Biological Characteristics and Odontogenic Differentiation Effects of Calcium Silicate-Based Pulp Capping Materials

Silicon impacts collagen remodelling and mineralization by human dental pulp stem cells in 3D pulp-like matrices

OBJECTIVES

Silicon-releasing biomaterials are widely used in the field of dentistry. However, unlike bone, very little is known about the role of silicon on dental tissue formation and repair. This study investigates the influence of silicic acid on the survival, differentiation and mineralizing ability of human dental pulp stem cells (hDPSCs) in 3D pulp-like environments METHODS: Dense type I collagen hydrogels seeded with hDPSCs were cultured over 4 weeks in the presence of silicic acid at physiological (10 μM) and supraphysiological (100 μM) concentrations. Cell viability and proliferation were studied by Alamar Blue and live/dead staining. The collagen network was investigated using second harmonic generation imaging. Mineral deposition was monitored by histology and scanning electron microscopy. Gene expression of mineralization- and matrix remodeling-associated proteins was studied by qPCR.

RESULTS

Presence of silicic acid did not show any significant influence on cell survival, metabolic activity and gene expression of key mineralization-related proteins (ALP, OCN, BSP). However, it induced enhanced cell clustering and delayed expression of matrix remodeling-associated proteins (MMP13, Col I). OPN expression and mineral deposition were inhibited at 100 μM. It could be inferred that silicic acid has no direct cellular effect but rather interacts with the collagen network, leading to a modification of the cell-matrix interface.

SIGNIFICANCE

Our results offer advanced insights on the possible role of silicic acid, as released by pulp capping calcium silicates biomaterials, in reparative dentine formation. More globally, these results interrogate the possible role of Si in pulp pathophysiology.

Biocompatibility and Bioactivity of a Dual-Cured Resin-Based Calcium Silicate Cement: In Vitro and in vivo Evaluation

INTRODUCTION

This study aimed to assess the biocompatibility and bioactivity of a dual-cured resin-based calcium silicate cement in vitro and in vivo.

METHODS

For in vitro analyses, standardized samples were prepared using TheraCal LC, TheraCal PT, and ProRoot MTA. The amount of residual monomer released from TheraCal LC and TheraCal PT was assessed using liquid chromatography/mass spectrometry. Calcium ion release from the materials was evaluated using inductively coupled plasma-optical emission spectroscopy. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to determine the calcium weight volume in the materials. For in vivo analysis, a rat direct pulp capping model with TheraCal LC, TheraCal PT, and ProRoot MTA groups (n = 16 per group) was used. The rats were euthanized after 7 or 28 days, and histological and immunohistochemical analyses (CD68 and DSPP) were performed.

RESULTS

Bisphenol A-glycidyl methacrylate and polyethylene glycol dimethacrylate release from TheraCal PT was lower than that from TheraCal LC (P < .05). Similar results were obtained for calcium-ion release and calcium weight volume, with ProRoot MTA showing the highest values. In the in vivo evaluation, TheraCal PT showed significantly greater hard tissue formation than TheraCal LC (P < .017). TheraCal PT showed lower CD68 expression and greater DSPP expression than TheraCal LC (P < .017). There were no significant differences in the expression of CD68 or DSPP between the TheraCal PT and ProRoot MTA groups.

CONCLUSIONS

Within the limitations of this study, the biocompatibility and bioactivity of TheraCal PT could be comparable to those of ProRoot MTA.

Effect of pulp capping materials on odontogenic differentiation of human dental pulp stem cells: An in vitro study

OBJECTIVES

Migration and differentiation of human dental pulp stem cells (hDPSCs) is a vital and key factor in the success of reparative dentin formation for maintenance of pulp vitality. Pulp capping materials are used to stimulate DPSCs to induce new dentin formation. Thus, the aim of the present study was to compare the response of DPSCs to four commercially available pulp capping materials: a bioactive bioceramic (Material 1), a nonresinous ready-to-use bioceramic cement (Material 2), a bioactive composite (Material 3), and a biocompatible, dual-cured, resin-modified calcium silicate (Material 4).

MATERIALS AND METHODS

hDPSCs were isolated and cultured from freshly extracted teeth and were then characterized by flow cytometry and multilineage differentiation. Discs prepared from pulp capping materials were tested with hDPSCs and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, cell migration assay and odontogenic differentiation assay was performed. Expression of osteogenic markers (osteopontin, RUNX family transcription factor 2, osteocalcin) and the odontogenic marker (dentin sialophosphoprotein) was detected using reverse transcription-polymerase chain reaction.

RESULTS

Materials 1, 2, and 3 generated more cell viability than Material 4. Furthermore, Material 4 showed the least wound exposure percentage, while Material 3 showed the highest percentage. Enhanced mineralization was found in hDSCPs cultured with Material 3, followed by Material 1, and then Material 2, while Material 4 revealed the least calcified mineralization.

CONCLUSIONS

The results of this study were inconclusive regards contemporary bioceramic materials designed for vital pulp therapy as they have different effects on hDPSC. Further testing for cytotoxicity using live-dead staining, animal experiments, clinical trials, and independent analyses of these biomaterials is necessary for clinicians to make an informed decision for their use.

Epigenetic therapeutics in dental pulp treatment: Hopes, challenges and concerns for the development of next-generation biomaterials

This opinion-led review paper highlights the need for novel translational research in vital-pulp-treatment (VPT), but also discusses the challenges in translating evidence to clinics. Traditional dentistry is expensive, invasive and relies on an outmoded mechanical understanding of dental disease, rather than employing a biological perspective that harnesses cell activity and the regenerative-capacity. Recent research has focussed on developing minimally-invasive biologically-based 'fillings' that preserve the dental pulp; research that is shifting the paradigm from expensive high-technology dentistry, with high failure rates, to smart restorations targeted at biological processes. Current VPTs promote repair by recruiting odontoblast-like cells in a material-dependent process. Therefore, exciting opportunities exist for development of next-generation biomaterials targeted at regenerative processes in the dentin-pulp complex. This article analyses recent research using pharmacological-inhibitors to therapeutically-target histone-deacetylase (HDAC) enzymes in dental-pulp-cells (DPCs) that stimulate pro-regenerative effects with limited loss of viability. Consequently, HDAC-inhibitors have the potential to enhance biomaterial-driven tissue responses at low concentration by influencing the cellular processes with minimal side-effects, providing an opportunity to develop a topically-placed, inexpensive bio-inductive pulp-capping material. Despite positive results, clinical translation of these innovations requires enterprise to counteract regulatory obstacles, dental-industry priorities and to develop strong academic/industry partnerships. The aim of this opinion-led review paper is to discuss the potential role of therapeutically-targeting epigenetic modifications as part of a topical VPT strategy in the treatment of the damaged dental pulp, while considering the next steps, material considerations, challenges and future for the clinical development of epigenetic therapeutics or other 'smart' restorations in VPT.

Comparative Biocompatibility and Odonto-/Osteogenesis Effects of Hydraulic Calcium Silicate-Based Cements in Simulated Direct and Indirect Approaches for Regenerative Endodontic Treatments: A Systematic Review

BACKGROUND

Regenerative dentistry is the operation of restoring dental, oral and maxillofacial tissues. Currently, there are no guidelines for the ideal cement/material in regenerative endodontic treatments (RET). Hydraulic calcium silicate-based cements (hCSCs) are currently the material of choice for RET.

OBJECTIVES

This systematic review was conducted to gather all of the different direct and indirect approaches of using hCSCs in RET in vitro and in vivo, and to ascertain if there are any superiorities to indirect approaches.

METHODS AND MATERIALS

This systematic review was conducted according to the 2020 PRISMA guidelines. The study question according to the PICO format was as follows: Comparison of the biological behavior (O) of stem cells (P) exposed to hCSCs through direct and indirect methods (I) with untreated stem cells (C). An electronic search was executed in Scopus, Google Scholar, and PubMed.

RESULTS

A total of 78 studies were included. Studies were published between 2010 and 2022. Twenty-eight commercially available and eighteen modified hCSCs were used. Seven exposure methods (four direct and three indirect contacts) were assessed. ProRoot MTA and Biodentine were the most used hCSCs and had the most desirable results. hCSCs were either freshly mixed or set before application. Most studies allowed hCSCs to set in incubation for 24 h before application, which resulted in the most desirable biological outcomes. Freshly mixed hCSCs had the worst outcomes. Indirect methods had significantly better viability/proliferation and odonto-/osteogenesis outcomes.

CONCLUSION

Biodentine and ProRoot MTA used in indirect exposure methods result in desirable biological outcomes.

Evaluation of dental pulp stem cells behavior after odontogenic differentiation induction by three different bioactive materials on two different scaffolds

BACKGROUND

To study the odontogenic potential of dental pulp stem cells (DPSCs) after induction with three different bioactive materials: activa bioactive (base/liner) (AB), TheraCal LC (TC), and mineral trioxide aggregate (MTA), when combined with two different types of scaffolds.

METHODS

DPSCs were isolated from freshly extracted premolars of young orthodontic patients, cultured, expanded to passage 4 (P), and characterized by flow cytometric analysis. DPSCs were seeded onto two scaffolds in contact with different materials (AB, TC, and MTA). The first scaffold contained polycaprolactone-nano-chitosan and synthetic hydroxyapatite (PCL-NC-HA), whereas the second scaffold contained polycaprolactone-nano-chitosan and synthetic Mg-substituted hydroxyapatite (PCL-NC-Mg-HA). DPSC viability and proliferation were evaluated at various time points. To assess odontoblastic differentiation, gene expression analysis of dentin sialophosphoprotein (DSPP) by quantitative real-time polymerase chain reaction (qRT-PCR) and morphological changes in cells were performed using inverted microscope phase contrast images and scanning electron microscopy. The fold-change in DSPP between subgroups was compared using a one-way ANOVA. Tukey's test was used to compare the fold-change in DSPP between the two subgroups in multiple comparisons, and P was set at p < 0.05.

RESULTS

DSPP expression was significantly higher in the PCL-NC-Mg-HA group than in the PCL-NC-HA group, and scanning electron microscopy revealed a strong attachment of odontoblast-like cells to the scaffold that had a stronger odontogenic differentiation effect on DPSCs than the scaffold that did not contain magnesium. MTA has a significantly higher odontogenic differentiation effect on cultured DPSCs than AB or TC does. The combination of scaffolds and bioactive materials improves DPSCs induction in odontoblast-like cells.

CONCLUSIONS

The PCL-NC-Mg-HA scaffold showed better odontogenic differentiation effects on cultured DPSCs. Compared to AB and TC, MTA is the most effective bioactive material for inducing the odontogenic differentiation of cultured DPSCs.

Bioceramics in Endodontics: Updates and Future Perspectives

Bioceramics, with excellent bioactivity and biocompatibility, have been widely used in dentistry, particularly in endodontics. Mineral trioxide aggregate (MTA) is the most widely used bioceramic in endodontics. Recently, many new bioceramics have been developed, showing good potential for the treatment of endodontic diseases. This paper reviews the characteristics of bioceramics and their applications in various clinical endodontic situations, including root-end filling, root canal therapy, vital pulp therapy, apexification/regenerative endodontic treatment, perforation repair, and root defect repair. Relevant literature published from 1993 to 2023 was searched by keywords in PubMed and Web of Science. Current evidence supports the predictable outcome of MTA in the treatment of endodontic diseases. Although novel bioceramics such as Biodentine, EndoSequence, and calcium-enriched mixtures have shown promising clinical outcomes, more well-controlled clinical trials are still needed to provide high-level evidence for their application in endodontics. In addition, to better tackle the clinical challenges in endodontics, efforts are needed to improve the bioactivity of bioceramics, particularly to enhance their antimicrobial activity and mechanical properties and reduce their setting time and solubility.

Effect of Biodentine on Odonto/Osteogenic Differentiation of Human Dental Pulp Stem Cells

This study aims to compare the biological characteristics of human dental pulp stem cells (hDPSCs) isolated from different-aged populations and examine the effects of Biodentine on proliferation and odonto/osteogenic differentiation of hDPSCs isolated from the elderly in vitro. hDPSCs were isolated from three different-aged populations: group A (≤18 years old), group B (19−59 years old), and group C (≥60 years old). The adhesion, proliferation, odonto/osteogenesis, and senescence were compared. The optimal concentration of aqueous Biodentine extract was determined by CCK-8 assay, alkaline phosphatase (ALP), and alizarin red staining (ARS). The effect of Biodentine on odonto/osteogenic gene and protein expression of hDPSCs in each group was evaluated by quantitative real-time PCR (QRT-PCR) and Western blot. hDPSCs were successfully isolated from three different-aged populations. Flow cytometry revealed that all isolated hDPSCs were positive for CD73 (>90%), CD90 (>90%), CD146 (<30%), and negative for CD45 (<1%). There existed an age-related decline in proliferation, odonto/osteogenic gene expression, and S-phase fraction (p < 0.05), an increase in senescence genes and p21 and p16 expression, and time needed for cell adhesion. Biodentine promoted hDPSC proliferation and mineralization in each group, particularly at a concentration of 0.2 mg/mL. Biodentine markedly enhanced odonto/osteogenesis-related gene and protein expression in each group (p < 0.05). hDPSCs can be obtained from populations of all ages. Though there is an age-related decline in their biological properties, hDPSCs from the elderly still maintain certain proliferation and multidirectional differentiation abilities. Biodentine can significantly promote the proliferation and odonto/osteogenic differentiation of hDPSCs isolated from the elderly over 60 years old, which could be considered a pulp capping material for vital pulp therapy in the elderly. Nevertheless, the efficacy of Biodentine in clinical application has to be further studied.

Comparative chemical properties, bioactivity, and cytotoxicity of resin-modified calcium silicate-based pulp capping materials on human dental pulp stem cells

OBJECTIVES

This study investigated the cytotoxicity, the residual monomer release, degree of conversion (DC), calcium ion (Ca²⁺) release, and crystal structure of TheraCal PT (ThPT) by comparison with TheraCal LC (ThLC) and mineral trioxide aggregate (MTA).

MATERIALS AND METHODS

The cytotoxicity of the cured materials was evaluated on human dental pulp stem cells (hDPSCs) isolated from third molars by the water-soluble tetrazolium salt (WST-1) method. The monomer release and DC of the resin-containing materials were analyzed by high-performance liquid chromatography (HPLC) and Fourier transform infrared (FTIR), respectively. The chemical composition and Ca²⁺ release of the materials were determined by scanning electronic microscopy-energy-dispersive spectroscopy (SEM-EDS), X-ray diffractometry (XRD), and inductively coupled plasma-optical emission spectroscopy (ICP-OES), respectively. Statistical differences were evaluated with one-way ANOVA, repeated measure ANOVA, and the Tukey test (p < 0.05).

RESULTS

MTA showed significantly lower cytotoxicity than either ThLC or ThPT after 1, 3, and 7 days (p < 0.05). TEGDMA release of ThPT is significantly higher than ThLC (p < 0.05). All materials showed calcium Ca²⁺ release, with MTA significantly higher than the others (p < 0.05).

CONCLUSIONS

MTA showed low cytotoxicity and high Ca²⁺ release compared to ThLC and ThPT.

CLINICAL RELEVANCE

The cytotoxicity and residual monomer release of ThLC and ThPT may raise concerns about the viability of hDPSCs. Further investigations with the use of in vivo research models are required to validate in vitro bioactivity properties and the potential adverse biological effects of ThLC and ThPT on hDPSCs.

Biocompatible Properties and Mineralization Potential of Premixed Calcium Silicate-Based Cements and Fast-Set Calcium Silicate-Based Cements on Human Bone Marrow-Derived Mesenchymal Stem Cells

Premixed calcium silicate-based cements (CSCs) and fast-set CSCs were developed for the convenience of retrograde filling during endodontic microsurgery. The aim of this study was to analyze the biocompatible properties and mineralization potential of premixed CSCs, such as Endocem MTA Premixed (EM Premixed) and EndoSequence BC RRM putty (EndoSequence), and fast-set RetroMTA on human bone marrow-derived mesenchymal stem cells (BMSCs) compared to ProRoot MTA. Using CCK-8, a significantly higher proliferation of BMSCs occurred only in the EM Premixed group on days 2 and 4 (p < 0.05). On day 6, the ProRoot MTA group had significantly higher cell proliferation than the control group (p < 0.05). Regardless of the experimental materials, all groups had complete cell migration by day 4. Alizarin Red-S staining and alkaline phosphatase assay demonstrated higher mineralization potential of all CSCs similar to ProRoot MTA (p < 0.05). The EndoSequence group showed more upregulation of SMAD1 and OSX gene expression than the other experimental groups (p < 0.05), and all experimental cements upregulated osteogenic gene expression more than the control group (p < 0.05). Therefore, using premixed CSCs and fast-set CSCs as retrograde filling cements may facilitate satisfactory biological responses and comparable osteogenic potential to ProRoot MTA.

Dental Pulp Response to Different Types of Calcium-Based Materials Applied in Deep Carious Lesion Treatment—A Clinical Study

Dental pulp vitality preservation in dental caries treatment is a major goal in odontotherapy. The main objective of this study was to compare dental pulp tissue responses to vital therapies in deep carious lesions, using different calcium-based materials. An ambispective study was conducted on 47 patients. Ninety-five teeth with deep carious lesions were treated. Among them, 25 (26.32%) were diagnosed with pulpal exposures and treated by direct pulp capping. Indirect pulp capping was applied when pulp exposure was absent (n = 70; 73.68%). Fifty teeth (52.63%) were treated with TheraCal LC (prospective study), 31 teeth (32.63%) with Calcimol LC, and 14 teeth (14.74%) with Life Kerr AC (retrospective study). The results show that the survival rate for dental pulp was 100% for Life Kerr AC, 92% for TheraCal LC, and 83.87% for Calcimol LC, without significant differences. Apparently, self-setting calcium hydroxide material provided better dental pulp response than the two light-cured materials, regardless of their composition, that is, either calcium -hydroxide or calcium silicate-based. We will need a significant number of long-term clinical studies with the highest levels of evidence to determine the most adequate biomaterials for vital pulp therapies.

Effects of calcium silicate-based cements on odonto/osteogenic differentiation potential in mesenchymal stem cells

The objective of this study was to evaluate the biological effects and odonto/osteogenic differentiation potential of Biodentine, NeoMTA Plus and TheraCal LC in tooth germ-derived stem cells (TGSCs). TGSCs were exposed to the material extracts. Biocompatibility was tested with MTS cell proliferation assay. Odonto/osteogenic differentiation was assessed with alkaline phosphatase (ALP) activity and mRNA gene expressions (RUNX2, DSPP and DMP-1). Scanning electronic microscopy/energy-dispersive X-ray (SEM/EDX) analysis and pH analysis were also performed for the materials. Data were evaluated using the one-way ANOVA and Tukey's tests. TGSCs remained viable after 7 days of incubation with all tested materials. Biodentine and NeoMTA Plus showed high ALP activity and increased expression of RUNX2, DSPP and DMP-1 compared to that of TheraCal LC. All materials can induce odonto/osteogenic differentiation of MSCs in various levels. Biocompatibility and odonto/osteogenic differentiation potential of Biodentine and NeoMTA Plus are similar and superior to that of TheraCal LC.

Effect of biodentine coated with emdogain on proliferation and differentiation of human stem cells from the apical papilla

BACKGROUND

This study assessed the effect of Biodentine coated with Emdogain (Biodentine/Emdogain) on proliferation and differentiation of human stem cells from the apical papilla (SCAPs). METHODS AND RESULTS: In this in vitro, experimental study, SCAPs were isolated from two immature impacted third molars and cultured. After ensuring the stemness of the cells by assessing the cell surface markers, they were exposed to Biodentine, Emdogain, and Biodentine/Emdogain for 24 and 72 h. The control cells did not receive any intervention. Cell viability was evaluated by the methyl thiazolyl tetrazolium assay. Expression of odontogenic differentiation genes was analyzed by the quantitative reverse transcription polymerase chain reaction. Alkaline phosphatase (ALP) activity was quantified by the respective kit. Data were analyzed by one-way ANOVA, t-test, and Mann-Whitney test (α = 0.05). Cell viability did not change after 24 h of exposure to biomaterials. At 72 h, the viability of the cells exposed to Biodentine and Biodentine/Emdogain decreased compared with the control group. The expression of dentin sialophosphoprotein, dentin matrix protein 1, and bone sialoprotein genes, and ALP activity significantly increased in all three experimental groups, compared with the control group at both 24 and 72 h; this increase was significantly greater in Biodentine/Emdogain group. The number of mineralized nodules significantly increased in all groups after 72 h with a greater rate in Biodentine/Emdogain group.

CONCLUSIONS

All biomaterials increased the differentiation of SCAPs, expression of odontogenic genes, and ALP activity, but Biodentine/Emdogain was significantly more effective for this purpose.

Biocompatibility and Osteogenic Potential of Calcium Silicate-Based Cement Combined with Enamel Matrix Derivative: Effects on Human Bone Marrow-Derived Stem Cells

The characteristics of retrograde filling material are important factors that can affect the long-term success of apical microsurgery. Various calcium silicate-based cements (CSC) were introduced to overcome drawbacks of mineral trioxide aggregate (MTA), while Emdogain is known to be effective in the regeneration of periodontal tissues. The aim of this study is to evaluate the biocompatibility and osteogenic potential of various CSCs combined with Emdogain on human bone marrow-derived mesenchymal stem cells. Experimental groups were classified into eight groups depending on the material and the presence of Emdogain. In the cell-counting kit test, all experimental groups combined with Emdogain showed higher cell viability compared with those without Emdogain at days 1 and 2. In the wound-healing assay, cell migration increased significantly over time, with or without Emdogain. In the alkaline phosphatase assay, all groups treated with Emdogain showed higher activity compared with those without Emdogain at day 3 (p < 0.05). Using alizarin red S staining, all groups treated with Emdogain showed greater calcium nodule formation compared with those without Emdogain at days 7 and 14 (p < 0.05). In conclusion, using CSCs as retrograde filling materials and the application of additional Emdogain will increase bone regeneration and improve the prognosis of apical microsurgery.