• Restorative Dentistry and Endodontics
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• v.41 no.1
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• pp.44-54
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• 2016

Objectives: The purpose of this study was to evaluate the histopathological effects of an antioxidant therapy on the pulp tissue of rat teeth exposed to a bleaching gel with 35% hydrogen peroxide. Materials and Methods: Forty rats were subjected to oral ingestion by gavage of distilled water (DW) or ascorbic acid (AA) 90 min before the bleaching therapy. For the bleaching treatment, the agent was applied twice for 5 min each to buccal surfaces of the first right mandibular molars. Then, the animals were sacrificed at 6 hr, 24 hr, 3 day, or 7 day post-bleaching, and the teeth were processed for microscopic evaluation of the pulp tissue. Results: At 6 hr, the pulp tissue showed moderate inflammatory reactions in all teeth of both groups. In the DW and AA groups, 100% and 80% of teeth exhibited pulp tissue with significant necrosis and intense tissue disorganization, respectively. At 24 hr, the AA-treated group demonstrated a greater regenerative capability than the DW group, with less intense inflammatory reaction and new odontoblast layer formation in 60% of the teeth. For up to the 7 day period, the areas of pulpal necrosis were replaced by viable connective tissue, and the dentin was underlined by differentiated odontoblast-like cells in most teeth of both groups. Conclusions: A slight reduction in initial pulpal damage during post-bleaching was promoted by AA therapy. However, the pulp tissue of AA-treated animals featured faster regenerative potential over time.

• Restorative Dentistry and Endodontics
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• v.31 no.3
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• pp.203-214
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• 2006

Dental pulp is a loose, mesenchymal tissue almost entirely enclosed in the dentin. It consists of cells, ground substance, and neural and vascular supplies. Damage to the dental pulp by mechanical, chemical, thermal, and microbial irritants can provoke various types of inflammatory response. Pulpal inflammation leads to the tissue degradation, which is mediated in part by Matrix metalloproteinase leads to accelerate extracellular matrix degradation with pathological pathway We have now investigated the induction of MMPs and inflammatory cytokines by Lipopolysaccharide (LPS) control of inflammatory mediators by peroxisome proliferator-activated receptors (PPARs). Human dental pulp cells exposed to various concentrations of LPS ($1-10{\mu}g/ml$) revealed elevated levels of MMP-2 and MMP-9 at 24 hrs of culture. LPS also stimulated the production of ICAM-1, VCAM-1, $IL-1{\beta},\;and\;TNF-{\alpha}$. Adenovirus $PPAR{\gamma}\;(Ad/PPAR{\gamma})\;and\;PPAR{\gamma}$ agonist rosiglitazone reduced the synthesis of MMPs, adhesion molecules and pro-inflammatory cytokines. The inhibitory effect of $Ad/PPAR{\gamma}$ was higher than that of $PPAR{\gamma}$ agonist. These result offer new insights in regard to the anti-inflammatory potential of $PPAR{\gamma}$ in human dental pulp cell.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.324-332
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• 2008

Traumatic crown fracture in mixed dentition or early permanent dentition is relatively common. Crown fracture is classified into simple or complicated crown fracture by the presence of pulp exposure. The condition of pulp must be considered in treatment of crown fractures with pulp exposure. Treatment of immature crown-fractured incisor with pulp exposure is more complex because of its incomplete root formation. Pulp capping, partial pulpotomy, cervical pulpotomy can be used for continuous root development in immature crown-fractured incisor with pulp exposure. The success rate of partial pulpotomy is very high and there are several advantages of partial pulpotomy because the cell-rich coronal pulp tissue is preserved. This paper reports 2 cases of crown-fractured permanent incisors with pulp exposure that had been treated by partial pulpotomy successfully.

• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.153-164
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• 1990

Human dental pulps obtained from normal teeth, hypersensitive teeth and teeth with inflamed pulp were studied to measure and to compare the endogenous levels of arachidonic acid metabolites in order to see the relative activities of the different pathways involved in arachidonic acid metabolism. Pulp homogenates were incubated with $^{14}C$-arachidonic acid and lipid solvent extracts were separated by thin layer chromatography (TLC) to be analyzed by autoradiography and TLC analyzer. 1. The most significant metabolite was HETEs showing $96.9{\pm}37.8$pmol/mg tissue protein/hr in normal pulp, $169.2{\pm}76.7$ in hypersensitive pulp and $385.4{\pm}113.2$ in inflamed pulp. In normal pulp $LTB_4$, 6-keto-$PGF_{1\alpha}+PGE_2$, $TXB_2$ and unidentified metabolite were formed in decreasing order. While in hypersensitive and inflamed pulp 6-keto-$PGF_{1\alpha}+PGE_2$, $LTB_4$, $TXB_2$ and unidentified metabolite were formed in decreasing order. 2. In hypersensitive pulp only HETEs were significantly increased when compared with that in normal pulp. The levels of all the converted metabolites in inflamed pulp were significantly increased compared with those in normal pulp. In inflamed pulp, the levels of $TXB_2$ and HETEs were significantly increased compared with those in hypersensitive pulp. 3. The ratio of each metabolites to the total converted metabolites showed an increased value of $TXB_2$ and 6-keto-$PGF_{1\alpha}+PGE_2$, as the degree of inflammation was increased, while that of HETEs decreased both in hypersensitive pulp and inflamed pulp more than in normal pulp. 4. The relative amounts of the total metabolites formed in lipoxygenase pathway to cyclo-oxygenase pathway were 6.8 fold in normal pulp, 4.4 fold in hypersensitive pulp and 3.8 fold in inflamed pulp.

• The Journal of the Korean dental association
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• v.10 no.1
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• pp.15-21
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• 1972

In the periodic amputated rat incisor pulp, the distribution of five isoenzymes of lactic acid dehydrogenase was evaluated and the total LDH activity was assayed. This study hs established the followings; 1) It demonstrates the existence of five distinct isoenzymes of LDH, with LDH-1 and LDH-2 predominating, in the rat incisor pulp. 2) The total LDH activity in periodically amputated rat incisor pulp is markedly increased as compared to the normal rat incisor pulp. 3) It is possible that the periodic amputation of tooth effects the pattern of LDH isoenzymes in the pulp, especially LDH-1 and LDH-2 region.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.223-228
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• 2015

Objectives: The aim of this study was to investigate the expression of 7 different sirtuin genes (SIRT1-SIRT7) in human dental pulp cells (HDPCs), and to determine the role of SIRTs in the odontoblastic differentiation potential of HDPCs. Materials and Methods: HDPCs were isolated from freshly extracted third molar teeth of healthy patients and cultulred in odontoblastic differentiation inducing media. Osteocalcin (OCN) and dentin sialophosphoprotein (DSPP) expression was analyzed to evaluate the odontoblastic differentiation of HDPCs by reverse transcription-polymerase chain reaction (RT-PCR), while alizarin red staining was used for the mineralization assay. To investigate the expression of SIRTs during odontoblastic differentiation of HDPCs, real time PCR was also performed with RT-PCR. Results: During the culture of HDPCs in the differentiation inducing media, OCN, and DSPP mRNA expressions were increased. Mineralized nodule formation was also increased in the 14 days culture. All seven SIRT genes were expressed during the odontogenic induction period. SIRT4 expression was increased in a time-dependent manner. Conclusions: Our study identified the expression of seven different SIRT genes in HDPCs, and revealed that SIRT4 could exert an influence on the odontoblast differentiation process. Further studies are needed to determine the effects of other SIRTs on the odontogenic potential of HDPCs.

• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.17.1-17.9
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• 2021

Objectives: In recent in vitro study, it was reported that osteostatin (OST) has an odontogenic effect and synergistic effect with mineral trioxide aggregate (MTA) in human dental pulp cells. Therefore, the aim of this study was to evaluate whether OST has a synergistic effect with MTA on hard tissue formation in vivo. Materials and Methods: Thirty-two maxillary molars of Spraque-Dawley rats were used in this study. An occlusal cavity was prepared and the exposed pulps were randomly divided into 3 groups: group 1 (control; ProRoot MTA), group 2 (OST 100 μM + ProRoot MTA), group 3 (OST 10 mM + ProRoot MTA). Exposed pulps were capped with each material and cavities were restored with resin modified glass ionomer. The animals were sacrificed after 4 weeks. All harvested teeth were scanned with micro-computed tomography (CT). The samples were prepared and hard tissue formation was evaluated histologically. For immunohistochemical analysis, the specimens were sectioned and incubated with primary antibodies against dentin sialoprotein (DSP). Results: In the micro-CT analysis, it is revealed that OST with ProRoot MTA groups showed more mineralized bridge than the control (p < 0.05). In the H&E staining, it is showed that more quantity of the mineralized dentin bridge was formed in the OST with ProRoot MTA group compared to the control (p < 0.05). In all groups, DSP was expressed in newly formed reparative dentin area. Conclusions: OST can be a supplementary pulp capping material when used with MTA to make synergistic effect in hard tissue formation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6340-6345
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• 2013

This study examined the involvement of histamine in heat-induced changes in pulpal blood flow(PBF) to determine the mechanism of neurogenic inflammation in feline dental pulp. The experiments were carried out in 10 felines anesthetized with sodium pentobartial and histamine injected into the dental pulp through the external carotid artery. The change in the pulpal PBF was measured using a laser Doppler flowmeter(Periflux 4001, Stockholm, Sweden). The probe of laser Doppler flowmeter was placed on the buccal surface of the ipsilateral canine teeth. Heat was applied to the tooth using a heat stimulator controlled script file with an input/output device. The application of heat ($40-65^{\circ}C$) induced a significant increase in PBF. The application of histamine($5{\mu}g/kg/1ml$) followed by heat($45^{\circ}C$) resulted in an increase in PBF. Therefore, the results of the present study showed that heat and histamine are capable of vasoconstriction caused by neurogenic inflammation in feline dental pulp. In addition, neurogenic inflammation plays an active role in modulating the microcirculation of the dental pulp.

• International Journal of Oral Biology
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• v.42 no.3
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• pp.91-97
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• 2017

Although anti-aging activities of melatonin, a hormone secreted by the pineal gland, have been reported in senescence-accelerated mouse models and several types of cells, its impact and mechanism on the senescence of human dental pulp cells (HDPCs) remains unknown. In this study, we examined the impact of melatonin on cellular premature senescence of HDPCs. Here, we found that melatonin markedly inhibited senescent characteristics of HDPCs after exposure to hydrogen peroxide ($H_2O_2$), including the increase in senescence-associated ${\beta}$-galactosidase (SA-${\beta}$-gal)-positive HDPCs and the upregulation of p21 protein, an indicator for senescence. In addition, as melatonin attenuated $H_2O_2$-stimulated phosphorylation of c-Jun N-terminal kinase (JNK), while selective inhibition of JNK activity with SP600125 significantly attenuated $H_2O_2$-induced increase in SA-beta-gal activity. Results reveal that melatonin antagonizes premature senescence of HDPCs via JNK pathway. Thus, melatonin may have therapeutic potential to prevent stress-induced premature senescence, possibly correlated with development of dental pulp diseases, and to maintain oral health across the life span.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.30-38
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• 2008

Dental pulp cells are assumed to possess the capacity to elaborate both bone and dentin matrix under the pathological conditions following tooth injury. The purpose of this study is to examine the effects of mineral trioxide aggregate (MTA) on various gene expression regarding dentinogenesis and cell viability assay in cultured primary human dental pulp cells. The author also examined the effects of this material on cellular alkaline phosphatase activity as a potential indicator of dentinogenesis. For gene expression on MTA, reverse transcriptase polymerase chain reaction was performed using primer sets of glyceraldehyde-3-phosphate dehydrogenase, type I collagen, alkaline phosphatase(ALP), osteonectin, and dentin sialoprotein after 2 and 4 days. Cell viability assay showed that the proportion of MTA-treated pulp cells which had been exposed for 5 days to MTA was higher than that of the control cells. Among the genes investigated in this study, ALP and osteonectin(SPARC) were increased in MTA treated group than in control. These findings suggest that this dental pulp culture system may be useful in the future as a model for studying the mechanisms underlying dentin regeneration after the treatment with MTA. Exposure to MTA material would not induce cytotoxic response in the dental pulp cells. In addition, MTA could influence the behavior of human pulp cells by increasing the ALP activity and SPARC synthesis.