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Introduction: The cytotoxicity of resin-based sealer is influential on the inflammatory reaction and cell survival for oral periapical cells. In this study, pachymic acid as an antioxidant was investigated for the improvement of bone disturbance against AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany)-induced inflammation in MC-3T3 E1 cells., Methods: AH Plus was prepared according to the manufacturer's instructions. Using mouse osteoblast cells (MC-3T3 E1), a specimen of AH Plus was eluted with the culture medium for 1 day and was diluted by 30%. The cellular cytotoxicity and reactive oxygen species formation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and 2',7'-dichlorodihydrofluorescein diacetate with fluorescence-activated cell sorting. The secretion of proinflammatory cytokines was determined by an enzyme-linked immunosorbent assay, and the expression of inflammatory and osteogenic molecules was determined by immunoblotting., Results: Cells with AH Plus elutes showed a decrease of cell viability and ALP activity. However, pachymic acid and N-acetyl-L-cysteine (control antioxidant) restored cell viability and ALP activity damaged by AH plus. The secretion of nitric oxide, tumor necrosis factor α, and interleukin-1β were increased in AH Plus-stimulated MC-3T3 E1 cells, but pachymic acid suppressed its production. Furthermore, pachymic acid reduced the receptor activator of nuclear factor-κB ligand, cyclooxygenase-2, matrix metalloproteinase-2 and -9, increased bone morphogenetic protein-2 and -7, and runt-related transcription factor 2 despite AH Plus stimuli. In addition, pachymic acid affected the removal effect of reactive oxygen species formation as did N-acetyl-L-cysteine. More importantly, pachymic acid inhibited nuclear factor-κB translocation., Conclusions: The property of pachymic acid can mitigate the unfavorable conditions induced by AH Plus stimuli. Therefore, the use of pachymic acid is suggested to prevent the complications of oral diseases such as inflammation and alveolar destruction of the oral cavity., (Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Dental pulp functions include pulp cell activity involvement in dentin formation. In this study we investigated the age-related changes in dental pulp cells that may influence pulp cell activity for restoring pulp function., Methods: Human dental pulp cells (HDPCs) were serially subcultured until spontaneously arrested. Altered expression of chronic inflammatory molecules and age-related molecules were determined by Western blotting. Odontogenic functions impaired by senescence were assayed by Western blotting, reverse transcriptase polymerase chain reaction, alkaline phosphatase activity, and alizarin red S staining. To understand the mechanism of aging process by stress-induced premature senescence (SIPS), the cells were treated with H(2)O(2). Replicative senescence and SIPS were also compared., Results: Replicative senescence of HDPCs was characterized by senescence-associated β-galactosidase activity and reactive oxygen species formation. These cells exhibited altered expression of chronic inflammatory molecules such as intracellular adhesion molecule-1, vascular cell adhesion molecule-1, peroxisome proliferator activated receptor-gamma, and heme oxygenase-1 and age-related molecules such as p53, p21, phosphorylated-extracellular signal-regulated kinase, and c-myb. SIPS cell results were similar to replicative senescence. Furthermore, HDPCs decreased odontogenic markers such as dentin sialophosphoprotein and dentin matrix-1 and osteogenic markers such as bone morphogenetic protein-2 and -7, runt-related transcription factor-2, osteopontin, alkaline phosphatase activity, and mineralized nodule formation by replicative senescence and SIPS., Conclusions: This study suggests that development of aging-related molecules in pulp cells offers understanding of cellular mechanisms and biological events responsible for tooth preservation and maintenance strategies for healthy teeth across the life span., (Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Peroxisome proliferator-activated receptor gamma (PPARγ) has well-known anti-inflammatory action in human dental pulp cells (HDPCs). The purpose of this study was to investigate whether the anti-inflammatory action of PPARγ involves in cellular cytoprotection and supports odontoblast differentiation under oxidative stress in HDPCs., Methods: To simulate long-term oxidative stress, pulp cells were treated with 150 μmol hydrogen peroxide (H(2)O(2)) for 12 days. The replication deficiency adenovirus (adenovirus PPARγ) was introduced for PPARγ overexpression in pulp cells. The cellular cytotoxicity and reactive oxygen species formation by H(2)O(2) were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and 2',7'-dichlorodihydrofluorescein diacetate with fluorescence-activated cell sorting assay. To determine the roles of PPARγ, several molecules of odontogenic/osteogenic and signal pathway were analyzed by reverse-transcription polymerase chain reaction and Western hybridization. Dentin mineralization was determined by alizarin red stain and alkaline phosphatase activity assay., Results: Pulp cells treated with long-term H(2)O(2) showed high reactive oxygen species formation, low cell viability, down-expression of antioxidant molecules (Cu/Zn and Mn superoxide dismutase), and odontogenic/osteogenic markers (eg, dentin sialophosphoprotein, dentin matrix protein-1, osteopontin, bone sialoprotein, Runx-2, and bone morphogenetic protein 2 and 7). In addition, pulp cells with oxidative stress underwent the activation of ERK1/2, activator protein-1, and nuclear factor-κB translocation to the nucleus. However, the PPARγ-overexpressed cells gave opposite results although under oxidative stress. Furthermore, PPARγ and its agonist rosiglitazone exhibited an induction of dentin mineralization under oxidative stress., Conclusions: PPARγ in pulp cells increases cell viability, odontoblastic differentiation, and dentin mineralization under oxidative stress. These results offer new insights into the potential antioxidative activity of PPARγ and its agonist for therapeutic agents for pulp vitality in HDPCs., (Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The cytotoxicity of AH26, a resin-based sealer, induces apoptosis in osteoblast cells. However, the apoptosis pathway is not completely understood. This study examined the apoptosis pathway and its regulation of AH26 through mitogen-activated protein kinase (MAPKs), which may play a role in reducing the cytotoxicity of AH26., Methods: Using mouse osteoblasts cells (MC-3T3-E1), specimens of AH26 were eluted with the culture medium for 1, 3, 5, and 7 days. The cytotoxicity was tested using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The induction of apoptosis was detected by Hoechst33258 staining and poly (ADP-ribose) polymerase (PARP) activation. The AH26-involved signal pathway was analyzed by immunoblotting with a specific antibody., Results: AH26 exhibited cytotoxicity toward MC-3T3-E1 cells, which resulted in mitochondria-mediated apoptosis, as confirmed by Bax expression and the displacement of cytochrome c from mitochondria to cytosol. As evidence of MAPKs activation, the cells treated with AH26 expressed stress-activated protein/c-jun N-terminal kinase (SAPK/JNK) and extracellular signal-regulated protein kinase (ERK1/2). SAPK/JNK activation appears to regulate apoptosis, whereas ERK activation protects cell survival., Conclusions: From these results, the toxicity of AH26 can be decreased by controlling the apoptosis signals. This approach might have potential applications for reducing the long-term stress of periapical tissue that improves endodontic treatment., (Copyright © 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)