Influence of dual-cure and self-cure abutment cements for crown implants on human gingival fibroblasts biological properties

Effects of Different Self-Adhesive Resin Cements and Curing Through Zirconia on Gingival Fibroblasts

INTRODUCTION

Self-adhesive resin cements (SARCs) are widely used for fixed prostheses. These cements and their eluted products may affect periodontal tissues. This study aimed to investigate the response of human gingival fibroblasts (HGFs) to eluates from SARCs in vitro, simulating clinical conditions after prosthesis fixation, to gain insights into their potential effects on gingival health.

METHODS

Two SARCs, RelyX U200 (RX) and Maxcem Elite Chroma (MC), were polymerised according to the manufacturer's protocols using various curing methods (light-cured, light-cured through 1- or 2 mm zirconia, and self-cured). HGFs were exposed to cement eluates at different concentrations. Cell viability, vitality, wound healing, and gene expression were assessed at different time points.

RESULTS

Self-cured MC and MC cured through 2-mm zirconia (both undiluted and 1:5 dilution) significantly decreased HGFs' viability. Lower cell viability and vitality were detected in MC compared with RX. Wound healing was delayed in cells treated with MC cured through zirconia compared to those cured with direct light, whereas zirconia had no effect on cells treated with RX. The expression of NRF2, a key regulator of cellular defence against oxidative and toxic insults, showed an increasing trend in cells treated with MC compared to RX. This finding suggests that MC may induce more oxidative stress than RX, leading to a more pronounced inflammatory response in HGFs and aligning with the observed delay in wound healing.

CONCLUSION

The use of MC, especially when cured through zirconia, may negatively impact gingival tissue health, highlighting the importance of carefully selecting cement types and curing methods in clinical practice.

CLINICAL RELEVANCE

This study highlights the potential risks of using MC, especially when cured through zirconia, which may impair gingival tissue health and delay wound healing. Proper choice of cement and curing methods is essential for optimal patient outcomes.

Three-dimensional finite element analysis of the biomechanical properties of different material implants for replacing missing teeth

The purpose of this study was to analyze the biomechanical properties of implants made of different materials to replace missing teeth by using three-dimensional finite element analysis and provide a theoretic basis for clinical application. CBCT data was imported into the Mimics and 3-Matic to construct the three-dimensional finite element model of a missing tooth restored by an implant. Then, the model was imported into the Marc Mentat. Based on the variations of the implant materials (titanium, titanium-zirconia, zirconia and poly (ether-ether-ketone) (PEEK)) and bone densities (high and low), a total of eight models were created. An axial load of 150 N was applied to the crown of the implant to simulate the actual occlusal situation. Both the maximum values of stresses in the cortical bone and implant were observed in the Zr-low model. The maximum displacements of the implants were also within the normal range except for the PEEK models. The cancellous bone strains were mainly distributed in the apical area of the implant, and the maximum value (3225 μstrain) was found in PEEK-low model. Under the premise of the same implant material, the relevant data from various indices in low-density bone models were larger than that in high-density bone models. From the biomechanical point of view, zirconia, titanium and titanium-zirconia were all acceptable implant materials for replacing missing teeth and possessed excellent mechanical properties, while the application of PEEK material needs to be further optimized and modified.

Biological Effects of New Chemical-Mechanical Caries Removal Products on Human Dental Pulp Stem Cells

INTRODUCTION

The aim of this study was to compare the biological effects of four chemical caries removal materials and to assess their cytotoxicity using human dental pulp stem cells (hDPSCs).

METHODS

The products evaluated are: 1 - papain-based product (BRIX 3000®); 2 - papain/chloramine based products (NATURAL-CARE and Papacárie Duo®); and 3 - chloramine based product (Cariesolut). The following in vitro experiments were carried out: IC50 measurement, cell metabolic activity (MTT) assay, cell migration, immunofluorescence experiment, cell apoptosis analysis, and reactive oxygen species (ROS) production analysis. Statistical analyses were performed using one-way ANOVA followed by Tukey's post hoc test (p < 0.05).

RESULTS

The IC50 values were: Brix 3000: 0.596%; Papacárie Duo: 0.052%; NATURAL CARE: 1.034%; and Cariesolut: 0.020%. The MTT assays showed non-adequate cell viability of all chemical-mechanical caries removal tested at 2% at 24, 48, and 72 h (p < 0.001). The same behaviour was observed at 0.1% in the Papacárie Duo and Cariesolut groups. In contrast, 0.1% of Brix 3000 at all times and NATURAL CARE at 24 h treated cells showed cell viability rates similar to the control group. At 0.01% only Brix 3000 did not show statistically significant differences at any time. Delayed cell migration was observed in all hDPSCs treated with Papacárie Duo and Cariesolut (p < 0.01 and p < 0.001). Phalloidin staining images showed a high confluence of cells in the presence of NATURAL CARE, similar to the control group. On the contrary, no cells were observed in Brix 3000 and Cariesolut at 2% and 0.1% concentrations. Papacárie Duo showed cells at all concentrations, but hDPSCs treated at 0.01% concentration exhibited better proliferation and spreading than those in the control group. Apoptosis essay showed that Brix 3000 at both 0.1% and 0.01% had a percentage of live cells higher than 99%, with 68.4% live cells at 2%, 3.69% early apoptotic cells, and 27.9% late apoptotic cells. Conversely, the rest of the materials showed an abundance of apoptotic cells, even at low concentrations. 0.1% and 0.01% of BRIX 3000 did not affect the ROS production levels, while 2% of BRIX 3000 counterpart very significantly increased the percentage of CM-H2DCFDA positive cells. Again, all concentrations of Cariesolut showed significantly higher levels of ROS production than those observed in control cells.

CONCLUSION

Our results suggest that Brix 3000 would be the most suitable material for chemical caries removal, with Papacárie Duo and NATURAL CARE also being good options, and discourage the use of Cariesolut due to its low cytocompatibility on dental pulp stem cells.

Comparative Cytotoxicity of Menthol and Eucalyptol: An In Vitro Study on Human Gingival Fibroblasts

The aim of this study was to assess the influence of eucalyptol and menthol on the cell viability, migration, and reactive oxygen species production of human gingival fibroblasts (GFs) in vitro. Three different concentrations of eucalyptol and menthol were prepared following ISO 10993-5 guidelines (1, 5, and 10 mM). GFs were isolated from extracted teeth from healthy donors. The following parameters were assessed: cell viability via MTT, Annexin-V-FITC and 7-AAD staining, and IC50 assays; cell migration via horizontal scratch wound assay; and cell oxidative stress via reactive oxygen species assay. Data were analyzed using one-way ANOVA and Tukey's post hoc test. Statistical significance was established at p < 0.05. Eucalyptol and Menthol exhibited high cytotoxicity on gingival fibroblasts, as evidenced by cytotoxicity assays. Eucalyptol showed lower levels of cytotoxicity than menthol, compared to the control group. The cytotoxicity of the tested substances increased in a concentration-dependent manner. The same occurred in a time-dependent manner, although even 10 min of exposure to the tested substances showed a high cytotoxicity to the GFs. Commercially available products for oral application with these substances in their composition should be tested for cytotoxicity before their use.

Effects of Surface Treatments and Cement Type on Shear Bond Strength between Titanium Alloy and All-Ceramic Materials

This study aimed to evaluate the effects of surface treatments and resin cement on the adhesion of ceramic and ceramic-like materials to titanium. A total of 40 specimens (5 mm diameter) of each material (lithium disilicate glass ceramic (LDGC-IPS e.maxCAD), lithium silicate glass ceramic (LSGC-VITA Suprinity) and a polymer-infiltrated ceramic network (PICN-Vita Enamic)) were fabricated using CAD/CAM technologies. In total, 120 titanium (Ti) specimens were divided into 12 groups, and half of the titanium specimens were tribochemically coated using CoJet. The titanium and all-ceramic specimens were cemented using either Self-curing adhesive cement (SCAC-Panavia 21) or a Self-curing luting composite (SCLC-Multilink Hybrid Abutment). After 5000 cycles of thermal aging, the shear bond strength (SBS) test was conducted using a universal testing machine. The failure modes of the specimens were analyzed using stereomicroscopy, and additionally, the representative specimens were observed using Scanning Electron Microscopy. ANOVA was used for the statistical analysis (p < 0.05). The post-hoc Duncan test was used to determine significant differences between the groups. The mean SBS values (mean ± STD) ranged from 15 ± 2 MPa to 29 ± 6 MPa. Significantly higher SBS values were acquired when the titanium surface was tribochemically coated (p < 0.05). The SCLC showed higher SBS values compared to the SCAC. While the LDGC showed the highest SBS values, the PICN presented the lowest. The tribochemical coating on the cementation surfaces of the titanium increased the SBS values. The specimens cemented with the SCLC showed higher SBS values than those with the SCAC. Additionally, the SCLC cement revealed a more significant increase in SBS values when used with the LDGC. The material used for restoration has a high impact on SBS than those of the cement and surface conditioning.

EFFECTIVENESS AND ABRASIVENESS OF ACTIVATED CHARCOAL AS A WHITENING AGENT: A SYSTEMATIC REVIEW OF IN VITRO STUDIES

INTRODUCTION

Tooth whitening is currently one of the most requested treatments to change the color of teeth. There are different types of whitening in the dental office and at home. There are also many whitening agents on the market. Nowadays, the public has shown great interest in a new natural compound: activated charcoal. It has an abrasive effect and it is included in toothpastes to whiten teeth quickly and easily.

OBJECTIVES

The main objective of the systematic review is to perform a qualitative synthesis of the available literature on the use of activated charcoal-based toothpaste for tooth whitening.

MATERIAL AND METHODS

An electronic search was carried out in PubMed, Web of Science, and Scopus databases. The search included the terms (charcoal-based OR activated charcoal OR charcoal OR soot) AND (toothpaste OR dentifrices OR bleaching OR oral hygiene OR enamel OR teeth). Inclusion criteria were articles that were published in English, that included activated charcoal toothpastes, that assessed the efficacy of activated charcoal bleaching and/or the safety of using activated charcoal toothpastes, that were conducted on humans or extracted teeth regardless of their origin and the year of publication.

RESULTS

Out of 208 articles, 11 met the inclusion criteria, the Risk of Bias of the selected studies was determined as medium-high. Regarding the whitening effect, there is a variety of results depending on the study: in some there are no significant differences between the proposed treatments and in others activated charcoal is not the most whitening agent. Regarding the abrasive effect, most studies agree that activated charcoal toothpaste has a higher abrasive potential.

CONCLUSION

Toothpastes based on activated charcoal possess a lower whitening effect than other alternatives and can be considered as less safe due to its high abrasive potential.

Weighted Gene Coexpression Network Analysis Identified IL2/STAT5 Signaling Pathway as an Important Determinant of Peri-Implantitis

Objective

Peri-implantitis (PI) is one of the main reasons for dental implant failure. Until now, the etiology and pathogenesis of PI remain unclear.

Methods

In this study, we used differentially expressed genes (DEGs) analysis and gene function enrichment analysis to assess the expression profile of peri-implant bone tissue and gingiva in PI public data from the Gene Expression Omnibus (GEO) database. Then, we used gingival tissues from patients with PI and healthy individual to construct gene coexpression networks to reveal the biological functions of the genes in PI using RNA sequencing data. Afterward, key gene modules were selected to reveal the critical biological process or signaling pathway using Hallmark's gene enrichment and expression analysis of the related pathway members in PI.

Results

DEGs were enriched in the formation of cellular responses to external stimuli in bone tissue. Cytokine production, lymphocyte activation, immune response-regulating signaling pathway, and blood vessel development were the top GO biology process or pathways of the DEGs in gingival tissue. Weighted gene coexpression network analysis (WGCNA) of RNA-seq data was used to assess the results of correlation analysis between modules and traits and correlation analysis between modules and functions. kMEpurple, kMEgreen, and kMEred modules were selected as the key gene modules. Signaling pathways and gene expression analysis were performed on selected modules, such as IL2/STAT5 signaling pathway, TNFα signaling pathway via NFκB, and angiogenesis were enriched in kMEpurple module. Hedgehog signaling pathway, Wnt β-catenin signaling pathway, and IL2/STAT5 signaling pathway were enriched in kMEgreen module. Peroxisome, IL2/STAT5 signaling pathway, and epithelial-mesenchymal transformation process were enriched in kMEred module. All the enrichment results of key modules contained IL2/STAT5 signaling pathway. Conclusion. Differential gene and enrichment analysis based on public data showed differences in gene expression patterns and biological process between bone and gingival tissues in PI. This spatial-temporal heterogeneity is reflected in the formation of cellular responses to external stimuli, which was enriched in bone tissue, but cytokine production, lymphocyte activation, immune response regulating signaling pathway, and blood vessel development were enriched in gingival tissue. WGCNA and Hallmark gene sets enrichment analysis of the gingival tissue expression profile and showed that IL2-mediated activation of immune cells could be a critical mechanism in PI. As a new clinical treatment alternative, we suggest that IL2/STAT5 pathway blockers could be helpful in the treatment of PI.

The Cytocompatibility of Silver Diamine Fluoride on Mesenchymal Stromal Cells from Human Exfoliated Deciduous Teeth: An In Vitro Study

Silver diamine fluoride (SDF) has been used for many years for the treatment of caries, and minimally invasive dentistry concepts have made it popular again. The fact that its application does not require the administration of anesthesia makes its use in children more desirable. The aim of this study was to determine the cytotoxicity of two new commercial SDF products: Riva Star (SDI Dental Limited) and e-SDF (Kids-e-Dental) on mesenchymal stromal cells from human exfoliated deciduous teeth (SHEDs). SHEDs were exposed to SDF products at different concentrations (0.1%, 0.01% and 0.005%). Then different assays were performed to evaluate their cytocompatibility on SHEDs: IC50, MTT, cell migration (wound healing), cell cytoskeleton staining, cell apoptosis, generation of intracellular reactive oxygen species (ROS), and ion chromatography. Statistical analyses were performed using one-way ANOVA and Tukey’s post hoc test (p < 0.05). Riva Star Step 2 showed the same cell metabolic activity when compared to the control condition at any time and concentration. Meanwhile, e-SDF displayed high cytotoxicity at any time and any concentration (*** p < 0.001), whereas Riva Star Step 1 displayed high cytotoxicity at any time at 0.1% and 0.01% (*** p < 0.001). Only e-SDF showed a statistically significant decreased cell migration rate (*** p < 0.001) at all times and in all concentrations. At 0.1%, e-SDF and Riva Star Step 1 only showed 4.37% and 4.47% of viable cells, respectively. These results suggest that Riva Star has better in vitro cytocompatibility on SHEDs than does e-SDF. Riva Star Step 1 was found to be as cytotoxic as e-SDF, but it had better biological properties when mixed with Riva Star Step 2. Our findings suggest that Riva Star is more suitable when used in deciduous teeth due to its lower cytotoxicity compared to e-SDF.