• Imaging Science in Dentistry
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• v.35 no.1
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• pp.9-14
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• 2005

Purpose : To observe the histopathological changes in the pulp tissues of mandibular molars in streptozotocin-induced diabetic rats after irradiation. Materials and Methods : The male Sprague-Dawley rats weighing approximately 250 gm were divided into four groups: control, diabetes, irradiation, and diabetes-irradiation groups. Diabetes mellitus was induced in the rats by injecting streptozotocin. Rats in control and irradiation groups were injected with citrate buffer only. After 5 days, the head and neck region of the rats in irradiation and diabetes-irradiation groups were irradiated with a single absorbed dose of 10 Gy. All the rats were sacrificed at 3, 7, 14, 21, and 28 days after irradiation. The specimen including the mandibular molars were sectioned and observed using a histopathological method. Results : In the diabetes group, capillary dilatation was observed. However, there was no obvious morphologic alteration of the odontoblasts. In the irradiation group, generalized necrosis of the dental pulp tissues was observed. Vacuolation of the odontoblasts and dilatation of the capillaries were noted in the early experimental phases. In the diabetes-irradiation group, generalized degeneration of the dental pulp tissues was observed. Vacuolation of the dental pulp cells and the odontoblasts was noted in the late experimental phases. Conclusion : This experiment suggests that dilatation of the capillaries in the dental pulp tissues is induced by diabetic state, and generalized degeneration of the dental pulp tissues is induced by irradiation of the diabetic group.

• Natural Product Sciences
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• v.19 no.1
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• pp.54-60
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• 2013

Rhus verniciflua Stokes (Anacadiaceae) is a plant that is native to East Asian countries, such as Korea, China, and Japan, and it has been found to exert various biological activities including antioxidative, anti-aggregatory, anti-inflammatory, anti-mutagenic, and apoptotic effects. Sulfuretin is one of the major flavonoid component isolated from the heartwood of R. verniciflua. Reactive oxygen species (ROS), produced via dental adhesive bleaching agents and pulpal disease, can cause oxidative stress. In the present study, we isolated sulfuretin from R. verniciflua and demonstrated that sulfuretin possesses cytoprotective effects against hydrogen peroxide ($H_2O_2$)-induced dental cell death. $H_2O_2$ is a representative ROS and causes cell death through necrosis in human dental pulp (HDP) cells. $H_2O_2$-induced cytotoxicity and production of ROS were blocked in the presence of sulfuretin, and these effects were dose dependent. Sulfuretin also increased heme oxygenase-1 (HO-1) protein expression. In addition, to determine whether sulfuretin-induced HO-1 expression mediated this cytoprotective effect, HDP cells were cotreated with sulfuretin in the absence or presence of SnPP, an inhibitor of HO activity. Sulfuretin-dependent HO-1 expression was required for suppression of $H_2O_2$-induced HDP cell death and ROS generation. These results indicate that sulfuretin-dependent HO-1 expression was required for the inhibition of $H_2O_2$-induced cell death and ROS generation. In addition, sulfuretin may be used to prevent functional dental cell death and thus may be useful as a pulpal disease agent.

• Restorative Dentistry and Endodontics
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• v.35 no.3
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• pp.152-163
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• 2010

This study investigated the changes in gene expression when mineral trioxide aggregate (MTA) was applied in vitro to human dental pulp cells (HDPCs). MTA in a teflon tube (diameter 10 mm, height 2 mm) was applied to HDPCs. Empty tube-applied HDPCs were used as negative control. For microarray analysis, total RNA was extracted at 6, 24, and 72 hrs after MTA application. The results were confirmed selectively by performing reverse transcriptase polymerase chain reaction for genes that showed changes of more than two-fold or less than half. Of the 24,546 genes, 109 genes were up-regulated greater than twofold (e.g., FOSB, THBS1, BHLHB2, EDN1, IL11, FN1, COL10A1, and TUFT1) and 69 genes were down-regulated below 50% (e.g., SMAD6 and DCN). These results suggest that MTA, rather than being a bio-inert material, may have potential to affect the proliferation and differentiation of pulp cells in various ways.

• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.101-108
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• 1987

The purpose of this study was to investigate the pulpal responses of dental adhesive resins. A total of 40 cavities of the permanent healthy teeth from 4 dogs were prepared. In the experimental group, the cavities were etched for 1 minute with citric acid and filled with experimental resins (ie. Super-Bond C & B$^{(R)}$). In the control group, the cavities were filled with calcium hydroxide base materials (ie. Dycal$^{(R)}$) without etching. The dogs were sacrificed at one, two, three and four weeks after the time of filling and the specimens were routinely prepared and stained with Hematoxylin-Eosin. The microscopic findings were as follows: Infiltration of inflammatory cells was not observed in both experimental and control groups. Change in the odontoblastic layer was not observed in all control groups but severe swelling was observed in deep dental pulp tissue of the control two and three week cases. Pulp tissue was recovered with plenty of fibrous component in the control four week case and reparative dentin formation was not occurred in all cases. Slight changes of the odontoblastic layer beneath the cavity were observed in the experimental one week case. In experimental two and three week cases, swelling of deep pulp tissue was increased and localized reparative dentin formation was observed. In the experimental four week case, odontoblastic layer was recovered with regular appearance and fibrous component of the pulp was increased, but reparative dentin formation was not evident.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.1
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• pp.25-32
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• 2014

Nitric oxide (NO) is recognized as a mediator and regulator of inflammatory responses. NO is produced by nitric oxide synthase (NOS), and NOS is abundantly expressed in the human dental pulp cells (HDPCs). NO produced by NOS can be cytotoxic at higher concentrations to HDPCs. However, the mechanism by which this cytotoxic pathway is activated in cells exposed to NO is not known. The purpose of this study was to elucidate the NO-induced cytotoxic mechanism in HDPCs. Sodium nitroprusside (SNP), a NO donor, reduced the viability of HDPCs in a dose- and time-dependent manner. We investigated the in vitro effects of nitric oxide on apoptosis of cultured HDPCs. Cells showed typical apoptotic morphology after exposure to SNP. Besides, the number of Annexin V positive cells was increased among the SNP-treated HDPCs. SNP enhanced the production of reactive oxygen species (ROS), and N-acetylcysteine (NAC) ameliorated the decrement of cell viability induced by SNP. However, a soluble guanylate cyclase inhibitor (ODQ) did not inhibited the decrement of cell viability induced by SNP. SNP increased cytochrome c release from the mitochondria to the cytosol and the ratio of Bax/Bcl-2 expression levels. Moreover, SNP-treated HDPCs elevated activities of caspase-3 and caspase-9. While pretreatment with inhibitors of caspase (z-VAD-fmk, z-DEVD-fmk) reversed the NO-induced apoptosis of HDPCs. From these results, it can be suggested that NO induces apoptosis of HDPCs through the mitochondria-dependent pathway mediated by ROS and Bcl-2 family, but not by the cyclic GMP pathway.

• Restorative Dentistry and Endodontics
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• v.41 no.2
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• pp.98-105
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• 2016

Objectives: The biocompatibility of two experimental scaffolds for potential use in revascularization or pulp regeneration was evaluated. Materials and Methods: One resilient lyophilized collagen scaffold (COLL), releasing metronidazole and clindamycin, was compared to an experimental injectable poly(lactic-co-glycolic) acid scaffold (PLGA), releasing clindamycin. Human dental pulp stem cells (hDPSCs) were seeded at densities of $1.0{\times}10^4$, $2.5{\times}10^4$, and $5.0{\times}10^4$. The cells were investigated by light microscopy (cell morphology), MTT assay (cell proliferation) and a cytokine (IL-8) ELISA test (biocompatibility). Results: Under microscope, the morphology of cells coincubated for 7 days with the scaffolds appeared healthy with COLL. Cells in contact with PLGA showed signs of degeneration and apoptosis. MTT assay showed that at $5.0{\times}10^4$ hDPSCs, COLL demonstrated significantly higher cell proliferation rates than cells in media only (control, p < 0.01) or cells co-incubated with PLGA (p < 0.01). In ELISA test, no significant differences were observed between cells with media only and COLL at 1, 3, and 6 days. Cells incubated with PLGA expressed significantly higher IL-8 than the control at all time points (p < 0.01) and compared to COLL after 1 and 3 days (p < 0.01). Conclusions: The COLL showed superior biocompatibility and thus may be suitable for endodontic regeneration purposes.

• International Journal of Oral Biology
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• v.43 no.3
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• pp.155-160
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• 2018

There exists very little information on the ultrastructure of substance P immunopositive (+) fibers in the human dental pulp, which may help in understanding the mechanism for substance P associated pulpal inflammatory pain. To address this issue, we investigated the presence of substance P+ fibers in the human dental pulp by light- and electron-microscopic immunohistochemistry. Light microscopy revealed that substance P+ fibers ran within neurovascular bundles in the radicular pulp and in the core of coronal pulp. They were also frequently present in the peripheral pulp. Substance P+ fibers showed beads like swellings interconnected by thin axonal strand, in a manner similar to bouton en passants and interconnecting axonal strand in the spinal cord. Electron microscopy revealed that almost all the substance P+ axons were unmyelinated. The axonal swellings of the substance P+ contained numerous clear round vesicles (40-50 nm in diameter) and many large dense-cored vesicles (80-110 nm in diameter) as well as many mitochondria. The vesicles and mitochondria were rarely observed in the thin axonal strand interconnecting the swellings. Intimate interrelationship or synaptic structure between the swellings of substance P+ axon and nearby pulpal cells or axons was not found. These findings suggest co-release of substance P and glutamate from the substance P+ pulpal axons and its action on nearby structures in a paracrine manner.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.374-387
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• 1997

The purpose of this study was to examine the distribution of lymphocyte populations in normal, reversibly inflamed and irreversibly inflamed human dental pulp tissues using flow cytometry. Flow cytometry, with specific antibody and fluorochrome reagent allows us to know cellular properties of hematolymphoid cells by measuring fluorescence of stained cells. Before extirpation of pulps in routine endodontic treatment, the clinical diagnosis were performed by symptom. The extirpated pulp tissues were divided into normal pulp group (N=5), reversible pulpit is group(N=10) and irreversible pulpitis group(N=7). The specimen was placed into RPMI 1640 medium, minced into small pieces, and then digested in medium with collagenase. The cell suspension was resuspended in PBS for monoclonal antibody staining of T lymhocytes(CD3+), B lymphocytes (CD19+), T helper cell (CD4+) and T supressor cell (CD8+). The percentages of cells were counted by FACStar(BD) flow cytometer. Following results were obtained; 1. In the most normal and inflamed pulps, the percentages of T lymphocyte, B lymphocytes, T helper cell and T suppressor/cytotoxic cell were less than 1 % in total counted pulpal cells. 2. The higher percentages of T, B, T helper and T suppressor cells were observed in irreversible pulpitis group as compared with the normal pulp and reversible pulpitis group but the differences between groups were not statistically significant (p>0.05). 3. The percentages of T helper cells (CD4 + cells) were greater than that of T suppressor/cytotoxic cells (CD8 + cells) in the inflamed pulps.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.350-357
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• 2017

The purpose of this study was to evaluate the difference of differentiation potential in each passage of dental pulp stem cells from supernumerary tooth (sDPSCs). The sDPSCs were obtained from a healthy 6-year-old male patient under the guidelines and got the informed consent. Cells were cultured until passage number 16 and divided into two groups; 1 - 8 passages as a young group and 9 - 16 passages as an old group. It was taken $2.25{\pm}0.46days$ in a young group and $3.25{\pm}0.46days$ in an old group to propagate cells of each passage until confluence and there were statistically significant differences between two groups (p < 0.05). In every passage, cell morphology was observed with microscope and evaluated the capacity to form high levels of minerals by alizarin red solution staining after treating differentiation medium. Fibroblast-like, spindle shaped, elongated cells and a few nodules were found in uninduced cultures of passage number 1, 8 and 9. But at 16 passage culture, cell size became larger and broader and observed with more nodules. After inducing differentiation, mineralized nodules were detected at the first passage of 7th day culture whereas at the 8 passage culture, nodules were seen clearly at 14th day culture. In addition, the amount of mineralized nodules were remarkably decreased after passage 9. From the data presented in this study, it is recommended to use sDPSCs of passage number within 8 for utilizing as stem cells.

• Journal of Oral Medicine and Pain
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• v.9 no.1
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• pp.127-138
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• 1984

The author had tried to identify the sex from single tooth by detecting F-body of Y-chromosome in the nucleus of the dental pulp cells of 70 persons aged from 4 to 61 years under a fluorescent miscroscope. The results were as follows : 1. In the cell nuclei of male and female dental pulp at refrigeratory, the rate of F-body appearancd ranged 42-86%(average 61.06%) in male, while it was 0-6%(average 1.86%) in female, indicationg that male could be distinctly differentiated from female by F-body. 2. With male and female dental pulp puterfide by leaving in at room temperature, the rate of F-body appearance ranged 35-58%(average 48.20%) in male, 1-3%(average1.70%) in female, indicating that it was possible to distinguish male and female by F-body. 3. Even in heat-treated male teeth at $100^{\circ}C$,10 mins, the rate of F-body appearace proved to be 32-56%(averaged 42.50%), also indicating the possibility of identifying male. 4. When detecting of F-body in process of time, the rate of F-body appearance did not show major charges. 5. It was reaffirmed that F-body detection method was a positive determination method of male.