The biocompatibility and mineralization potential of mineral trioxide aggregate containing calcium fluoride-An in vitro study.

BACKGROUND/PURPOSE: MTA is used to induce hard tissue regeneration in various procedures. This study evaluated the biocompatibility and mineralization potential of mineral trioxide aggregate (MTA) containing calcium fluoride (CaF2). To verify if the change of components affected physical properties, the setting time, solubility, and surface roughness were measured. MATERIALS AND METHODS: Human dental pulp cells (HDPCs) were treated with powder and set MTA containing CaF2 (0, 1, 5, and 10 wt %). The proliferation of HDPCs was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The mineralization potential of HDPCs was investigated with the relative gene expression of alkaline phosphatase (ALP), collagen type I (ColI), osteocalcin (OCN), and runt-related transcription factor 2 (Runx2) using real-time reverse transcription polymerase chain reaction (RT-PCR). For investigating the physical properties, setting time and solubility were tested. Surface profiles of material were analyzed by a non-contact surface profiler and a scanning electron microscope (SEM). RESULTS: MTA-5% CaF2 mixtures increased the proliferation and the mineralization-related gene expression of HDPCs to a greater degree than pure MTA. The addition of CaF2 to MTA delayed the setting, but the difference was only significant in the MTA-10% CaF2. Solubility and surface roughness was not altered. CONCLUSION: The addition of more than 5% CaF2 can be considered to increase the regeneration potential of pulp cells without adverse effects on physical property.

Differentiating spontaneous vertical root fracture in endodontically treated tooth.

Although vertical root fracture (VRF) is mostly found in endodontically treated teeth, it also occurs spontaneously. If VRF is recognized after endodontic treatment, it is considered to be iatrogenic and can lead to legal trouble. However, legal problems can be averted if the dentist can prove that the VRF existed before endodontic treatment. This case report describes an unusual, spontaneous VRF in an endodontically treated tooth and presents a useful tip for determining whether a fracture is iatrogenic. We performed nonsurgical endodontic treatment on a mandibular first molar with irreversible pulpitis. After 6 months, the patient revisited with localized swelling, and we diagnosed VRF of the mesial root. We extracted the tooth and prepared it for microscopic examination. We found gutta-percha in the fracture line of the transversely sectioned root, and it appeared to have penetrated to the fracture line through the force generated from the filling. The patient was informed and agreed that the fracture occurred spontaneously before treatment. This case demonstrates the time point of VRF occurrence by identifying the presence of gutta-percha in the fracture line. We suggest that this procedure can be used to demonstrate whether VRFs in endodontically treated teeth are spontaneous or iatrogenic.

In vitro evaluation of a newly produced resin-based endodontic sealer.

OBJECTIVES: A variety of root canal sealers were recently launched to the market. This study evaluated physicochemical properties, biocompatibility, and sealing ability of a newly launched resin-based sealer (Dia-Proseal, Diadent) compared to the existing root canal sealers (AHplus, Dentsply DeTrey and ADseal, Metabiomed). MATERIALS AND METHODS: The physicochemical properties of the tested sealers including pH, solubility, dimensional change, and radiopacity were evaluated. Biocompatibility was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. For microleakage test, single-rooted teeth were instrumented, and obturated with gutta-percha and one of the sealers (n = 10). After immersion in 1% methylene blue solution for 2 weeks, the specimens were split longitudinally. Then, the maximum length of staining was measured. Statistical analysis was performed by one-way analysis of variance followed by Tukey test (p = 0.05). RESULTS: Dia-Proseal showed the highest pH value among the tested sealers (p < 0.05). ADseal showed higher dimensional change compared to AHplus and Dia-Proseal (p < 0.05). The solubility values of AHplus and Dia-Proseal were similar, whereas ADseal had the lowest solubility value (p < 0.05). The flow values of sealer in increasing order were AHplus, DiaProseal, and ADseal (p < 0.05). The radiopacity of AHplus was higher than those of ADseal and Dia-Proseal (p < 0.05). The cell viability of the tested materials was statistically similar throughout the experimental period. There were no significant differences in microleakage values among the tested samples. CONCLUSIONS: The present study indicates that Dia-Proseal has acceptable physicochemical properties, biocompatibility, and sealing ability.

Tooth discoloration induced by a novel mineral trioxide aggregate-based root canal sealer.

OBJECTIVES: The aim of this study was to evaluate tooth discoloration caused by contact with a novel injectable mineral trioxide aggregate (MTA)-based root canal sealer (Endoseal; Maruchi, Wonju, Korea) compared with a widely used resin-based root canal sealer (AHplus; Dentsply De Trey, Konstanz, Germany) and conventional MTA (ProRoot; Dentsply, Tulsa, OK, USA). MATERIALS AND METHODS: Forty standardized bovine tooth samples were instrumented and divided into three experimental groups and one control group (n = 10/group). Each material was inserted into the cavity, and all specimens were sealed with a self-adhesive resin. Based on CIE Lab system, brightness change (ΔL) and total color change (ΔE) of each specimen between baseline and 1, 2, 4, and 8 weeks were obtained. RESULTS: At all time points, Endoseal showed no significant difference in ΔL and ΔE compared to AHplus and control group (P > 0.05), whereas the ProRoot group showed significantly higher ΔL and ΔE values than the Endoseal group at 2, 4, and 8 weeks (P < 0.05). Therefore, Endoseal showed less discoloration than conventional MTA and a similar color change to AHplus. CONCLUSIONS: Within the limitations of this study, our data indicate that the MTA-based sealer produces a similar amount of tooth discoloration as AHplus which is considered to be acceptable.

Effects of epicatechin, a crosslinking agent, on human dental pulp cells cultured in collagen scaffolds.

OBJECTIVE: The purpose of this study was to investigate the biological effects of epicatechin (ECN), a crosslinking agent, on human dental pulp cells (hDPCs) cultured in collagen scaffolds. MATERIAL AND METHOD: To evaluate the effects of ECN on the proliferation of hDPCs, cell counting was performed using optical and fluorescent microscopy. Measurements of alkaline phosphatase (ALP) activity, alizarin red staining, and real-time polymerase chain reactions were performed to assess odontogenic differentiation. The compressive strength and setting time of collagen scaffolds containing ECN were measured. Differential scanning calorimetry was performed to analyze the thermal behavior of collagen in the presence of ECN. RESULTS: Epicatechin increased ALP activity, mineralized nodule formation, and the mRNA expression of dentin sialophosphoprotein (DSPP), a specific odontogenic-related marker. Furthermore, ECN upregulated the expression of DSPP in hDPCs cultured in collagen scaffolds. Epicatechin activated the extracellular signal-regulated kinase (ERK) and the treatment with an ERK inhibitor (U0126) blocked the expression of DSPP. The compressive strength was increased and the setting time was shortened in a dose-dependent manner. The number of cells cultured in the ECN-treated collagen scaffolds was significantly increased compared to the cells in the untreated control group. CONCLUSIONS: Our results revealed that ECN promoted the proliferation and differentiation of hDPCs. Furthermore, the differentiation was regulated by the ERK signaling pathway. Changes in mechanical properties are related to cell fate, including proliferation and differentiation. Therefore, our study suggests the ECN treatment might be desirable for dentin-pulp complex regeneration.

Effects of epicatechin, a crosslinking agent, on human dental pulp cells cultured in collagen scaffolds

ABSTRACT Objective The purpose of this study was to investigate the biological effects of epicatechin (ECN), a crosslinking agent, on human dental pulp cells (hDPCs) cultured in collagen scaffolds. Material and Method To evaluate the effects of ECN on the proliferation of hDPCs, cell counting was performed using optical and fluorescent microscopy. Measurements of alkaline phosphatase (ALP) activity, alizarin red staining, and real-time polymerase chain reactions were performed to assess odontogenic differentiation. The compressive strength and setting time of collagen scaffolds containing ECN were measured. Differential scanning calorimetry was performed to analyze the thermal behavior of collagen in the presence of ECN. Results Epicatechin increased ALP activity, mineralized nodule formation, and the mRNA expression of dentin sialophosphoprotein (DSPP), a specific odontogenic-related marker. Furthermore, ECN upregulated the expression of DSPP in hDPCs cultured in collagen scaffolds. Epicatechin activated the extracellular signal-regulated kinase (ERK) and the treatment with an ERK inhibitor (U0126) blocked the expression of DSPP. The compressive strength was increased and the setting time was shortened in a dose-dependent manner. The number of cells cultured in the ECN-treated collagen scaffolds was significantly increased compared to the cells in the untreated control group. Conclusions Our results revealed that ECN promoted the proliferation and differentiation of hDPCs. Furthermore, the differentiation was regulated by the ERK signaling pathway. Changes in mechanical properties are related to cell fate, including proliferation and differentiation. Therefore, our study suggests the ECN treatment might be desirable for dentin-pulp complex regeneration.

Effect of mineral trioxide aggregate on dentin bridge formation and expression of dentin sialoprotein and heme oxygenase-1 in human dental pulp.

This study was conducted to evaluate the pulpal response to direct capping with either mineral trioxide aggregate (MTA) or calcium hydroxide (CH) cement in humans, with a focus on dentin bridge formation and dentin sialoprotein (DSP) and heme oxygenase-1 (HO-1) expression. Direct pulp capping was performed in 20 cases of caries-free human third molars. The pulps were exposed and capped with either MTA or hard-setting CH. After 2 months, the teeth were extracted, and the specimens were prepared for histologic and immunohistochemical evaluations. Histologically, 100% of the MTA group and 60% of the CH group developed dentin bridges. The mean thickness of the dentin bridges observed in the MTA group was statistically greater than that of CH group. In addition, DSP and HO-1 were expressed in the odontoblast-like cells and pulp fibroblasts beneath the dentin bridge; furthermore, significantly greater immunostaining was observed in the MTA group than in the CH group. Collectively, these results indicate that MTA is superior to CH in terms of inducing the dentinogenic process in human pulp capping.

Involvement of mitogen-activated protein kinases and nuclear factor-kappa B activation in nitric oxide-induced interleukin-8 expression in human pulp cells.

OBJECTIVE: This study examined the effect of nitric oxide (NO) on interleukin-8 (IL-8) production and the involvement of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-kappaB) signaling pathways in primary cultured human pulp cells. STUDY DESIGN: IL-8 production was measured using enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. MAPK activation and IkappaB degradation and phosphorylation were determined by western blotting. RESULTS: Sodium nitroprusside (SNP), an NO donor, has increased IL-8 secretion and mRNA expression in a dose- and time-dependent manner. SNP induced the phosphorylation of p38 MAPK and extracellular-regulated kinase (ERK), degradation and phosphorylation of IkappaB, and activation of NF-kappaB. Furthermore, inhibition of the ERK, p38, and NF-kappaB pathways blocked SNP-induced IL-8 secretion. CONCLUSION: Human pulp cells showed NO-induced IL-8 expression via the MAPK and NF-kappaB pathways, which may play an important role in the inflammatory responses of pulp and periapical lesions.

Evaluation of the radiopacity and cytotoxicity of Portland cements containing bismuth oxide.

OBJECTIVE: This study aimed at evaluating the radiopacity and cytotoxicity of Portland cements containing bismuth oxide (PcBo) in varying ratios. STUDY DESIGN: Specimens measuring 10 mm in diameter and 1 mm in thickness were radiographed with an aluminum step wedge using an occlusal film. The radiographs were digitized, and the radiopacity of each material was compared to the different thicknesses of the aluminum step wedge. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of each material was determined in immortalized human periodontal ligament (IPDL) cells. RESULTS: The results demonstrated that Portland cement with 20% bismuth oxide presented greater radiopacity (P < .05) compared to the mixtures with less bismuth oxide. The cell viabilities of all PcBo groups were statistically similar (P > .05) throughout the experimental period. CONCLUSION: These results indicate that Portland cement with 20% bismuth oxide has a greater potential for being used as a root-end filling material compared to Portland cement with less bismuth oxide.

The induction of heme oxygenase-1 modulates bismuth oxide-induced cytotoxicity in human dental pulp cells.

The aim of this study was to investigate the cytotoxic and nitric oxide (NO)-inducing effects of bismuth oxide (Bi(2)O(3))-containing Portland cement (BPC) on human dental pulp cells. We also assessed whether heme oxygenase-1 (HO-1) is involved in BPC-induced cytotoxicity in dental pulp cells. Cytotoxicity and NO production induced by BPC were higher than those induced by Portland cement at 12 and 24 hours, and the former gradually decreased to the level observed for PC. HO-1 and inducible nitric oxide synthase messenger RNA expressions in the BPC group showed maximal increase at 24 hours, and it gradually decreased with increasing cultivation time. Hemin treatment reversed the BPC-induced cytotoxicity, whereas zinc protoporphyrin IX treatment increased the cytotoxicity. These results suggested that NO production by BPC correlates with HO-1 expression in dental pulp cells. Moreover, BPC-induced HO-1 expression in dental pulp cells plays a protective role against the cytotoxic effects of BPC.

Human pulp cells response to Portland cement in vitro.

The aim of this study was to investigate the cellular effects of Portland cement on cultured human pulp cells. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, no cytotoxicity was observed in the Portland cement group in comparison with the negative control group, whereas the glass ionomer cement, intermediate restorative material, and Dycal groups showed a survival rate of less than 40% at 12 hours. Scanning electron microscopy revealed that human pulp cells attached to the Portland cement were flat and had numerous cytoplasmic extensions. In the groups in which other materials were used, a few rounded cells were observed on the material but no living cells were observed. The expression of both osteonectin and dentin sialophosphoprotein mRNAs was induced in the Portland cement-treated group. These results suggest that Portland cement is biocompatible, allows the expression of mineralization-related genes on cultured human pulp cells, and has the potential to be used as a proper pulp-capping material.