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This study aimed to investigate the potential of low-level laser irradiation (LLLI) to promote odontogenic differentiation and biomineralization by dental pulp stem cells (DPSCs) seeded inside bioceramic scaffolds. Mg-based, Zn-doped bioceramic scaffolds, synthesized by the sol-gel technique, were spotted with DPSCs and exposed to LLLI at 660 nm with maximum output power of 140 mw at fluencies (a) 2 and 4 J/cm to evaluate cell viability/proliferation by the MTT assay and (b) 4 J/cm to evaluate cell differentiation, using real-time PCR (expression of odontogenic markers) and a p-nitrophenylphosphate (pNPP)-based assay for alkaline phosphatase (ALP) activity measurement. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were used for structural/chemical characterization of the regenerated tissues. Exposure of the DPSCs/scaffold complexes to the proposed LLLI scheme was associated with statistically significant increase of odontogenesis-related markers (bone morphogenetic protein 2 (BMP-2): 22.4-fold, dentin sialophosphoprotein (DSPP): 28.4-fold, Osterix: 18.5-fold, and Runt-related transcription factor 2 (Runx2): 3.4-fold). ALP activity was significantly increased at 3 and 7 days inside the irradiated compared to that in the non-irradiated SC/DPSC complexes, but gradually decreased until 14 days. Newly formed Ca-P tissue was formed on the SC/DPSC complexes after 28 days of culture that attained the characteristics of bioapatite. Overall, LLLI treatment proved to be beneficial for odontogenic differentiation and biomineralization of DPSCs inside the bioceramic scaffolds, making this therapeutic modality promising for targeted dentin engineering.

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R !~ S U M EThe gray-green limestone from Agios Panteleimonas is studied in this paper after submitting it in special technological analyses in order to determine the possibility for quicklime production. Cubic test specimens with mean 50 mm edge length were calcined at 850, 950 and 1,050~ with 150 rain preheating time and 120 rain retention time at each calcination temperature. At the dissociation temperature of pure calcite (898~ only one half of the initial limestone has been calcined. The dissociation of the specimens started at 740~ and almost completed at 1,050~ Probably, the large edge length of the cubic specimens and the low retention time are responsible for the incomplete calcination at 1,050~ The dry apparent weight of the calcined limestone (1.577 g/cm3), its low shrinkage (0.1-0.3%), the 2% impurities content and the 24% value of the attrition and abrasion resistance, characterize this quicklime and classify it to the high quality products. Dans cet article, le calcaire gris-vert d'Agios