The primary objective of this study was to assess the biological effects of a new dentine substitute based on Ca₃SiO₅ (Biodentine™) for use in pulp-capping treatment, on pseudo-odontoblastic (MDPC-23) and pulp (Od-21) cells. The secondary objective was to evaluate the effects of Biodentine and mineral trioxide aggregate (MTA) on gene expression in cultured spheroids. We used the acid phosphatase assay to compare the biocompatibility of Biodentine and MTA. Cell differentiation was investigated by RT-qPCR. We investigated the expression of genes involved in odontogenic differentiation (Runx2), matrix secretion (Col1a1, Spp1) and mineralisation (Alp). ANOVA and PLSD tests were used for data analysis. MDPC-23 cells cultured in the presence of MTA had higher levels of viability than those cultured in the presence of Biodentine and control cells on day 7 (P = 0.0065 and P = 0.0126, respectively). For Od-21 cells, proliferation rates on day 7 were significantly lower in the presence of Biodentine or MTA than for control (P < 0.0001). Col1a1 expression levels were slightly lower in cells cultured in the presence of MTA than in those cultured in the presence of Biodentine and in control cells. Biodentine and MTA may modify the proliferation of pulp cell lines. Their effects may fluctuate over time, depending on the cell line considered. The observed similarity between Biodentine and MTA validates the indication for direct pulp-capping claimed by the manufacturers.

The retention and survival of microorganisms on toothbrushes pose a threat of recontamination for certain patients at risk. In order to measure the influence of brush design and optimize the choice of toothbrush model for complementary studies, the in vitro retention of three microbial species (Porphyromonas gingivalis ATCC 33277, Streptococcus mutans ATCC 25175 and Candida albicans ATCC 26555) was evaluated for three types of toothbrush. Two series of standardized experiments were carried out for each brush and microorganism. The first series tested the retention of the microorganisms on the head portion of the brush, while the second measured retention on the head of the brush and the part of the handle inserted in the mouth during brushing. For each series, the microorganisms were counted at T0 and T24 (after storage of the brushes at room temperature for 24 h). Depending on the microorganism studied, from 0.2% to 2% of the initial inoculum was retained on the brush. The number detected increased with the size of the exposed area. After 24 h, P. gingivalis and S. mutans were found on only one type of brush. C. albicans survived on all three. These results confirm that microorganisms can quickly colonize toothbrushes.

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Porphyromonas gingivalis (P. gingivalis) is considered to be one of the main periodontal pathogens. The goal of this work was to confirm the ability of P. gingivalis to invade host cells. We detected P. gingivalis inside KB cells by confocal microscopy and analyzed the various aspects of the adherence and internalization process. Lysates of P. gingivalis-infected KB cells were also examined using anaerobic growth techniques. The results showed the viability and ability to replicate, inside the host cells, of the internalized pathogen. The production of vesicles was also tracked for the first time. Confocal microscopy revealed P. gingivalis in a perinuclear position.The literature is unanimous in assigning Porphyromonas gingivalis (P. gingivalis) a role as a major periodontal pathogen (17, 39). While it occasionally expresses its virulence on its own, P. gingivalis more commonly acts in cooperation with other microorganisms (21, 23). P. gingivalis is an opportunistic pathogen (22, 24) which can express an outstanding arsenal of virulence factors (6). As with many enteropathogens (5,7,26,32), invasion of host cells seems to be an important strategy used by P. gingivalis to protect itself against the host immune system and to advance through tissues (36). A possible connection has been made between the incidence of periodontal infections in pregnant women and an increased risk of their having preterm low-birth-weight babies (31). P. gingivalis has also been cited as a potential etiological factor in myocardial infarction and atherosclerosis (2, 27). The internalization was first quantified, and the ability of this pathogen to multiply within the eukaryotic cells was assessed. The survival conditions in the host cell were then determined.Epithelial cell growth. KB cells (ATCC CL17) derived from an epidermoid cancer of the oral cavity were used. The cells were inoculated into 24-well macroplates at a concentration of 10 5 cells/ml. The growth medium was replaced every day to maintain confluent cultures. For confocal microscopy, the cells were inoculated at the same concentration in glass culture dishes coated with 1% collagen I.Bacterial growth. P. gingivalis ATCC 33277 was maintained on blood agar plates in an anaerobic chamber at 37°C. ToddHewitt broth cultures were inoculated 48 h prior to each experiment.Bacterial contamination. The epithelial cells were washed twice with unsupplemented RPMI 1640 and covered with 500 l of a bacterial suspension for 1 h at 37°C. The bacterial concentration was adjusted by dilution in phosphate-buffered saline (PBS) containing 1 mM ␤2-mercaptoethanol to a ratio of 100 bacteria per epithelial cell as determined by optical density. RPMI alone and bacteria alone served as negative controls.Cell lysate culturing. The epithelial cells were washed and incubated with 500 l of metronidazole (100 g/ml) for 3 h (25). The cells were lysed in 1 ml of sterile distilled water for 15 min. The lysates were serially diluted, and 200 l of each dilution was spread on a blood agar plate. The plates we...

The necrosis process occurred in human dental pulp fibroblasts and is different between the two cell types studied. This in vitro experimental necrosis model could become an interesting inflammatory tool. More investigations are needed to compare necrosis process in dental pulp fibroblast and inflammation during pulpitis.

Summary Objectives Mechanobiology phenomena constitute a major element of the cellular and tissue response during orthodontic treatment and the implantation of a biomaterial. Better understanding these phenomena will improve the effectiveness of our treatments. The objective of this work is to validate a model of three-dimensional (3D) culture of osteoblasts to study mechanobiology. Materials and methods The hFOB 1.19 cell line was cultured either traditionally on a flat surface or in aggregates called spheroids. They were embedded in 0.8% low-melting agarose type VII and placed in a polyethylene terephthalate transwell insert. Compressive forces of 1 and 4 g/cm2 were applied with an adjustable weight. Proliferation was evaluated by measuring diameters, monitoring glucose levels, and conducting Hoechst/propidium iodide staining. Enzyme-linked immunosorbent assays focusing on the pro-inflammatory mediators interleukin (IL)-6 and IL-8 and bone remodelling factor osteoprotegerin were performed to evaluate soluble factor synthesis. quantitative reverse transcription-polymerase chain reaction was performed to evaluate bone marker transcription. Results The 3D model shows good cell viability and permits IL dosing. Additionally, three gene expression profiles are analysable. Limitations The model allows analysis of conventional markers; larger exploration is needed for better understanding osteoblast mechanobiology. However, it only allows an analysis over 3 days. Conclusion The results obtained by applying constant compressive forces to 3D osteoblastic cultures validate this model system for exploring biomolecule release and analysing gene transcription. In particular, it highlights a disturbance in the expression of markers of osteogenesis.

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Porphyromonas gingivalis, implicated in the pathogenesis of periodontitis, can adhere to epithelial cells and gingival fibroblasts. This study employed flow cytometry to evaluate the adherence of P. gingivalis to epithelial cells under various conditions. The cell lines SK-MES and KB were used in the first experiments. The P. gingivalis strains employed were ATCC 33277, ATCC 49417 and W83. Different adherence conditions were tested (contact time, bacteria/cell ratio, contact temperature). In later experiments, adherence of P. gingivalis to human gingival epithelial cells (GEC) obtained by explant was studied under various conditions. Results showed that P. gingivalis had a high affinity for buccal keratinocytes compared with SK-MES. Adherence showed a level of saturation. The number of receptors may be limited for each epithelial cell line, and there may be more receptors for gingival keratinocytes. Depending on contact time, P. gingivalis showed a higher affinity for GEC, compared with the other two lines. P. gingivalis thus showed specific adherence for a host cell type from a site associated with periodontal disease.