Hydraulic Calcium Silicate Cements Research Articles

Performance of a Biodegradable Composite with Hydroxyapatite as a Scaffold in Pulp Tissue Repair.

Vital pulp therapy is an important endodontic treatment. Strategies using growth factors and biological molecules are effective in developing pulp capping materials based on wound healing by the dentin-pulp complex. Our group developed biodegradable viscoelastic polymer materials for tissue-engineered medical devices. The polymer contents help overcome the poor fracture toughness of hydroxyapatite (HAp)-facilitated osteogenic differentiation of pulp cells. However, the composition of this novel polymer remained unclear. This study evaluated a novel polymer composite, P(CL-co-DLLA) and HAp, as a direct pulp capping carrier for biological molecules. The biocompatibility of the novel polymer composite was evaluated by determining the cytotoxicity and proliferation of human dental stem cells in vitro. The novel polymer composite with BMP-2, which reportedly induced tertiary dentin, was tested as a direct pulp capping material in a rat model. Cytotoxicity and proliferation assays revealed that the biocompatibility of the novel polymer composite was similar to that of the control. The novel polymer composite with BMP-2-induced tertiary dentin, similar to hydraulic calcium-silicate cement, in the direct pulp capping model. The BMP-2 composite upregulated wound healing-related gene expression compared to the novel polymer composite alone. Therefore, we suggest that novel polymer composites could be effective carriers for pulp capping.

Wound Lavage in Studies on Vital Pulp Therapy of Permanent Teeth with Carious Exposures: A Qualitative Systematic Review.

The aim of this study was to systematically review pulp wound lavage in vital pulp therapy (VPT). A search was conducted in six life science databases to identify clinical trials carried out on permanent teeth with a carious pulp exposure and a recall interval of at least six months. Twenty-seven trials of low to moderate risk of bias (RoB-2 and ROBINS-I) were included. Data was extracted and analyzed regarding study characteristics and methods used for pulp wound lavage. The agent used for pulp wound lavage was specified in all included trials. Most of the identified trials (23/27) randomized the pulp capping material. Many (14/27) reported the use of sodium hypochlorite (NaOCl); ten used only saline or water. One trial was identified that compared pulp wound lavage with 2.5% (NaOCl) to saline, another compared 5% glutaraldehyde to water, both in immature molar pulpotomies. Both studies were underpowered. Neither showed a significant difference between treatments. The use of NaOCl was positively correlated to recent year of publication and use of hydraulic calcium silicate cements for pulp capping (p < 0.05). In conclusion, despite a lack of well-designed trials on pulp wound lavage in VPT, a trend towards using NaOCl for this purpose was observed.

An In-vitro Study to Determine the Sealing Ability of Biodentine when used as a Class II Restorative Material

Introduction: Microleakage is a major setback to restorative dentistry. Leakage at the tooth/restoration interface may lead to numerous problems like postoperative sensitivity, recurrent caries, marginal sealing and later total failure of restoration. Aim: To determine the sealing ability (microleakage) of a new hydraulic calcium silicate cement (Biodentine) as a base material and a bulk filling material. Materials and Methods: An in-vitro study was conducted with ten freshly extracted maxillary molars from March 2019 to June 2019. Standardised Class II cavities were prepared on mesial and distal proximal surfaces. The twenty prepared samples were randomly divided into two groups (n=10)- G1 (BiodentineTM group) and G2 (BiodentineTM + Tetric N-Ceram group). The samples were subjected to thermocycling, followed by 1% methylene blue dye immersion. They were subsequently sectioned both buccolingually and mesiodistally in order to separate to proximal restorations (mesial and distal) and appreciate the amount of dye penetration at tooth/restoration interface respectively. Microleakage was evaluated by observing the samples under a stereomicroscope (30x). The data obtained was analysed using one-way ANOVA test and compared using Post-hoc test. p-value &lt;0.05 to be considered significant. Results: Biodentine showed no significant difference between the sealing ability as a bulk filling and a base material. Group G2 (0.35) indicated comparatively less microleakage as compared to Group G1 (0.6) but the difference in microleakages in both groups was insignificant (p-value 0.083467). Conclusion: BiodentineTM exhibits microleakage when used as a bulk filling material and as a dentin substitute in Class II cavities since there is no significant difference in both the groups.

Development of self-adhesive pulp-capping agents containing a novel hydrophilic and highly polymerizable acrylamide monomer.

Several studies have shown the clinical success of hydraulic calcium-silicate cements (hCSCs) for direct and indirect pulp capping and root repair. However, hCSCs have various drawbacks, including long setting time, poor mechanical properties, low bond strength to dentin, and relatively poor handling characteristics. To overcome these limitations, a light-curable, resin-based hCSC (Theracal LC, Bisco) was commercially introduced; however, it did not exhibit much improvement in bond strength. We developed a light-curable self-adhesive pulp-capping material that contains the novel acrylamide monomer N,N'-{[(2-acrylamido-2-[(3-acrylamidopropoxy)methyl]propane-1,3-diyl)bis(oxy)]bis(propane-1,3-diyl)}diacrylamide (FAM-401) and the functional monomer 4-methacryloxyethyl trimellitate anhydride (4-MET). Two experimental resin-based hCSCs containing different calcium sources (portlandite: Exp_Pl; tricalcium silicate cement: Exp_TCS) were prepared, and the commercial hCSCs Theracal LC and resin-free hCSC Biodentine served as controls. The performance of each cement was evaluated based on parameters relevant for vital pulp therapy, such as curing degree on a wet surface, mechanical strength, as determined using a three-point bending test, shear bond strength to dentin, cytotoxicity, as determined using an MTT assay, and the amount of calcium released, as determined using inductively coupled plasma atomic emission spectrometry. Both experimental cements cured on wet surfaces and showed relatively low cytotoxicity. Furthermore, their flexural and shear bond strength to dentin were significantly higher than those of the commercial references. High calcium release was observed for both Exp_Pl and Biodentine. Thus, Exp_Pl as a new self-adhesive pulp-capping agent performed better than the commercial resin-based pulp-capping agent in terms of mechanical strength, bond strength, and calcium release.

Is pulpotomy preferable to root treatment where there is pulp exposure?

Data sources Embase, MEDLINE, Web of Science, Trip Pro, Cochrane Library, the International Clinical Trials Registry Platform and ClinicaTrials.gov, including a grey literature search.Study selection Randomised or quasi-randomised clinical trials (RCT).Data extraction and synthesis Two reviewers screened independently and extracted data separately with focus on study and population characteristics, treatment, pulp capping materials and clinical and radiographical outcome measures. Incremental cost effective ratios were collated.Results Seventeen studies reported in 21 articles were included. Three were completed trials and one ongoing trial comparing (partial/full) pulpotomy with other interventions for vital pulp therapy. The remaining 13 studies compared hydraulic calcium silicate cements with calcium hydroxide. Only three studies were considered as low risk of bias, except for performance bias (the inherent impossible task of blinding the clinician). Five trials comparing the capping materials were the basis of a quantitative synthesis. No cost-effectiveness studies were found.Conclusions Firm evidence has not been reached with respect to pulpotomy being the preferred intervention substituting root canal treatment; however better pulpotomy outcomes were reported when hydraulic calcium silicate cements are used, when compared to procedures where calcium hydroxide was used.

Interaction of hydraulic calcium silicate and glass ionomer cements with dentine

Restoration of missing tooth structure may require the use of a dentine replacement material to protect the dental pulp. Hydraulic calcium silicate cements and glass ionomers have been reported to exhibit ion exchange at the interface, and this interaction may be enhanced by removal of the smear layer that is formed when dentine is cut. The nature of the interaction and effects of smear layer have not been investigated for hydraulic cements. Biodentine and Chemfil Rock were used as dentine replacement materials in human molar teeth. The dentine was either left untreated or was functionalized by application of 17% ethylene diamine tetracetic acid (EDTA) or 20% polyacrylic acid applied for 1 min. The interface and dentine interaction were assessed by confocal microscopy (CM) with Rhodamine B, atomic force microscopy (AFM), scanning electron microscopy (SEM) and elemental mapping and by bond strength evaluation. Two extra groups with Rhodamine B were observed by AFM and SEM to assess the effect of Rhodamine B on the material and interfacial characteristics. The addition of dye to the materials effected the material properties and modified the interfacial zone. The mineral infiltration zone is an artefact caused by specimen preparation for CM, thus the use of Rhodamine B is not recommended for assessment of tooth-material interface. Dentine functionalization with EDTA improved the Biodentine contact to the tooth structure. Silicon migration from the material to the tooth structure occurred for Biodentine and the clinical implications of this need to be investigated further. Statement of significanceThe interaction of pulp preservation materials with the underlying dentine is important for maintenance of pulp vitality. This interaction is usually based on ion exchange of calcium between the material and dentine and is affected by the smear layer which is formed when the dentine is prepared with rotary instruments. These interactions are studied by various microscopy techniques with the confocal microscopy being very popular as the fluorescent dye clearly maps out the material interaction with the substrate. Unfortunately, the fluorescent dyes affect the interface and the level of penetration. The presence of a mineral infiltration zone, which is linked to the hydraulic tricalcium silicate cements is an artefact. Dentine functionalization with calcium chelators could be an alternative to the use of weak acids and could be more clinically acceptable to avoid pulp damage in deep cavities.

Surface Pre-Reacted Glass Filler Contributes to Tertiary Dentin Formation through a Mechanism Different Than That of Hydraulic Calcium-Silicate Cement.

The induction of tissue mineralization and the mechanism by which surface pre-reacted glass-ionomer (S-PRG) cement influences pulpal healing remain unclear. We evaluated S-PRG cement-induced tertiary dentin formation in vivo, and its effect on the pulp cell healing process in vitro. Induced tertiary dentin formation was evaluated with micro-computed tomography (μCT) and scanning electron microscopy (SEM). The distribution of elements from the S-PRG cement in pulpal tissue was confirmed by micro-X-ray fluorescence (μXRF). The effects of S-PRG cement on cytotoxicity, proliferation, formation of mineralized nodules, and gene expression in human dental pulp stem cells (hDPSCs) were assessed in vitro. μCT and SEM revealed that S-PRG induced tertiary dentin formation with similar characteristics to that induced by hydraulic calcium-silicate cement (ProRoot mineral trioxide aggregate (MTA)). μXRF showed Sr and Si ion transfer into pulpal tissue from S-PRG cement. Notably, S-PRG cement and MTA showed similar biocompatibility. A co-culture of hDPSCs and S-PRG discs promoted mineralized nodule formation on surrounding cells. Additionally, S-PRG cement regulated the expression of genes related to osteo/dentinogenic differentiation. MTA and S-PRG regulated gene expression in hDPSCs, but the patterns of regulation differed. S-PRG cement upregulated CXCL-12 and TGF-β1 gene expression. These findings showed that S-PRG and MTA exhibit similar effects on dental pulp through different mechanisms.

Bioactivity potential of Portland cement in regenerative endodontic procedures: From clinic to lab

ObjectiveThe aim of this study was to evaluate the bioactivity potential of an hydraulic calcium-silicate cement, Pure Portland Cement Med-PZ (Medcem, Weinfelden, Switzerland: ‘MPC’), applied in a tooth extracted because of failed regenerative endodontic procedures (REP) and by means of ex vivo (EV) specimens. MethodsTen EV cylindrical dentin cavities were prepared and filled with MPC and stored for 1 month in distilled water (DW), Hank’s balanced salt solution (HBSS), Dulbecco’s phosphate-buffered saline (DPBS), simulated body fluid (SBF), versus no media (NM) serving as control. Six additional EV specimens were filled with MPC and exposed for 2 weeks to leucocyte-and-platelet-rich fibrin (LPRF)-clot (C), LPRF-membrane (M) and LPRF-exudate (E). MPC in the EV specimens and in the coronal part of the REP tooth was analyzed by means of micro-Raman spectroscopy (MR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). ResultsSEM showed rough crystallite surfaces for the EV samples and a porous surface for the REP tooth. EDS of the EV samples revealed prominent peaks for Ca, Si and O. Storage in HBSS, DPBS, SBF, exposure to LPRF and the REP tooth showed considerable amounts of P as well. MR exhibited vibrations of phosphate (DPBS, SBF), carbonated hydroxyapatite (DPBS, SBF), calcium carbonate (DW, HBSS, NM, REP-tooth, LPRF-E), oxidized (ferric) proteins (LPRF-E/C/M) and the amide III band (all samples). Hence, only storage of MPC in DPBS and SBF for 1 month revealed bioactivity. SignificanceThe environmental conditions, namely the laboratory and clinical settings, affect the bioactivity potential of MPC.

Survival of human dental pulp cells after 4-week culture in human tooth model

ObjectivesThis study aimed to validate the human tooth model by investigating the growth efficiency, expression of mesenchymal stem cell (MSC) markers and differentiation ability of human dental pulp cells (hDPCs) harvested from extracted immature third molars and cultured for different periods. Moreover, the effect of exposure and capping with a hydraulic calcium-silicate cement on pulp tissue after 4-week culture in the tooth model was investigated. MethodsPrimary hDPCs were collected from 18 molars from six individuals (15–19 years). One tooth of each patient was immediately cultured (control), while the other teeth were exposed to culture medium for 1, 2 or 4 weeks. After different culture periods, cells were harvested using the explant method, upon which cells were evaluated for cell-doubling time, colony-forming efficiency and expression of cell surface markers. The osteogenic, adipogenic and chondrogenic differentiation efficacy was also determined. Two teeth from three different patients (n = 6) were used for the pulp-capping assay. Three teeth were capped with ProRoot MTA (Dentsply Sirona), while three other exposed teeth remained uncapped (control). ResultsCells were found to grow, express MSC markers and showed osteogenic, adipogenic and chondrogenic differentiation potential at all time periods. Histology of the teeth subjected to the pulp-capping assay showed the formation of mineralized tissue after 4-week exposure to ProRoot MTA (Dentsply Sirona) and normal histological features in the control teeth. ConclusionsThis study confirmed that hDPCs of teeth cultured for up to 4 weeks in a human tooth model are viable, express MSC markers and show differentiation ability.Clinical Significance: The human tooth model can be seen as an advanced cell-culture model that makes use of the original 3D pulp-chamber structure. It can serve as a screening tool to evaluate new pulp-capping formulations in a relatively cheap and fast manner.

Remineralization ability of two hydraulic calcium-silicate based dental pulp capping materials: Cell-independent model.

BackgroundThis study aimed to evaluate remineralizing ability of two hydraulic calcium-silicate cements (Biodentine and TheraCal LC).Material and MethodsArtificial carious lesions were introduced into the pulpal floors (1-1.5 mm) and axial walls of occlusal prepared cavity halves through pH cycling. Cycling was made through demineralizing solution (pH 3), for 8 hours and remineralizing solution (pH 7) for 16 hours. The total period of pH cycling was 14 days. Prepared cavities with the tested materials seated directly on the pulpal floor and in contact with the axial walls were stored in phosphate buffer solutions (PBS) (pH 7.2–7.4). The changes in the weight percentages (wt%) of calcium (Ca) and phosphorus (P) were detected using SEM and energy dispersive X-ray spectroscopy with reference to sound dentin after three intervals (one week, 3 and 6 months). Data were statistically analyzed using two-way ANOVA and Tukey’s post hoc test.ResultsDemineralized dentin, next to Biodentine, showed statistically higher intensities of Ca and P wt% after the three periods of incubation (p< 0.05). Surface mapping of both tested cements and their adjacent demineralized dentin showed increase in overall distribution of previous ions. SEM of subsurface layer under both materials showed filling of most intra-tubular areas with rod-like mineralized structure without significant difference.ConclusionsBiodentine has a higher ability to enrich the artificial carious dentin with significantly higher mineral contents available for remineralization. Both pulp-capping materials have significantly induced remineralization of demineralized dentin beneath them after total period of incubation. Key words:Artificial Caries, Hydraulic Cements, pH Cycling, Remineralization.

FTIR characterization of the setting reaction of biodentine™

ObjectiveTo provide insight of the setting reactions of Biodentine™, a hydraulic calcium silicate cement, based upon observations using Fourier Transform Infra-Red (FTIR) spectroscopy. MethodsFTIR spectra of components before and during the setting reaction were taken using the attenuated total reflectance (ATR) technique. Measurements over wavelengths 600–4000cm−1 were taken at regular intervals for two days. ResultsFTIR spectrum of Biodentine™ powder revealed a number of peaks from 650 to 1100cm−1 and a plateau from 1400 to 1500cm−1, indicative of SiO and CO3-bonding, while the mixing fluid exhibited water peaks. Results following mixing displayed three distinct regimes; (i) incubation phase, during the first 35min, when minimal change occurred, (ii) rapid transitory stage, between 35 and 90min, when major changes occurred, and (iii) slow sustained reaction stage for remaining 45h. Incubation appears to be associated with the presence of CO3-peaks. The transition region indicates formation of CaOH and Jennite OH-peaks, anticipated intermediate reaction phases. At 90min, the end of second stage, CaOH and Jennite are replaced by a dominant Portlandite (Ca(OH)2)-peak and minor presence of Tobermorite, another anticipated intermediate phase, and water reduction. During the following 45h Portlandite and Tobermorite decline while the water peak increases. SignificanceFTIR can be used to follow the chemical reactions in dental cements and provides insight into the relatively slow setting reactions of hydraulic calcium silicate cements.

Experimental tricalcium silicate cement induces reparative dentinogenesis

ObjectivesTo overcome shortcomings of hydraulic calcium-silicate cements (hCSCs), an experimental tricalcium silicate (TCS) cement, named ‘TCS 50’, was developed. In vitro research showed that TCS 50 played no negative effect on the viability and proliferation of human dental pulp cells, and it induced cell odontogenic differentiation. The objective was to evaluate the pulpal repair potential of TCS 50 applied onto exposed minipig pulps. MethodsTwenty permanent teeth from three minipigs were mechanically exposed and capped using TCS 50; half of the teeth were scheduled for 7-day and the other half for 70-day examination (n=10). Commercial hCSCs ProRoot MTA and TheraCal LC were tested as references (n=8). Tooth discoloration was examined visually. After animal sacrifice, the teeth were scanned using micro-computed tomography; inflammatory response at day 7 and day 70, mineralized tissue formation at day 70 were assessed histologically. ResultsUp to 70 days, TCS 50 induced no discoloration, ProRoot MTA generated gray/black discoloration in all teeth. For TCS 50, 40.0% pulps exhibited a mild/moderate inflammation at day 7. No inflammation was detected and complete reparative dentin with tubular structures was formed in all pulps after 70 days. ProRoot MTA induced a similar response, TheraCal LC generated a less favorable response in terms of initial inflammation and reparative dentin formation; however, these differences were not significant (Chi-square test of independence: p>0.05). SignificanceTCS 50 induced reparative dentinogenesis in minipig pulps. It can be considered as a promising pulp-capping agent, also for aesthetic areas.

Freshly-mixed and setting calcium-silicate cements stimulate human dental pulp cells

ObjectivesTo evaluate the effect of the eluates from 3 freshly-mixed and setting hydraulic calcium-silicate cements (hCSCs) on human dental pulp cells (HDPCs) and to examine the effect of a newly developed hCSC containing phosphopullulan (PPL) on HDPCs. MethodsHuman dental pulp cells, previously characterized as mesenchymal stem cells, were used. To collect the eluates, disks occupying the whole surface of a 12-well plate were prepared using an experimental hCSC containing phosphopullulan (GC), Nex-Cem MTA (GC), Biodentine (Septodont) or a zinc-oxide (ZnO) eugenol cement (material-related negative control). Immediately after preparing the disks (non-set), 3ml of Dulbecco's Modified Eagle Medium (DMEM) with 10% fetal bovine serum (FBS) were added. The medium was left in contact with the disks for 24h before being collected. Four different dilutions were prepared (100%, 50%, 25% and 10%) and cell-cytotoxicity, cell-proliferation, cell-migration and odontogenic differentiation were tested. The cell-cytotoxicity and cell-proliferation assays were performed by XTT-colorimetric assay at different time points. The cell-migration ability was tested with the wound-healing assay and the odontogenic differentiation capacity of hCSCs on HDPCs was tested with RT-PCR. ResultsConsidering all experimental data together, the eluates from 3 freshly-mixed and setting hCSCs appeared not cytotoxic toward HDPCs. Moreover, all three cements stimulated proliferation, migration and odontogenic differentiation of HDPCs. SignificanceThe use of freshly-mixed and setting hCSCs is an appropriate approach to test the effect of the materials on human dental pulp cells. The experimental material containing PPL is non-cytotoxic and positively stimulates HDPCs.

How effectively do hydraulic calcium-silicate cements re-mineralize demineralized dentin

ObjectiveTo characterize the chemical interplay and to quantify the re-mineralization potential of hydraulic calcium-silicate cements (hCSCs) at demineralized dentin. MethodsPairs of class-I cavities were prepared in non-carious human third molars. One dentin cavity was demineralized with 10% formic acid (5h); the other served as control. The cavities were filled with two resin-free hCSCs (Biodentine, Septodont; ProRoot MTA, Dentsply Sirona) or one resin-based hCSC (TheraCal LC, Bisco). After 1-week, 1-, 3-, and 6-month storage in simulated body fluid (SBF), polished specimen cross-sections were chemically characterized using Field-emission-gun Electron Probe Micro-Analysis (Feg-EPMA) and micro-Raman spectroscopy (μRaman). ResultsFeg-EPMA line-scans and elemental mappings confirmed early re-mineralization induced by all three hCSCs at 1week. The relative depth and intensity of re-mineralization were for the resin-free hCSCs in the range of 50.5%–84.8% and 68.1%–89.2%, respectively. Re-mineralization did not significantly differ for the storage periods (p>0.05). Significantly less re-mineralization was achieved by the resin-based hCSC TheraCal LC that reached only at 6months a re-mineralization level that was no longer significantly different from that achieved by the resin-free hCSCs at 1week (p>0.05). Re-mineralization of intertubular dentin, including tubular occlusion, was observed; Si was occasionally detected to have infiltrated the dentin tubules. Dentin re-mineralization by hCSCs was confirmed using μRaman that revealed an increased phosphate peak at 960cm−1. SignificancehCSCs do re-mineralize demineralized dentin. The resin-free cements induced re-mineralization at a higher speed/intensity than the resin-based hCSC. However, re-mineralization was incomplete for all hCSCs tested, this even at 6months.

Osteoinductive potential and bone-bonding ability of ProRoot MTA, MTA Plus and Biodentine in rabbit intramedullary model: Microchemical characterization and histological analysis

ObjectiveTo study the in vivo osteoinductive potential, bone-bonding ability (bioactivity) and bone biomineralization of current hydraulic calcium silicate cements used as graft materials and placed in contact with medullary bone. MethodsProRoot MTA, MTA Plus and Biodentine were used to fill surgical bone defects (2-mm diameter through the entire cortical thickness to reach the medullary bone) in the tibia of mature male rabbits. Tibiae were retrieved after 30days and submitted to histological analysis and microchemical characterization using Optical Microscopy (OM) and Environmental Scanning Electron Microscopy with Energy Dispersive X-ray analysis (ESEM-EDX). Bone neoformation and histomorphometric evaluations, degree of mineralization (by Ca/P, Ca/N and P/N ratios) and the diffusion of material elements were studied. ResultsBone neoformation was observed in response to all materials. No sign of necrosis were found on the walls of the pre-existing cortical bone. No osteoclasts and no formation of fibrous tissue were evident. Sign of angiogenesis were present.EDX (element content, line profile and element mapping) showed the increase in Ca and P and decrease in C, S and N from the mature bone towards the mineralizing interface.Ca/P, Ca/N and P/N ratios showed differences in the degree of mineralization/maturation stage of bone.MTA Plus and ProRoot MTA exhibited close contact with the pre-existing bone and good bone-bonding with neoformed bone juxtaposed on the medullary side of the materials without interposed connective tissue or resorption lacunae or gaps. The materials showed a dense appearance with 100% of residual materials and no colonization by fluids and cells. No migration of Bi or Al material elements to the newly formed bone was found.Biodentine showed newly formed trabecular bone with marrow spaces and sparse traces of residual material (≈9%). SignificanceThe in vivo osteoinductive properties with dynamic biomineralization processes around these calcium silicate materials extruded in medullary bone in appropriate animal model have been demonstrated by ESEM-EDX in association with OM. Good biocompatibility was evident as only slight inflammatory infiltrate and no sign of necrosis at the interface with the pre-existing bone were found.MTA Plus and ProRoot MTA exhibited bioactive potential as they can bond to bone directly without interposed connective tissue. Biodentine was replaced by newly formed bone. Clinical significanceThe results of the study demonstrate the capacity of calcium silicate cements to allow osteoid matrix deposition by activated osteoblasts and favour its biomineralization, and to achieve a direct bond between the (bioactive) materials surface and the mineralized bone matrix.

Modified tricalcium silicate cement formulations with added zirconium oxide.

This study aims to investigate the effect of modifying tricalcium silicate (TCS) cements on three key properties by adding ZrO2. TCS powders were prepared by adding ZrO2 at six different concentrations. The powders were mixed with 1M CaCl2 solution at a 3:1 weight ratio. Biodentine (contains 5wt.% ZrO2) served as control. To evaluate the potential effect on mechanical properties, the mini-fracture toughness (mini-FT) was measured. Regarding bioactivity, Ca release was assessed using ICP-AES. The component distribution within the cement matrix was evaluated by Feg-SEM/EPMA. Cytotoxicity was assessed using an XTT assay. Adding ZrO2 to TCS did not alter the mini-FT (p=0.52), which remained in range of that of Biodentine (p=0.31). Ca release from TSC cements was slightly lower than that from Biodentine at 1day (p>0.05). After 1week, Ca release from TCS 30 and TCS 50 increased to a level that was significantly higher than that from Biodentine (p<0.05). After 1month, Ca release all decreased (p<0.05), yet TCS 0 and TCS 50 released comparable amounts of Ca as at 1day (p>0.05). EPMA revealed a more even distribution of ZrO2 within the TCS cements. Particles with an un-reacted core were surrounded by a hydration zone. The 24-, 48-, and 72-h extracts of TCS 50 werethe least cytotoxic. ZrO2 can be added to TCS without affecting the mini-FT; Ca release was reduced initially, to reach a prolonged release thereafter; adding ZrO2 made TCS cements more biocompatible. TCS 50 is a promising cement formulation to serve as a biocompatible hydraulic calcium silicate cement.

Correlative micro-Raman/EPMA analysis of the hydraulic calcium silicate cement interface with dentin.

This study aims to characterize the chemical interplay of hydraulic calcium silicate cements at dentin. Class I cavities were prepared in non-carious human third molars and filled with Biodentine (Septodont) or ProRoot MTA (Dentsply). After 1-day, 1-week, and 1-month Dulbecco's phosphate-buffered saline (DPBS) storage, the specimens were cross-sectioned perpendicular to the cement-dentin interface. The interfaces were evaluated using micro-Raman (μRaman) spectroscopy and at a higher spatial resolution using field emission gun electron probe microanalysis (Feg-SEM/EPMA). μRaman spectroscopy revealed the formation of a transition zone at the interface of both Biodentine (Septodont) and ProRoot MTA (Dentsply) with dentin, having an average thickness of, respectively, 7.5 ± 4.2 and 6.2 ± 5.4μm, which however was not statistically different. No difference in interfacial ultrastructure and chemistry was found using μRaman spectroscopy between 1day, 1week, and 1month DPBS-stored specimens. The observation of a transition zone at the cement-dentin interfaces contrasts with the EPMA data that revealed a sharper transition from cement to dentin. Again, no difference in interfacial ultrastructure and chemistry was found for different storage periods, with the exception of one 1month DPBS-stored specimen prepared using Biodentine (Septodont). More specifically, EPMA revealed a gap of about 10-μm wide in the latter specimen that was filled up with newly formed calcium phosphate depositions. Up to 1month, the interaction of hydraulic calcium silicate cements investigated did not reveal ultrastructural or chemical changes at unaffected dentin with the exception of a calcium phosphate gap-filling property. Hydraulic calcium silicate cements were found to fill gaps by calcium phosphate deposition, however, without conducting chemical changes to the adjacent dentin.

Endodontics in motion: new concepts, materials and techniques 1. Hydraulic Calcium Silicate Cements

Hydraulic Calcium Silicate Cements (HCSCs) constitute a group of materials that have become increasingly popular in endodontics since the introduction of Mineral Trioxide Aggregate (MTA) in the 1990s. MTA is Portland cement to which bismuth oxide has been added to increase its radiopacity. The most important property of MTA is its capacity to set in water or a humid environment. However, MTA also has important limitations, for example, it's difficult to work with and can discolour teeth. Recently, numerous products based on HCSC chemistry, which can be considered as modifications of MTA intended to reduce its limitations, have become available on the market. Despite their potential advantages, all of these materials have their own specific limitations that are currently insufficiently known and investigated.

Calcium silicate bioactive cements: Biological perspectives and clinical applications

ObjectiveTo introduce and to examine the research progress and the investigation on hydraulic calcium silicate cements (HCSCs), well-known as MTA (mineral trioxide aggregate). MethodsThis review paper introduces the most important investigations of the last 20 years and analyze their impact on HCSCs use in clinical application. ResultsHCSCs were developed more than 20 years ago. Their composition is largely based on Portland cement components (di- and tri-calcium silicate, Al- and Fe-silicate). They have important properties such as the ability to set and to seal in moist and blood-contaminated environments, biocompatibility, adequate mechanical properties, etc. Their principal limitations are long setting time, low radiopacity and difficult handling.New HCSCs-based materials containing additional components (setting modulators, radiopacifying agents, drugs, etc.) have since been introduced and have received a considerable attention from laboratory researchers for their biological and translational characteristics and from clinicians for their innovative properties.HCSCs upregulate the differentiation of osteoblast, fibroblasts, cementoblasts, odontoblasts, pulp cells and many stem cells. They can induce the chemical formation of a calcium phosphate/apatite coating when immersed in biological fluids.These properties have led to a growing series of innovative clinical applications such as root-end filling, pulp capping and scaffolds for pulp regeneration, root canal sealer, etc.The capacity of HCSCs to promote calcium-phosphate deposit suggests their use for dentin remineralization and tissue regeneration. Several in vitro studies, animal tests and clinical studies confirmed their ability to nucleate apatite and remineralize and to induce the formation of (new) mineralized tissues. SignificanceHCSCs play a critical role in developing a new approach for pulp and bone regeneration, dentin remineralization, and bone/cementum tissue healing. Investigations of the next generation HCSCs for “Regenerative Dentistry” will guide their clinical evolution.

Clinical and Technical Considerations of Luting Agents for Fixed Prosthodontics

Clinical and Technical Considerations of Luting Agents for Fixed Prosthodontics