Effect of final irrigation protocols with chitosan nanoparticle and genipin on dentine against collagenase degradation: An ex-vivo study

AIM

Endodontic irrigants may affect the mechanical and chemical properties of dentine. This study evaluated the effects of various final irrigation protocols including the use of chitosan nanoparticle (CSnp) and cross-linking with genipin on the (1) mechanical and (2) chemical properties of dentine against enzymatic degradation.

METHODOLOGY

CSnp was synthesized and characterized considering physiochemical parameters and stability. The root canals of 90 single-rooted teeth were prepared and irrigated with NaOCl. Dentine discs were obtained and divided into groups according to the following irrigation protocols: Group NaOCl+EDTA, Group NaOCl+CSnp, Group NaOCl+EDTA+CSnp, Group NaOCl+CSnp+Genipin, Group NaOCl+EDTA+CSnp+Genipin and Group distilled water. (1) Mechanical changes were determined by microhardness analysis using Vickers-tester. (2) Chemical changes were determined by evaluating molecular and elemental compositions of dentine using Fourier transform infrared spectroscopy (FTIR) analysis and scanning electron microscope (SEM)/energy dispersive X-ray spectroscopy (EDS) analysis, respectively. All analyses were repeated after the discs were kept in collagenase for 24 h. Data were analysed with repeated measures analysis of variance and Bonferroni correction for microhardness analysis, and Kruskal-Wallis and Wilcoxon tests for FTIR and SEM/EDS analyses (p = .05).

RESULTS

(1) Collagenase application did not have a negative effect on microhardness only in Group NaOCl+EDTA+CSnp+Genipin when compared with the post-irrigation values (p > .05). Post-collagenase microhardness of Group NaOCl+EDTA+CSnp and Group NaOCl+CSnp+Genipin was similar to the initial microhardness (p > .05). (2) After collagenase, Amide III/PO 4 3 - ratio presented no change in Group NaOCl+EDTA+CSnp, Group NaOCl+CSnp+Genipin and Group NaOCl+EDTA+CSnp+Genipin (p > .05), while decreased in other groups (p < .05). Collagenase did not affectCO 3 2 - /PO 4 3 - ratio in the groups (p > .05). There were no changes in the groups in terms of elemental level before and after collagenase application (p > .05).

CONCLUSIONS

CSnp and genipin positively affected the microhardness and molecular composition of dentine. This effect was more pronounced when CSnp was used after EDTA.

Development of tumor-specific liposomes containing quantum dots-photosensitizer conjugate used for radiotherapy

This study aims to develop a multifunctional liposomal radiosensitizer to destroy more tumor cells by using lower radiation doses compared to clinically used 6 MV X-ray doses. To achieve this aim, first Chlorine-e6 (Ce6) was covalently bound to functional groups of outer surfaces of quantum dots (QDs) through EDC/NHS reactions. Then, QDs-Ce6 conjugate loaded, nanosized, PEG-coated, and tumor-specific folic acid-modified immunoliposome dispersions were prepared by film method. Enhanced anti-proliferation activity of free and liposomal conjugate against 4T1 (murine breast cancer) cell lines was investigated at different X-ray doses (5, 10, 15, and 20 Gy). As a result, the best radiosensitizer effect was observed at a 5 Gy X-ray dose and it was found that following the X-ray irradiation, immunoliposome dispersions containing QDs-Ce6 conjugate killed 26.8 ± 1.7% more cancer cells than radiation alone.

VEGF/BMP-2 loaded three-dimensional model for enhanced angiogenic and odontogenic potential of dental pulp stem cells

AIM

To investigate the proliferation and differentiation potential of human dental pulp stem cells (DPSCs) in a three-dimensional culture model (TDM) by incorporation of VEGF and BMP-2.

METHODOLOGY

TDM was established using fibrin gel (fg) as a soft tissue matrix and demineralized dentine disc (dd) as a hard tissue matrix. DPSCs and vascular endothelial growth factor (VEGF) were encapsulated in fibrin gel (fg-VEGF) and then inserted into bone morphogenetic protein (BMP-2)-coated demineralized dentine discs (dd-BMP-2). DPSCs were incubated for 28 days in various fg/dd combinations in the absence or presence of VEGF and BMP-2. Proliferation and morphology of DPSCs in fibrin gel were analysed using MTT and Live&Dead assays. Release profiles of VEGF and BMP-2 from fibrin gel and dentine discs were quantified using ELISA, and the expressions of angiogenic and odontogenic differentiation markers were determined with RT-qPCR analysis. Data were analysed statistically using Wilcoxon signed rank tests, Kruskal-Wallis tests with Mann-Whitney U tests and Bonferroni adjustment. The level of significance was set at P < 0.05.

RESULTS

DPSCs were able to proliferate and showed interconnected cellular elongations in fibrin gel depending on fibrinogen concentration whilst monolayer control group showed typical fibroblast-like cell morphology. Encapsulating of VEGF in fibrin gel and BMP-2 in gelatin that was used to coat dentine discs allowed the controlled releases of growth factors, which induced angiogenic and odontogenic gene expressions by DPSCs. Higher expressions of PECAM as an angiogenic factor, and BSP, DMP-1, OCN and CBFA as odontogenic factors, were observed in TDM as compared to the other fg/dd combinations and the monolayer control group (P < 0.05).

CONCLUSIONS

TDM consisting of fibrin gel and dentine matrix allowed cell-cell interactions. TDM was highly effective in delivering both VEGF and BMP-2 that enhanced the angiogenic and odontogenic potential of DPSCs.

EGF containing gelatin-based wound dressings

In case of bulk loss of tissue or non-healing wounds such as burns, trauma, diabetic, decubitus and venous stasis ulcers, a proper wound dressing is needed to cover the wound area, protect the damaged tissue, and if possible to activate the cell proliferation and stimulate the healing process. In this study, synthesis of a novel polymeric bilayer wound dressing containing epidermal growth-factor (EGF) -loaded microspheres was aimed. For this purpose, a natural, nontoxic and biocompatible material, gelatin, was chosen as the underlying layer and various porous matrices in sponge form were prepared from gelatin by freeze-drying technique. As the external layer, elastomeric polyurethane membranes were used. Two different doses of EGF was added into the prepared gelatin sponges (1 and 15 microg/cm2) to activate cell proliferation. EGF addition was carried out either in free form or within microspheres to achieve prolonged release of EGF for higher efficiency. The prepared systems were tested in in vivo experiments on full-thickness skin defects created on rabbits. At certain intervals, wound areas were measured and tissues from wound areas were biopsied and processed for histological examinations. The wound areas decreased upon low-dose EGF application but the difference between the affects of free EGF and microsphere loaded EGF was not so distinct. Upon increasing the dose of EGF by a factor of 15, it was observed that controlled release of EGF from microspheres provided a higher degree of reduction in the wound areas. Histological investigations showed that the prepared dressings were biocompatible and did not cause any mononuclear cell infiltration or foreign body reaction. The structure of the newly formed dermis was almost the same as that of the normal skin.

Morphologic and mechanical characteristics of engineered bovine arteries

OBJECTIVE

The ideal small-caliber arterial graft remains elusive despite several decades of intense research. A novel approach to the development of small-caliber arterial prostheses with a biomimetic system for in vitro vessel culture has recently been described. In this study we examined the effects of culture time and tissue culture scaffolding on engineered vessel morphology and function and found that these parameters greatly influence the function of engineered vessels.

METHODS

This report describes the effects of culture time and scaffold type on vessel morphology, cellular differentiation, and vessel mechanical characteristics. Engineered vessels were cultured from bovine aortic smooth muscle cells (SMCs) and endothelial cells that were seeded onto biodegradable polymer scaffolds and cultured under physiologically pulsatile conditions. Engineered vessels were subjected to histologic, ultrastructural, immunocytochemical, and mechanical analyses.

RESULTS

Vessel morphology and mechanical characteristics improved as time in culture increased to 8 weeks. SMCs in the engineered vessel wall were organized into a highly lamellar structure, with cells separated by alternating layers of collagen fibrils. Polymer scaffold remnants were present in vessels cultured for 8 weeks, and SMCs that were in proximity to polymer remnants exhibited a dedifferentiated phenotype.

CONCLUSIONS

These findings aid in the systematic understanding of the effects of in vitro parameters on engineered vessels and will be useful for the translation of vessel culture techniques to human cells for the development of autologous human vascular grafts.

Bond strength and failure analysis of lining materials to denture resin

OBJECTIVES

This study was conducted to investigate the bonding properties of five lining materials to a denture base resin. Two hard (chemical-cured resin: Kooliner "Coe Labs, USA" and light-cured VLC resin: Triad "Dentsply, USA") and three soft (chemical-cured resin: Express "Alcos,-USA", heat-temperature vulcanized 'HTV' silicone material: Molloplast-B "Regneri GmbH, Germany" and room-temperature vulcanized 'RTV' silicone material:Ufi Gel-P "Voco, Germany") liners were used.

METHODS

Paladent 20 "Heraeus Kulzer GmbH, Germany", a conventional heat-cured polymethylmethacrylate (PMMA), was used as the denture base resin and as the control material. Bonding strength and adhesion properties of the liners to PMMA were compared by tensile test and scanning electron microscope (SEM) analysis. After curing, an aging process was applied and the samples were immersed and stored in distilled water at 37 +/- 1 degrees C and taken out at certain aging intervals (at 0, 15, 30 and 90 days) for examination. Specimens (168) were processed for tensile tests and other specimens (24) for fracture tests. The mean and standard deviation values were calculated. Changes in the mechanical properties and the SEM findings of the adhered surfaces were evaluated.

RESULTS

Triad (a hard liner) has the closest tensile strength to the control, indicating the strongest bonding between the base and the liner. Also, during the aging process, formation of better adhesion was observed in SEM micrographs. From the SEM analysis it was found that, Molloplast-B (a soft liner) also has a very good filling capacity.

SIGNIFICANCE

Among the hard lining materials, VLC resin to chemical-cured resin; and among the soft lining materials, HTV resin to RTV and chemical-cured ones should be preferred for relining procedures. Molloplast-B and Express as resilient liners were found to have adequate adhesive values for clinical use.

Wetting properties of saliva substitutes on acrylic resin

The good wetting of the acrylic resin by saliva substitutes is of clinical importance in xerostomic patients. This study evaluated the wetting properties of different artificial saliva formulations that were mucin-based, carboxymethylcellulose-based, and concentrated ion-based on poly(methyl methacrylate) denture base resin, and compared these properties with natural saliva. The wetting properties of the test materials were examined by contact angle measurements. Ninety-six samples that measured 30 x 30 x 3 mm were examined. The wetting properties of mucin-containing and carboxymethylcellulose-containing substitutes on poly(methyl methacrylate) were significantly better than those of human saliva. Mucin-containing artificial salivas had the best wetting properties on the acrylic resin for the materials tested.