Effect of additives on the compressive strength and setting time of a Portland cement

Portland Cement: An Overview as a Root Repair Material

Portland cement (PC) is used in challenging endodontic situations in which preserving the health and functionality of pulp tissue is of considerable importance. PC forms the main component of mineral trioxide aggregate (MTA) and demonstrates similar desirable properties as an orthograde or retrograde filling material. PC is able to protect pulp against bacterial infiltration, induce reparative dentinogenesis, and form dentin bridge during the pulp healing process. The biocompatibility, bioactivity, and physical properties of PC have been investigated in vitro and in animal models, as well as in some limited clinical trials. This paper reviews Portland cement's structure and its characteristics and reaction in various environments and eventually accentuates the present concerns with this material. This bioactive endodontic cement has shown promising success rates compared to MTA; however, considerable modifications are required in order to improve its characteristics and expand its application scope as a root repair material. Hence, the extensive chemical modifications incorporated into PC composition to facilitate preparation and handling procedures are discussed. It is still important to further address the applicability, reliability, and cost-effectiveness of PC before transferring into day-to-day clinical practice.

A Scanning Electron Microscopic Study on Effect of Blood and Artificial Salivary Contamination on Marginal Adaptation of Mineral Trioxide Aggregate, When Used as a Retrograde Filling Material: An In Vitro Study

Aim and objective

The present study was conducted to evaluate the marginal adaptability of mineral trioxide aggregate (MTA) as a root-end filling material when manipulated using two different IV fluids intended for pediatric usage; in the presence of blood and salivary contamination.

Materials and methods

Sixty single-rooted teeth were selected. Conventional endodontic root canal preparation was performed on all specimens followed by root-end resection and retrograde cavity preparation. The roots were randomly divided into two groups (n = 30). In the specimens of group I, fresh blood was used as a contaminant and in group II artificial saliva was used as a contaminant. In both groups, MTA (e-MTA, Kids-e-Dental®) manipulated using either Ringer's lactate IV fluid (n = 15) or Tetraspan IV fluid (n = 15) was used for root-end filling in blood or artificial saliva-coated retrocavities. Furthermore, these roots were placed in beakers pooled with fresh phlebotomized blood or artificial saliva. After incubating for 48 hours, the roots were divided longitudinally to expose the retrofilled cavities and were then sputter-coated with gold-platinum dust. To assess the marginal adaptation of MTA to radicular dentin "maximum gap width" and "gap perimeter" were measured in images obtained from scanning electron microscopy of root specimens. SPSS 21 was employed for statistical analysis at (p < 0.05). Mann-Whitney U test and ANOVA were used for analyzing the data obtained.

Results

The gap width was more among samples exposed to blood (p < 0.05) than artificial saliva. No significant difference was reported in the gap perimeter when cavities were filled with MTA mixed with either IV fluids (p > 0.05).

Conclusion

Exposure to blood during setting had a negative effect on gap width when retrocavities were filled with MTA using Tetraspan. No effect was seen on the arch perimeter in retrocavities filled with MTA mixed with Ringer's lactate or Tetraspan.

Clinical significance

For avoiding failure, it is critical to select a biocompatible root-end filling material with high sealing ability. Hence, by doing the same, the clinical situation can be simulated.

How to cite this article

Mody A, Arora R, Chauhan P, et al. A Scanning Electron Microscopic Study on Effect of Blood and Artificial Salivary Contamination on Marginal Adaptation of Mineral Trioxide Aggregate, When Used as a Retrograde Filling Material: An In Vitro Study. Int J Clin Pediatr Dent 2021;14(5):674-680.

Physical, Chemical, Mechanical, and Biological Properties of Four Different Commercial Root-End Filling Materials: A Comparative Study

Commercial mineral trioxide aggregate (MTA) materials such as Endocem MTA (EC), Dia-Root Bio MTA (DR), RetroMTA (RM), and ProRoot MTA (PR) are increasingly used as root-end filling materials. The aim of this study was to assess and compare the physicochemical and mechanical properties and cytotoxicity of these MTAs. The film thicknesses of EC and DR were considerably less than that of PR; however, RM’s film thickness was greater than that of PR. In addition, the setting times of EC, DR, and RM were shorter than that of PR (p < 0.05). The solubility was not significantly different among all groups. The three relatively new MTA groups (EC, DR, and RM) exhibited a significant difference in pH variation and calcium ion release relative to the PR group (p < 0.05). The radiopacity of the three new MTAs was considerably less than that of PR. The mechanical strength of RM was not significantly different from that of PR (p > 0.05); however, the EC and DR groups were not as strong as PR (p < 0.05). All MTA groups revealed cytocompatibility. In conclusion, the results of this study confirmed that EC, RM, DR, and PR exhibit clinically acceptable physicochemical and mechanical properties and cell cytotoxicity.

Porosity Pattern of 3D Chitosan/Bioactive Glass Tissue Engineering Scaffolds Prepared for Bone Regeneration

Aim:

The study was conducted to investigate the obtained external and internal porosity and the pore-interconnectivity of specific fabricated bioactive composite tissue engineering scaffolds for bone regeneration in dental applications.

Materials and Methods:

In this study, the bioactive glass [M] was elaborated as a quaternary system to be incorporated into the chitosan [C] scaffold preparation on a magnetic stirrer to provide bioactivity and better strength properties for the attempted composite scaffolds [C/ M] of variable compositions. The homogenous chitosan/bioactive glass mix was poured into tailor-made cylindrical molds [10cm×10cm]; a freeze-dryer program was used for the creation of uniform and interconnected macropores for all prepared chitosan-based scaffolds. The morphology of fabricated chitosan [C] and chitosan-bioactive glass [C/ M] composite scaffolds was studied by a scanning electron microscope [SEM] and a mercury porosimeter. In addition, the in-vitro biodegradation rate of all elaborated scaffolds was reported after immersing the prepared scaffolds in a simulated body fluid [SBF] solution. Furthermore, for every prepared scaffold composition, characterization was performed for phase identification, microstructure, porosity, bioactivity, and mechanical properties using an X-ray diffraction analysis [XRD], an X-ray Fourier transfer infrared spectroscopy [FTIR], a mercury porosimetry, a scanning electron microscopy [SEM] coupled to an energy-dispersive X-ray spectrometry [EDS] and a universal testing machine, respectively.

Results:

All the prepared porous chitosan-based composite materials showed pore sizes suitable for osteoblasts seeding, with relatively larger pore sizes for the C scaffolds.

Conclusion:

The smart blending of the prepared bioactive glass [M] with the chitosan matrix offered some advantages, such as the formation of an apatite layer for cell adhesion upon the scaffold surfaces, the reasonable decrease in scaffold pore size, and the relative increase in compressive strength that were enhanced by the incorporation of [M]. Therefore, the morphology, microstructure, and mechanical behavior of the elaborated stress loaded biocomposite tissue engineering scaffolds seem highly dependent on their critical contented bioactive glass.

Tannic acid speeds up the setting of mineral trioxide aggregate cements and improves its surface and bulk properties

HYPOTHESIS

The setting time and mechanical properties of cements are a major technical concern for a long time in civil engineering. More recently those practical problems became a major concern for biomedical applications -in bone surgery and in dentistry- in particular concerning the setting time which should be minimized. The possibility to add organic additives to interact with the different constituting ions in cements constitutes a way to modify the setting kinetics. We made the assumption that a hydrolysable polyphenol like tannic acid could modify the setting time and the physical properties of Mineral Trioxide Aggregate (MTA).

EXPERIMENTS

Tannic acid is added in variable proportions to the water used to set MTA. The formation of the hybrid organic-mineral cements is investigated using a combination of structural, chemical and mechanical methods. X-ray tomography was also used to investigate the changes in porosity and pore size distribution upon incorporation of tannic acid in MTA based cements. The hydrophilicity of the cements was evaluated by measuring the permeation kinetics of small water droplets.

FINDINGS

We found that tannic acid allowed to reduce markedly the setting time of MTA based cements. The obtained cements have an increased hydrophilicity and display excellent resistance to compression. The number of pores but not the average pore size is also affected. The possible roles of tannic acid in modifying the cement properties are discussed.

Characterization and antimicrobial efficacy of Portland cement impregnated with silver nanoparticles

PURPOSE

This study investigated the effects of silver nanoparticle (SN) loading into hydraulic calcium silicate-based Portland cement on its mechanical, antibacterial behavior and biocompatibility as a novel dental bone substitute.

MATERIALS AND METHODS

Chemically reduced colloidal SN were combined with Portland cement (PC) by the concentrations of 0 (control), 1.0, 3.0, and 5.0 wt%. The physico-mechanical properties of silver-Portland cement nanocomposites (SPNC) were investigated through X-ray diffraction (XRD), setting time, compressive strength, solubility, and silver ion elution. Antimicrobial properties of SPNC were tested by agar diffusion against Streptococcus mutans and Streptococcus sobrinus. Cytotoxic evaluation for human gingival fibroblast (HGF) was performed by MTS assay.

RESULTS

XRD certified that SN was successfully impregnated in PC. SPNC at above 3.0 wt% significantly reduced both initial and final setting times compared to control PC. No statistical differences of the compressive strength values were detected after SN loadings, and solubility rates of SPNC were below 3.0%, which are acceptable by ADA guidelines. Ag ion elutions from SPNC were confirmed with dose-dependence on the concentrations of SN added. SPNC of 5.0 wt% inhibited the growth of Streptococci, whereas no antimicrobial activity was shown in control PC. SPNC revealed no cytotoxic effects to HGF following ISO 10993 (cell viability > 70%).

CONCLUSION

Addition of SN promoted the antibacterial activity and favored the bio-mechanical properties of PC; thus, SPNC could be a candidate for the futuristic dental biomaterial. For clinical warrant, further studies including the inhibitory mechanism, in vivo and long-term researches are still required.

A comparative evaluation of the effect of various additives on selected physical properties of white mineral trioxide aggregate

Aims:

This study examined the setting time, compressive strength, and pH of white mineral trioxide aggregate (MTA) mixed with various additives: Calcium chloride (CaCl₂), calcium formate (CaF), disodium hydrogen orthophosphate (Na₂HPO₄).

Materials and Methods:

Group 1 (Control) was obtained by mixing MTA with distilled water. In Groups 2 and 3, MTA containing 10% CaCl₂ and 20% CaF, respectively, was mixed with distilled water. In Group 4, MTA was mixed with 15% Na₂HPO₄. Setting time, compressive strength, and pH of each group were examined.

Statistical Analysis Used:

Analysis was done using Statistical Package for Social Sciences (SPSS) version 14. A P-value < 0.05 was considered statistically significant. Comparison of mean values was done using analysis of variance (ANOVA) with post-hoc Games-Howell test.

Results:

The setting time of test groups were significantly shorter than that of control group (P < 0.001). The compressive strengths of test groups were lower than that of control group (P < 0.001). The pH value obtained for Groups 3 and 4 were higher than that of the control group (P < 0.001).

Conclusions:

Study result showed that additives significantly reduced the setting time of MTA and also maintained the pH at a high value. However, there was not much improvement in the compressive strength of the material.