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

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.

Radiopacity evaluation of calcium silicate cements

BACKGROUND

The aim of this study was to compare the radiopacity of calcium silicate cements using a digital imaging method.

METHODS

Four calcium silicate cements, NeoMTA 2, OrthoMTA, ProRoot MTA, and Biodentine, were used in this study. Disk-shaped samples were prepared from each material and placed on a plexiglass plate. An aluminum step-wedge was placed alongside the samples on a digital sensor and exposed to 70 kVp and 8 mA from 30 cm away for 0.32 s. The greyness values ​​of the tested materials were measured digitally with the system software and compared with those of the step-wedge to determine the equivalent aluminum thickness.

RESULTS

The radiopacity values, expressed in equivalent millimetres of aluminum, of the studied materials ProRoot MTA, OrthoMTA, NeoMTA 2, and Biodentine were 4.32 ± 0.17 mm Al, 3.92 ± 0.09 mm Al, 3.83 ± 0.07 mm Al, and 2.29 ± 0.21 mm Al, respectively. Statistically significant differences were found between the mean radiographic density values of the tested materials (p < 0.05).

CONCLUSION

ProRoot MTA was the most radiopaque root canal filling material among the tested materials. All materials, except Biodentine, were found to be compliant with the minimum radiopacity requirements of ISO 6876 and ADA 57 standards.

Bismuth release from endodontic materials: in vivo analysis using Wistar rats

Calcium silicate-based materials are used to block the communication between the root canal and the periodontal ligament space. This brings the materials into contact with tissues and the potential for local and systemic elemental release and movement. The aim of the study was to evaluate the elemental release of bismuth from ProRoot MTA in contact with connective tissues after 30 and 180 days as well as any accumulation in peripheral organs using an animal model. Tricalcium silicate and hydroxyapatite containing 20% bismuth oxide (HAp-Bi) were used as controls. The null hypothesis was that bismuth migrates from tricalcium silicate-based materials when associated with silicon. The materials were examined using scanning electron microscopy, energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction prior to implantation as well as using SEM/EDS, micro X-ray fluorescence and Raman spectroscopy after implantation to assess elemental presence in surrounding tissues. Histological analysis was used to evaluate the changes in tissue architecture and inductively coupled plasma mass spectrometry (ICP-MS) was used to investigate the elemental deposition. For the systemic investigation, routine blood analysis was performed and organs were obtained to evaluate the presence of bismuth and silicon using ICP-MS after acid digestion. In the histological analysis of the implantation sites, macrophages and multinucleated giant cells could be observed after 30 days which after 180 days became a chronic infiltrate; although, no major differences were identified in red and white blood cell analyses and biochemical tests. Implantation altered the materials as observed in the Raman analysis and bismuth was detected both locally and within kidney samples after both periods of analysis, indicating the potential for accumulation of bismuth in this organ. Smaller amounts of bismuth than observed in the kidney were also detected in blood, liver and brain for the ProRoot MTA and HAp-Bi after 180 days. Bismuth was released from the ProRoot MTA locally and was detected systemically and in samples without silicon; thus, the null hypothesis was rejected. The bismuth release demonstrated that this element accumulated both locally and systemically, mainly in the kidneys in comparison with brain and liver regardless of the material base.

Fast-Setting Calcium Silicate-Based Pulp Capping Cements-Integrated Antibacterial, Irritation and Cytocompatibility Assessment

Calcium silicate-based cements (CSCs) are endodontic materials widely used in vital pulp-capping approaches. Concerning the clinical application, the reduced set time and pre-mixed formulations are relevant characteristics during the operative management of pulpal exposure, aiming to optimise the work time and improve cross-infection/asepsis control. Additionally, clinical success seems to be greatly dependent on the biological performance of the materials that directly contact the living pulp. As such, this work approaches an integrative biological characterisation (i.e., antibacterial, irritation, and cytocompatibility assays) of three fast-setting CSCs-Biodentine^TM, TotalFill^® BC RRM™ Fast Putty, and Theracal LC^®. These cements, after setting for 24 h, presented the expected topography and elemental composition (assessed by scanning electron microscopy, coupled with EDS analysis), in accordance with the information of the manufacturer. The set cements displayed a significant and similar antibiofilm activity against S. mutans, in a direct contact assay. Twenty-four-hour eluates were not irritant in the standardised CAM assay, but elicited distinct dose- and time-dependent cytotoxicity profiles on fibroblastic cells-i.e., Biodentine was devoid of toxicity, TotalFill presented a slight dose-dependent initial toxicity that was easily overcome, and Theracal LC was deleterious at high concentrations. When compared to long-setting ProRoot MTA cement, which highlighted the pursued integrative approach, Biodentine presented a similar profile, but TotalFill and Theracal LC displayed a poorer performance regarding antibiofilm activity/cytocompatibility features, and Theracal LC suggested eventual safety concerns.

Cytotoxicity and Antibacterial Activity of Mineral Trioxide Aggregate Cement with Radiopacity Introduced by ZrO2

The article presents the results of in vitro studies on cytotoxicity and antibacterial activity of new MTA-type cements, developed on the basis of the sintered tricalcium silicate enriched with ZnO, along with an agent introducing the radiopacity in the form of ZrO₂. The new materials have been developed to ensure that their physical and chemical properties are suited for endodontic applications. The cements were evaluated via characterisation of setting time, compressive strength, as well as translucency on X-ray images, and bioactivity in the simulated body fluid (SBF). The μCT was used to test the influence of the ZrO₂ grains in the powder component on the microstructure of the produced cement. Then, the cytotoxic action of the cements was evaluated by applying a reference L-929 cell line. The conditions of the culture upon contact with the tested materials or with extracts from the cements were assessed using image analysis or an MTT colorimetric assay. Two strains of streptococci, Streptococcus mutans and Streptococcus sanguinis, were used to study the antibacterial activity of the tested cements with ZrO₂ acting as the agent introducing the radiopacity. The new cements are characterised by appropriate properties as far as retrograde root canal filling is concerned.

Fabrication and Characterization of a Nanofast Cement for Dental Restorations

This study was aimed at fabricating and evaluating the physical and bioproperties of nanofast cement (NFC) as a replacement of the MTA. The cement particles were decreased in nanoscale, and zirconium oxide was used as a radiopacifier. The setting time and radiopacity were investigated according to ISO recommendations. Analysis of color, bioactivity, and cytotoxicity was performed using spectroscopy, simulated body fluid (SBF), and MTT assay. The setting time of cement pastes significantly dropped from 65 to 15 min when the particle sizes decreased from 2723 nm to 322 nm. Nanoparticles provide large surface areas and nucleation sites and thereby a higher hydration rate, so they reduced the setting time. Based on the resulting spectroscopy, the specimens did not exhibit clinically noticeable discoloration. Resistance to discoloration may be due to the resistance of zirconium oxide to decomposition. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and infrared spectroscopy (FTIR) examinations of the immersed SBF samples showed apatite formation that was a reason for its suitable bioactivity. The results of cell culture revealed that NFC is nontoxic. This study showed that NFC was more beneficial than MTA in dental restorations.

Biological assessment of a new ready-to-use hydraulic sealer

Objectives

This study compared the cytotoxicity, biocompatibility, and tenascin immunolabeling of a new ready-to-use hydraulic sealer (Bio-C Sealer) with MTA-Fillapex and white MTA-Angelus.

Materials and Methods

L929 fibroblasts were cultivated and exposed to undiluted and diluted material extracts. Polyethylene tubes with or without (the control) the materials were implanted into the dorsa of rats. At 7 days and 30 days, the rats were euthanized, and the specimens were prepared for analysis; inflammation and immunolabeling were measured, and statistical analysis was performed (p < 0.05).

Results

MTA-Fillapex exhibited greater cytotoxicity than the other materials at all time points (p < 0.05). The undiluted Bio-C Sealer exhibited greater cytocompatibility at 6 and 48 hours than white MTA-Angelus, with higher cell viability than in the control (p < 0.05). White MTA-Angelus displayed higher cell viability than the control at 24 hours, and the one-half dilution displayed similar results at both 6 and 48 hours (p < 0.05). At 7 days and 30 days, the groups exhibited moderate inflammation with thick fibrous capsules and mild inflammation with thin fibrous capsules, respectively (p > 0.05). At 7 days, moderate to strong immunolabeling was observed (p > 0.05). After 30 days, the control and MTA-Fillapex groups exhibited strong immunolabeling, the white MTA-Angelus group exhibited moderate immunolabeling (p > 0.05), and the Bio-C Sealer group exhibited low-to-moderate immunolabeling, differing significantly from the control (p < 0.05).

Conclusions

Bio-C Sealer and white MTA-Angelus exhibited greater cytocompatibility than MTA-Fillapex; all materials displayed adequate biocompatibility and induced tenascin immunolabeling.

Injectable calcium phosphate and styrene–butadiene polymer-based root canal filling material

Background

Three-dimensional obturation of the root canal system is mandatory for a successful root canal treatment. Using a filling material with optimal properties may enable the root canal to be sealed well and therefore obtain the desired obturation.

Objective

To develop a new injectable paste endodontic filling material using calcium phosphate powder and a styrene–butadiene emulsion polymer.

Methods

The powder phase comprised an equivalent molar ratio of tetracalcium phosphate, anhydrous dicalcium phosphate, bismuth oxide, and calcium chloride. The liquid phase comprised a styrene–butadiene rubber emulsion in distilled water. The powder and the liquid were mixed to achieve a paste consistency. The paste was subjected to various tests including flow, setting time, dimensional change, solubility, and radiopacity to indicate its suitability as a root canal filling material. All these tests were conducted according to the American National Standards Institute–American Dental Association for endodontic sealing materials. After passing these tests, the paste was submitted to an injectability test.

Results

The material showed acceptable flowability with 19.1 ± 1.3 min setting time and 0.61 ± 0.16% shrinkage after 30 days of storage. We found the highest solubility at 24 h (6.62 ± 0.58%), then the solubility decreased to 1.09 ± 0.08% within 3 days. The material was more radiopaque than a 3 mm step on an aluminum wedge. Furthermore, the material showed good injectability of 93.67 ± 1.80%.

Conclusions

The calcium phosphate powder in styrene–butadiene emulsion met basic requirements for a root canal filling material with promising properties.

Injectable calcium phosphate and styrene-butadiene polymer-based root canal filling material

Background

Three-dimensional obturation of the root canal system is mandatory for a successful root canal treatment. Using a filling material with optimal properties may enable the root canal to be sealed well and therefore obtain the desired obturation.

Objective

To develop a new injectable paste endodontic filling material using calcium phosphate powder and a styrene-butadiene emulsion polymer.

Methods

The powder phase comprised an equivalent molar ratio of tetracalcium phosphate, anhydrous dicalcium phosphate, bismuth oxide, and calcium chloride. The liquid phase comprised a styrene-butadiene rubber emulsion in distilled water. The powder and the liquid were mixed to achieve a paste consistency. The paste was subjected to various tests including flow, setting time, dimensional change, solubility, and radiopacity to indicate its suitability as a root canal filling material. All these tests were conducted according to the American National Standards Institute-American Dental Association for endodontic sealing materials. After passing these tests, the paste was submitted to an injectability test.

Results

The material showed acceptable flowability with 19.1 ± 1.3 min setting time and 0.61 ± 0.16% shrinkage after 30 days of storage. We found the highest solubility at 24 h (6.62 ± 0.58%), then the solubility decreased to 1.09 ± 0.08% within 3 days. The material was more radiopaque than a 3 mm step on an aluminum wedge. Furthermore, the material showed good injectability of 93.67 ± 1.80%.

Conclusions

The calcium phosphate powder in styrene-butadiene emulsion met basic requirements for a root canal filling material with promising properties.

Cytotoxicity, inflammation, biomineralization, and immunoexpression of IL-1β and TNF-α promoted by a new bioceramic cement

Aim To evaluate the cytotoxicity, biocompatibility and mineralization capacity of BIO-C PULPO, and MTA. Methodology L929 fibroblasts were cultured and MTT assay was used to determine the material cytotoxicity on 6, 24, and 48 h. A total of 30 male rats (Wistar) aged between 4 and 6 months, weighing between 250 and 300 g were used. Polyethylene tubes containing BIO-C PULPO, MTA, and empty tubes were implanted into dorsal connective tissue. After the experimental periods (7, 15, 30, 60, and 90 days) the tubes were histologically analyzed using hematoxylin-eosin (H&E), immunolabeling of IL-1β and TNF-α, and von Kossa staining, or without staining for polarized light analysis. The average number of inflammatory cells was quantified; the mineralization assessment was determined by the area marked in μm2 and semiquantitative immunolabeling analyses of IL-1β and TNF-α were performed. Then, data underwent statistical analysis with a 5% significance level. Results It was observed that BIO-C PULPO and MTA presented cytocompatibility at 6, 24, and 48 similar or higher than control for all evaluated period. On periods 7 and 15 days, BIO-C PULPO was the material with the highest number of inflammatory cells (p<0.05). On periods 30, 60, and 90 days, BIO-C PULPO and MTA presented similar inflammatory reactions (p>0.05). No statistical differences were found between Control, BIO-C PULPO, and MTA for immunolabeling of IL-1β and TNF-α in the different periods of analysis (p<0.05). Positive von Kossa staining and birefringent structures under polarized light were observed in all analyzed periods in contact with both materials, but larger mineralization area was found with BIO-C PULPO on day 90 (p<0.05). Conclusion BIO-C PULPO was biocompatible and induced mineralization similar to MTA.

Cytotoxicity and Bioactivity of Dental Pulp-Capping Agents towards Human Tooth-Pulp Cells: A Systematic Review of In-Vitro Studies and Meta-Analysis of Randomized and Controlled Clinical Trials

Background. In the era of biology-driven endodontics, vital pulp therapies are regaining popularity as a valid clinical option to postpone root-canal treatment. In this sense, many different materials are available in the market for pulp-capping purposes. Objectives. The main aim of this systematic review and meta-analysis was to examine literature regarding cytotoxicity and bioactivity of pulp-capping agents by exposure of human dental pulp cells of primary origin to these materials. A secondary objective was to evaluate the inflammatory reaction and reparative dentin-bridge formation induced by the different pulp-capping agents on human pulp tissue. Data sources. A literature search strategy was carried out on PubMed, EMBASE and the Web of Science databases. The last search was done on 1 May 2020. No filters or language restrictions were initially applied. Two researchers independently selected the studies and extracted the data. Study selection included eligibility criteria, participants and interventions, study appraisal and synthesis methods. In vitro studies were included when human dental pulp cells of primary origin were (in)directly exposed to pulp-capping agents. Parallel or split-mouth randomized or controlled clinical trials (RCT or CCT) were selected to investigate the effects of different pulp-capping agents on the inflammation and reparative bridge-formation capacity of human pulp tissue. Data were synthesized via odds ratios (95% confidence interval) with fixed or random effects models, depending on the homogeneity of the studies. The relative risks (95% confidence interval) were presented for the sake of interpretation. Results. In total, 26 in vitro and 30 in vivo studies were included in the systematic review and meta-analysis, respectively. The qualitative analysis of in vitro data suggested that resin-free hydraulic calcium-silicate cements promote cell viability and bioactivity towards human dental pulp cells better than resin-based calcium-silicate cements, glass ionomers and calcium-hydroxide cements. The meta-analysis of the in vivo studies indicated that calcium-hydroxide powder/saline promotes reparative bridge formation better than the popular commercial resin-free calcium-silicate cement Pro-Root MTA (Dentsply-Sirona), although the difference was borderline non-significant (p = 0.06), and better than calcium-hydroxide cements (p < 0.0001). Moreover, resin-free pulp-capping agents fostered the formation of a complete reparative bridge better than resin-based materials (p < 0.001). On the other hand, no difference was found among the different materials tested regarding the inflammatory effect provoked at human pulp tissue. Conclusions. Calcium-hydroxide (CH) powder and Pro-Root MTA (Dentsply-Sirona) have shown excellent biocompatibility in vitro and in vivo when tested on human cells and teeth. Their use after many years of research and clinical experience seems safe and proven for vital pulp therapy in healthy individuals, given that an aseptic environment (rubber dam isolation) is provided. Although in vitro evidence suggests that most modern hydraulic calcium-silicate cements promote bioactivity when exposed to human dental pulp cells, care should be taken when these new materials are clinically applied in patients, as small changes in their composition might have big consequences on their clinical efficacy. Key findings (clinical significance). Pure calcium-hydroxide powder/saline and the commercial resin-free hydraulic calcium-silicate cement Pro-Root MTA (Dentsply-Sirona) are the best options to provide a complete reparative bridge upon vital pulp therapy. Systematic review registration number. PROSPERO registration number: CRD42020164374.

Nitric Oxide in Dental Pulp Tissue: From Molecular Understanding to Clinical Application in Regenerative Endodontic Procedures

Nitric oxide (NO), which is synthesized by the enzyme NO synthase (NOS), is a versatile endogenous molecule with multiple biological effects on many tissues and organs. In dental pulp tissue, NO has been found to play multifaceted roles in regulating physiological activities, inflammation processes, and tissue repair events, such as cell proliferation, neuronal degeneration, angiogenesis, and odontoblastic differentiation. However, there is a deficiency of detailed discussion on the NO-mediated interactions between inflammation and reparative/regenerative responses in wounded dental pulp tissue, which is a central determinant of ultimate clinical outcomes. Thus, the purpose of this review is to outline the current molecular understanding on the roles of Janus-faced molecule NO in dental pulp physiology, inflammation, and reparative activities. Based on this knowledge, advanced physicochemical techniques designed to manipulate the therapeutic potential of NOS and NO production in endodontic regeneration procedures are further discussed. Impact statement The interaction between inflammation and reparative/regenerative responses is very important for regenerative endodontic procedures, which are biologically based approaches intended to replace damaged tissues. Inside dental pulp tissue, endogenous nitric oxide (NO) is generated mainly by immunocompetent cells and dental pulp cells and mediates not only inflammatory/immune activities but also signaling cascades that regulate tissue repair and reconstruction, indicating its involvement in both tissue destruction and regeneration. Thus, it is feasible that NO acts as one of the indicators and modulators in dental pulp repair or regeneration under physiological and pathological conditions.

Impact of calcium aluminate cement with additives on dental pulp-derived cells

Calcium aluminate cement (CAC) has been highlighted as a promising alternative for endodontic use aiming at periapical tissue repair. However, its effects on dental pulp cells have been poorly explored. Objective: This study assessed the impact of calcium chloride (CaCl₂) and bismuth oxide (Bi2O₃) or zinc oxide (ZnO) additives on odontoblast cell response to CAC. Methodology: MDPC-23 cells were exposed for up to 14 d: 1) CAC with 2.8% CaCl₂ and 25% ZnO (CACz); 2) CAC with 2.8% CaCl₂ and 25% Bi₂O₃ (CACb); 3) CAC with 10% CaCl₂ and 25% Bi₂O₃ (CACb+); or 4) mineral trioxide aggregate (MTA), placed on inserts. Non-exposed cultures served as control. Cell morphology, cell viability, gene expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), and dentin matrix protein 1 (DMP-1), ALP activity, and extracellular matrix mineralization were evaluated. Data were compared using ANOVA (α=5%). Results: Lower cell density was detected only for MTA and CACb+ compared with Control, with areas showing reduced cell spreading. Cell viability was similar among groups at days one and three (p>0.05). CACb+ and MTA showed the lowest cell viability values at day seven (p>0.05). CACb and CACb+ promoted higher ALP and BSP expression compared with CACz (p<0.05); despite that, all cements supported ALP activity. Matrix mineralization were enhanced in CACb+ and MTA. Conclusion: In conclusion, CAC with Bi₂O₃, but not with ZnO, supported the expression of odontoblastic phenotype, but only the composition with 10% CaCl₂ promoted mineralized matrix formation, rendering it suitable for dentin-pulp complex repair.

A comparison of the sealing abilities between Biodentine and MTA as root-end filling materials and their effects on bone healing in dogs after periradicular surgery

Objectives:

To compare the sealing ability and biocompatibility of Biodentine with mineral trioxide aggregate (MTA) when used as root-end filling materials.

Methodology:

The Cell Counting Kit-8 (CCK-8) assay was used to compare the cytotoxicity of MTA and Biodentine. Twenty-one extracted teeth with a single canal were immersed in an acidic silver nitrate solution after root-end filling. Then, the volume and depth of silver nitrate that infiltrated the apical portion of the teeth were analyzed using micro-computed tomography (micro-CT). Seventy-two roots from 3 female beagle dogs were randomly distributed into 3 groups and apical surgery was performed. After six months, the volume of the bone defect surrounding these roots was analyzed using micro-CT.

Results:

Based on the results of the CCK-8 assay, MTA and Biodentine did not show statistically significant differences in cytotoxicity (P>0.05). The volume and the depth of the infiltrated nitrate solution were greater in the MTA group than in the Biodentine group (P<0.05). The volume of the bone defect was larger in the MTA group than in the Biodentine group. However, the difference was not significant (P>0.05). The volumes of the bone defects in the MTA and Biodentine groups were smaller than the group without any filling materials (P<0.05).

Conclusions:

MTA and Biodentine exhibited comparable cellular biocompatibility. Biodentine showed a superior sealing ability to MTA in root-end filling. Both Biodentine and MTA promoted periradicular bone healing in beagle dog periradicular surgery models.

The Application of 29Si NMR Spectroscopy to the Analysis of Calcium Silicate-Based Cement using Biodentine™ as an Example

Biodentine is one of the most successful and widely studied among the second generation of calcium silicate-based endodontic cements. Despite its popularity, the setting reactions of this cement system are not currently well understood. In particular, very little is known about the formation and structure of the major calcium silicate hydrate (C-S-H) gel phase, as it is difficult to obtain information on this poorly crystalline material by the traditional techniques of powder X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). In this study, the hydration reactions of Biodentine are monitored by XRD, FTIR, isothermal conduction calorimetry and, for the first time, 29Si magic angle spinning nuclear magnetic resonance spectroscopy (29Si MAS NMR) is used to investigate the structures of the anhydrous calcium silicate phases and the early C-S-H gel product. XRD analysis indicated that the anhydrous powder comprises 73.8 wt% triclinic tricalcium silicate, 4.45 wt% monoclinic β-dicalcium silicate, 16.6 wt% calcite and 5.15 wt% zirconium oxide. Calorimetry confirmed that the induction period for hydration is short, and that the setting reactions are rapid with a maximum heat evolution of 28.4 mW g-1 at 42 min. A progressive shift in the FTIR peak maximum from 905 to 995 cm-1 for the O-Si-O stretching vibrations accompanies the formation of the C-S-H gel during 1 week. The extent of hydration was determined by 29Si MAS NMR to be 87.0%, 88.8% and 93.7% at 6 h, 1 day and 1 week, respectively, which is significantly higher than that of MTA. The mean silicate chain length (MCL) of the C-S-H gel was also estimated by this technique to be 3.7 at 6 h and 1 day, and to have increased to 4.1 after 1 week. The rapid hydration kinetics of Biodentine, arising from the predominance of the tricalcium silicate phase, small particle size, and 'filler effect' of calcite and zirconium oxide, is a favorable characteristic of an endodontic cement, and the high values of MCL are thought to promote the durability of the cement matrix.

In vitro induction of odontogenic activity of human dental pulp stem cells by white Portland cement enriched with zirconium oxide and zinc oxide components

Background. The aim of this in vitro study was to investigate the effect of zinc oxide (ZnO) and zirconium oxide (ZrO₂) microparticles (MPs) and nanoparticles (NPs) in combination with white Portland cement (WPC) on odontogenic capacity of human dental pulp stem cells over a period of 21 days.

Methods. Synthesized ZnO and ZrO₂ particles were characterized using scanning electron microscopy and transmission electron microscopy. The viability of human dental pulp stem cells was measured by a 3-(4,5-dimethylthiazolyl-2-yl)-2,5- diphenyltetrazolium bromide assay at 7-, 14- and 21-day intervals after seeding on WPC disks enriched with ZnO and ZrO₂ MPs and NPs. Odontogenic potential of ZnO and ZrO₂ particles in combination with WPC was investigated by alkaline phosphatase (ALP) activity and ionized calcium level of supernatant culture media at different time intervals. Data were analyzed using one-way ANOVA and post hoc Tukey tests.

Results. All the materials exhibited cell viability over a 21-day period, except for WPC with ZnO NPs on day 7, although it was not statistically significant (P>0.05). The ALP activity and ionized calcium level increased in all the groups compared to the control group (P<0.05). ZnO NPs had superior effect on odontogenic activity and calcium ion release compared to ZnO MPs (P=0.046). There was no significant difference between ZrO₂ MPs and NPs in odontogenic activity (P>0.05).

Conclusion. WPC enriched with ZnO and ZrO₂ increased ALP activity and calcium ion release of human dental pulp stem cells over a period of 21 days in vitro.

Biocompatibility evaluation of Jordanian Portland cement for potential future dental application

Background

The demand for novel Portland cement (PC)-based formulations to be used in dental applications is ever increasing in viewing the foregoing knowledge on the favorable effects of these formulations on cellular proliferation and healing, leading to treatment success.

Aim

This study investigated the effect of white and gray mineral trioxide aggregate (W-MTA and G-MTA) and white and gray Jordanian PC (W-PC and G-PC) in their raw state on the viability of Balb/C 3T3 fibroblasts using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Materials and Methods

Materials were prepared in the form of disks, with a diameter of 5 mm and a thickness of 2 mm. In the first experiment, Balb/C 3T3 fibroblasts were cultured with the material disks using culture plate inserts. In the second experiment, material elutes were added to cultured cells. The elutes were prepared by adding 2 ml serum-free media to 10 disks of each material and then incubated at 37°C for different time intervals. Material elutes were analyzed using ion chromatography for traces of calcium. The data were analyzed using analysis of variance followed by Dunnett test (α = 0.05) or Tukey test (α = 0.05).

Results

In response to material disks, G-PC had a proliferative effect on cells at day 1 and day 2 with a significant difference from the control at day 1. G-MTA reduced cell viability with a significant difference from the control level at day 2. Elutes of PC showed biocompatible and even proliferative effects on Balb/C 3T3 fibroblasts. Calcium ions were found to leach continuously over the measurement period for all the materials tested in this work.

Conclusion

Jordanian PC in its raw state was found to be biocompatible, and the results of this work give promise of its wider use as a base for further development to improve the physiochemical and mechanical properties of the material.

Protection evaluation of non-lead radiation-shielding fabric: preliminary exposure-dose study

OBJECTIVES

The aim of this study was to evaluate the effectiveness and shielding performance of a novel recently developed non-lead radiation-shielding fabric containing bismuth oxide (BO-fabric).

METHODS

BO-fabric was fabricated using urethane resin and bismuth nanopowder. A dose-measurement method was employed to evaluate the radiation-attenuation characteristics of the shielding fabric in accordance with the Korean Standards standard. The shielding performances (%) were calculated by measuring the radiation doses after lamination with increasing layers of fabric (1-10 layers). The physical performance of the fabric in terms of flexural and abrasion resistances was evaluated by the Korea Apparel Testing and Research Institute (KATRI).

RESULTS

The radiation-attenuation capabilities of one layer of BO-fabric were 58.5, 49.9, and 43.0% at tube voltages of 60, 80, and 100 kVp, respectively. The radiation-shielding performance upon lamination of BO-fabric gradually increased as the number of layers increased. Excellent flexural and abrasion resistances were observed in the KATRI evaluation.

CONCLUSIONS

A non-lead radiation-shielding fabric based on urethane resin and bismuth was fabricated and examined, revealing an excellent shielding performance. Owing to the flexibility and simple operation of the fabric, it can be employed for various designs of clothing and protective apparel with many purposes.

Sintering Pmperature-Dependence on Radiopacity of Bi(2-x) ZrxO(3+x/2) Powders Prepared by Sol-Gel Process

Bismuth oxide (Bi₂O₃) is an effective additive used to enhance radiography resolution for dental materials. However, there are potential concerns regarding its biocompatibility and connection to tissue discoloration. In the present study, we modified the radiopacity properties of Bi₂O₃ with zirconium oxide (ZrO₂) using a sol-gel process and investigated the composition, as well as the effects of heat treatment temperature using Thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The harvested Bi2-xZrxO3+x/2 particles showed that the dominant phase transferred from α-Bi₂O₃ to β-Bi7.38Zr0.62O12.31 after a heat treatment of over 750 °C for 2 h. As the x values of Bi2-xZrxO3+x/2 increased from 0.2 to 1.0, more zirconium oxide precipitated onto the particle surface, thus enhancing the surface roughness of particles. For sol-gel Bi1.8Zr0.2O3.1 powders (x = 0.2), the radiopacity values became 4.90 ± 0.23 and 5.83 ± 0.22 mmAl after a heat treatment of 500 °C and 750 °C, respectively.

In vivo biocompatibility and biomineralization of calcium silicate cements

A new mineral trioxide aggregate (MTA) material has been developed with a modified composition that requires investigations to support its clinical use. This study evaluated the biocompatibility and biomineralization of this new MTA material and compared it with that of two other MTA cements over time. Tubes containing materials (or empty tubes as controls) were inserted into the subcutaneous tissues of 40 rats. On days 7, 15, 30, 60, and 90, the tubes were removed with the surrounding tissues, which were either stained with haematoxylin and eosin or von Kossa for further analyses or unstained for observation under polarized light. On days 7 and 15, moderate inflammation was observed in most specimens, and the fibrous capsule was thick. On day 30, there was mild inflammation in all groups, and the fibrous capsule was thin. On days 60 and 90, there was mild inflammation in the material groups, while the control group showed no inflammation, although no statistically significant difference between the groups was observed and the fibrous capsule was thin. All material groups showed structures that stained with von Kossa and could be observed under polarized light; this was not found for the control. In conclusion, the new MTA material had biocompatibility and biomineralization properties similar to those of the two existing MTA materials.

Effects of different radio-opacifying agents on physicochemical and biological properties of a novel root-end filling material

Background/Purpose

Radio-opacity is an essential attribute of ideal root-end filling materials because it is important for clinicians to observe root canal filling and to facilitate the follow-up instructions. The novel root-end filling material (NRFM) has good cytocompatibility and physicochemical properties but low intrinsic radio-opacity value. To improve its radio-opacity value, three novel radio-opaque root-end filling materials (NRRFMs) were developed by adding barium sulphate (NRFM-Ba), bismuth trioxide (NRFM-Bi) and zirconium dioxide (NRFM-Zr) to NRFM, respectively. The purpose of this study was to identify the suitable radio-opacifier for NRFM through evaluating their physicochemical and biological properties, in comparison with NRFM and glass ionomer cement (GIC).

Methods

NRRFMs were characterized using X-ray diffraction (XRD) and Fourier transform infrared spectrophotometry (FTIR). Physicochemical properties including setting time, compressive strength, porosity, pH variation, solubility, washout resistance, contact angle and radiopacity were investigated. Cytocompatibility of both freshly mixed and set NRRFMs was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Alkaline phosphatase (ALP) activity assay and alizarin red staining were used to investigate the osteogenic differentiation potential of NRFM-Zr. Data were analyzed using two-way ANOVA (pH variation, solubility and ALP activity) and one-way ANOVA (for the other variables).

Results

(1) NRRFMs were primarily composed of hydroxyapatite, calcium carboxylate salt and the corresponding radio-opacity agents (barium sulphate, bismuth trioxide or zirconium dioxide). (2) Besides similar physicochemical properties in terms of setting time, pH variation, solubility, washout resistance and contact angle to NRFM, NRFM-Bi and NRFM-Zr exhibited lower porosity and greater compressive strength after being set for 7 days and their radio-opacity were greater than the 3 mm aluminium thickness specified in ISO 6876 (2001). (3) MTT assay revealed that freshly mixed and set NRFM-Zr presented better cell viability than NRFM-Ba and NRFM-Bi at 24 hours and 48 hours (P<0.05). (4) NRFM-Zr significantly enhanced ALP activity and calcium formation of human osteoblast-like Saos-2 cells when compared with negative group and GIC (P<0.05).

Conclusion

NRFM-Zr presents desirable physicochemical and biological properties, thus zirconium dioxide may be a suitable radio-opacifier for NRFM.

Composition and physicochemical properties of calcium silicate based sealers: A review article

Background

Recently a new generation of endodontic sealers has been developed based on calcium silicate as MTA Fillapex, Endoseal MTA, Total Fill BC Sealer, EndoSequence BC Sealer, iRoot SP, Endo CPM sealer, MTA-Angelus and ProRoot Endo Sealer. A review of literature was conducted to discuss the composition, physicochemical properties, and clinical perspectives of calcium silicate based sealers.

Material and Methods

A literature search was conducted in PubMed and web of knowledge databases with appropriate MeSh terms and keywords. A total of 71 studies were reviewed for data extraction.

Results and Conclusions

Calcium silicate based sealers showed suitable physical properties to be used as an endodontic sealer. However, its high solubility remains an important issue. They show good performance regarding calcium ion release, film thickness, and fowability. More researches are required about features of calcium silicate based sealers before recommending them for clinical applications.

Key words:Calcium silicate, root canal filling materials, composition, physical properties.

Cytotoxicity, Biocompatibility, and Biomineralization of the New High-plasticity MTA Material

INTRODUCTION

Mineral trioxide aggregate (MTA) has excellent biological properties, but its handling properties have been criticized for both ProRoot MTA (Tulsa Dental Products, Tulsa, OK) and white MTA-Angelus (MTA-Ang; Angelus Indústria de Produtos Odontológicos S/A, Londrina, PR, Brazil). Angelus MTA HP (high plasticity) (Angelus Indústria de Produtos Odontológicos S/A) has been introduced recently. Considering the importance of biological properties of materials that will be in contact with the tissues, this study evaluated the cytotoxicity, biocompatibility, and biomineralization of MTA HP compared with white MTA-Ang.

METHODS

L929 fibroblast cell lines were cultured, and cell viability was assessed at 6, 24, 48, and 72 hours using the alamar Blue assay (Thermo Fisher Scientific, Waltham, MA). A subcutaneous implant test was performed with polyethylene tubes containing 1 of the materials or empty tubes (control) using 20 Wistar rats. After 7 and 30 days of implantation, the tubes with surrounding tissues were removed for analysis using hematoxylin-eosin or von Kossa stain or they remained unstained for observation under polarized light. The results were statistically analyzed (P < .05).

RESULTS

A significant increase in cell viability for MTA HP was observed after 24, 48, and 72 hours compared with the control (P < .05). At 72 hours, MTA HP exhibited a higher viability compared with white MTA-Ang (P < .05). Histologic analysis performed at 7 days showed moderate inflammation and a thick fibrous capsule in all groups (P > .05). At 30 days, mild inflammation and a thin fibrous capsule were observed in all groups (P > .05). All materials had structures positive for von Kossa and birefringent to polarized light.

CONCLUSIONS

MTA HP showed biocompatibility and biomineralization similar to MTA-Ang. In addition, MTA HP showed increased fibroblast cell viability compared with white MTA-Ang after a longer period.

Push-out Bond Strength of Fast-setting Mineral Trioxide Aggregate and Pozzolan-based Cements: ENDOCEM MTA and ENDOCEM Zr

INTRODUCTION

The present study investigated the root canal dentin bond strength of 2 newly developed fast-setting mineral trioxide aggregate (MTA) and pozzolan-based cements: ENDOCEM MTA (Maruchi, Wonju, Korea) and ENDOCEM Zr (Maruchi). White MTA (Angelus, Londrina, Brazil) was used as the reference material for comparison.

METHODS

Root slices (1 mm ± 0.1 mm) were obtained from the middle third of 15 maxillary incisors previously selected. Three canal-like holes (0.8 diameter) were drilled perpendicularly on the axial surface of each root slice. A standardized irrigation protocol was applied for all samples, and after drying, each hole was filled with 1 of 3 test repair materials. Finally, slices were stored in contact with phosphate-buffered saline solution (pH = 7.2) for 7 days at 37°C before the push-out assay. Data were nonparametrically evaluated at α = 5%.

RESULTS

The Friedman test was unable to confirm a significant dissimilarity in push-out ranks among the tested cements (P = .220).

CONCLUSIONS

The new fast-setting MTA and pozzolan-based cements ENDOCEM MTA and ENDOCEM Zr present suitable bond strength performance, which is comparable with white MTA.

Deconvolution of the particle size distribution of ProRoot MTA and MTA Angelus

Objective Mineral trioxide aggregate (MTA) cements contain two types of particles, namely Portland cement (PC) (nominally 80% w/w) and bismuth oxide (BO) (20%). This study aims to determine the particle size distribution (PSD) of PC and BO found in MTA.

Materials and methods The PSDs of ProRoot MTA (MTA-P) and MTA Angelus (MTA-A) powder were determined using laser diffraction, and compared to samples of PC (at three different particle sizes) and BO. The non-linear least squares method was used to deconvolute the PSDs into the constituents. MTA-P and MTA-A powders were also assessed with scanning electron microscopy.

Results BO showed a near Gaussian distribution for particle size, with a mode distribution peak at 10.48 μm. PC samples milled to differing degrees of fineness had mode distribution peaks from 19.31 down to 4.88 μm. MTA-P had a complex PSD composed of both fine and large PC particles, with BO at an intermediate size, whereas MTA-A had only small BO particles and large PC particles.

Conclusions The PSD of MTA cement products is bimodal or more complex, which has implications for understanding how particle size influences the overall properties of the material. Smaller particles may be reactive PC or unreactive radiopaque agent. Manufacturers should disclose particle size information for PC and radiopaque agents to prevent simplistic conclusions being drawn from statements of average particle size for MTA materials.

In Vitro Cytotoxicity of Calcium Silicate-Based Endodontic Cement as Root-End Filling Materials

The aim of this study was to evaluate the cytotoxicity of three types of calcium silicate-based endodontic cement after different incubation periods with human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were cultured from extracted third molars and seeded in 96-well plates. MTA, calcium enriched mixture (CEM) cement, and Biodentine were prepared and added to culture insert plates which were immediately placed into 96-well plates containing cultured cells. After incubation periods of 24, 48, and 72 hours, cell viability was determined with WST-1 assay. Data were analysed statistically by ANOVA with repeated measures and Bonferroni tests. There was no significant difference in cell viability amongst the test materials after each incubation period (P > 0.05). MTA and CEM presented more than 90% cell viability after 24 and 48 hours of incubation and showed statistically significant decrease in cell viability after 72 hours of incubation (P < 0.05). Biodentine showed significantly less cell viability (73%) after 24 hours of incubation, whereas more than 90% cell viability was seen after 48 and 72 hours of incubation (P < 0.05). Despite the significant changes in cell viability over time, materials presented similar cytotoxicity profile. Biodentine and CEM can be considered as alternative materials for root-end surgery procedures.

Physical properties and biocompatibility of an injectable calcium-silicate-based root canal sealer: in vitro and in vivo study

Background

The aim of this study was to investigate the physical properties and biological effects of an experimentally developed injectable premixed calcium-silicate root canal sealer (Endoseal) in comparison with mineral trioxide aggregate (MTA) and a resin-based sealer (AHplus).

Methods

The pH, solubility, dimensional change, flow, and radiopacity of the materials were evaluated. Biocompatibility was evaluated on the basis of cell morphology and a viability test using MC3T3-E1 cells. For evaluate inflammatory reaction, the tested sealers were implanted into dorsal subcutaneous connective tissue of Sprague Dawley rats. After 7 days, the implants with the surrounding tissue were retrieved, and histological evaluation was performed.

Results

Endoseal showed high alkalinity similar to that of MTA. The solubility of the tested materials was similar. The dimensional change and flow of Endoseal was significantly higher than that of other materials (P < 0.05). The radiopacity of Endoseal was lower than that of AHplus (P < 0.05). The biocompatibility was similar to those of MTA. Inflammatory reaction of Endoseal was similar with that of MTA, but lower than that of AHplus (P < 0.05).

Conclusions

The present study indicates that Endoseal has favorable physical properties and biocompatibility. Therefore, we suggest that Endoseal has the potential to be used as a predictable root canal sealer.

Odontogenic effects of a fast-setting calcium-silicate cement containing zirconium oxide

A fast-setting calcium-silicate cement (Endocem) was introduced in the field of dentistry for use in vital pulp therapy. Similar to mineral trioxide aggregate (MTA), it contains bismuth oxide to provide radiopacity. Recently, another product, EndocemZr, which contains zirconium oxide (ZrO2) as a radiopacifier, was developed by the same company. In this study, the biological/odontogenic effects of EndocemZr were investigated in human primary dental pulp cells (hpDPCs) in vitro and on capped rat teeth in vivo. The biocompatibility of EndocemZr was similar to that of ProRoot and Endocem on the basis of cell viability tests and cell morphological analysis. The mineralization nodule formation, expression of odontogenic-related markers, and reparative dentin formation of EndocemZr group was similar to those of other material groups. Our results suggest that EndocemZr has the potential to be used as an effective material for vital pulp therapy, similar to ProRoot and Endocem.

Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement

Objectives

To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement.

Material and Methods

White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05).

Results

The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05).

Conclusions

The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.

Hydration kinetics, ion-release and antimicrobial properties of white Portland cement blended with zirconium oxide nanoparticles

This study examines the impact of 20 wt% zirconium oxide nanoparticles on the early hydration kinetics of white Portland cement by isothermal conduction calorimetry and transmission electron microscopy. The findings confirm that the nano-ZrO2 particles do not directly participate in the chemical reactions during cement hydration; although, they do divert the normal hydration processes and accelerate the initial setting reactions. The rate of heat evolution and the extent of the exotherm associated with these reactions are reduced in the presence of nano-ZrO2. The incorporation of nano-ZrO2 into the cement also decreases the solubility of the silicate phases but does not compromise its capacity to release hydroxide ions. There was no observed difference in the antimicrobial activity of the nano-ZrO2-blended and unblended cement pastes against S. aureus and E. coli; however, a modest reduction in this property was noted against P. aeruginosa for the blended cement.

Premixed calcium silicate cement for endodontic applications: injectability, setting time and radiopacity

Calcium silicate-based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid-to-powder ratio, amount of radiopacifier and amount of calcium sulfate (added to control the setting time) were screened using a statistical model. In the second part of the study, the liquid-to-powder ratio was optimized for cements containing three different amounts of radiopacifier. Finally, the effect of using glycerol rather than water was evaluated in terms of radiopacity. The setting time was found to increase with the amount of radiopacifier when the liquid-to-powder ratio was fixed. This was likely due to the higher density of the radiopacifier in comparison to the calcium silicate, which gave a higher liquid-to-powder ratio in terms of volume. Using glycerol rather than water to mix the cements led to a decrease in radiopacity of the cement. In conclusion, we were able to produce premixed calcium silicate cements with acceptable properties for use in endodontic applications.

Comparison of the radiopacities of different root-end filling and repair materials

This study evaluated the radiopacity of 3 repair materials, Biodentine, MM-MTA, and MTA Angelus. Standardized cylindrical rings were prepared. Samples of Biodentine MM-MTA and MTA Angelus were prepared (n = 10 in each group), filled into the rings, and preserved at 37°C until setting. A 1 mm thick dentin slice was used as control. All set specimens were removed and radiographed along with the dentine slice and a graduated aluminium step wedge. Digital images were transferred to the computer using a software. The radiographic densities of the specimens were determined, and the values were converted into millimetres of aluminium (mm Al). One-way ANOVA was used for intergroup comparison, whereas Tukey HSD test was used for detecting the group with the difference. The mean radiopacities of Biodentine, MTA Angelus, and MM-MTA were 2.8 ± 0.48, 4.72 ± 0.45, and 5.18 ± 0.51 mm Al, respectively. The radiopacity of Biodentine was significantly lower compared to other materials (P = 0.001), whereas no significant difference was noted between MTA Angelus and MM-MTA (P = 0.109). All materials had significantly higher radiopacities compared to dentine. The relatively lower radiopacity of Biodentine can be improved to achieve more reliable results in procedures such as retrograde fillings.

Genotoxic effects of Bismuth (III) oxide nanoparticles by Allium and Comet assay

Genotoxic effects of Bismuth (III) oxide nanoparticles (BONPs) were investigated on the root cells of Allium cepa by Allium and Comet assay. A. cepa roots were treated with the aqueous dispersions of BONPs at five different concentrations (12.5, 25, 50, 75, and 100ppm) for 4h. Exposure of BONPs significantly increased mitotic index (MI) except 12.5ppm, total chromosomal aberrations (CAs) in Allium test. While stickiness chromosome laggards, disturbed anaphase-telophase and anaphase bridges were observed in anaphase-telophase cells, pro-metaphase and c-metaphase in other cells. A significant increase in DNA damage was also observed at all concentrations of BONPs except 12.5ppm by Comet assay. The results were also analyzed statistically by using SPSS for Windows; Duncan's multiple range test was performed. These results indicate that BONPs exhibit genotoxic activity in A. cepa root meristematic cells.

In Vitro Cytotoxicity of White MTA, MTA Fillapex® and Portland Cement on Human Periodontal Ligament Fibroblasts

The aim of this study was to compare the in vitro cytotoxicity of white mineral trioxide aggregate (MTA), MTA Fillapex® and Portland cement (PC) on human cultured periodontal ligament fibroblasts. Periodontal ligament fibroblast culture was established and the cells were used for cytotoxic tests after the fourth passage. Cell density was set at 1.25 X10 4 cells/well in 96-well plates. Endodontic material extracts were prepared by placing sealer/cement specimens (5X3mm) in 1mL of culture medium for 72 h. The extracts were then serially two-fold diluted and inserted into the cell-seeded wells for 24, 48 and 72 h. MTT assay was employed for analysis of cell viability. Cell supernatants were tested for nitric oxide using the Griess reagent system. MTA presented cytotoxic effect in undiluted extracts at 24 and 72 h. MTA Fillapex® presented the highest cytotoxic levels with important cell viability reduction for pure extracts and at ½ and ¼ dilutions. In this study, PC did not induce alterations in fibroblast viability. Nitric oxide was detected in extract-treated cell supernatants and also in the extracts only, suggesting presence of nitrite in the soluble content of the tested materials. In the present study, MTA Fillapex displayed the highest cytotoxic effect on periodontal ligament fibroblasts followed by white MTA and PC.

The impact of zirconium oxide radiopacifier on the early hydration behaviour of white Portland cement

Zirconium oxide has been identified as a candidate radiopacifying agent for use in Portland cement-based biomaterials. During this study, the impact of 20 wt.% zirconium oxide on the hydration and setting reactions of white Portland cement (WPC) was monitored by powder X-ray diffraction (XRD), (29)Si and (27)Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), transmission electron microscopy (TEM) and Vicat apparatus. The presence of 20 wt.% zirconium oxide particles in the size-range of 0.2 to 5 μm was found to reduce the initial and final setting times of WPC from 172 to 147 min and 213 to 191 min, respectively. Zirconium oxide did not formally participate in the chemical reactions of the hydrating cement; however, the surface of the zirconium oxide particles presented heterogeneous nucleation sites for the precipitation and growth of the early C-S-H gel products which accelerated the initial setting reactions. The presence of zirconium oxide was found to have little impact on the development of the calcium (sulpho)aluminate hydrate phases.

Effects of simvastain and enamel matrix derivative on Portland cement with bismuth oxide-induced growth and odontoblastic differentiation in human dental pulp cells

INTRODUCTION

We previously reported that bismuth oxide containing Portland cement (BPC) showed similar biocompatibility to Portland cement (PC) in periodontal ligament cells. However, the bioactivity of simvastatin and Emdogain (Biora AB, Malmö, Sweden) on BPC was not reported. The aim of this study was to evaluate the effects of simvastatin and Emdogain on BPC compared with mineral trioxide aggregate (MTA) in human dental pulp cells (HDPCs).

METHODS

Cell growth was determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) assay. Differentiation was evaluated by alkaline phosphatase (ALP) activity, alizarin red staining, and reverse-transcriptase polymerase chain reaction.

RESULTS

The cell growth of HDPCs exposed to Emdogain and simvastatin plus BPC was superior to those administered BPC alone and similar to those that received MTA for 14 days. The simvastatin and Emdogain groups increased the odontogenic potential of the BPC group with respect to ALP activity, mineralization nodules, messenger RNA expression of ALP, osteopontin, osteocalcin, Runx2, and osterix.

CONCLUSIONS

These results suggest that simvastatin and Emdogain improved cell growth and the differentiation of the BPC group in HDPCs and may be useful ingredients in BPC as pulp-capping material.

In vitro antibacterial activity and cytocompatibility of bismuth doped micro-arc oxidized titanium

Chemical manipulations of the implant surface produce a bactericidal feature to prevent infections around dental implants. Despite the successful use of bismuth against mucosal and dermis infections, the antibacterial effect of bismuth in the oral cavity remains under investigation. The aim of this study was to evaluate the antibacterial activities of bismuth compounds against Actinobacillus actinomycetemcomitans, Staphylococcus mutans, and methicillin-resistant Staphylococcus aureus (MRSA), and to investigate the antimicrobial effects of bismuth doped micro-arc oxidation (MAO) titanium via an agar diffusion test. Cell viability, alkaline phosphatase activity, and mineralization level of MG63 osteoblast-like cells seeded on the coatings were evaluated at 1, 7, and 14 days. The results demonstrate that bismuth nitrate possess superior antibacterial activity when compared with bismuth acetate, bismuth subgallate, and silver nitrate. The bismuth doped MAO coating (contained 6.2 atomic percentage bismuth) had good biological affinities to the MG63 cells and showed a higher antibacterial efficacy against Actinobacillus actinomycetemcomitans and MRSA, where the reduction rates of colony numbers is higher than that of the control group by 1.5 and 1.9 times, respectively. These in vitro evaluations demonstrate that titanium implants with bismuth on the surface may be useful for better infection control.

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.