Biocompatibility of human osteosarcoma cells to root end filling materials

A study of the interactions between human osteoblast-like cells and polymer composites with functionalized graphene derivatives using 2D correlation spectroscopy (2D-COS)

In response to the growing need for development of modern biomaterials for applications in regenerative medicine strategies, the research presented here investigated the biological potential of two types of polymer nanocomposites. Graphene oxide (GO) and partially reduced graphene oxide (rGO) were incorporated into a poly(ε-caprolactone) (PCL) matrix, creating PCL/GO and PCL/rGO nanocomposites in the form of membranes. Proliferation of osteoblast-like cells (human U-2 OS cell line) on the surface of the studied materials confirmed their biological activity. Fluorescence microscopy was able to distinguish the different patterns of interaction between cells (depending on the type of material) after 15 days of the test run. Raman micro-spectroscopy and two-dimensional correlation spectroscopy (2D-COS) applied to Raman spectra distinguished the nature of cell-material interactions after only 8 days. Combination of these two techniques (Raman micro-spectroscopy and 2D-COS analysis) facilitated identification of a much more complex cellular response (especially from proteins) on the surface of PCL/GO. The presented approach can be regarded as a method for early study of the bioactivity of membrane materials.

The Effect of Calcium Chloride on Push-Out Bond Strength of Calcium-Enriched Mixture Cement and Mineral Trioxide Aggregate

Introduction:

This in vitro study investigated the effect of adding 10% calcium chloride (CaCl₂) on push out bond strength of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA) to root canal dentin.

Methods and Materials:

A total of 120 root dentin slices with 2 mm thickness were prepared from sixty single-rooted human teeth. Dentinal discs were enlarged to achieve 1.3 mm diameter. The specimens were randomly allocated into eight groups (n=15). Dentin discs were filled with either CEM cement or MTA with or without CaCl₂ and the push out test was performed after 3 and 21 days. Data were analyzed with two-way ANOVA test. The level of significance was set at 0.05.

Results:

There was an interaction effect amongst all groups (P=0.028). After 3 days, CEM cement showed a significantly lower bond strength than other groups (P<0.05) while MTA demonstrated significantly higher bond strength than CEM cement with or without CaCl₂ (P=0.001). After 21 days, CEM cement with or without CaCl₂ had no significant difference with other groups (P>0.05). However, the bond strength of MTA decreased when CaCl₂ was added (P=0.011).

Conclusion:

The addition of 10% CaCl₂ increased the push out bond strength of CEM cement and improved it over time; while, this substance aggravated this property for MTA.

Selective apoptotic cell death effects of oral cancer cells treated with destruxin B

BACKGROUND

Recent studies have revealed that destruxins (Dtx) have potent cytotoxic activities on individual cancer cells, however, data on oral cancer cells especial human are absent.

METHODS

Destruxin B (DB) was isolated and used to evaluate the selective cytotoxicity with human oral cancer cell lines, GNM (Neck metastasis of gingival carcinoma) and TSCCa (Tongue squamous cell carcinoma) cells, and normal gingival fibroblasts (GF) were also included as controls. Cells were tested with different concentrations of DB for 24, 48, and 72 h by MTT assay. Moreover, the mechanism of cytotoxicity was investigated using caspase-3 Immunofluorescence, annexin V/PI staining, and the expression of caspase-3, Bax, and Bcl-2 by western blotting after treated with different concentrations of DB for 72 h as parameters for apoptosis analyses.

RESULTS

The results show that DB exhibited significant (p < 0.01) and selective time- and dose-dependent inhibitory effects on GNM and TSCCa cells viability but not on GF cells. The data suggested that DB is capable to induce tumor specific growth inhibition in oral GNM and TSCCa cancer cells via Bax/Bcl-2-mediated intrinsic mitochondrial apoptotic pathway in time- and dose-dependent manners.

CONCLUSIONS

This is the first report on the anti-proliferation effect of DB in oral cancer cells. The results reported here may offer further evidences to the development of DB as a potential complementary chemotherapeutic target for oral cancer complications.

Biocompatibility of root-end filling materials: recent update

The purpose of a root-end filling is to establish a seal between the root canal space and the periradicular tissues. As root-end filling materials come into contact with periradicular tissues, knowledge of the tissue response is crucial. Almost every available dental restorative material has been suggested as the root-end material of choice at a certain point in the past. This literature review on root-end filling materials will evaluate and comparatively analyse the biocompatibility and tissue response to these products, with primary focus on newly introduced materials.

Biocompatibility of sealers used in apical surgery: a histological study in rat subcutaneous tissue

The aim of this study was to evaluate the biocompatibility of sealers used in apical surgery in rat subcutaneous tissue. Sterile polyethylene tubes were filled with the following sealers: Sealapex, Sealapex with addition of zinc oxide, Sealer 26, Sealer 26 with thicker consistency (greater powder-to-resin ratio) and White MTA. The tubes were implanted in the dorsum of male rats and after 7, 21 and 42 days, the animals were killed, obtaining 5 specimens for each sealer in each evaluation period. The lateral surface of the tube was used as negative control. The inflammatory reaction to contact with the sealers was classified as absent, mild, moderate and severe. At 7 days, all sealers caused similar inflammatory reactions in the connective tissue of the animals, with most specimens presenting a moderate to intense chronic inflammatory reaction, with presence of multinucleated giant cells. At 21 days, Sealer 26 and Sealer 26 with thicker consistency presented more intense inflammatory reaction (p=0.004), whereas after 42 days, the inflammatory reaction ranged from absent to mild with statistically similar results for both materials (p=0.08). Except for MTA, all sealers presented foreign-body granulomatous reaction at 42 days. All sealers but Sealapex presented a statistically significant decrease of the inflammatory reaction over time. In conclusion, all sealers caused moderate to severe inflammation in the earlier evaluation period. However, Sealer 26 and Sealer 26 with thicker consistency caused more intense inflammatory reactions after 21 days of contact with the tissues and no granulomatous reaction was observed for MTA at the final period of analysis.

Periradicular regeneration after endodontic surgery with calcium-enriched mixture cement in dogs

INTRODUCTION

The aim of this in vivo study was to compare the response of periradicular tissues to mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement as root-end fillings and to analyze hard tissue healing after periradicular surgery.

METHODS

Intentional periradicular lesions were induced in 32 premolar teeth in 4 beagle dogs. The root canals were prepared, dried, and obturated with laterally condensed gutta-percha with sealer, and the coronal access cavities were filled with amalgam. After surgical exposure of the apices, 2-3 mm of the apical root was resected, and root-end cavities were ultrasonically prepared. The root-end cavities were randomly filled with MTA or CEM cement. After 2 months, the animals were killed; tissue blocks were removed and prepared for histologic examination. Hard tissue healing including cementum and new bone formation in addition to concentration and extent of inflammation were evaluated.

RESULTS

Eight samples were excluded. The major finding was the cementum deposition adjacent to MTA in 11 of 12 samples and CEM cement in 10 of 12 samples. With one-way analysis of variance, no significant difference was observed between the periradicular tissue response to tested materials.

CONCLUSIONS

CEM cement and MTA were associated with regenerative periapical tissue response when used as root-end filling biomaterials.

The effect of a physiologic solution pH on properties of white mineral trioxide aggregate

The purpose of this study was to investigate the effect of two solutions differing by pH (6.4 and 4.0) and the use of a setting accelerator (15% Na(2)HPO(4) solution) on the properties of white-colored mineral trioxide aggregate (WMTA). These studies indicated that pH 4.0 had a deleterious effect on the morphology of WMTA mixed with water, however, not for WMTA mixed with Na(2)HPO(4). When immersed in a pH 4.0 solution for 7 days, WMTA mixed with water or Na(2)HPO(4) achieved a diametral tensile strength of 7.9 and 9.0 MPa, respectively, which was significantly lower (p < 0.05) than those obtained at pH 6.4 (11.2 and 12.0 MPa) but significantly higher (p < 0.05) than day 0 samples (4.4 and 4.8 MPa). Mixing WMTA with the accelerator did not significantly affect the microstructure, solubility, or strength in an acidic environment.

Prostaglandin E2 production and viability of cells cultured in contact with freshly mixed endodontic materials

AIM

To determine whether commonly used endodontic sealers could either induce or increase the release of prostaglandin E2 (PGE2) when in contact with cell types found in the periapical tissues.

METHODOLOGY

Freshly mixed samples of Roth 801 sealer, Sealapex and ProRoot mineral trioxide aggregate (MTA) were placed in contact with cultured macrophages and fibroblasts for 24 h. The supernatant from the cultures was assayed for PGE2 using enzyme-linked immunosorbent assay. Cell viability counts were made. As a positive control, similar cultures were also exposed to lipopolysaccharide and the supernatant analysed for PGE2. Data were compared by anova.

RESULTS

The three materials examined in these experiments did not stimulate increased PGE2 release from either of the cell lines. In control cultures, lipopolysaccharide increased PGE2 release from macrophages but not from fibroblasts. Viability counts revealed that, whilst Roth 801 sealer caused some cell death in both fibroblasts and macrophages, Sealapex led to cell death only in the macrophage cultures. ProRoot MTA did not lead to statistically significant cell death in either culture.

CONCLUSIONS

Under 24-h culture conditions, the three freshly mixed test materials did not increase directly either production or release of PGE2 from either macrophages or gingival fibroblasts. Roth 801 decreased cell viability counts for both fibroblasts and macrophages. Sealapex decreases macrophage viability. ProRoot MTA did not affect viability in either cell line.