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International Journal of Molecular... May 2024It is remarkable how teeth maintain their healthy condition under exceptionally high levels of mechanical loading. This suggests the presence of inherent mechanical... (Review)
Review
It is remarkable how teeth maintain their healthy condition under exceptionally high levels of mechanical loading. This suggests the presence of inherent mechanical adaptation mechanisms within their structure to counter constant stress. Dentin, situated between enamel and pulp, plays a crucial role in mechanically supporting tooth function. Its intermediate stiffness and viscoelastic properties, attributed to its mineralized, nanofibrous extracellular matrix, provide flexibility, strength, and rigidity, enabling it to withstand mechanical loading without fracturing. Moreover, dentin's unique architectural features, such as odontoblast processes within dentinal tubules and spatial compartmentalization between odontoblasts in dentin and sensory neurons in pulp, contribute to a distinctive sensory perception of external stimuli while acting as a defensive barrier for the dentin-pulp complex. Since dentin's architecture governs its functions in nociception and repair in response to mechanical stimuli, understanding dentin mechanobiology is crucial for developing treatments for pain management in dentin-associated diseases and dentin-pulp regeneration. This review discusses how dentin's physical features regulate mechano-sensing, focusing on mechano-sensitive ion channels. Additionally, we explore advanced in vitro platforms that mimic dentin's physical features, providing deeper insights into fundamental mechanobiological phenomena and laying the groundwork for effective mechano-therapeutic strategies for dentinal diseases.
Topics: Dentin; Humans; Animals; Odontoblasts; Mechanotransduction, Cellular; Biomechanical Phenomena; Dental Pulp; Extracellular Matrix
PubMed: 38891829
DOI: 10.3390/ijms25115642 -
Journal of Dental Research Nov 2015Members of the fibroblast growth factor (FGF) family play essential and important roles in primary and reparative dentinogenesis. Although there appears to be a general...
Members of the fibroblast growth factor (FGF) family play essential and important roles in primary and reparative dentinogenesis. Although there appears to be a general agreement on the effects of FGF signaling on the proliferation of pulp cells, there are conflicting results regarding its effects on odontoblast differentiation. We recently examined the effects of continuous exposure of dental pulp cells to FGF2 and showed that the effects of FGF2 on differentiation of progenitor cells into odontoblasts were stage specific and dependent on the stage of cell maturity. The purpose of this study was to gain further insight into cellular and molecular mechanisms regulating the stimulatory effects of FGF2 on odontoblast differentiation. To do so, we examined the effects of early and limited exposure of pulp cells from a series of green fluorescent protein (GFP) reporter transgenic mice that display stage-specific activation of transgenes during odontoblast differentiation to FGF2. Our results showed that early and limited exposure of pulp cells to FGF2 did not have significant effects on the extent of mineralization but induced significant increases in the expression of Dmp1 and Dspp and the number of DMP1-GFP(+) and DSPP-Cerulean(+) odontoblasts. Our results also showed that the stimulatory effects of FGF2 on odontoblast differentiation were mediated through FGFR/MEK/Erk1/2 signaling, increases in Bmp2, and activation of the BMP/BMPR signaling pathway. These observations show that early and limited exposure of pulp cells to FGF2 alone promotes odontoblast differentiation and provides critical insight for applications of FGF2 in dentin regeneration.
Topics: Animals; Butadienes; Cell Cycle; Dental Pulp; Dentinogenesis; Fibroblast Growth Factor 2; Mice; Mice, Transgenic; Nitriles; Pyrroles; Signal Transduction; Stem Cells
PubMed: 26276371
DOI: 10.1177/0022034515599768 -
Cell Death Discovery Dec 2021Alleviating odontoblast inflammation is crucial to control the progression of pulpitis. Mitochondrial DNA (mtDNA) is a vital driver of inflammation when it leaks from...
Alleviating odontoblast inflammation is crucial to control the progression of pulpitis. Mitochondrial DNA (mtDNA) is a vital driver of inflammation when it leaks from mitochondria of inflamed odontoblasts into the cytosol. Bacteria-induced inflammation leads to a novel type of cell death named pyroptosis. The canonical pyroptosis is a gasdermin (GSDM)-dependent cytolytic programmed cell death characterized by cell swelling and pore formation in the plasma membrane. To date, whether odontoblast cytosolic mtDNA regulates dental pulp inflammation through the canonical pyroptosis pathway remains to be elucidated. In this study, high gasdermin D (GSDMD) expression was detected in human pulpitis. We found that LPS stimulation of mDPC6T cells promoted BAX translocation from the cytosol to the mitochondrial membrane, leading to mtDNA release. Moreover, overexpression of isolated mtDNA induced death in a large number of mDPC6T cells, which had the typical appearance of pyroptotic cells. Secretion of the inflammatory cytokines CXCL10 and IFN-β was also induced by mtDNA. These results suggest that cytosolic mtDNA participates in the regulation of odontoblast inflammation through GSDMD-mediated pyroptosis in vitro. Interestingly, after overexpression of mtDNA, the expression of inflammatory cytokines CXCL10 and IFN-β was increased and not decreased in GSDMD knockdown mDPC6T cells. We further proposed a novel model in which STING-dependent inflammation in odontoblast-like cell is a compensatory mechanism to control GSDMD-mediated pyroptosis, jointly promoting the immune inflammatory response of odontoblasts. Collectively, these findings provide the first demonstration of the role of the mtDNA-GSDMD-STING in controlling odontoblast inflammation and a detailed description of the underlying interconnected relationship.
PubMed: 34887391
DOI: 10.1038/s41420-021-00770-z -
Biochemical and Biophysical Research... Dec 2021Tooth development involves the coordinated transcriptional regulation of extracellular matrix proteins produced by ameloblasts and odontoblasts. In this study,...
Tooth development involves the coordinated transcriptional regulation of extracellular matrix proteins produced by ameloblasts and odontoblasts. In this study, whole-genome ChIP-seq analysis was applied to identify the transcriptional regulatory gene targets of Sp6 in mesenchymal cells of the developing tooth. Bioinformatic analysis of a pool of Sp6 target peaks identified the consensus nine nucleotide binding DNA motif CTg/aTAATTA. Consistent with these findings, a number of enamel and dentin matrix genes including amelogenin (Amelx), ameloblastin (Ambn), enamelin (Enam) and dental sialophosphoprotein (Dspp), were identified to contain Sp6 target sequences. Sp6 peaks were also found in other important tooth genes including transcription factors (Dlx2, Dlx3, Dlx4, Dlx5, Sp6, Sp7, Pitx2, and Msx2) and extracellular matrix-related proteins (Col1a2, Col11a2, Halpn1). Unsupervised UMAP clustering of tooth single cell RNA-seq data confirmed the presence of Sp6 transcripts co-expressed with many of the identified target genes within ameloblasts and odontoblasts. Lastly, transcriptional reporter assays using promoter fragments from the Hapln1 and Sp6 gene itself revealed that Sp6 co-expression enhanced gene transcriptional activity. Taken together these results highlight that Sp6 is a major regulator of multiple extracellular matrix genes in the developing tooth.
Topics: Ameloblasts; Amelogenin; Animals; Animals, Newborn; Collagen Type I; Dental Enamel Proteins; Extracellular Matrix Proteins; Gene Expression Regulation, Developmental; Gene Regulatory Networks; Kruppel-Like Transcription Factors; Mice; Mice, Inbred C57BL; Molar; Odontoblasts; Odontogenesis; Promoter Regions, Genetic; Proteoglycans; RNA, Messenger; Sequence Analysis, RNA; Signal Transduction; Single-Cell Analysis; Sp7 Transcription Factor
PubMed: 34662808
DOI: 10.1016/j.bbrc.2021.10.017 -
Journal of Dentistry Apr 2022This study aims to review systematically the dental pulp response to silver diamine fluoride (SDF) treatment, including the inflammatory response, pulp cells activity,... (Review)
Review
OBJECTIVE
This study aims to review systematically the dental pulp response to silver diamine fluoride (SDF) treatment, including the inflammatory response, pulp cells activity, dentinogenesis, silver penetration, and the presence of the bacteria in the dental pulp.
DATA
In vitro studies, animal studies, clinical studies, and case reports on the use of SDF on vital dental pulp were included. Quality assessment of the included studies was conducted. A narrative synthesis of the collected data was performed.
SOURCES
A systematic search was performed in ProQuest, PubMed, SCOPUS, and Web of Science databases for articles published from inception to Nov 1, 2021.
STUDY SELECTION
The initial search identified 1,433 publications, of which five publications met the inclusion criteria. These five publications reported the effect of direct/ indirect SDF application on the vital pulp of a total of 30 teeth. Direct SDF application on vital pulp caused pulp necrosis. Indirect SDF application caused none or mild inflammatory response of dental pulp. The odontoblasts in the dental pulp showed increased cellular activity. Tertiary dentine was formed in the pulpal side of the cavity with indirect SDF application. Accentuated incremental lines of tertiary dentine reflected disturbances in mineralisation. Silver ions were found to penetrate along the dentinal tubules but were not detected inside the pulp.
CONCLUSION
According to the limited available literature, direct SDF application causes pulp necrosis. Indirect SDF application is generally biocompatible to dental pulp tissue with a mild inflammatory response, increased odontoblastic activity, and increased tertiary dentine formation. Future studies with precise quantitative and qualitative tests, larger sample size and longer follow-up time are imperative to understand the biological activity of dental pulp to SDF treatment.
Topics: Animals; Dental Caries; Dental Pulp; Dental Pulp Necrosis; Dentin, Secondary; Fluorides, Topical; Quaternary Ammonium Compounds; Silver Compounds
PubMed: 35139409
DOI: 10.1016/j.jdent.2022.104066 -
Biochemistry and Biophysics Reports Dec 2016Amelogenin (AMELX) is the main component of the developing tooth enamel matrix and is essential for enamel thickness and structure. However, little is known about its...
Amelogenin (AMELX) is the main component of the developing tooth enamel matrix and is essential for enamel thickness and structure. However, little is known about its transcriptional regulation. Using gene expression analysis, we found that MIZ-1, a potent transcriptional activator of , is expressed during odontoblastic differentiation of hDPSCs (human dental pulp stem cells), and is essential for odontoblast differentiation and mineralization. We also investigated how MIZ-1 regulates gene expression of . Oligonucleotide-pull down assays showed that MIZ-1 binds to an MRE (MIZ-1 binding element) of the proximal promoter region (bp, -170 to -25). Combined, our ChIP, transient transcription assays, and promoter mutagenesis revealed that MIZ-1 directly binds to the MRE of the promoter recruits p300 and induces gene transcription. Finally, we show that the zinc finger protein MIZ-1 is an essential transcriptional activator of , which is critical in odontogenesis and matrix mineralization in the developing tooth.
PubMed: 28955974
DOI: 10.1016/j.bbrep.2016.10.007 -
Modulators of Wnt Signaling Pathway Implied in Dentin Pulp Complex Engineering: A Literature Review.International Journal of Molecular... Sep 2022The main goal of vital pulp therapy (VPT) is to preserve the vitality of the pulp tissue, even when it is exposed due to bacterial invasion, iatrogenic mechanical... (Review)
Review
The main goal of vital pulp therapy (VPT) is to preserve the vitality of the pulp tissue, even when it is exposed due to bacterial invasion, iatrogenic mechanical preparation, or trauma. The type of new dentin formed as a result of VPT can differ in its cellular origin, its microstructure, and its barrier function. It is generally agreed that the new dentin produced by odontoblasts (reactionary dentin) has a tubular structure, while the dentin produced by pulp cells (reparative dentin) does not or has less. Thus, even VPT aims to maintain the vitality of the pulp. It does not regenerate the dentin pulp complex integrity. Therefore, many studies have sought to identify new therapeutic strategies to successfully regenerate the dentin pulp complex. Among them is a Wnt protein-based strategy based on the fact that Wnt proteins seem to be powerful stem cell factors that allow control of the self-renewal and proliferation of multiple adult stem cell populations, suitable for homeostasis maintenance, tissue healing, and regeneration promotion. Thus, this review outlines the different agents targeting the Wnt signaling that could be applied in a tooth environment, and could be a potential therapy for dentin pulp complex and bone regeneration.
Topics: Adult; Dental Pulp; Dentin; Humans; Odontoblasts; Stem Cells; Wnt Proteins; Wnt Signaling Pathway
PubMed: 36142496
DOI: 10.3390/ijms231810582 -
The International Journal of... 2024Tooth formation is a process tightly regulated by reciprocal interactions between epithelial and mesenchymal tissues. These epithelial-mesenchyme interactions regulate...
Tooth formation is a process tightly regulated by reciprocal interactions between epithelial and mesenchymal tissues. These epithelial-mesenchyme interactions regulate the expression of target genes via transcription factors. Among the regulatory elements governing this process, Epiprofin/Sp6 is a zinc finger transcription factor which is expressed in the embryonic dental epithelium and in differentiating pre-odontoblasts. knockout (-/-) mice present severe dental abnormalities, such as supernumerary teeth and enamel hypoplasia. Here, we describe dentin defects in molars and incisors of -/- mice. We observed that in the absence of Epfn, markers of early odontoblast differentiation, such as alkaline phosphatase activity, expression, and Collagen Type I deposition, are downregulated. In addition, the expression of tight and gap junction proteins was severely impaired in the predontoblastic cell layer of developing -/- molars. Altogether, our data shows that Epfn is crucial for the proper differentiation of dental mesenchymal cells towards functional odontoblasts and subsequent dentin-matrix deposition.
Topics: Mice; Animals; Odontoblasts; Dentin Dysplasia; Cell Differentiation; Odontogenesis; Transcription Factors
PubMed: 38591690
DOI: 10.1387/ijdb.240029lj -
Frontiers in Cell and Developmental... 2020Odontoblast differentiation is an important process during tooth development in which pre-odontoblasts undergo elongation, polarization, and finally become mature...
Odontoblast differentiation is an important process during tooth development in which pre-odontoblasts undergo elongation, polarization, and finally become mature secretory odontoblasts. Many factors have been found to regulate the process, and our previous studies demonstrated that autophagy plays an important role in tooth development and promotes odontoblastic differentiation in an inflammatory environment. However, it remains unclear how autophagy is modulated during odontoblast differentiation. In this study, we found that HDAC6 was involved in odontoblast differentiation. The odontoblastic differentiation capacity of human dental papilla cells was impaired upon HDAC6 inhibition. Moreover, we found that HDAC6 and autophagy exhibited similar expression patterns during odontoblast differentiation both and ; the expression of HDAC6 and the autophagy related proteins ATG5 and LC3 increased as differentiation progressed. Upon knockdown of HDAC6, LC3 puncta were increased in cytoplasm and the autophagy substrate P62 was also increased, suggesting that autophagic flux was affected in human dental papilla cells. Next, we determined the mechanism during odontoblastic differentiation and found that the HDAC6 substrate acetylated-Tubulin was up-regulated when HDAC6 was knocked down, and LAMP2, LC3, and P62 protein levels were increased; however, the levels of ATG5 and Beclin1 showed no obvious change. Autophagosomes accumulated while the number of autolysosomes was decreased as determined by mRFP-GFP-LC3 plasmid labeling. This suggested that the fusion between autophagosomes and lysosomes was blocked, thus affecting the autophagic process during odontoblast differentiation. In conclusion, HDAC6 regulates the fusion of autophagosomes and lysosomes during odontoblast differentiation. When HDAC6 is inhibited, autophagosomes can't fuse with lysosomes, autophagy activity is decreased, and it leads to down-regulation of odontoblastic differentiation capacity. This provides a new perspective on the role of autophagy in odontoblast differentiation.
PubMed: 33330506
DOI: 10.3389/fcell.2020.605609 -
Scientific Reports Jan 2023Ascorbic acid (AA; vitamin C) plays a crucial role in the biosynthesis and secretion of collagen to produce the organic matrix of hard tissues. Nevertheless, the...
Ascorbic acid (AA; vitamin C) plays a crucial role in the biosynthesis and secretion of collagen to produce the organic matrix of hard tissues. Nevertheless, the detailed mechanism by which AA induces reparative dentinogenesis is still unknown. This study aimed to investigate the pathway and function of AA during wound healing in a rat pulpotomy model. Sodium-dependent vitamin C transporter (SVCT) 2 and glucose transporter (GLUT) 1 were detected in odontoblasts, endothelial cells, and nerve fibers in normal pulp tissues. SVCT2 and GLUT1 were also expressed in odontoblast-like cells in pulpotomized tissues of Wistar rats, and immunopositive cells of SVCT2 were significantly increased at 5 days after pulpotomy (p < 0.05). By contrast, osteogenic disorder Shionogi (ODS) rats, which cannot generate AA, also expressed SVCT2 and GLUT1 in normal and wound healing conditions. However, in ODS rats, when compared with the AA-addition group, the formation of dentin bridges in the AA-loss group was not evident, a layer of osteopontin was significantly increased beneath the wound surface (p < 0.05), and alpha smooth muscle actin at the odontoblast-like cells observed along this layer was significantly increased (p < 0.05), but not Nestin. Moreover, the amounts of type 1 collagen generated in the reparative dentin and beneath the wound healing site were significantly diminished (p < 0.05). Macrophages expressing CD68 and CD206 increased beneath the wound site. Hence, AA may be involved in odontoblast-like cell differentiation and anti-inflammatory response during dental pulp wound healing. Our results provide new insights into the function of AA through SVCT2 and GLUT1 in reparative dentinogenesis and may help in developing new therapeutic targets for dental pulpal disease.
Topics: Rats; Animals; Rats, Wistar; Endothelial Cells; Dental Pulp; Glucose Transporter Type 1; Dentin, Secondary; Wound Healing; Odontoblasts; Sodium-Coupled Vitamin C Transporters; Ascorbic Acid
PubMed: 36690706
DOI: 10.1038/s41598-023-28197-9