RESUMO
BACKGROUND: The dental pulp's environment is essential for the regulation of mesenchymal stem cells' homeostasis and thus, it is of great importance to evaluate the materials used in regenerative procedures. AIM: To assess in vitro (i) the effect of chitosan nanoparticles, 0.2% chitosan irrigation solution, Dual Rinse®, 17% EDTA, 10% citric acid and 2.5% NaOCl on DSCS viability; (ii) the effect of different concentrations of TGF-ß1 on DCSC proliferation; and (iii) whether treatment with TGF-ß1 following exposure to the different irrigation solutions could compensate for their negative effects. METHODOLOGY: (i) DSCS were treated with three dilutions (1:10, 1:100 and 1:1000) of the six irrigation solutions prepared in DMEM for 10 and 60 min to assess the effect on viability. (ii) The effect of different concentrations (0, 1, 5 and 10 ng/mL) of TGF-ß1 on DCSC proliferation was assessed at 1, 3 and 7 days. (iii) The proliferative effect of TGF-ß1 following 10-min exposure to 1:10 dilution of each irrigation solution was also tested. We used MTT assay to assess viability and proliferation. We performed statistical analysis using Prism software. RESULTS: (i) The different endodontic irrigation solutions tested showed a significant effect on cell viability (p ≤ .0001). Significant interactions between the endodontic irrigation solutions and their dilutions were also found for all parameters (p ≤ .0001). Chitosan nanoparticles and 0.2% chitosan irrigation solution were the least cytotoxic to DSCS whilst 2.5% NaOCl was the most cytotoxic followed by 17% EDTA. (ii) TGF-ß1 at concentrations of 1 and 5 ng/mL resulted in significantly higher proliferation compared to the control group. (iii) Exposure to 17% EDTA or 2.5% NaOCl for 10 min was sufficient to make DSCS cells refractory to the proliferative effects of TGF-ß1. DSCS groups treated with TGF-ß1 following exposure to chitosan nanoparticles, 0.2% chitosan irrigation solution, Dual Rinse® and 10% CA demonstrated significantly higher proliferation compared to non-TGF-ß1-treated groups (p ≤ .0001, p ≤ .0001, p ≤ .0001 and p = .01 respectively). CONCLUSIONS: The current study offers data that can be implemented to improve the outcome of regenerative endodontic procedures by using less toxic irrigation solutions and adding TGF-ß1 to the treatment protocol.
RESUMO
AIM: To develop a formulation in which calcium hydroxide (Ca(OH)2) was successfully loaded into poly(lactic-co-glycolic acid) (PLGA) biodegradable nanoparticles (NPs) to be used in the field of endodontics as an intracanal medicament, including NP optimization and characterization, plus drug release profile of the NPs compared with free Ca(OH)2. Additionally, the depth and area of penetration of the NPs inside the dentinal tubules of extracted teeth were compared with those of the free Ca(OH)2. METHODOLOGY: Ca(OH)2 NPs were prepared using the solvent displacement method. NPs was optimized with a central composite design to obtain a final optimized formulation. The morphology of the NPs was examined under transmission electron microscopy (TEM), and characterization was carried out using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC). The drug release profile of the Ca(OH)2 NPs and free Ca(OH)2 was evaluated up to 48 h. Finally, the depth and area of penetration inside the dentinal tubules of extracted teeth were examined for both the Ca(OH)2 NPs and free Ca(OH)2 using the Mann-Whitney U test to determine any significant differences. RESULTS: Utilizing the optimized formulation, the Ca(OH)2 NPs had an average size below 200 nm and polydispersity index lower than 0.2, along with a highly negative zeta potential and suitable entrapment efficiency percentage. The spherical morphology of the Ca(OH)2 NPs was confirmed using TEM. The results of the XRD, FTIR and DSC revealed no interactions and confirmed that the drug was encapsulated inside the NPs. The drug release profile of the Ca(OH)2 NPs exhibited a prolonged steady release that remained stable up to 48 h with higher concentrations than the free Ca(OH)2. After examination by confocal laser scanning microscopy, Ca(OH)2 NPs had a significantly greater depth and area of penetration inside dentinal tubules compared with the free drug. CONCLUSIONS: Ca(OH)2-loaded PLGA NPs were successfully optimized and characterized. The NPs exhibited a prolonged drug release profile and superior penetration inside dentinal tubules of extracted teeth when compared to Ca(OH)2 .