Assessment of the anti-inflammatory and biological properties of Bioroot Flow: A novel bioceramic sealer

INTRODUCTION

BioRoot Flow (BRF) is a novel premixed bioceramic sealer indicated for endodontic treatments, but the biological and immunomodulatory effects of this endodontic sealer on human periodontal ligament stem cells (hPDLSCs) have not been elucidated.

METHODS

To ascertain the biological impact of BRF, TotalFill BC Sealer (TFbc), and AH Plus (AHP) on human Periodontal Ligament Stem Cells (hPDLSCs), assessments were conducted to evaluate the cytocompatibility, cellular proliferation, migratory capacity, osteo/cementogenic differentiation potential, the ability to form mineralized nodules, and the immunomodulatory characteristics of hPDLSCs following treatment with these endodontic sealers.

RESULTS

Biological assays showed adequate cell metabolic activity and cell migration in BRF, while SEM assay evidenced that TFbc and BRF groups demonstrated a superior cell adhesion process, including substrate adhesion, cytoskeleton development, and spreading on the niche-like structures of the cement as compared to the AHP group. TFbc and BRF-treated groups exhibited a significantly lower IL6 and IL8 production than AHP (* p <.05). The bioceramic sealers stimulated heightened expression of BSP, CEMP-1, and CAP genes within a 7-14 day period. Notably, BRF and TFbc demonstrated a significant enhancement in the mineralization of hPDLSCs when compared to the negative control. Among these, cells treated with BRF showed a more substantial accumulation of calcium (*** p < .001).

CONCLUSIONS

Taken together, these findings indicate that BRF can potentially enhance cell differentiation by promoting the expression of essential genes related to bone and cement formation. In addition, BRF and TFbc displayed anti-inflammatory effects.

Premixed calcium silicate-based ceramic sealers promote osteogenic/cementogenic differentiation of human periodontal ligament stem cells: A microscopy study

To evaluate the effects of premixed calcium silicate based ceramic sealers on the viability and osteogenic/cementogenic differentiation of human periodontal ligament stem cells (hPDLSCs). The materials evaluated were TotalFill BC Sealer (TFbc), AH Plus Bioceramic Sealer (AHPbc), and Neosealer Flo (Neo). Standardized discs and 1:1, 1:2, and 1:4 eluates of the tested materials were prepared. The following in vitro experiments were carried out: ion release, cell metabolic activity 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell migration, immunofluorescence experiment, cell attachment, gene expression, and mineralization assay. Statistical analyses were performed using one-way ANOVA followed by Tukey's post hoc test (p < .05). Increased Ca2+ release was detected in TFbc compared to AHPbc and Neo (*p < .05). Biological assays showed a discrete cell metabolic activity and cell migration in Neo-treated cell, whereas scanning electronic microscopy assay exhibited that TFbc group had a better cell adhesion process of substrate attachment, spreading, and cytoskeleton development on the niche-like structures of the cement than AHPbc and Neo. The sealers tested were able to induce overexpression of the CEMP-1, ALP, and COL1A1 genes in the first days of exposure, particularly in the case of TFbc (***p < .001). All materials tested significantly increased the mineralization of hPDLSCs when compared to the negative control, although more pronounced calcium deposition was observed in the TFbc-treated cells (***p < .001). Our results suggested that TFbc promotes cell differentiation, both by increasing the expression of key osteo/odontogenic genes and by promoting mineralization of the extracellular matrix, whereas this phenomenon was less evident in Neo and AHPbc. RESEARCH HIGHLIGHTS: TFbc group had a better cell adhesion process of substrate attachment, spreading, and cytoskeleton development on the niche-like structures of the cement than AHPbc and Neo. The sealers tested were able to induce overexpression of the CEMP-1, ALP, and COL1A1 genes in the first days of exposure, particularly in the case of TFbc. All materials tested significantly increased the mineralization of hPDLSCs when compared to the negative control, although more pronounced calcium deposition was observed in the TFbc-treated cells.

3D Graphene/silk fibroin scaffolds enhance dental pulp stem cell osteo/odontogenic differentiation

OBJECTIVES

The current in vitro study aims to evaluate silk fibroin with and without the addition of graphene as a potential scaffold material for regenerative endodontics.

MATERIAL AND METHODS

Silk fibroin (SF), Silk fibroin/graphene oxide (SF/GO) and silk fibroin coated with reduced graphene oxide (SF/rGO) scaffolds were prepared (n = 30). The microarchitectures and mechanical properties of scaffolds were evaluated using field emission scanning electron microscopy (FESEM), pore size and water uptake, attenuated total reflectance fourier transformed infrared spectroscopy (ATR-FTIR), Raman spectroscopy and mechanical compression tests. Next, the study analyzed the influence of these scaffolds on human dental pulp stem cell (hDPSC) viability, apoptosis or necrosis, cell adhesion, odontogenic differentiation marker expression and mineralized matrix deposition. The data were analyzed with ANOVA complemented with the Tukey post-hoc test (p < 0.005).

RESULTS

SEM analysis revealed abundant pores with a size greater than 50 nm on the surface of tested scaffolds, primarily between 50 nm and 600 µm. The average value of water uptake obtained in pure fibroin scaffolds was statistically higher than that of those containing GO or rGO (p < 0.05). ATR-FTIR evidenced that the secondary structures did not present differences between pure fibroin and fibroin coated with graphene oxide, with a similar infrared spectrum in all tested scaffolds. Raman spectroscopy showed a greater number of defects in the links in SF/rGO scaffolds due to the reduction of graphene. In addition, adequate mechanical properties were exhibited by the tested scaffolds. Regarding biological properties, hDPSCs attached to scaffolds were capable of proliferating at a rate similar to the control, without affecting their viability over time. A significant upregulation of ALP, ON and DSPP markers was observed with SF/rGO and SF/GO groups. Finally, SF/GO and SF/rGO promoted a significantly higher mineralization than the control at 21 days.

SIGNIFICANCE

Data obtained suggested that SF/GO and SF/rGO scaffolds promote hDPSC differentiation at a genetic level, increasing the expression of key osteo/odontogenic markers, and supports the mineralization of the extracellular matrix. However, results from this study are to be interpreted with caution, requiring further in vivo studies to confirm the potential of these scaffolds.

In vitro biocompatibility of ammonia-free silver fluoride products on human dental pulp stem cells

OBJECTIVES

Silver fluoride (SF) is a preventive and therapeutic option for dental pathological processes involving structural alterations of the hard tissues, either during their formation or those caused by caries or other pathological reasons. This study aimed to compare the biological properties of two commercial SF products, one of them with ammonium (Riva Star; SDF) and the other ammonium-free (Riva Star Aqua; AgF), both with or without potassium iodide (KI), by the assessment of the cytotoxicity of the materials' eluates.

METHODS

Human dental pulp stem cells (hDPSCs) were obtained from healthy 18-23-year-old donors. Three dilutions were prepared for the tested materials (0.005%, 0.0005%, and 0.0001%). The following groups were assessed: (AgF, AgF+KI, SDF, SDF+KI, KI, negative control). A series of cytocompatibility assays were performed: MTT assay, IC50 assay, wound healing (migration) assay, cell cytoskeleton staining, analysis of cell apoptosis and necrosis, and reactive oxygen species production. The normality in the distribution of the data was previously confirmed via a Q-Q plot. Statistical significance was tested using one way ANOVA and Tukey's post hoc test.

RESULTS

The incorporation of KI improved the cytocompatibility of both SF products in terms of viability, migration, morphology, apoptosis, and reactive oxygen species production. This difference was higher in the AgF group. The lowest dilutions of SF+KI and AgF+KI showed a similar cytocompatibility to that of the control group (MTT assay (p > 0.05 after 24, 48, and 72 h of culture); migration assay (p > 0.05 after 24, 48, and 72 h of culture); reactive oxygen species production (p > 0.05 after 72 h of culture).

SIGNIFICANCE

Riva Star Aqua shows lower cytotoxicity than Riva Star on hDPSCs. It can be considered as a good alternative in the conservative treatment of dental caries and in the preservation and remineralisation of viable dentine tissue.

Biological properties of Ceraputty as a retrograde filling material: an in vitro study on hPDLSCs

OBJECTIVES

To assess the cytocompatibility and bioactive potential of the new calcium silicate-based cement Ceraputty on human periodontal ligament stem cells (hPDLSCs) compared to Biodentine and Endosequence BC root repair material (ERRM).

MATERIALS AND METHODS

hPDLSCs were isolated from extracted third molars from healthy donors. Standardized sample discs and 1:1, 1:2, and 1:4 eluates of the tested materials were prepared. The following assays were performed: surface element distribution via SEM-EDX, cell attachment and morphology via SEM, cell viability via a MTT assay, osteo/cemento/odontogenic marker expression via RT-qPCR, and cell calcified nodule formation via Alizarin Red S staining. hPDLSCs cultured in unconditioned or osteogenic media were used as negative and positive control groups, respectively. Statistical analysis was performed using one-way ANOVA or two-way ANOVA and Tukey's post hoc test. Statistical significance was established at p < 0.05.

RESULTS

The highest Ca2+ peak was detected from Biodentine samples, followed by ERRM and Ceraputty. hPDLSC viability was significantly reduced in Ceraputty samples (p < 0.001), while 1:2 and 1:4 Biodentine and ERRM samples similar results to that of the negative control (p > 0.05). Biodentine and ERRM exhibited an upregulation of at least one cemento/odonto/osteogenic marker compared to the negative and positive control groups. Cells cultured with Biodentine produced a significantly higher calcified nodule formation than ERRM and Ceraputty (p < 0.001), which were also higher than the control groups (p < 0.001).

CONCLUSION

Ceraputty evidenced a reduced cytocompatibility towards hPDLSCs on its lowest dilutions compared to the other tested cements and the control group. Biodentine and ERRM promoted a significantly higher mineralization and osteo/cementogenic marker expression on hPDLSCs compared with Ceraputty. Further studies are necessary to verify the biological properties of this new material and its adequacy as a retrograde filling material.

CLINICAL RELEVANCE

This is the first study to elucidate the adequate biological properties of Ceraputty for its use as a retrograde filling material.

In Vitro Biocompatibility of CPP-ACP and Fluoride-containing Desensitizers on Human Gingival Cells

OBJECTIVES

To analyze the biocompatibility of different desensitizers containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride in their composition: MI Varnish (MV), Clinpro White Varnish (3M Oral Care), Profluorid Varnish (VOCO), Duraphat (Colgate) and Embrace Varnish (Pulpdent) on human gingival fibroblast cells (hGF).

METHODS AND MATERIALS

Human gingival fibroblast (hGF) cells were exposed to several desensitizer extracts at different concentrations (0.1%, 1%, and 4% eluates). Then, in vitro biocompatibility was studied by analyzing the IC50 value, cell proliferation (MTT assay and cell cycle), cell migration (wound healing assay), cell morphology and F-actin content (immunocytofluorescence), and induction of apoptosis/necrosis (flow cytometry). Data were analyzed by one-way analysis of variance (ANOVA) followed by Tukey test.

RESULTS

The lowest cell viability and IC50 were observed in all concentrations of Embrace Varnish-treated hGFs (p<0.001), whereas the highest were exhibited by those treated with Clinpro White Varnish. Similar effects were evidenced when induction of apoptosis/necrosis and cell migration assays were assessed. Finally, MI Varnish, Profluorid Varnish, Duraphat, and Embrace Varnish extracts showed lower numbers of attached cells, some of them with an unusual fibroblastic morphology when cultured with 4% concentration of the varnishes, while Clinpro White Varnish exhibited a similar number of cells with an evident actin cytoskeleton compared to the control group.

CONCLUSIONS

The results obtained in this study indicate that hGFs show better in vitro biocompatibility after exposure to Clinpro White Varnish, even at the highest concentration employed, making it the most eligible for topical applications. In contrast, Embrace Varnish exhibited a high cytotoxicity towards hGFs that could potentially delay the healing process and regeneration of the oral mucosa, although more studies are needed to confirm this hypothesis.

Dental Healthcare Amid the COVID-19 Pandemic

The hustle and bustle of the planet Earth have come to a halt thanks to the novel coronavirus. The virus has affected approximately 219 million people globally; taken the lives of 4.55 million patients as of September 2021; and created an ambiance of fear, social distancing, and economic instability. The purpose of this review article is to trace the historical origin and evolution of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). The virus is highly contagious with a unique feature of rapid mutations-the scientific research is paving the way for discoveries regarding novel coronavirus disease (COVID-19) diagnosis, features, prevention, and vaccination. The connections between the coronavirus pandemic and dental practices are essential because COVID-19 is transmitted by aerosols, fomites, and respiratory droplets, which are also produced during dental procedures, putting both the patient and the dentist at risk. The main emphasis of this paper is to highlight the psychological, economic, and social impact of this pandemic on dental practices throughout the world and under what circumstances and guidelines can dental health care be provided. In the current situation of the pandemic, an appropriate screening tool must be established either by using rapid molecular testing or saliva point-of-care technology, which will be effective in identifying as well as isolating the potential contacts and carriers in hopes to contain and mitigate infection. The blessing in disguise is that this virus has united the leaders, scientists, health care providers, and people of all professions from all around the world to fight against a common enemy.

Comparative Biological Properties and Mineralization Potential of 3 Endodontic Materials for Vital Pulp Therapy: Theracal PT, Theracal LC, and Biodentine on Human Dental Pulp Stem Cells

INTRODUCTION

The aim of this study was to assess the biological properties and mineralization potential of the new Theracal PT (Bisco Inc, Schaumburg, IL) compared with its predecessor Theracal LC (Bisco Inc) and the hydraulic silicate-based cement Biodentine (Septodont, Saint-Maur-des-Fossés, France) on human dental pulp stem cells (hDPSCs) in vitro.

METHODS

Standardized sample discs were obtained for each material (n = 30) together with 1:1, 1:2, and 1:4 material eluates. Previously characterized hDPSCs were cultured with the different materials in standardized conditions, and the following assays were performed: a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, a wound healing assay, Annexin-V-FITC and 7-AAD staining (BD Biosciences, San Jose, CA), reactive oxygen species production analysis, cell adhesion and morphology evaluation via scanning electron microscopy and immunofluorescence, quantification of the expression of osteo/odontogenic markers via real-time quantitative reverse-transcriptase polymerase chain reaction, and alizarin red S staining. Statistical significance was established at P < .05.

RESULTS

All of the tested dilutions of Theracal LC exhibited a significantly higher cytotoxicity and reactive oxygen species production (P < .001) and a lower cell migration rate than the control group (hDPSCs cultured in growth medium without material extracts) at all of the measured time points (P < .001). Both 1:4 Theracal PT and Biodentine-treated hDPSCs exhibited similar levels of cytocompatibility to that of the control group, a significant up-regulation of at least 1 odontogenic marker (Biodentine: dentin sialophosphoprotein (P < .05); Theracal PT: osteonectin and runt-related transcription factor 2 [P < .001]), and a significantly higher mineralized nodule formation (P < .001).

CONCLUSIONS

The newly introduced TheraCal PT offers an improved in vitro cytocompatibility and mineralization potential on hDPSCs compared with its predecessor, TheraCal LC, and comparable biological properties to Biodentine.

Topical fluoride varnishes promote several biological responses on human gingival cells

OBJECTIVE

To compare the in vitro cytotoxicity of four commercial topical fluoride varnishes widely used in daily dental practice for the prevention of caries on human fibroblasts: Cervitec F, Fixofluor, Fluor Protector S and Duraphat.

MATERIAL AND METHODS

Human gingival fibroblasts (hGF) were exposed to different concentrations of fluoride varnishes extracts. Biological assays, including MTT and IC50 value determination, annexin-V/7-AAD staining, cell migration and F-actin staining with phalloidin were carried out. Statistical analyses were performed using one-way ANOVA and Tukey's post hoc test.

RESULTS

At 4% concentration, all of the fluoride varnishes extracts affected fibroblasts metabolic activity, exhibiting a high degree of cytotoxicity at all measured time points. At 0.1% and 1%, Duraphat and Fixofluor or Fluor Protector S and Cervitec F exerted the lowest or highest cytotoxic effects, respectively. Similar effects were evidenced when induction of apoptosis/necrosis and cell migration assays were analyzed. Immunocytochemical assays revealed a similar number of fibroblasts, without changes in the morphology and F-actin content at 0.1% concentration of all tested materials, while at 1% concentration, Fluor Protector S and Cervitec F showed few cells with aberrant morphology or non-adhered cells, respectively.

CONCLUSIONS

Different commercial topical fluoride varnishes with the same therapeutic indication may exhibit different biological effects and cytotoxicity on fibroblasts.

Melatonin Treatment Alters Biological and Immunomodulatory Properties of Human Dental Pulp Mesenchymal Stem Cells via Augmented Transforming Growth Factor Beta Secretion

INTRODUCTION

Melatonin is an endogenous neurohormone with well-reported anti-inflammatory and antioxidant properties, but the direct biological and immunomodulatory effects of melatonin on human dental pulp stem cells (hDPSCs) has not been fully elucidated. The aim of this study was to evaluate the influence of melatonin on the cytocompatibility, proliferation, cell migration, odontogenic differentiation, mineralized nodule formation, and immunomodulatory properties of hDPSCs.

METHODS

To address the melatonin biological effects on hDPSCs, the cytocompatibility, proliferation, cell migration, odontogenic differentiation, mineralized nodule formation, and immunomodulatory properties of hDPSCs after melatonin treatment were evaluated. The statistical differences were evaluated using 1-way analysis of variance with the Tukey multiple comparison test.

RESULTS

We found that melatonin did not alter hDPSC immunophenotype or cell viability, even at the highest concentrations used. However, using intermediate melatonin concentrations (10-300 μmol/L), a significantly higher proliferation rate (P < .05 and P < .01) and migration of hDPSCs (P < .01) were observed. Importantly, melatonin treatment (100 μmol/L) significantly increased the secretion of the anti-inflammatory cytokine transforming growth factor beta (P < .05 and P < .01) and provoked a more robust antiproliferative effect on mitogen-stimulated T cells (P < .05). Finally, and unlike previous results found with mesenchymal stem cells from other sources, melatonin fails to induce or accelerate the spontaneous osteogenic differentiation of hDPSCs.

CONCLUSIONS

Together, these findings provide key data on the bioactivity of melatonin and its effects on hPDSC biological and immunomodulatory properties.

Are Denture Adhesives Safe for Oral Cells?

PURPOSE

To compare the cytotoxicity of six commercially available denture adhesives on human gingival cells: Poligrip Flavour Free Fixative Cream, Fixodent Pro Duo Protection, Novafix cream, FittyDent, Polident Total Action, and Fixodent Pro Plus Duo Protection.

MATERIAL AND METHODS

Eluates of denture adhesives were brought into contact with human gingival cells and compared to untreated cells (w/o any dental adhesive elute). Cell toxicity was assessed by measuring cell viability (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assays), cell morphology (immunofluorescence assays), induction of apoptosis/necrosis and production of reactive oxygen species (ROS) (flow cytometry assays). In addition, the pH of each sample was determined. Data were analyzed using one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparisons test.

RESULTS

All denture adhesives tested led to a reduction in pH, especially Fixodent Pro Duo Protection and Fixodent Pro Plus Duo Protection. The cell viability assays showed that Fixodent Pro Duo Protection (1:1 72 hours, p = 3.04 × 10^-6 ; 1:2 72 hours, p = 2.07 × 10^-6 ; 1:4 72 hours, p = 2.04 × 10^-6 ) and Fixodent Pro Plus Duo Protection (1:1 72 hours, p = 2.01 × 10^-6 ; 1:2 72 hours, p = 3.03 × 10^-6 ; 1:4 72 hours, p = 2.02 × 10^-6 ) significantly decreased cell viability at all dilutions. Compared to the control group and the rest of the adhesives, Poligrip Flavour Free Fixative Cream (PFF 1:1 72 hours, p = 2.24 × 10^-6 ; 1:2 72 hours, p = 2.44 × 10^-6 ; 1:4 72 hours, p = 2.04 × 10^-6 ) showed a significantly higher cell viability score at all dilutions. Fixodent Pro Duo Protection and Fixodent Pro Plus Duo Protection, both adhesives containing zinc salts in their composition, were responsible for necrosis, and the number of cells was much reduced, with aberrant morphology and pyknotic nucleus. Finally, Fixodent (1:2, p = 2.04 × 10^-6 , 1:4, p = 0.00036; 1:2, p = 8.82 × 10^-6 , 1:4, p = 2.30 × 10^-6 ) products significantly promoted ROS production in gingival cells.

CONCLUSIONS

The results suggest that denture adhesives containing zinc in their composition could be responsible of the decrease of cell viability, ROS production, aberrant cell morphology, and induction of apoptosis and cell death. However, other possible additional cytotoxic factors must be considered. Thus, more studies are necessary to confirm this hypothesis.

Microstructural composition, ion release, and bioactive potential of new premixed calcium silicate-based endodontic sealers indicated for warm vertical compaction technique

OBJECTIVE

The aim of this study was to evaluate the microstructural composition, ion release, cytocompatibility, and mineralization potential of Bio-C Sealer ION+ (BCI) and EndoSequence BC Sealer HiFlow (BCHiF), compared with AH Plus (AHP), in contact with human periodontal ligament cells (hPDLCs).

MATERIALS AND METHODS

The sealers' ionic composition and release were assessed using energy-dispersive spectroscopy (EDS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. For the biological assays, hPDLCs were isolated from third molars, and sealer extracts were prepared (undiluted, 1:2, and 1:4 ratios). An MTT assay, wound-healing assay, and cell morphology and adhesion analysis were performed. Activity-related gene expression was determined using RT-qPCR, and mineralization potential was assessed using Alizarin Red staining (ARS). Statistical analyses were performed using one-way ANOVA and Tukey's post hoc test (α < 0.05).

RESULTS

The three sealers exhibited variable levels of silicon, calcium, zirconium, and tungsten release and in their composition. Both BCI and BCHiF groups showed positive results in cytocompatibility assays, unlike AHP. The BCHiF group showed an upregulation of CAP (p < 0.01), CEMP1, ALP, and RUNX2 (p < 0.001) compared with the negative control, while the BCI group showed an upregulation of CEMP1 (p < 0.01), CAP, and RUNX2 (p < 0.001). Both groups also exhibited a greater mineralization potential than the negative and positive controls (p < 0.001).

CONCLUSIONS

The calcium silicate-based sealers considered in the present in vitro study exhibited a high calcium ion release, adequate cytocompatibility, upregulated osteo/cementogenic gene expression, and increased mineralized nodule formation in contact with hPDLCs.

CLINICAL RELEVANCE

From a biological perspective, BCI and BCHiF could be clinically suitable for root canal filling.

Comparison of diffusion, cytotoxicity and tissue inflammatory reactions of four commercial bleaching products against human dental pulp stem cells

Multiple side effects related to bleaching were found to occur in the dental pulp tissue, including decreased cell metabolism and viability. In this work we evaluated the in vitro diffusion capacity, cytotoxicity and biocompatibility of four commercial bleaching products on stem cells from human dental pulp (hDPSCs). Two commercial bleaching gels hydrogen peroxide-based (HP), Norblanc Office 37.5% (Nor-HP) and Opalescence Boost 40% (Opal-HP) were applied for 30 min to enamel/dentine discs. Another two gels from the same manufacturers, 16% carbamide peroxide-based (CP), Norblanc Home (Nor-CP) and Opalescence CP 16% (Opal-CP), were applied for 90 min. The diffusion of HP was analysed by fluorometry. Cytotoxicity was determined using the MTT assays, the determination of apoptosis, immunofluorescence assays and intracellular reactive oxygen species (ROS) level. Tissue inflammatory reactions were evaluated histopathologically in rats. Statistical differences were performed by one-way ANOVA and Bonferroni post-test (α < 0.05). Normon products showed lower cytotoxicity and diffusion capacity than the Ultradent products. A high intracellular ROS level was measured in hDPSCs after exposure to Opal-HP. Finally, a severe necrosis of both coronal and radicular pulp was observed with Opal-HP. Similar concentrations of hydrogen peroxide and carbamide peroxide in a variety of bleaching products exhibited different responses in cells and dental pulp tissue, suggesting that bleaching products contain unknown agents that could influence their toxicity.

Canal shaping with a reciprocating system is easy to learn

AIM

To assess progressive learning of root canal shaping in order to define the number of simulated canals in resin blocks needed to reach a level of learning beyond which no further improvement in performance is observed.

METHODOLOGY

A total of 216 simulated canals in resin blocks were instrumented by 18 operators without experience in Endodontics and by 18 Endodontists. The R25 file of the Reciproc system (VDW, Munich, Germany) was used to prepare the canals. The blocks were photographed before and after instrumentation. An analysis was made of the variations in the dimensions of the canals at 6 locations and of the instrumentation time. A Student's t-test was used to analyse the data (P < 0.05).

RESULTS

The group without experience were associated with significant differences in instrumentation time between the first canal and the subsequent canals (P < 0.05) but differences in canal dimensions were not significant (P > 0.05). In the group with experience, the instrumentation time did not differ significantly after the fifth canal, and no significant variations in canal dimensions were observed (P > 0.05).

CONCLUSIONS

When conducting studies on root canal shaping or educating students with new instruments, a simulated canal sample size of 6 was appropriate to achieve competence.

Physicochemical, cytotoxicity and in vivo biocompatibility of a high-plasticity calcium-silicate based material

The purpose of this work was to evaluate the physicochemical properties, the cytotoxicity and in vivo biocompatibility of MTA Repair HP (MTA HP) and White MTA (WMTA). The setting time, flow, radiopacity and water solubility were assessed. To the cytotoxicity assay, primary human osteoblast cells were exposed to several dilutions of both materials eluates. MTT assay, apoptosis assay and cell adhesion assay were performed. The in vivo biocompatibility was evaluated through histological analysis using different staining techniques. No differences were observed between MTA HP and WMTA for setting time, radiopacity, solubility and water absorption (P > 0.05). However, MTA HP showed a significantly higher flow when compared to WMTA (P < 0.05). Cell viability results revealed that the extracts of WMTA and MTA HP promoted the viability of osteoblasts. After incubation of cells with the endodontic cement extracts, the percentage of apoptotic or necrotic cells was very low (<3%). Furthermore, SEM results showed a high degree of cell proliferation and adhesion on both groups. MTA HP showed similar in vivo biocompatibility to the WMTA and the control group in all time-points. The MTA HP presented adequate physicochemical and biological properties with improved flow ability when compared to WMTA. Such improved flow ability may be a result of the addition of a plasticizing agent and should be related to an improvement in the handling of MTA HP.

Biological effects of acid-eroded MTA Repair HP and ProRoot MTA on human periodontal ligament stem cells

OBJECTIVE

The aim of this study was to analyze the biological effects of MTA Repair HP and ProRoot MTA on human periodontal ligament stem cells (hPDLSCs) after exposure to acidic and neutral environments.

MATERIALS AND METHODS

Discs of each material (n = 30) were exposed to phosphate buffered saline (pH = 7.4) or butyric acid (pH = 5.2) for 7 days, and biological testing was carried out in vitro on hPDLSCs. Cell viability and apoptosis assays were performed using eluates of each root-end filling material. To evaluate cell attachment to the different materials, hPDLSCs were directly seeded onto the material surfaces and analyzed by scanning electron microscopy. The chemical composition of the root-end filling materials was determined by energy-dispersive x-ray and eluates were analyzed by inductively coupled plasma-mass spectrometry. Statistical differences were assessed by ANOVA and Tukey test (p < 0.05).

RESULTS

Under an acidic environment, both materials displayed similar ion release abilities, with the increased release of Si and Ca ions. Substantial changes in microstructure were observed for both materials after exposure to acidic pH. In addition, material exposure to an acidic environment showed a similar degree of cell adherence, and, surprisingly, MTA Repair HP exhibited higher cell viability rates at pH 5.2 than ProRoot MTA.

CONCLUSIONS

Exposure to an acidic environment promoted Si and Ca ion release from ProRoot MTA and MTA Repair HP. Moreover, we observed optimal biological properties of ProRoot MTA and MTA Repair HP in terms of cell viability, cell death, and cell attachment in both environments.

CLINICAL RELEVANCE

These results may suggest that MTA Repair HP and ProRoot exhibited optimal biological properties in terms of cell viability, cell death and cell attachment in acidic environment, being considered as materials for root-end filling and perforations.

Thermo-setting glass ionomer cements promote variable biological responses of human dental pulp stem cells

OBJECTIVE

To evaluate the in vitro cytotoxicity of Equia Forte (GC, Tokyo, Japan) and Ionostar Molar (Voco, Cuxhaven, Germany) on human dental pulp stem cells (hDPSCs).

METHODS

hDPSCs isolated from third molars were exposed to several dilutions of Equia Forte and Ionostar Molar eluates (1/1, 1/2 and 1/4). These eluates were obtained by storing material samples in respective cell culture medium for 24h (n=40). hDPSCs in basal growth culture medium were the control. Cell viability and cell migration assays were performed using the MTT and wound-healing assays, respectively. Also, induction of apoptosis and changes in cell phenotype were evaluated by flow cytometry. Changes in cell morphology were analysed by immunocytofluorescence staining. To evaluate cell attachment to the different materials, hDPSCs were directly seeded onto the material surfaces and analyzed by scanning electron microscopy (SEM). The chemical composition of the materials was determined by energy dispersive X-ray (EDX) and eluates were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). Statistical analysis was performed with analysis of variance (ANOVA) and Student's t-test (α<0.05).

RESULTS

Undiluted Equia Forte extracts led to a similar cell proliferation rates than the control group from 72h onwards. There were no significance differences between Equia Forte and Ionostar Molar in terms of cell apoptosis and phenotype. However, in presence of Equia extracts the migration capacity of hDPSCs was higher than in presence of Ionostar Molar (p<0.05). Also, SEM studies showed a higher degree of cell attachment when Equia Forte extracts were used. Finally, EDX analysis pointed to different weight percentages of C, O and Ca ions in glass ionomer cements, while other elements such as La, Al, Si, W, Mo and F were also detected.

SIGNIFICANCE

In summary, Equia Forte promoted better biological responses in hDPSCs than Ionostar Molar.

Implementation of augmented reality in operative dentistry learning

OBJECTIVE

To evaluate the efficacy of augmented reality (AR) in the gaining of knowledge and skills amongst dental students in the design of cavity preparations and analyse their degree of satisfaction.

MATERIAL AND METHODS

AR cavity models were prepared for use with computers and mobile devices. Forty-one students were divided into two groups (traditional teaching methods vs AR). Questionnaires were designed to evaluate knowledge and skills, with the administration of a satisfaction questionnaire for those using AR. The degree of compliance with the standards in cavity design was assessed. The Mann-Whitney U-test was used to compare knowledge and skills between the two groups, and the Wilcoxon test was applied to compare intragroup differences. The chi-square test in turn was used to compare the qualitative parameters of the cavity designs between the groups. Statistical significance was considered for P<.05 in all cases.

RESULTS

No significant differences were observed in level of knowledge before, immediately after or 6 months after teaching between the two groups (P>.05). Although the results corresponding to most of the studied skills parameters were better in the experimental group, significant differences (P<.05) were only founded for cavity depth and extent for Class I and divergence of the buccal and lingual walls for the Class II. The experience was rated as favourable or very favourable by 100% of the participants. The students showed preference for computers (60%) vs mobile devices (10%).

CONCLUSIONS

The AR techniques favoured the gaining of knowledge and skills and were regarded as a useful tool by the students.

Biological effects of silk fibroin 3D scaffolds on stem cells from human exfoliated deciduous teeth (SHEDs)

The aim is to investigate in vitro biological effects of silk fibroin 3D scaffolds on stem cells from human exfoliated deciduous teeth (SHEDs) in terms of proliferation, morphological appearance, cell viability, and expression of mesenchymal stem cell markers. Silk fibroin 3D scaffolding materials may represent promising suitable scaffolds for their application in regenerative endodontic therapy approaches. SHEDs were cultured in silk fibroin 3D scaffolds. Then, cell numbers were counted and the Alamar blue colorimetric assay was used to analyse cell proliferation after 24, 48, 72, and 168 h of culture. The morphological features of SHEDs cultured on silk fibroin scaffolds were evaluated by scanning electron microscopy (SEM). Finally, cell viability and the expression of mesenchymal stem cell markers were analysed by flow cytometry. One-way analysis of variance (ANOVA) followed by a Bonferroni post-test was performed (P < 0.05). At 24 and 48 h of culture, SHED proliferation on scaffolds was modest compared to the control although still significant (p < 0.05). However, cell proliferation progressively increased from 72 to 168 h compared with the control (p < 0.001; p < 0.01). In addition, flow cytometry analysis showed that the culture of SHEDs on silk fibroin scaffolds did not significantly alter the level of expression of the mesenchymal markers CD73, CD90, or CD105 up to 168 h; in addition, cell viability in silk fibroin was similar to than obtained in plastic. Moreover, SEM studies revealed a suitable degree of proliferation, cell spreading, and attachment, especially after 168 h of culture. The findings from the current study suggest that silk fibroin 3D scaffolds had a favourable effect on the biological responses of SHEDs. Further in vivo investigations are required to confirm these results.

Clinical management of the homozygous α-thalassemia with unusual mandibular manifestation of hematopoiesis

Alpha (α)-thalassemias are the most common genetic disorder of hemoglobin (Hb) synthesis, affecting up to 5% of the world's population. These congenital hemolytic anemias induce extramedullary hematopoiesis, including the liver, spleen, sinuses, and the diploic spaces of the skull. Oral health problems in patients with thalassemias are mostly related to a varied degree of facial deformities, malocclusions, and/or dental arch dimensions. We present a case with a 49-year-old man, diagnosed with homozygous α thalassemia that came to the Faculty of Dentistry at the University of Murcia for a dental treatment. It was observed that the patient had an unusual mandibular manifestation of hematopoiesis.

Evaluation of cytocompatibility of calcium silicate-based endodontic sealers and their effects on the biological responses of mesenchymal dental stem cells

AIM

To investigate in vitro the cytocompatibility of the calcium silicate-containing endodontic sealers MTA Fillapex and TotalFill BC Sealer on human periodontal ligament stem cells (hPDLSCs) by assaying their biological responses and compare them with that observed when using an epoxy resin-based sealer (AH Plus).

METHODOLOGY

Specimens from the three different endodontic sealers were eluated with culture medium for 24 h. The cytotoxicity of these eluates was evaluated using the MTT assay. In addition, an in vitro scratch wound healing model was used to determine their effects on cell migration. Cell adhesion to collagen type I after treatment with the different sealer eluates was also measured, whereas cytotoxicity was determined using the DNA-specific fluorochrome Hoechst 33342. Finally, to assess cell morphology and attachment to the different sealers, hPDLSCs were directly seeded onto the material surfaces and analysed by scanning electron microscopy (SEM). One-way analysis of variance (anova) followed by a Bonferroni post-test were performed (P < 0.05).

RESULTS

hPDLSCs exposed to different dilutions of TotalFill BC Sealer eluates had significantly higher cell proliferation compared with that observed when cells were treated with AH Plus and MTA Fillapex eluates (P < 0.001). In addition, TotalFill eluates were associated with significantly increased cell adhesion to collagen type I and migration of hPDLSCs in a concentration-dependent manner than displayed after treatment with MTA Fillapex or AH Plus eluates (P < 0.001). Moreover, TotalFill BC Sealer-induced cytotoxicity was significantly lower than observed using AH Plus and MTA Fillapex eluates (P < 0.001). Finally, SEM studies revealed suitable proliferation, cell spreading and attachment, especially when using TotalFill BC Sealer discs.

CONCLUSION

TotalFill BC Sealer exhibited a higher cytocompatibility than AH Plus and MTA Fillapex. Further investigations using in vivo animal models are required to validate the potential biological responses of TotalFill BC Sealer on hPDLSCs.

Novel aberrant genetic and epigenetic events in Friedreich's ataxia

It is generally accepted that Friedreich's ataxia (FRDA) is caused by a deficiency in frataxin expression, a mitochondrial protein involved in iron homeostasis, which mainly affects the brain, dorsal root ganglia of the spinal cord, heart and in certain cases the pancreas. However, there is little knowledge as to other possible genes that may be affected in this disorder, and which can contribute to its complexity. In the current study we compared human periodontal ligament cells gene expression of healthy individuals and FRDA patients. The expression of active-caspase 3, as well as other apoptosis-related genes, was increased in the FRDA cells. Furthermore, iron-sulphur cluster genes, as well as oxidative stress-related genes were overexpressed in FRDA. Moreover, brain-derived neurotrophic factor, neuregulin 1 and miR-132 were all upregulated. These three genes are capable of regulating the expression of each other. Interestingly, when the cells from FRDA patients were co-cultured in the presence of idebenone and deferiprone, caspase expression decreased while antioxidant gene expression, as well as frataxin expression, increased. Regarding epigenetic mechanisms, the frataxin gene was hypermethylated, compared to the healthy counterparts, in the upstream GAA repetitive region. Of the three DNA methyltransferases, DNMT1 but not DNMT3׳s gene expression was higher in FRDA cells. In conclusion, our data show that FRDA cells present altered expression of genes related to cell cycle, oxidative stress and iron homeostasis which may be implicated in the increased apoptotic levels. Also, the altered expression is in a certain degree normalized in the presence of idebenone and deferiprone.

Effects of composite films of silk fibroin and graphene oxide on the proliferation, cell viability and mesenchymal phenotype of periodontal ligament stem cells

In regenerative dentistry, stem cell-based therapy often requires a scaffold to deliver cells and/or growth factors to the injured site. Graphene oxide (GO) and silk fibroin (SF) are promising biomaterials for tissue engineering as they are both non toxic and promote cell proliferation. On the other hand, periodontal ligament stem cells (PDLSCs) are mesenchymal stem cells readily accessible with a promising use in cell therapy. The purpose of this study was to investigate the effects of composite films of GO, SF and GO combined with fibroin in the mesenchymal phenotype, viability, adhesion and proliferation rate of PDLSCs. PDLSCs obtained from healthy extracted teeth were cultured on GO, SF or combination of GO and SF films up to 10 days. Adhesion level of PDSCs on the different biomaterials were evaluated after 12 h of culture, whereas proliferation rate of cells was assessed using the MTT assay. Level of apoptosis was determined using Annexin-V and 7-AAD and mesenchymal markers expression of PDLSCs were analyzed by flow cytometry. At day 7 of culture, MTT experiments showed a high rate of proliferation of PDLSCs growing on GO films compared to the other tested biomaterials, although it was slightly lower than in plastic (control). However PDLSCs growing in fibroin or GO plus fibroin films showed a discrete proliferation. Importantly, at day 10 of culture it was observed a significant increase in PDLSCs proliferation rate in GO films compared to plastic (P < 0.05), as well as in GO plus fibroin compared to fibroin alone (P < 0.001). Flow cytometry analysis showed that culture of PDLSCs in fibroin, GO or GO plus fibroin films did not significantly alter the level of expression of the mesenchymal markers CD73, CD90 or CD105 up to 168 h, being the cell viability in GO even better than obtained in plastic. Our findings suggest that the combination of human dental stem cells/fibroin/GO based-bioengineered constructs have strong potential for their therapeutic use in regenerative dentistry.

Effects of two low-shrinkage composites on dental stem cells (viability, cell damaged or apoptosis and mesenchymal markers expression)

To investigate the effects of new two low-shrinkage composites SDR(®) and Venus(®)Bulk Fill on the cell viability, cellular damage and expression of mesenchymal markers on dental stem cells. Specimens from two low-shrinkage composites were eluted with culture medium for 24 h. After 24 h of incubation, cytotoxicity of elutes were evaluated by MTT assay; apoptosis was determined using the DNA-specific fluorochrome Hoechst 33342 and the mesenchymal stem cells markers expression was analyzed by immunofluorescence staining. After 24 h of cell exposure to each extract media, dental stem cells expressed MSCs markers. The interaction among the material and cell line was not significantly correlated [F(1,60) = 2.251, P = 0.39], whereas statistically significant differences among cells lines were observed [F(1,60) = 9.157, P = 0.004], being dental pulp stem cells more resistant that periodontal ligament stem cells. Also, we did not find any significant effect between the tested materials [F(1,60) = 0.090, P = 0.765]. Furthermore, a very low proportion of exposed cells showed condensed or fragmented nuclei, typical of apoptotic cells at 24 h. The results suggest that SDR(®) and Venus(®) Bulk fill and should be considered when selecting an appropriate resin-based dental restorative material.

Human adult periodontal ligament-derived cells integrate and differentiate after implantation into the adult mammalian brain

Previous studies suggest that neural crest (NC)-derived stem cells may reside in NC derivatives including the human periodontal ligament (hPDL). The isolation and manipulation of autologous NC-derived cells could be an accessible source of adult neural stem cells for their use in cell replacement and gene transfer to the diseased central nervous system. In this study, we examined the expression of NC markers and neural differentiation potential of hPDL-derived cells both in vitro and in vivo. In vitro we found that hPDL-derived cells expressed stem cell markers (Oct3/4, Nestin, Sox2, and Musashi-1) and a subset of NC cell markers (Slug, p75(NTR), Twist, and Sox9). hPDL-derived cells differentiated into neural-like cells based on cellular morphology and neural marker expression (TUJ1, MAP2, MAP1b, GAD65/67, GABA, NeuN, ChAT, GAT1, synaptophysin, GFAP, NG2, and O4). In vivo, hPDL-derived cells survive, migrate, and give rise to DCX(+), NF-M(+), GABA(+), GFAP(+), and NG2(+) cells after grafting the adult mouse brain. Some of the grafted hPDL-derived cells were located in stem cell niches such as the ventricular epithelium and the subventricular zone of the anterolateral ventricle wall as well as in the subgranular zone of the hippocampal dentate gyrus. Thus, the hPDL contains stem cells that originate from the NC and can differentiate into neural cells. The engraftment and differentiation properties of hPDL-derived cells in the adult brain indicate that they are a potential stem cell source to be used in neuroregenerative and/or neurotrophic medicine.

Orofacial problems in musicians: a review of the literature

OBJECTIVE

The objective of our study was to review the different pathologies of the stomatognathic system that can present in musicians as a result of playing their instruments.

DESIGN

The National Library of Medicine's PubMed database was searched to identify all peer-reviewed articles in the English literature dealing with orofacial problems in musicians, using both subject headings such as MeSH terms (PubMed) and free text words in combination (oral, musician, violin, wind instruments, vocalists, orthodontic, tooth, temporomandibular disorders [TMD]). The identified studies were assessed independently by two authors. We included any instruments that involved the orofacial area: i.e., wind and brass instruments, vocalists, and violins and violas.

RESULTS

Thirty-two articles were selected that were of many different types (clinical reviews, longitudinal and transverse studies of therapeutic procedures, case-control studies). Among orofacial problems, the most common disorders that affect musicians are TMDs, herpes simplex virus infections, orthodontic problems, and problems with perioral musculature.

CONCLUSIONS

Musicians may suffer from pathological conditions that are worsened by their occupation due to excessive practice and stress. These conditions can cause permanent injuries that subsequently prevent the musicians from playing. Depending on the characteristics of the musical instrument and the way it is played, professional musicians generally show a propensity for buccodental problems.

Mesenchymal stem cells derived from dental tissues

Regeneration of tissues occurs naturally due to the existence of stem cells with the capacity to self-regenerate and differentiate; however, regenerative capacity decreases with age, and in many cases, regeneration is not sufficient to repair the damage produced by degenerative, ischaemic, inflammatory, or tumour-based diseases. In the last decade, advances have been made in the understanding of stem cells, the genes that control the alternative fates of quiescence and differentiation, and the niches that provide specific signals that modulate cell fate decisions. Embryonic stem-cell research is shedding light on the secrets of development. Adult stem cells (AS cells) are available from several sources. Bone marrow and connective tissue have been used in preliminary clinical trials for regenerative therapy. Recently, several types of AS cells have been isolated from teeth, including dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, dental follicle progenitor stem cells and stem cells from apical papilla. Preliminary data suggest that these cells have the capacity to differentiate into osteoblasts, adipocytes, chondrocytes and neural cells. If confirmed, these data would support the use of these cells, which are easily obtained from extracted teeth, in dental therapies, including in regenerative endodontics, providing a new therapeutic modality.