared to other commercially available endodontic filling materials: Real Seal (SybronEndo, Orange, CA, USA) and Thermafil (Tulsa Dental, Tulsa, OK, USA).

MATERIAL AND METHODS

Periodontal ligament cells from healthy patients were cultured. The eluate of Real Seal 1(TM) (RS1), Real Seal (RS) and Thermafil (TF) samples was used for the cells viability tests, both diluted (50%) or undiluted (100%). Incubation of the specimens was performed in culture medium for 24 h, 48 h and 72 h at 37 °C under sterile conditions. The cellular mortality was evaluated by MTT test. Results were statistically analysed and the statistical significance was set at p< 0.05.

RESULTS

None of the studied materials showed toxic effects during the period of observation (0 -72 h) when compared to the control group. Only RS induced a very modest increase in cell mortality (about 3% at both concentrations used, during the first 24 hours), when increasing the incubation time, however, only the lower concentration continued to show modest toxicity.

CONCLUSIONS

Results of the present study showed that all tested materials did not exhibit cytotoxic effects when compared to the control group.

A laboratory evaluation of the physical and mechanical properties of selected root canal sealers

AIM

To evaluate and compare the porosity, degree of conversion (DC) and hardness of two resin-based sealers; RealSeal and EndoRez, and a silicon-based sealer; GuttaFlow to that of a traditional zinc oxide-based sealer; TubliSeal.

METHODOLOGY

For porosity, four samples from each sealer were prepared and scanned using a SkyScan 1072 Micro-CT. Porosity was then calculated using specialized software. For DC, 10 samples from each sealer were prepared and placed onto a Fourier transform infrared spectroscopy spectrometer. Spectra readings were carried out before and after curing of the sealers, and the DC for each sealer was calculated. For hardness, 10 samples from each sealer were prepared and then tested using a Wallace hardness tester. SPSS software was used for statistical analysis of the data using one-way anova and independent t-tests.

RESULTS

TubliSeal had the highest percentage porosity (3.52%), whilst RealSeal had the lowest percentage porosity (0.41%). Statistically significant differences (P = 0.01) in porosity were present between all groups except between RealSeal and EndoRez groups. RealSeal exhibited a significantly higher DC% than EndoRez (P = 0.01), whereas EndoRez had the highest hardness number [28.54 Vickers hardness number (VHN)] whilst TubliSeal showed the lowest (13.57 VHN). Statistically significant differences in hardness were found between all groups (P = 0.01) except between RealSeal and EndoRez groups.

CONCLUSIONS

Resin-based sealers had less porosity, greater hardness and a high DC.