Atp6i deficient mouse model uncovers transforming growth factor-β1 /Smad2/3 as a key signaling pathway regulating odontoblast differentiation and tooth root formation / 国际口腔科学杂志·英文版

The biomolecular mechanisms that regulate tooth root development and odontoblast differentiation are poorly understood. We found that Atp6i deficient mice (Atp6i-/-) arrested tooth root formation, indicated by truncated Hertwig's epithelial root sheath (HERS) progression. Furthermore, Atp6i deficiency significantly reduced the proliferation and differentiation of radicular odontogenic cells responsible for root formation. Atp6i-/- mice had largely decreased expression of odontoblast differentiation marker gene expression profiles (Col1a1, Nfic, Dspp, and Osx) in the alveolar bone. Atp6i-/- mice sample RNA-seq analysis results showed decreased expression levels of odontoblast markers. Additionally, there was a significant reduction in Smad2/3 activation, inhibiting transforming growth factor-β (TGF-β) signaling in Atp6i-/- odontoblasts. Through treating pulp precursor cells with Atp6i-/- or wild-type OC bone resorption-conditioned medium, we found the latter medium to promote odontoblast differentiation, as shown by increased odontoblast differentiation marker genes expression (Nfic, Dspp, Osx, and Runx2). This increased expression was significantly blocked by anti-TGF-β1 antibody neutralization, whereas odontoblast differentiation and Smad2/3 activation were significantly attenuated by Atp6i-/- OC conditioned medium. Importantly, ectopic TGF-β1 partially rescued root development and root dentin deposition of Atp6i-/- mice tooth germs were transplanted under mouse kidney capsules. Collectively, our novel data shows that the prevention of TGF-β1 release from the alveolar bone matrix due to OC dysfunction may lead to osteopetrosis-associated root formation via impaired radicular odontoblast differentiation. As such, this study uncovers TGF-β1 /Smad2/3 as a key signaling pathway regulating odontoblast differentiation and tooth root formation and may contribute to future therapeutic approaches to tooth root regeneration.

KLF6 facilitates differentiation of odontoblasts through modulating the expression of P21 in vitro / 国际口腔科学杂志·英文版

Multiple signaling pathways are involved in the regulation of cell proliferation and differentiation in odontogenesis and dental tissue renewal, but the details of these mechanisms remain unknown. Here, we investigated the expression patterns of a transcription factor, Krüppel-like factor 6 (KLF6), during the development of murine tooth germ and its function in odontoblastic differentiation. KLF6 was almost ubiquitously expressed in odontoblasts at various stages, and it was co-expressed with P21 (to varying degrees) in mouse dental germ. To determine the function of Klf6, overexpression and knockdown experiments were performed in a mouse dental papilla cell line (iMDP-3). Klf6 functioned as a promoter of odontoblastic differentiation and inhibited the proliferation and cell cycle progression of iMDP-3 through p21 upregulation. Dual-luciferase reporter assay and chromatin immunoprecipitation showed that Klf6 directly activates p21 transcription. Additionally, the in vivo study showed that KLF6 and P21 were also co-expressed in odontoblasts around the reparative dentin. In conclusion, Klf6 regulates the transcriptional activity of p21, thus promoting the cell proliferation to odontoblastic differentiation transition in vitro. This study provides a theoretical basis for odontoblast differentiation and the formation of reparative dentine regeneration.

Aberrant NF-κB activation in odontoblasts orchestrates inflammatory matrix degradation and mineral resorption / 国际口腔科学杂志·英文版

Inflammation-associated proteinase functions are key determinants of inflammatory stromal tissues deconstruction. As a specialized inflammatory pathological process, dental internal resorption (IR) includes both soft and hard tissues deconstruction within the dentin-pulp complex, which has been one of the main reasons for inflammatory tooth loss. Mechanisms of inflammatory matrix degradation and tissue resorption in IR are largely unclear. In this study, we used a combination of Cre-loxP reporter, flow cytometry, cell transplantation, and enzyme activities assay to mechanistically investigate the role of regenerative cells, odontoblasts (ODs), in inflammatory mineral resorption and matrices degradation. We report that inflamed ODs have strong capabilities of matrix degradation and tissue resorption. Traditionally, ODs are regarded as hard-tissue regenerative cells; however, our data unexpectedly present ODs as a crucial population that participates in IR-associated tissue deconstruction. Specifically, we uncovered that nuclear factor-kappa b (NF-κB) signaling orchestrated Tumor necrosis factor α (TNF-α)-induced matrix metalloproteinases (Mmps) and Cathepsin K (Ctsk) functions in ODs to enhance matrix degradation and tissue resorption. Furthermore, TNF-α increases Rankl/Opg ratio in ODs via NF-κB signaling by impairing Opg expression but increasing Rankl level, which utterly makes ODs cell line 17IIA11 (A11) become Trap+ and Ctsk+ multinucleated cells to perform resorptive actions. Blocking of NF-κB signaling significantly rescues matrix degradation and resorptive functions of inflamed ODs via repressing vital inflammatory proteinases Mmps and Ctsk. Utterly, via utilizing NF-κB specific small molecule inhibitors we satisfactorily attenuated inflammatory ODs-associated human dental IR in vivo. Our data reveal the underlying mechanisms of inflammatory matrix degradation and resorption via proteinase activities in IR-related pathological conditions.

Role of connexin 43 in odontoblastic differentiation and structural maintenance in pulp damage repair / 国际口腔科学杂志·英文版

Dental pulp can initiate its damage repair after an injury of the pulp-dentin complex by rearrangement of odontoblasts and formation of newly differentiated odontoblast-like cells. Connexin 43 (Cx43) is one of the gap junction proteins that participates in multiple tissue repair processes. However, the role of Cx43 in the repair of the dental pulp remains unclear. This study aimed to determine the function of Cx43 in the odontoblast arrangement patterns and odontoblastic differentiation. Human teeth for in vitro experiments were acquired, and a pulp injury model in Sprague-Dawley rats was used for in vivo analysis. The odontoblast arrangement pattern and the expression of Cx43 and dentin sialophosphoprotein (DSPP) were assessed. To investigate the function of Cx43 in odontoblastic differentiation, we overexpressed or inhibited Cx43. The results indicated that polarized odontoblasts were arranged along the pulp-dentin interface and had high levels of Cx43 expression in the healthy teeth; however, the odontoblast arrangement pattern was slightly changed concomitant to an increase in the Cx43 expression in the carious teeth. Regularly arranged odontoblast-like cells had high levels of the Cx43 expression during the formation of mature dentin, but the odontoblast-like cells were not regularly arranged beneath immature osteodentin in the pulp injury models. Subsequent in vitro experiments demonstrated that Cx43 is upregulated during odontoblastic differentiation of the dental pulp cells, and inhibition or overexpression of Cx43 influence the odontoblastic differentiation. Thus, Cx43 may be involved in the maintenance of odontoblast arrangement patterns, and influence the pulp repair outcomes by the regulation of odontoblastic differentiation.

High glucose affects proliferation, reactive oxygen species and mineralization of human dental pulp cells

Abstract Diabetes is a group of metabolic disorders that can lead to damage and dysfunction of many organs including the dental pulp. Increased inflammatory response, reduction of dentin formation and impaired healing were reported in diabetic dental pulp. Hyperglycemia, which is a main characteristic of diabetes, was suggested to play a role in many diabetic complications. Therefore our aim was to investigate the effects of high glucose levels on proliferation, reactive oxygen species (ROS) production and odontogenic differentiation of human dental pulp cells (HDPCs). HDPCs were cultured under low glucose (5.5mM Glucose), high glucose (25 mM Glucose) and mannitol (iso-osmolar control) conditions. Cell proliferation was analyzed by MTT assay for 11 days. Glutathione and DCFH-DA assay were used to assess ROS and antioxidant levels after 24 h of glucose exposure. Odontogenic differentiation was evaluated and quantified by alizarin red staining on day 21. Expression of mineralization-associated genes, which were alkaline phosphatase, dentin sialophosphoprotein and osteonectin, was determined by RT-qPCR on day 14. The results showed that high glucose concentration decreased proliferation of HDPCs. Odontogenic differentiation, both by gene expression and mineral matrix deposit, was inhibited by high glucose condition. In addition, high DCF levels and low reduced glutathione levels were observed in high glucose condition. However, no differences were observed between mannitol and low glucose conditions. In conclusion, the results clearly showed the negative effect of high glucose condition on HDPCs proliferation and differentiation. Moreover, it also induced ROS production of HDPCs.

Resumo O diabetes abrange um grupo de distúrbios metabólicos que podem levar a danos e disfunções de muitos órgãos, incluindo a polpa dentária. Aumento da resposta inflamatória, redução da formação de dentina e comprometimento da cicatrização foram relatados na polpa dentária diabética. A hiperglicemia, que é uma característica determinante do diabetes, desempenha um papel importante em muitas complicações diabéticas. Portanto, nosso objetivo foi investigar os efeitos dos altos níveis de glicose na proliferação, produção de espécies reativas de oxigênio (ROS, em inglês) e diferenciação odontogênica das células da polpa dental humana (HDPCs, em inglês). As HDPCs foram cultivadas em condições de baixa glicose (glicose 5,5 mM), alta glicose (glicose 25 mM) e manitol (controle iso-osmolar). A proliferação celular foi analisada pelo ensaio MTT por 11 dias. Glutationa e DCFH-DA foram utilizados para avaliar os níveis de ROS e antioxidantes após 24 h de exposição à glicose. A diferenciação odontogênica foi avaliada e quantificada pela coloração com vermelho de alizarina no dia 21. A expressão de genes associados à mineralização, que eram fosfatase alcalina, sialofosfoproteína de dentina e osteonectina, foi determinada por RT-qPCR no dia 14. Os resultados mostraram que a alta concentração de glicose diminuiu a proliferação de HDPCs. A diferenciação odontogênica, tanto pela expressão gênica quanto pelo depósito da matriz mineral, foi inibida pela condição de alta glicose. Além disso, altos níveis de DCF e níveis reduzidos de glutationa foram observados na condição de alta glicose. No entanto, não foram observadas diferenças entre o manitol e as condições de baixa glicose. Em conclusão, os resultados mostraram claramente o efeito negativo da condição de alta glicose na proliferação e diferenciação de HDPCs. Além disso, essa condição também induziu a produção de ROS em HDPCs.

Role of autophagy in lipopolysaccharide-induced apoptosis of odontoblasts / 南方医科大学学报

OBJECTIVE@#To investigate the role of autophagy in lipopolysaccharide (LPS)-induced apoptosis of murine odontoblasts.@*METHODS@#Murine odontoblasts (mDPC-23 cells) were treated with 5 μg/mL LPS for 6, 12 and 24 h, and the changes in cell viability was examined using CCK8 kit and cell apoptosis was detected by TUNEL staining. The changes in the protein levels of LC3, Beclin1, Atg5, AKT, p-AKT, mTOR and p-mTOR were detected using Western blotting. The effect of 3-MA treatment for 24 h on LPS-induced apoptosis of mDPC-23 cells was evaluated by detecting the expressions of apoptosis-related proteins caspase-3 and Bax using Western blotting.@*RESULTS@#Stimulation with LPS for 6 and 12 h did not cause significant changes in the proliferation or apoptosis of mDPC-23 cells, but LPS treatment for 24 h significantly suppressed cell proliferation (@*CONCLUSIONS@#LPS stimulation induces autophagy to promote apoptosis of mDPC-23 cells, and suppression of autophagy attenuates LPS-induced apoptosis. Autophagy may play an important role in the injury of inflamed pulp tissues.

Effects of the injectable glycol-chitosan based hydrogel on the proliferation and differentiation of human dental pulp cells / 北京大学学报(医学版)

OBJECTIVE@#To prepare glycol-chitosan (GC)-based single/dual-network hydrogels with different composition ratios (GC31, DN3131 and DN6262) and to investigate the effects of hydrogel scaffolds on biological behavior of human dental pulp cell (hDPC) encapsulated.@*METHODS@#GC-based single-network hydrogels (GC31) and GC-based dual-network hydrogels (DN3131, DN6262) with different composition ratios were prepared. The injectability was defined as the average time needed to expel a certain volume of hydrogel under a constant force. The degradation of the hydrogel was determined by the weight loss with time. The fracture stress was measured using a universal testing machine. The proliferation of hDPCs in hydrogels was detected using the cell counting kit-8 (CCK-8) method and CalceinAM/PI Live/Dead assay. After 14 days of odontoblastic induction, the expression of alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1) was detected by real-time quantitative reverse transcription PCR (real-time RT-PCR) and the mineralized nodules was observed by Von Kossa staining.@*RESULTS@#The injectability of all three groups of hydrogels was acceptable. The time of injection of GC31 was the shortest, and that of DN6262 was longer than DN3131 (P<0.05). The degradation rate of GC31 hydrogel in vitro was significantly faster than that of the dual-network hydrogel groups (P<0.05). There was no significant difference between DN3131 and DN6262 (P>0.05). The compressive resistance failure point of GC31 group was 1.10 kPa, while it was 7.33 kPa and 43.30 kPa for DN3131 and DN6262. The compressive strength of dual-network hydrogel was significantly enhanced compared with single-network hydrogel. hDPCs were in continuous proliferation in all the three groups, and the GC31 group showed a higher proliferation rate (P<0.05). The expression levels of DSPP, DMP-1 and ALP in the dual-network hydrogel groups (DN3131, DN6262) were significantly higher than that of GC31 after culturing for 14 days (P<0.05), there was no difference in the expression levels of DMP-1 and ALP between DN3131 and DN6262 (P>0.05); Von Kossa staining showed that more mineralization deposition and mass-shaped mineralized nodules formed in DN3131 and DN6262, while only light brown calcium deposition staining was observed in GC31 group, which was scattered in granular forms.@*CONCLUSION@#GC-based single/dual network hydrogels with different composition ratios met the injectable requirements. GC31 group had a lower mechanical properties, in which hDPCs exhibited a higher proliferation rate. dual-network hydrogels had slower degradation rate and higher mechanical properties, in which hDPCs exhibited better odontoblastic differentiation potential and mineralization potential.

Evaluation of dentinogenesis inducer biomaterials: an in vivo study

Abstract When exposure of the pulp to external environment occurs, reparative dentinogenesis can be induced by direct pulp capping to maintain pulp tissue vitality and function. These clinical situations require the use of materials that induce dentin repair and, subsequently, formation of a mineralized tissue. Objective: This work aims to assess the effect of tricalcium silicate cements and mineral trioxide aggregate cements, including repairing dentin formation and inflammatory reactions over time after pulp exposure in Wistar rats. Methodology: These two biomaterials were compared with positive control groups (open cavity with pulp tissue exposure) and negative control groups (no intervention). The evaluations were performed in three stages; three, seven and twenty-one days, and consisted of an imaging (nuclear medicine) and histological evaluation (H&E staining, immunohistochemistry and Alizarin Red S). Results: The therapeutic effect of these biomaterials was confirmed. Nuclear medicine evaluation demonstrated that the uptake of 99mTc-Hydroxymethylene diphosphonate (HMDP) showed no significant differences between the different experimental groups and the control, revealing the non-occurrence of differences in the phosphocalcium metabolism. The histological study demonstrated that in mineral trioxide aggregate therapies, the presence of moderate inflammatory infiltration was found after three days, decreasing during follow-ups. The formation of mineralized tissue was only verified at 21 days of follow-up. The tricalcium silicate therapies demonstrated the presence of a slight inflammatory infiltration on the third day, increasing throughout the follow-up. The formation of mineralized tissue was observed in the seventh follow-up day, increasing over time. Conclusions: The mineral trioxide aggregate (WhiteProRoot®MTA) and tricalcium silicate (Biodentine™) present slight and reversible inflammatory signs in the pulp tissue, with the formation of mineralized tissue. However, the exacerbated induction of mineralized tissue formation with the tricalcium silicate biomaterial may lead to the formation of pulp calcifications

Impact of calcium aluminate cement with additives on dental pulp-derived cells

Abstract Calcium aluminate cement (CAC) has been highlighted as a promising alternative for endodontic use aiming at periapical tissue repair. However, its effects on dental pulp cells have been poorly explored. Objective: This study assessed the impact of calcium chloride (CaCl2) and bismuth oxide (Bi2O3) or zinc oxide (ZnO) additives on odontoblast cell response to CAC. Methodology: MDPC-23 cells were exposed for up to 14 d: 1) CAC with 2.8% CaCl2 and 25% ZnO (CACz); 2) CAC with 2.8% CaCl2 and 25% Bi2O3 (CACb); 3) CAC with 10% CaCl2 and 25% Bi2O3 (CACb+); or 4) mineral trioxide aggregate (MTA), placed on inserts. Non-exposed cultures served as control. Cell morphology, cell viability, gene expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), and dentin matrix protein 1 (DMP-1), ALP activity, and extracellular matrix mineralization were evaluated. Data were compared using ANOVA (α=5%). Results: Lower cell density was detected only for MTA and CACb+ compared with Control, with areas showing reduced cell spreading. Cell viability was similar among groups at days one and three (p>0.05). CACb+ and MTA showed the lowest cell viability values at day seven (p>0.05). CACb and CACb+ promoted higher ALP and BSP expression compared with CACz (p<0.05); despite that, all cements supported ALP activity. Matrix mineralization were enhanced in CACb+ and MTA. Conclusion: In conclusion, CAC with Bi2O3, but not with ZnO, supported the expression of odontoblastic phenotype, but only the composition with 10% CaCl2 promoted mineralized matrix formation, rendering it suitable for dentin-pulp complex repair.

Bone morphogenetic proteins 2, 6, and 9 differentially regulate the osteogenic differentiation of immortalized preodontoblasts

Our study attempted to compare the efficacies of bone morphogenetic protein (BMP) 2, 6, and 9 in inducing osteogenic differentiation of preodontoblasts (PDBs). We immortalized PDBs by introducing a reversible SV40 T antigen-based immortalization system. Cell proliferation capability was examined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. The effects of BMP2, 6, and 9 on the osteogenic differentiation of immortalized preodontoblasts (iPDBs) were measured by alkaline phosphatase (ALP) activity assays and alizarin red S staining. The expression of osteogenic markers was evaluated by semiquantitative real-time polymerase chain reaction analysis. To assess ectopic bone formation, rat-derived iPDBs were transfected in culture with adenoviral vectors designated Ad-BMP2, 6, and 9 and subcutaneously or intramuscularly injected into mice. Several BMPs retained endogenous expression in PDBs and regulated the mRNA expression of mineralized tissue-associated proteins. ALP activity and mineralized nodule formation were significantly increased in the Ad-BMP9-transfected group relative to the control group. In addition, the most significant hard tissue formation was in this group. The results indicated that BMP signaling was involved in the osteogenic differentiation of iPDBs. BMP9 could be an efficacious accelerant of the osteogenic differentiation of iPDBs.

Effects of scaffold microstructure and mechanical properties on regeneration of tubular dentin / 华西口腔医学杂志

Tubular dentin is of great significance in the process of tooth tissue and tooth regeneration, because it is not only the structural feature of primary dentin, but also can affect the tooth sensory function, affect the differentiation of dental pulp cells and provide strong mechanical support for teeth. Scaffold is one of the three elements of tissue engineering dentin regeneration. Most experiments on dentin regeneration involve the study of the microstructure and mechanical properties of the scaffold. The microstructure and mechanical characteristics of scaffold materials have important effects on the differentiation and adhesion of odontoblast, it can directly affect the tissue structure of regenerated dentin.

Comparison of odontoblast differentiation capacity between stem cells from human exfoliated deciduous teeth and dental pulp stem cells / 中南大学学报(医学版)

OBJECTIVES@#To explore the difference in odontoblast differentiation capacity between stem cells from human exfoliated deciduous teeth (SHED) and dental pulp stem cells (DPSCs), and to examine the expression level of ephrinB1 in odontoblast differentiation of these stem cells.@*METHODS@#The stems cells were divided into a SHED group and a DPSCs group. After odontoblast differentiation induction, the above 2 groups were also randomly divided into a 3 d group and a 7 d group, respectively.The calcium deposition was detected by alkaline phosphatase (ALP) staining and alizarin red staining.The mRNA and protein expressions of ephrinB1, dentin matrix protein-1 (DMP-1) and dentin sialophosphoprotein (DSPP) were detected by real-time PCR and Western blotting.@*RESULTS@#ALP staining and alizarin red staining showed that there was stronger mineralization capacity in the SHED group than that in the DPSCs group. The relative mRNA and protein expressions of DMP-1, DSPP, and ephrinB1 in the SHED group were higher than those in the DPSCs group except for the protein expression of DMP-1 in the SHED 3 d group (all <0.05).@*CONCLUSIONS@#SHED has stronger odontoblast differentiation capacity than DPSCs. In addition, ephrinB1 may be involved in the processes of odontoblast differentiation in the SHED and DPSCs.

Histometry Analysis of Osteoclasts, Osteoblasts and Fibroblasts in Immediate Placement Implants with Addition of Aloe Vera Extract

Objective: To analyze the effect of immediate placement of implants with extract from the new bone formation histometically. Material and Methods: In this true-experimental design with randomized post test control group, 9 mongrel dogs weighing 10 to 12 kg were used, which were divided into 3 groups, based on observation time of 14 days, 28 days and 56 days. On the installation of implants (∅3.5x10 mm) sequentially, the former socket extraction of the lower jaw's right second premolar tooth in the study sample injected 10% Aloe vera gel extract and left second left premolar tooth without injection of 10% Aloe vera extract. To compare independent groups use the Mann-Whitney test. All analysis were carried out using SPSS version 20. Results: There was an increase in the number of osteoblast cells in both treatment and control groups, but the value of the treatment group was greater. There were significant differences in the number of osteoblast cells between the treatment and control groups 14 days (p=0.019), 28 days: (p=0.018), and 56 days (p=0.009). There were no significant differences in the number of fibroblast cells between the treatment and control groups (p>0.05). But at observations 28 and 56 days, it was showed a significant difference in the number of fibroblast cells between the treatment and control groups (p=0.353 and p=0.024, respectively). Conclusion: Immediate placement of implants with 10% Aloe vera extract gel on extracted socket increases the number of osteoblasts and suppresses the number of osteoclasts and fibroblasts.

Effects of electrospun collagen nanofibrous matrix on the biological behavior of human dental pulp cells / 北京大学学报(医学版)

OBJECTIVE@#To compare cell adhesion, proliferation and odontoblastic differentiation of human dental pulp cells (hDPCs) on electrospun collagen nanofibrous matrix (Col_NFM) with that on collagen flat film (Col-FF), to investigate the biological effect of collagen nanofibrous matrix on hDPCs.@*METHODS@#The surface morphology of the two different collagen scaffold was analyzed by scanning electron microscopy (SEM), and the contact angle and the swelling ratio were also measured. Then hDPCs were implanted on the two different collagen scaffolds, the cell morphology was observed using SEM and laser scanning microscope (LSM), and cell proliferation was evaluated by the CCK-8 assay. After hDPCs cultured on the two different collagen scaffold with odontoblastic medium for 14 days, the expression of odontoblastic differentiation related genes was detected by real-time PCR, and alizarin red staining was used to test the formation of mineralized nodules.@*RESULTS@#From the SEM figures, the fibers' diameter of Col_NFM was (884±159) nm, and there were abundant three dimensional connected pore structures between the fibers of Col_NFM, while the surface of Col_FF was completely flat without pore structure. The contact angle at 0 s of Col_NFM was 85.03°±4.45°, and that of Col_FF was 98.98°±5.81°. The swelling ratio of Col_NFM was approximately 3 folds compared with dry weight sample, while that of Col_FF was just 1 fold. Thus Col_NFM indicated better hydrophilicity and swelling property. SEM and LSM showed that hDPCs on Col_NFM presented an irregular and highly branched phenotype, and could penetrate into the nanofibrous scaffold. In contrast, the cells were spread only on the surface of Col_FF with a spindle-shaped morphology. CCK-8 assays showed that hDPCs on Col_NFM showed higher proliferation rate than on Col_FF. After hDPCs were cultured on the two different collagen scaffolds with odontoblastic medium for 14 days, more expressions of odontoblastic differentiation related genes, such as dentin sialophosphoprotein (DSPP) and dentin matrix proten-1 (DMP1) were determined in Col_NFM group (P<0.05), and more mineralization depositions were also observed in Col_NFM group according to the results of alizarin red staining.@*CONCLUSION@#Col_NFM with nanoscale microstructure achieves better hydrophilic and swelling properties than Col_FF, and hDPCs cultured with Col_NFM present higher activity on cell adhesion, proliferation and odontoblastic differentiation.

Spatio-temporal expression of dentin sialophosphoprotein and collagen Ⅰ during molar tooth germ development in vps4b knockout mouse / 华西口腔医学杂志

OBJECTIVE@#To verify the effect of the mutant gene vps4b on the expression of tooth development-related proteins, dentin sialophosphoprotein (DSPP) and collagenⅠ (COL-Ⅰ).@*METHODS@#Paraffin tissue sections of the first molar tooth germ were obtained from the heads of fetal mice at the embryonic stages of 13.5, 14.5, and 16.5 days and from the mandibles of larvae aged 2.5 and 7 days after birth. The immunohistochemical method was used to detect the expression and location of DSPP and COL-Ⅰ in wild-type mouse and vps4b knockout mouse.@*RESULTS@#DSPP and COL-Ⅰ were not found in the bud and cap stages of wild-type mouse molar germ. In the bell stage, DSPP was positively expressed in the inner enamel epithelium and dental papilla, whereas COL-Ⅰ was strongly expressed in the dental papilla and dental follicle. During the secretory and mineralized periods, DSPP and COL-Ⅰ were intensely observed in ameloblasts, odontoblasts, and dental follicles, but COL-Ⅰ was also expressed in the dental papilla. After vps4b gene knockout, DSPP was not expressed in the dental papilla of the bell stage and in the dental papilla and dental follicle of the secretory phase. The expression position of COL-Ⅰ in the bell and mineralization phase was consistent with that in the wild-type mice. Moreover, the expression of COL-Ⅰ in the dental papilla changed in the secretory stage.@*CONCLUSIONS@#Gene vps4b plays a significant role in the development of tooth germ. The expression of DSPP and COL-Ⅰ may be controlled by gene vps4b and regulates the development of tooth dentin and cementum together with vps4b.

Polarity of ameloblasts and odontoblasts and their related regulators / 华西口腔医学杂志

The polarity of ameloblasts and odontoblasts is crucial for their differentiation and function. Polarity-related molecules play an important role in this process. This review summarizes the process of polarity formation of ameloblasts and odontoblasts and their related regulators.

Regeneration of Neural Networks in Immature Teeth with Non-Vital Pulp Following a Novel Regenerative Procedure

BACKGROUND AND OBJECTIVES: Recombinant amelogenin protein (RAP) was reported to induce soft-tissue regeneration in canine infected endodontically treated permanent teeth with open apices. To characterize identities of the cells found in the RAP regenerated tissues compared to authentic pulp by identifying: 1) stem cells by their expression of Sox2; 2) nerve fibers by distribution of the axonal marker peripherin; 3) axons by their expression of calcitonin gene–related peptide (CGRP); 4) the presence of astrocytes expressing glial fibrillary acidic proteins (GFAP).METHODS: A total of 240 open-apex root canals in dogs were used. After establishment of oral contamination to the pulp, the canals were cleaned, irrigated, and 120 canals filled with RAP, and the other 120 with calcium hydroxide.RESULTS: After 1, 3, and 6 months, teeth were recovered for immune-detection of protein markers associated with native pulp tissues. Regenerated pulp and apical papilla of RAP group revealed an abundance of stem cells showing intense immunoreactivity to Sox2 antibody, immunoreactivity of peripherin mainly in the A-fibers of the odontoblast layer and immunoreactivity to CGRP fibers in the central pulp region indicative of C-fibres. GFAP immunoreactivity was observed near the odontoblastic, cell-rich regions and throughout the regenerated pulp.CONCLUSIONS: RAP induces pulp regeneration following regenerative endodontic procedures with cells identity by gene expression demonstrating a distribution pattern similar to the authentic pulp innervation. A- and C-fibers, as well as GFAP specific to astrocytic differentiation, are recognized. The origin of the regenerated neural networks may be derived from the Sox2 identified stem cells within the apical papilla.

Effects of MTA and Brazilian propolis on the biological properties of dental pulp cells

Abstract: The aim of this study was to evaluate the effect of mineral trioxide aggregate (MTA) and Brazilian propolis on the cell viability, mineralization, anti-inflammatory ability, and migration of human dental pulp cells (hDPCs). The cell viability was evaluated with CCK-8 kit after 1, 5, 7, and 9 days. The deposition of calcified matrix and the expression of osteogenesis-related genes were evaluated by Alizarin Red staining and real-time PCR after incubation in osteogenic medium for 21 days. The expression of inflammation-related genes in cells was determined after exposure to 1 μg/mL LPS for 3 h. Finally, the numbers of cells that migrated through the permeable membranes were compared during 15 h. Propolis and MTA significantly increased the viability of hDPCscompared to the control group on days 7 and 9. In the propolis group, significant enhancement of osteogenic potential and suppressed expression of IL-1β and IL-6 was observed after LPS exposure compared to the MTA and control groups. The number of migration cells in the propolis group was similar to that of the control group, while MTA significantly promoted cell migration. Propolis showed comparable cell viability to that of MTA and exhibited significantly higher anti-inflammatory and mineralization promotion effects on hDPCs.

Increased whitening efficacy and reduced cytotoxicity are achieved by the chemical activation of a highly concentrated hydrogen peroxide bleaching gel

Abstract Objective This study was designed for the chemical activation of a 35% hydrogen peroxide (H2O2) bleaching gel to increase its whitening effectiveness and reduce its toxicity. Methodology First, the bleaching gel - associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT) - was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H2DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05). Results All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness. Conclusion Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.

Fisiopatología de los odontoblastos: una revisión / Odontoblast pathophysiology: a review

Los odontoblastos son células posmitóticas de origen mesenquimal dispuestas en forma de palizada en la periferia de la pulpa dental y responsables de la formación de la dentina. Los odontoblastos derivan de la cresta neural,y su diferenciación es la consecuencia de las interacciones epitelio-mesénquima entre las células de la papila dental y el epitelio dental interno. Este trabajo tiene como objetivo revisar los aspectos fisiológicos y patológicos de los odontoblastos, comprendiendo su origen, mecanismos de diferenciación y propiedades funcionales. Se realizó una búsqueda electrónica de literatura desde el año 2000 hasta febrero de 2018y seseleccionaron 2.889 artículos, de los cuales 52 fueron analizados y discutidos. Los resultados exponen el origen, las etapas y los factores relacionados con la diferenciación odontoblástica, junto con los aspectos principales de la organización estructural y las funciones que desempeñan los odontoblastos. Esta revisión demuestra mediante la evidencia científica actual cómo los estudios concernientes a los odontoblastos se focalizan en comprender los mecanismos en la formación de la dentina reparativa, la respuesta inmunitaria y su rol en los procesos de inflamación y dolor. Trabajos futuros deberán esclarecer las diferentes señales involucradas en los procesos fisiopatológicos celulares y moleculares llevados a cabo por los odontoblastos.

The odontoblasts are post-mitotic cells of mesenchymal origin arranged in the form of a palisade in the periphery of the dental pulp and responsible for the formation of the dentin. The odontoblasts are derived from the neural crest and their differentiation is the consequence of epithelial-mesenchymal interactions between the cells of the dental papilla and the internal dental epithelium. This work aims to review the physiological and pathological aspects of odontoblasts, including their origin, mechanismsof differentiation and functional properties. An electronic literature search was conducted from 2000 to February 2018, selecting 2889articles, of which 52 articles were analyzed and discussed. The results show the origin, stages and factors related to odontoblastic differentiation, together with the main aspects of the structural organization and functions performed by odontoblasts. This review demonstrates through current scientific evidence that the studies concerning odontoblasts focus on understanding the mechanisms in the formation of reparative dentin, the immune response and its role in the processes of inflammation and pain. Future work should clarify the different signals involved in the cellular and molecular pathophysiological processes carriedout by the odontoblasts.