Cytotoxicity of dilutions of bioceramic materials in stem cells of human exfoliated deciduous teeth.

OBJECTIVE: Several materials have been developed to preserve pulp vitality. They should have ideal cytocompatibility characteristics to promote the activity of stem cells of human exfoliated deciduous teeth (SHED) and thus heal pulp tissue. OBJECTIVE: To evaluate the cytotoxicity of different dilutions of bioceramic material extracts in SHED. METHODOLOGY: SHED were immersed in αMEM + the material extract according to the following experimental groups: Group 1 (G1) -BBio membrane, Group 2 (G2) - Bio-C Repair, Group 3 (G3) - MTA Repair HP, Group 4 (G4) - TheraCal LC, and Group 5 (G5) - Biodentine. Positive and negative control groups were maintained respectively in αMEM + 10% FBS and Milli-Q Water. The methods to analyze cell viability and proliferation involved MTT and Alamar Blue assays at 24, 48, and 72H after the contact of the SHED with bioceramic extracts at 1:1 and 1:2 dilutions. Data were analyzed by the three-way ANOVA, followed by Tukey's test (p<0.05). RESULTS: At 1:1 dilution, SHED in contact with the MTA HP Repair extract showed statistically higher cell viability than the other experimental groups and the negative control (p<0.05), except for TheraCal LC (p> 0.05). At 1:2 dilution, BBio Membrane and Bio-C showed statistically higher values in intra- and intergroup comparisons (p<0.05). BBio Membrane, Bio-C Repair, and Biodentine extracts at 1:1 dilution showed greater cytotoxicity than 1:2 dilution in all periods (p<0.05). CONCLUSION: MTA HP Repair showed the lowest cytotoxicity even at a 1:1 dilution. At a 1:2 dilution, the SHED in contact with the BBio membrane extract showed high cell viability. Thus, the BBio membrane would be a new non-cytotoxic biomaterial for SHED. Results offer possibilities of biomaterials that can be indicated for use in clinical regenerative procedures of the dentin-pulp complex.

Leaching and cytotoxicity of bismuth oxide in ProRoot MTA - A laboratory investigation.

AIM: The present study examined the leaching and cytotoxicity of bismuth from ProRoot MTA and aimed to identify whether bismuth leaching was affected by the cement base and the immersion regime used. METHODOLOGY: The leaching profile of bismuth was examined from ProRoot MTA and compared with hydroxyapatite containing 20% bismuth oxide as well as hydroxyapatite and tricalcium silicate to investigate whether bismuth release changed depending on the cement base. Bismuth leaching was determined after 30 and 180 days of ageing immersed in Dulbecco's modified Eagle's medium (DMEM) using mass spectroscopy (ICP-MS). The media were either unchanged or regularly replenished. The pH, surface microstructure and phase changes of aged materials were assessed. Wistar rat femoral bone marrow stromal cells (BMSCs) and cutaneous fibroblasts were isolated, cultured and seeded for cell counting (trypan blue live/dead) after exposure to non-aged, 30- and 180-days-aged samples in regularly replenished DMEM. Aged DMEM in contact with materials was also used to culture BMSCs to investigate the effect of material leachates on the cells. Gene expression analysis was also carried out after direct exposure of cells to non-aged materials. Differences between groups were statistically tested at a significance level of 5%. RESULTS: All materials exhibited alterations after immersion in DMEM and this increased with longer exposure times. The bismuth leached from ProRoot MTA as detected by ICP-MS. Aged ProRoot MTA samples exhibited a black discolouration and surface calcium carbonate deposition. ProRoot MTA influenced cell counts after direct exposure and its 180-days leachates reduced BMSC viability. After direct BMSC contact with non-aged ProRoot MTA an upregulation of metallothionein (MT1 and MT2A) expression and down-regulation of collagen-1a (Col-1a) and bone sialoprotein (BSP) expression was identified. CONCLUSIONS: Bismuth leaching was observed throughout 180-days observation period from all materials containing bismuth oxide. This negatively influenced cell viability and gene expression associated with bismuth exposure. This is the first study to report that metallothionein gene expression was influenced by exposure to ProRoot MTA.

Bismuth-based nanoparticles impair adipogenic differentiation of human adipose-derived mesenchymal stem cells.

Bismuth-based nanoparticles (BiNPs) have attracted attention for their potential biomedical applications. However, there is a lack of information concerning their interaction with biological systems. In this study, it was investigated the effect of physically synthesized BiNPs to human adipose-derived stem cells (ADSCs). We first evaluated the influence of BiNPs on cell viability, cell morphology, mitochondrial function and cell proliferation. Further, the impact of BiNPs on adipogenic differentiation was also explored. Cytotoxicity assays have demonstrated that BiNPs did not reduce relative cell viability of ADSC except at the highest tested concentration (345 µg/ml). Analysis of cell morphology performed by transmission electron microscopy confirmed that BiNPs induced cell damage only at a high concentration (302.24 µg/ml), equivalent to IC50 concentration. Moreover, BiNPs exposure increased the expression of the cell proliferation marker Ki-67 and the incorporation of the thymidine analogue EdU into cell DNA, suggesting that these nanoparticles could be stimulating ADSC proliferation. BiNPs also increased the mitochondrial membrane potential. Furthermore, BiNPs reduced ADSC adipogenic differentiation as measured by lipid droplet accumulation and mRNA expression levels of the specific adipogenesis biomarkers PPARγ, C/EPBɑ and FABP4. Thus, BiNPs affect the nonspecific (viability, proliferation and mitochondrial activity) and specific (adipogenesis) cellular mechanisms of ADSCs.

Cytotoxicity of bismuth nanoparticles in the murine macrophage cell line RAW 264.7.

A promising use of bismuth nanoparticles (BiNPs) for different biomedical applications leads to a search for the elucidation of their toxicity mechanisms, since toxicity studies are still at early stage. In the current study, cytotoxic effects of BiNPs produced by laser ablation in solution (LASiS) was investigated in the murine macrophage line RAW 264.7. The cells were exposed to 0.01-50 µg ml-1 of BiNPs for 24 and 48 h and then cytotoxicity assays were performed. Decrease of MTT conversion to formazan and of cell attachment were observed with no effects on cell proliferation. No loss of membrane integrity or significant changes of ROS and RNS levels were observed in exposed cells. Foremost, increased phagocytic activity and DNA repair foci occurred for cells exposed to BiNPs. These effects are important findings that must be considered in the case of biomedical application of BiNPs, since inappropriate macrophages activation and inactivation may lead to immunotoxicity. Bismuth nanoparticles (BiNPs) produced by laser ablation in solution and stabilized with BSA decrease enzyme-dependent MTT conversion to formazan and increase phagocytic activity and DNA repair foci in murine macrophage line RAW 264.7 when exposed to 50 µg ml-1. These effects are findings that should be considered in the case of biomedical application of BiNPs, since inappropriate macrophages activation and inactivation may lead to immunotoxicity.

Dose-dependent cytotoxicity of bismuth nanoparticles produced by LASiS in a reference mammalian cell line BALB/c 3T3.

Nanoparticles (NPs) have emerged as new potential tools for many applications in previous years. Among all types of NPs, bismuth NPs (BiNPs) have a very low cost and potential for many applications, ranging from medicine to industry. Although the toxic effects of bismuth have been studied, little is known about its toxicity at the nanoscale level. Therefore, in this study, we aimed to investigate the cytotoxic effects of BiNPs produced by laser ablation synthesis in solution (LASiS) in a reference mammalian cell line to evaluate their cytotoxicity (BALB/c 3 T3 cells). We also stabilized BiNPs in two different solutions: culture medium supplemented with fetal bovine serum (FBS) and bovine serum albumin (BSA). The cytotoxicity of BiNPs in culture medium (IC50:28.51 ±â€¯9.96 µg/ml) and in BSA (IC50:25.54 ±â€¯8.37 µg/ml) was assessed, and they were not significantly different. Second, the LD50 was predicted, and BiNPs were estimated as GHS class 4. We also found that cell death occurs due to apoptosis. By evaluating the interaction between BiNPs and cells at ultrastructural level, we suggest that cell death occurs once BiNPs are internalized. Additionally, we suggest that BiNPs cause cell damage because myelin figures were found inside cells that had internalized BiNPs. To date, this is the first study to assess the cytotoxicity of BiNPs produced by LASiS and to predict the possible LD50 and GHS class of BiNPs.

Photodegradation applied to the treatment of phenol and derived substances catalyzed by TiO2/BiPO4 and biological toxicity analysis.

For this work, a phenol solution model was treated by an advanced oxidation process (AOPs), using the heterogeneous catalyst TiO2/BiPO4 and hydrogen peroxide combined with UVA for 240 min. An annular reactor containing a UVA lamp (80 W) was employed. A central composite rotacional design was developed employing a TiO2/BiPO4 concentration of 87 mg L-1 and a hydrogen peroxide concentration of 1800 mg L-1, being evaluated by the degradation percentage and phenol mineralization percentage as responses; 94.30 and 67.00 % were obtained for the phenol degradation and total organic carbon (TOC) conversion, respectively. The lumped kinetic model (LKM) was applied and a satisfactory profile of the residual fractions of the organic compounds present in the liquid phase as a time function with a determination coefficient (R 2 = 0.9945). The toxicity tests employing microbiological species indicated that the organisms tested for the evaluation of the toxic compounds present in the contaminated samples presented a practical low cost test, rapid execution, and high sensibility as an indicator of the presence of toxic substances in liquid effluents.

Cytotoxicity and osteogenic potential of silicate calcium cements as potential protective materials for pulpal revascularization.

OBJECTIVES: In pulpal revascularization, a protective material is placed coronal to the blood clot to prevent recontamination and to facilitate osteogenic differentiation of mesenchymal stem cells to produce new dental tissues. Although mineral trioxide aggregate (MTA) has been the material of choice for clot protection, it is easily displaced into the clot during condensation. The present study evaluated the effects of recently introduced calcium silicate cements (Biodentine and TheraCal LC) on the viability and osteogenic differentiation of human dental pulp stem cells (hDPSCs) by comparing with MTA Angelus. METHODS: Cell viability was assessed using XTT assay and flow cytometry. The osteogenic potential of hDPSCs exposed to calcium silicate cements was examined using qRT-PCR for osteogenic gene expressions, alkaline phosphatase enzyme activity, Alizarin red S staining and transmission electron microscopy of extracellular calcium deposits. Parametric statistical methods were employed for analyses of significant difference among groups, with α=0.05. RESULTS: The cytotoxic effects of Biodentine and TheraCal LC on hDPSCs were time- and concentration-dependent. Osteogenic differentiation of hDPSCs was enhanced after exposure to Biodentine that was depleted of its cytotoxic components. This effect was less readily observed in hDPSCs exposed to TheraCal LC, although both cements supported extracellular mineralization better than the positive control (zinc oxide-eugenol-based cement). SIGNIFICANCE: A favorable tissue response is anticipated to occur with the use of Biodentine as a blood clot-protecting material for pulpal revascularization. Further investigations with the use of in vivo animal models are required to validate the potential adverse biological effects of TheraCal LC on hDPSCs.

Rat subcutaneous tissue response to calcium silicate containing different arsenic concentrations

Objective: To evaluate the response of rat subcutaneous tissue in implanted polyethylene tubes that were filled with GMTA Angelus and Portland cements containing different arsenic concentrations. Material and Methods: Atomic absorption spectrophotometry was utilized to obtain the values of the arsenic concentration in the materials. Thirty-six rats were divided into 3 groups of 12 animals for each experimental period. Each animal received two implants of polyethylene tubes filled with different test cements and the lateral of the tubes was used as a control group. After 15, 30 and 60 days of implantation, the animals were killed and the specimens were prepared for descriptive and morphometric analysis considering: inflammatory cells, collagen fibers, fibroblasts, blood vessels and other components. The results were analyzed utilizing the Kuskal-Wallis test and the Dunn's Multiple test for comparison (p<0.05). Results: The materials showed, according to atomic absorption spectrophotometry, the following doses of arsenic: GMTA Angelus: 5.01 mg/kg, WPC Irajazinho: 0.69 mg/kg, GPC Minetti: 18.46 mg/kg and GPC Votoran: 10.76 mg/kg. In a 60-day periods, all specimens displayed a neoformation of connective tissue with a structure of fibrocellular aspect (capsule). Control groups and MTA Angelus produced the lower amount of inflammatory reaction and GPC Minetti, the highest reaction. Conclusions: There was no direct relationship between the concentration of arsenic present in the composition of the materials and the intensity of the inflammatory reactions. Higher values, as 18.46 mg/kg of arsenic in the cement, produce characteristics of severe inflammation reaction at the 60-day period. The best results were found in MTA angelus. .

Rat subcutaneous tissue response to calcium silicate containing different arsenic concentrations.

OBJECTIVE: To evaluate the response of rat subcutaneous tissue in implanted polyethylene tubes that were filled with GMTA Angelus and Portland cements containing different arsenic concentrations. MATERIAL AND METHODS: Atomic absorption spectrophotometry was utilized to obtain the values of the arsenic concentration in the materials. Thirty-six rats were divided into 3 groups of 12 animals for each experimental period. Each animal received two implants of polyethylene tubes filled with different test cements and the lateral of the tubes was used as a control group. After 15, 30 and 60 days of implantation, the animals were killed and the specimens were prepared for descriptive and morphometric analysis considering: inflammatory cells, collagen fibers, fibroblasts, blood vessels and other components. The results were analyzed utilizing the Kuskal-Wallis test and the Dunn's Multiple test for comparison (p<0.05). RESULTS: The materials showed, according to atomic absorption spectrophotometry, the following doses of arsenic: GMTA Angelus: 5.01 mg/kg, WPC Irajazinho: 0.69 mg/kg, GPC Minetti: 18.46 mg/kg and GPC Votoran: 10.76 mg/kg. In a 60-day periods, all specimens displayed a neoformation of connective tissue with a structure of fibrocellular aspect (capsule). Control groups and MTA Angelus produced the lower amount of inflammatory reaction and GPC Minetti, the highest reaction. CONCLUSIONS: There was no direct relationship between the concentration of arsenic present in the composition of the materials and the intensity of the inflammatory reactions. Higher values, as 18.46 mg/kg of arsenic in the cement, produce characteristics of severe inflammation reaction at the 60-day period. The best results were found in MTA angelus.

Novel experimental cements for use on the dentin-pulp complex.

This aim of this study was to evaluate the physicochemical and biological properties of novel experimental cements (Hybrid, Paste and Resin) based on synergistic combinations of existing materials, including pH, diametral tensile strength (DTS) and cytotoxicity comparing them with mineral trioxide aggregate (MTA - Angelus®) and a glass ionomer cement (GIC) developed at our laboratory. For the physicochemical and biological tests, specimens with standard dimensions were produced. pH measurements were performed with digital pH meter at the following time intervals: 3, 24, 48 and 72 h. For the DTS test, cylindrical specimens were subjected to compressive load until fracture. The MTT assay was performed for cytotoxicity evaluation. Data were analyzed by ANOVA and Tukey's test (α=0.05). Paste group showed pH values similar to MTA, and Hybrid group presented pH values similar to GIC (p>0.05). The tested materials showed pH values ranging from alkaline to near neutrality at the evaluated times. MTA and GIC showed similar DTS values. The lowest and highest DTS values were seen in the Paste and Resin groups, respectively (p<0.05). Cell viability for MTA and experimental Hybrid, Paste and Resin groups was 49%, 93%, 90% and 86%, respectively, when compared with the control group. The photo-cured experimental resin cement showed similar or superior performance compared with the current commercial or other tested experimental materials.

Novel experimental cements for use on the dentin-pulp complex

This aim of this study was to evaluate the physicochemical and biological properties of novel experimental cements (Hybrid, Paste and Resin) based on synergistic combinations of existing materials, including pH, diametral tensile strength (DTS) and cytotoxicity comparing them with mineral trioxide aggregate (MTA - Angelus®) and a glass ionomer cement (GIC) developed at our laboratory. For the physicochemical and biological tests, specimens with standard dimensions were produced. pH measurements were performed with digital pH meter at the following time intervals: 3, 24, 48 and 72 h. For the DTS test, cylindrical specimens were subjected to compressive load until fracture. The MTT assay was performed for cytotoxicity evaluation. Data were analyzed by ANOVA and Tukey's test (α=0.05). Paste group showed pH values similar to MTA, and Hybrid group presented pH values similar to GIC (p>0.05). The tested materials showed pH values ranging from alkaline to near neutrality at the evaluated times. MTA and GIC showed similar DTS values. The lowest and highest DTS values were seen in the Paste and Resin groups, respectively (p<0.05). Cell viability for MTA and experimental Hybrid, Paste and Resin groups was 49%, 93%, 90% and 86%, respectively, when compared with the control group. The photo-cured experimental resin cement showed similar or superior performance compared with the current commercial or other tested experimental materials.

O objetivo deste estudo foi avaliar propriedades físico-químicas e biológicas de novos cimentos experimentais (Híbrido, Pasta e Resinoso) baseado na combinação sinérgica de materiais existentes, incluindo pH, resistência à tração diametral (RTD) e citotoxidade, comparando-os ao MTA (Angelus®) e a um cimento de ionômero de vidro (CIV) desenvolvido em nosso laboratório. Para a realização dos testes físico-mecânico e biológico, foram confeccionados espécimes com dimensões padrão. O teste de pH foi realizado por meio de pH-metro digital nos tempos: 3, 24, 48 e 72 h. Para o teste de RTD, espécimes cilíndricos foram submetidos a carga compressiva até sua fratura. Para avaliação da citotoxidade, utilizou-se o teste MTT. Os dados foram analisados utilizando ANOVA e teste de Tukey (α=0,05). O grupo Pasta apresentou valores de pH semelhantes ao MTA, assim como o grupo Híbrido seguiu os parâmetros do CIV (p>0,05). Todos os materiais apresentaram valores de pH alcalinos ou próximosà neutralidade nos tempos avaliados. MTA e CIV apresentaram valores de RTD similares. Os menores e maiores valores observados foram do grupo Pasta e Resinoso, respectivamente (p<0,05). A viabilidade celular para os grupos MTA, Híbrido, Pasta, Resinoso, quando comparados ao grupo controle foi de: 49, 93, 90 e 86%, respectivamente. O cimento experimental Resinoso apresentou desempenho similar ou superior aos materiais comerciais e experimentais avaliados.

Cytotoxicity of Portland cement with different radiopacifying agents: a cell death study.

INTRODUCTION: The aim of this study was to investigate the cytotoxicity of white Portland cement (PC) alone or associated with bismuth oxide (PCBi), zirconium oxide (PCZir), and calcium tungstate (PCCa) in 2 cell lineages. METHODS: Murine periodontal ligament cells (mPDL) and rat osteosarcoma cells (ROS 17/2.8) were exposed for 24 hours to specific concentrations of fresh PC and PC associations with radiopacifiers. Zinc oxide-eugenol cement and hydrogen peroxide treatment were applied as cytotoxic positive controls. Cell viability after incubation with the cements was assessed by mitochondrial dehydrogenase enzymatic assay. Cell morphology was microscopically analyzed by cresyl violet staining, and the mechanism of cell death was determined by acridine orange/ethidium bromide methodology. All data were analyzed statistically by analysis of variance and Tukey post hoc test (P < .05). The correlation among cell death by apoptosis or necrosis and pH values was established by Pearson linear coefficient. RESULTS: The mitochondrial dehydrogenase enzymatic assay only revealed significant cell death rate at high concentrations of cement elutes. PC alone was not cytotoxic, even at 100 mg/mL. Microscopic images showed that none of the PC formulations caused damage to any cell lines. Statistical analysis of apoptosis/necrosis data demonstrated that PC and PC plus radiopacifying agents promoted significant necrosis cell death only at 100 mg/mL. CONCLUSIONS: The mPDL cells were more sensitive than ROS17/2.8. The results showed that PC associated with bismuth oxide, zirconium oxide, or calcium tungstate is not cytotoxic to mPDL or ROS17/2.8. Zirconium oxide and calcium tungstate might be good alternatives as radiopacifying agents.

Ex vivo assessment of genotoxicity and cytotoxicity in murine fibroblasts exposed to white MTA or white Portland cement with 15% bismuth oxide.

AIMS: To evaluate whether white mineral trioxide aggregate (MTA) or white Portland cement with 15% bismuth oxide were able to induce genetic damage and cellular death ex vivo. METHODOLOGY: Aliquots of 1 × 10(4) murine fibroblasts were incubated at 37 °C for 3 h with MTA (white) or white Portland cement with 15% bismuth oxide, at final concentrations ranging from 10 to 1000 µg mL(-1) individually. Data of three independent repeats from the comet assay and the trypan blue exclusion test were assessed by the one-way anova followed by Tukey's test. RESULTS: Mineral trioxide aggregate or Portland cement containing bismuth oxide did not produce genotoxic effects with respect to the single-cell gel (comet) assay data for all concentrations evaluated. Furthermore, no cytotoxicity was observed for MTA or Portland cement. CONCLUSION: White MTA or white Portland cement containing 15% bismuth oxide were not genotoxic and cytotoxic.

Cytotoxicity evaluation of two root canal sealers and a commercial calcium hydroxide paste on THP1 cell line by Trypan Blue assay.

OBJECTIVE: The aim of this investigation was to evaluate the cytotoxicity of two brands of root canal sealers, epoxy-resin based and zinc oxide-eugenol based, and one commercial calcium hydroxide paste on a monocyte cell line THP-1. MATERIAL AND METHODS: Undiluted (crude extract) and diluted extracts to 10%, 1%, 0.1%, 0.01%, 0.001% and 0.0001% of the sealers were tested for cytotoxicity to THP-1 cells using the trypan blue assay. Extracts were obtained according to ISO standard. Data were analyzed statistically by the Kruskal-Wallis and Mann-Whitney tests at 5% significance level. RESULTS: Crude extract of AH Plus and Fill Canal killed approximately 90% of THP-1 cells versus 36% of THP-1 cells killed by L&C crude extract (p<0.05). Ten-fold dilutions of L&C, Fill Canal and AH Plus killed 24, 35 and 61% of THP-1 cells (p<0.05), respectively. Dilutions lesser than 1% caused minimal cell death as compared to the control groups (p>0.05), except for L&C 1% extract. CONCLUSIONS: The results revealed that the L&C paste crude extract was less cytotoxic to THP-1 cells than AH Plus or Fill Canal crude extracts.

Cytotoxicity evaluation of two root canal sealers and a commercial calcium hydroxide paste on THP1 cell line by Trypan Blue assay

OBJECTIVE: The aim of this investigation was to evaluate the cytotoxicity of two brands of root canal sealers, epoxy-resin based and zinc oxide-eugenol based, and one commercial calcium hydroxide paste on a monocyte cell line THP-1. MATERIAL AND METHODS: Undiluted (crude extract) and diluted extracts to 10 percent, 1 percent, 0.1 percent, 0.01 percent, 0.001 percent and 0.0001 percent of the sealers were tested for cytotoxicity to THP-1 cells using the trypan blue assay. Extracts were obtained according to ISO standard. Data were analyzed statistically by the Kruskal-Wallis and Mann-Whitney tests at 5 percent significance level. RESULTS: Crude extract of AH Plus and Fill Canal killed approximately 90 percent of THP-1 cells versus 36 percent of THP-1 cells killed by L&C crude extract (p<0.05). Ten-fold dilutions of L&C, Fill Canal and AH Plus killed 24, 35 and 61 percent of THP-1 cells (p<0.05), respectively. Dilutions lesser than 1 percent caused minimal cell death as compared to the control groups (p>0.05), except for L&C 1 percent extract. CONCLUSIONS: The results revealed that the L&C paste crude extract was less cytotoxic to THP-1 cells than AH Plus or Fill Canal crude extracts.

Radiopacifiers do not induce genetic damage in murine fibroblasts: an in vitro study.

AIM: To evaluate whether several radiopacifiers are able to induce genetic damage in a laboratory cell culture study. METHODOLOGY: Murine fibroblasts were exposed to barium sulphate, bismuth oxide or zirconium oxide, at final concentrations ranging from 10 to 1000 microg mL(-1) for 1 h at 37 degrees C. The negative control group was treated with a vehicle control [phosphate buffered solution (PBS)] for 1 h at 37 degrees C and the positive control group was treated with hydrogen peroxide (at 10 microM) for 5 min on ice. Genotoxicity data were assessed by the single-cell gel (comet) assay. RESULTS: All the tested compounds did not induce DNA breakage as depicted by the mean tail moment in all the concentrations analysed. CONCLUSION: Exposure to the tested radiopacifiers may not be a factor that increases the level of DNA lesions in mammalian cells as detected by a single-cell gel (comet) assay.

Radiopacity and histological assessment of Portland cement plus bismuth oxide.

OBJECTIVE: The present study evaluated the subcutaneous connective tissue reactions and the radiopacity of MTA, Portland cement (PC), and Portland cement plus bismuth oxide (BO). STUDY DESIGN: Forty rats were divided into 5 groups (n = 8 per group): A1: Control (empty capsule); A2: Pro-Root MTA; A3: PC; A4: PC + BO 1:1; and A5: PC + BO 2:1. Polyethylene tubes were filled with the test materials and standardized radiographic images were taken. Histological evaluation was done after 7 and 60 days. Student t test and Fisher's test were used in the statistical analysis (P < .05). RESULTS: The radiopacity of the materials were in decreasing order: A2 > A4 > A5 > A3. No differences were found for the tissue response in the 2 experimental periods. A positive correlation between BO concentration and radiopacity of PC was determined. CONCLUSION: The histological evaluation suggests that all studied materials were biocompatible at 7 and 60 days.

Cell-cycle deregulation induced by three different root canal sealers in vitro.

The aim of this study was to investigate the effects of 3 root canal sealers on the cell cycle of mouse fibroblasts (3T3 cell line). Freshly mixed root canal sealers (AH Plus, Endofill, and Sealer 26) were eluted for 24 h using cell culture medium. Antiproliferation activity of different eluate dilutions was determined by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay. Cell cycle was subsequently evaluated by flow cytometry. Differences were tested by analysis of variance with Tukey test (P < .05). Results showed that the root canal sealers inhibited cell growth in a dose-dependent manner. Antiproliferation activity of the root canal sealers was associated with cell-cycle deregulation. This event involved cell-cycle arrest in the S/G2/M phases and an increase of the sub-G1 population, which are consistent with both cytostatic and cytotoxic effects. This information may contribute to a better understanding of the toxicity mechanism displayed by root canal sealers currently used in clinical practice.

Rheological properties and biocompatibility of endodontic sealers.

AIM: To determine the flow characteristics and subcutaneous tissue reactions to five endodontic sealers. METHODOLOGY: The materials used were Procosol, AH26, Endomethasone, Sealapex and Endion. The sealers were prepared following the manufacturers' instructions, and 0.075 mL of each material was placed on a glass surface, which was then rotated 90 degrees. The samples were stored at 37 degrees C and 95% humidity. The displacement of the sealer was recorded by measuring the difference between its original position and the position recorded at 15 and 60 min. Three samples of each material were used. Two pockets were created in the back of Wistar rats, and one silicone tube, 1 mm in diameter and 1 cm in length, was implanted in each. One was filled with one of the materials under study, and the other empty tube was implanted as a control. Fourteen days after implantation, the animals were sacrificed, and samples of the skin containing the tubes were histologically processed. Histological and histomorphometric evaluations of the tissues adjacent to the open end of the tube were carried out the volume of tissue reaction was measured histomorphometrically according to standard stereological principles. Results were statistically analysed using analysis of variance and Duncan's test. RESULTS: The highest flow values were obtained with Sealapex and AH26. Time significantly affected the flow and the material (P < (1001). Procosol and Endion produced the most severe histological reactions: these were outlined by fibrous tissue; AH26. Endomethasone and Sealapex produced reactions of smaller size and with more moderately defined limits. CONCLUSIONS: The flow did not correlate with the degree of inflammatory response. Procosol and Endion produced the most severe tissue reactions, whereas Endomethasone, Sealapex and AH26 produced only minimum reactions.

Evaluation of cell culture cytotoxicity of five root canal sealers.

The cytotoxicity of four calcium hydroxide-based root canal sealers (Sealapex, CRCS, Apexit, and Sealer 26) and one zinc oxide-eugenol-based sealer (Fill Canal) was evaluated microscopically for morphological changes in rat peritoneal macrophages. The least cytotoxic sealer was Fill Canal, followed in increasing order of cytotoxicity by CRCS, Sealer 26, Apexit, and Sealapex.