Biocompatibility Investigation of New Endodontic Materials Based on Nanosynthesized Calcium Silicates Combined with Different Radiopacifiers

Biocompatibility Study of a New Dental Cement Based on Hydroxyapatite and Calcium Silicates: Focus on Liver, Kidney, and Spleen Tissue Effects

The effects of a new material based on hydroxyapatite and calcium silicates, named ALBO-MPCA, were investigated on the liver, kidney and spleen. The material was administrated orally for 120 days in an in vivo model in Wistar rats, and untreated animals served as a control. Hematological and biochemical blood parameters were analyzed. Qualitative histological analysis of tissues, change in mitotic activity of cells, and histological characteristics was conducted, as well as quantitative stereological analysis of parenchymal cells, blood sinusoids, and connective tissues. Additionally, the protein expressions of Ki67 and CD68 markers were evaluated. Histological analysis revealed no pathological changes after the tested period. It showed the preservation of the architecture of blood sinusoids and epithelial cells and the presence of mitosis. Additionally, the significantly increased number of the Ki67 in the presence of ALBO-MPCA confirmed the proliferative effect of the material noticed by stereological analysis, while immunoreactive CD68 positive cells did not differ between groups. The study showed non-toxicity of the tested material based on the effects on the hematological, biochemical, and observed histological parameters; in addition, it showed evidence of its biocompatibility. These results could be the basis for further steps toward the application of tested materials in endodontics.

Cytotoxicity Evaluation of Endodontic Pins on L929 Cell Line

Objective

The aim of this study was to evaluate the cytotoxic potential of a type of endodontic pin on L929 cell line according to the UNI EN ISO 10993/2009 rule.

Methods

L929 cells were used for the assays; extracts were prepared from three different-diameter endodontic pins, made of epoxy resin and fiberglass matrix and from Reference Materials (ZDEC, ZDBC, and HDP films). MTS assay was performed after 24 h, 48 h, and 72 h of exposure of L929 cells to pin and Reference Material extracts, 5% phenol solution, and control reagent. Cells cultured with different media containing extracts were monitored for up to 72 h and stained with haematoxylin/eosin.

Results

Pins of different diameters had no cytotoxic effects on L929 cells at 24 h, 48 h, and 72 h (all values >70%). Cells cultured in medium containing pin extracts grew without any differences compared to the control cells.

Conclusion

The endodontic pins tested showed no cytotoxic effects and did not induce changes in morphology for up to 72 h.

Influence of nanostructured calcium aluminate and calcium silicate on the liver: histological and unbiased stereological analysis

AIM

To examine the potential systemic toxicity of nanostructured materials based on calcium silicate and calcium aluminate, for potential application in Dentistry.

METHODOLOGY

Twenty-four Albino Wistar rats aged 2 months were used as an in vivo animal model for subcutaneous implantation of the investigated materials, placed in polyethylene tubes. Thirty days after implantation, the livers of the rats were analysed and following histological and stereological parameters were evaluated for volume density of hepatocytes and blood sinusoids, number and numerical density of hepatocytes, surface of hepatocytes and their nucleuses, nucleocytoplasmic ratio and mitotic index of hepatocytes. Stereological measurements were achieved using Cavalieri's principle, with grid P2 and unbiased analysis. Additionally, immunohistochemistry studies were performed to further analyse changes in liver tissue. Several haematological and biochemical parameters of blood of experimental animals were also analysed, as well as local tissue reactions around the implants. Statistical analysis was performed using parametric (anova and t-test) and nonparametric tests (Kruskal-Wallis and Mann-Whitney U-test) depending on data distribution.

RESULTS

Implanted dental cements led to an increase in stereological and histological parameters in liver tissue compared to control rats. Although the investigated parameters mostly showed significant differences between control and experimental animals, the liver tissue of the experimental animals did not have visible signs of pathological changes. This was supported by the analysis of blood parameters which were not significantly different between control and experimental animals. Also, the subcutaneous tissues had minimal inflammatory reactions. Immunohistochemistry studies revealed that nanostructured materials induced proliferation of hepatocytes, but that the immunological response to the materials was not strong enough to induce proliferation of immunoreactive cells in liver in the observed time period.

CONCLUSIONS

This study was performed as a contribution to the attestation of the biocompatibility of dental cements based on calcium silicate and calcium aluminate. Although these materials induced several changes in the liver structure, they were not clinically relevant and represent a normal and reversible response of the liver to the presence of biocompatible materials in the body. Blood and immunohistochemistry analyses and local tissue reactions further confirmed that these materials possess good biocompatible potential.

Nanostructured endodontic materials mixed with different radiocontrast agents-biocompatibility study

The aim of this study was to investigate the biocompatibility of nanostructured materials based on highly active calcium silicates mixed with different radiocontrast agents in comparison to MTA⁺ using in vitro and in vivo model. Morphology of materials' samples was analyzed using SEM while the phase compositions were identified by XRD. pH values of materials' suspensions were conducted by pH-meter. The cytotoxicity of materials' solutions was tested by MTT test (100, 50, 25 and 12.5 mg/ml). LDH and ³H-thymidine assay were utilized for biocompatibility investigations of materials' eluates (24 h, 7 day and 21 day). Eighteen Guinea pigs were used for intramuscular implantation, as teflon tubes with freshly prepared materials were placed into intramuscular pockets. All samples were composed of round and needle-like particles equally distributed with Ca/Si ratio ~2.7 at%, with the presence of hydrated calcium silicate phases. The pH values of ALBO-MPCA₁ and ALBO-MPCA₂ were high alkaline, while in case of MTA⁺ they were lower and continuously declined (p < 0.05). Investigated materials didn't exhibit dose-dependent effect on metabolic activity of L929 cells (p > 0.05). Significant differences in the percentage of cytotoxicity between diluted and undiluted extracts between all tested materials after 24 h and 7 day were noticed (p < 0.05). Increase in L929 cells proliferation was noticed in case of undiluted eluates of ALBO-MPCA₁ and ALBO-MPCA₂ after 7 day (p < 0.05). There were no statistically significant differences in the intensity of inflammatory response between investigated materials and control group after 60 day (p > 0.05). Evaluation of biocompatibility of both ALBO-MPCA₁ and ALBO-MPCA₂ indicate their potential clinical use.

Mineral Trioxide Aggregate Mixed with 5-Aminolevulinic Acid for the Photodynamic Antimicrobial Strategy in Hard Tissue Regeneration

Aminolevulinic acid (ALA) based photodynamic antimicrobial strategy can provide good antimicrobial effects and be used for medical applications. The aim of this study was to apply this strategy to Mineral Trioxide Aggregate (MTA), which is commonly used as a filling material for root endings and by doing so, to increase the bactericidal capability of MTA, as well as to investigate its characterization, cytocompatibility, and odontogenic differentiation potential. MTA is known to be a derivative of calcium silicate (CS). In this study, MTA specimens with or without ALA and light treatment were prepared. Diametral tensile strength values (DTS), setting durations, X-ray diffraction (XRD) spectra, apatite-mineralization, and antimicrobial abilities of the MTA, were also analyzed. Human dental pulp cells (hDPCs) can proliferate into the newly formed matrix and differentiate into odontoblasts to reinforce and strengthen the root. Levels of hDPCs proliferation and its odontogenic capabilities when cultured on MTA with ALA and light treatment, and the percentages of cells existing in the various cell cycle stages, were further evaluated in this study. The results indicated that MTA added ALA with light treatment had greater antibacterial ability and cytocompatibility, compared to MTA alone. A higher percentage S phase of the cells cultured on MTA added ALA with light treatment was observed. Furthermore, hDPCs cultured on MTA added ALA with light treatment had the highest expression levels of the odontoblastic differentiation markers. ALA has great antimicrobial efficiency and is a potential material for future medical applications. ALA-based photodynamic antibacterial strategy applied in the MTA has great antibacterial ability, cytocompatibility, and odontoblastic differentiation potential, and can facilitate the development of root canal treatment.

In vitro biocompatibility of nanostructured endodontic materials using SCAP cells

Background/Aim: Lately, fully innovative sol-gel method with high-temperature self-propagating reaction was used for the synthesis of new nanostructured endodontic materials, in combination with different radiopacifiers: bismuth (ALBO-MPCA1) and barium (ALBO-MPCA2). The aim of this study was to investigate the biocompatibility of nanostructured endodontic materials based on highly active calcium silicates and mixed with different radiopacifiers in comparison to MTA+ using human stem cells from the apical papilla- SCAP cells. Material and Methods: Morphology of the samples was studied by SEM. The tested materials were mixed with distilled water in a ratio 2:1 (m/m). Fifteen minutes after the preparation, samples were used in the experiment. The biocompatibility of fresh materials, after 3h and 7 days, was tested using 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide- MTT test. Results: Samples mostly consisted of spherical and rode-like. The relative viability of cells increased following the exposure time. Conclusion: The biocompatibility of synthesized materials is comparable to the control material MTA+, and therefore these materials can be recommended for further clinical studies.