Effect of loading rate and pH on glycerol fermentation and microbial population in an upflow anaerobic filter reactor.

A reactor with silicone tubes as support medium was used for glycerol fermentation. The experimental set-up consisted of three phases. In P1, the applied glycerol loading rate (gly-LR) was in the range of 6-10 g.L-1.d-1 at an influent pH of 7.9 ± 0.4. In P2, gly-LR was kept constant (18.0 ± 1.8 g.L-1.d-1) with different doses of NaHCO3. Finally in P3, two different gly-LR (9 and 18 g.L-1.d-1) were evaluated, dosing 1 g-NaHCO3 per g-COD of glycerol. Glycerol consumption was close 90%. The main end-product was 1,3-propanediol (1,3-PDO) (0.40 mol.mol-gly-1), but ethanol was also generated, particularly at pH above 8 and low gly-LR (0.20 mol.mol-gly-1). After 1-year operation with glycerol as the only carbon source, a drastic shift in the bacterial community was observed. The 1,3-PDO producers Lacrimispora and Clostridium became dominant, although non-glycerol-degrading fermentative genera, e.g., Actinomyces and Eubacterium, thrived at the expense of cellular breakdown products.

Marine sediments in the Gulf of Gabes (Tunisia) heavily polluted by phosphogypsum and human microbiota bacteria: phytoremediation by Salicornia europaea as a natural-based solution.

A huge amount of phosphogypsum (PG) wastes generated from the processing phosphate ore in Tunisia Industrial Group Area-Gabes is getting discarded into the sea. Within this framework, the basic objective of this research is to elaborate and discuss a natural-based solution focused on phytoremediation of contaminated (PG) soils and marine sediments with the halophilic plant Salicornia europaea. A significant drop of the organic matter (53.09%), moisture (26.47%), and sediment porosity with (5.88%) was detected in the rhizosphere Salicornia europaea area (RS). Removal of hazardous elements concentrations, such as Pb, Fe, Cu, Cd, and Zn, between contaminated sediment (CS) and RS displayed a significant difference, ranging from 5.33 to 50.02% of hazardous elements removal concentration, which was observed in the rhizosphere zone. The microbiota of both areas (RS and CS) were analyzed by massive sequencing. In both samples, all the sequences belong to only four phyla: Firmicutes and, to a much lower extent, Proteobacteria, Bacteroidetes, and Actinobacteria. The CS sediment seems to be heavily polluted by human activities. Most of the found genera are inhabitants of the intestine of warm-blooded animals (Escherichia, Bacteroides, Prevotella, Faecalibacterium, Ruminococcus, Enterococcus); hence, activities in this area pose a health risk. On the other hand, it may be surprising that 76.4% of the total high-quality sequences retrieved from the RS sample were affiliated to the family Bacillaceae. The salinity of the studied soil exerts a stress on the microbial populations that inhabit it, directing the selection of halotolerant species.

A Literature Review of the Effect of Heat on the Physical-Chemical Properties of Calcium Silicate-Based Sealers.

INTRODUCTION: Recently, calcium silicate-based sealers (CSSs) have gained popularity in endodontic practice due to their biocompatibility and antimicrobial properties. They are considered viable alternatives to epoxy resin-based sealers. With the increased use of CSSs and warm vertical compaction techniques in root canal treatment, evaluating the impact of heat on CSSs properties is essential, therefore this review aimed to present a qualitative synthesis of available in vitro studies assessing the impact of heat on the physical-chemical properties of CSSs. METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020 guidelines, a systematic advanced electronic search was performed in Scopus, Embase, Medline (via PubMed), Web of Science, and Cochrane databases in November 2023 and updated in April 2024. In vitro studies that evaluated the physical-chemical properties of CSSs were eligible. PRILE 2021 guidelines were used for the assessment of the risk of bias-included studies. RESULTS: The search identified a total of 6421 preliminary results and 10 studies were included for qualitative assessment. Eleven different physiochemical properties were assessed by the included studies. Setting time and flow were the most evaluated property among the studies. A qualitative synthesis of the evidence on each property is presented. CONCLUSIONS: Based on the in vitro studies assessed in the present systematic review, results reveal that exposing CSSs to heat can accelerate their setting time, reduce their flow, and increase their film thickness. Concerns persist regarding solubility, viscosity, radiopacity, dimensional change, microhardness, porosity, and compressive strength, requiring further research. Certain CSSs, such as MTA Fillapex and Endosequence BC sealer HiFlow, show minimal changes under heat, making them potential candidates for warm filling techniques.

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.

GPS Data and Machine Learning Tools, a Practical and Cost-Effective Combination for Estimating Light Vehicle Emissions.

This paper focuses on the emissions of the three most sold categories of light vehicles: sedans, SUVs, and pickups. The research is carried out through an innovative methodology based on GPS and machine learning in real driving conditions. For this purpose, driving data from the three best-selling vehicles in Ecuador are acquired using a data logger with GPS included, and emissions are measured using a PEMS in six RDE tests with two standardized routes for each vehicle. The data obtained on Route 1 are used to estimate the gears used during driving using the K-means algorithm and classification trees. Then, the relative importance of driving variables is estimated using random forest techniques, followed by the training of ANNs to estimate CO2, CO, NOX, and HC. The data generated on Route 2 are used to validate the obtained ANNs. These models are fed with a dataset generated from 324, 300, and 316 km of random driving for each type of vehicle. The results of the model were compared with the IVE model and an OBD-based model, showing similar results without the need to mount the PEMS on the vehicles for long test drives. The generated model is robust to different traffic conditions as a result of its training and validation using a large amount of data obtained under completely random driving conditions.

Comparative bioactivity and immunomodulatory potential of the new Bioroot Flow and AH Plus Bioceramic sealer: An in vitro study on hPDLSCs.

OBJECTIVES: To evaluate the cytocompatibility, bioactivity, and anti-inflammatory potential of the new pre-mixed calcium silicate cement-based sealers Bioroot Flow (BrF) and AH Plus Bioceramic Sealer (AHPbcs) on human periodontal ligament stem cells (hPDLSCs) compared to the epoxy resin-based sealer AH Plus (AHP). MATERIALS AND METHODS: Standardized discs and 1:1, 1:2, and 1:4 eluates of BrF, AHPbcs and AHP after setting were prepared. The following assays were performed: cell attachment and morphology via SEM, cell viability via a MTT assay, cell migration/proliferation via a wound-healing assay, cytoskeleton organization via immunofluorescence staining; cytokine release via ELISA; osteo/cemento/odontogenic marker expression via RT-qPCR, and cell mineralized nodule formation via Alizarin Red S staining. HPDLSCs were isolated from extracted third molars from healthy patients. Comparisons were made with hPDLSCs cultured in unconditioned (negative control) or osteogenic (positive control) culture media. Statistical significance was established at p < 0.05. RESULTS: Both BrF and AHPbcs showed significantly positive results in the cytocompatibility assays (cell metabolic activity, migration, attachment, morphology, and cytoskeleton organization) compared with a negative control group, while AHP showed significant negative results. BrF exhibited an upregulation of at least one osteo/cementogenic marker compared to the negative and positive control groups. BrF showed a significantly higher calcified nodule formation than AHPbcs, the negative and positive control groups, while AHPbcs was higher than the negative control group. Both were also significantly higher than AHP group. CONCLUSION: BrF and AHPbcs exhibit adequate and comparable cytocompatibility on hPDLSCs. BrF also promoted the osteo/cementogenic differentiation of hPDLSCs. Both calcium silicate-based sealers favored the downregulation of the inflammatory cytokine IL-6 and the calcified nodule formation from hPDLSCs. BrF exerted a significantly higher influence on cell mineralization than AHPbcs. CLINICAL RELEVANCE: This is the first study to elucidate the biological properties and immunomodulatory potential of Bioroot Flow and AH Plus Bioceramic Sealer. The results act as supporting evidence for their use in root canal treatment.

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.

Remineralizing Ability of Resin Modified Glass Ionomers (RMGICs): A Systematic Review.

The selective caries removal approach leads to the need to use materials with the ability to remineralize remaining partially demineralized dentin. Among the materials proposed are resin-modified glass ionomer cements (RMGICs). The aim of this systematic review was to evaluate, based on in vitro experimental studies, whether RMGICs are suitable for remineralizing affected dentin. A systematic literature search was performed in four databases, followed by article selection, data extraction, and quality assessment. Studies assessing the remineralizing potential of RMGICs on dentin were included in our review. Studies which compared such properties between different RMGICs or with other materials were also eligible. The studies report the remineralizing ability of RMGICs, albeit with differences between different commercial products. RMGICs show a similar ability to conventional GICs to remineralize affected dentin, fulfilling the function for which they are designed. Moreover, the incorporation of additives, such as bioactive glass (BAG) or CCP-ACP, improves their remineralizing potential. The results of this review support the use of RMGICs as restorative materials after selective caries removal.

Prognosis in home dental bleaching: a systematic review.

OBJECTIVES: The aim of this systematic review was to evaluate the prognosis of at-home dental bleaching using low concentration bleaching products. MATERIALS AND METHODS: This review was conducted was performed following the recommendations of the 2020 PRISMA statement and was registered in the International Prospective Register of Systematic Reviews (PROSPERO-CRD42022360530). The PICO question was "What is the prognosis of home teeth whitening treatment?". An advanced electronic search was made in three databases: PubMed, Web of Science, and Embase. RESULTS: The database search led to the retrieval of 225 articles. After elimination of duplicate references, the titles and abstracts of the articles were analyzed with respect to the eligibility criteria, and 24 studies were included for the development of the systematic review. CONCLUSIONS: Most authors state that the color remains stable between 1 and 2.5 years regardless of the type of bleaching agent or the forms of administration, and color stability in cases of severe discolorations presents a higher degree of recurrence. CLINICAL RELEVANCE: Given the growing demand for dental cosmetic treatments, the following systematic review may aid the clinician's continuing education and evidence-based practice by providing knowledge on the field of at-home dental bleaching agents and their long-term effects.

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.

Volumetric Changes of the Paranasal Sinuses with Age: A Systematic Review.

BACKGROUND: There are four pairs of paranasal sinuses: maxillary, ethmoidal, frontal, and sphenoidal. It is common to see changes in size and shape throughout life, so understanding the effect of age on sinus volume can help in radiographic studies and in planning dental and surgical procedures in the sinus-nasal region. The aim of the present systematic review was to perform a qualitative synthesis of available studies which assess the volumetric characteristics of the sinuses and their changes according to age. MATERIALS AND METHODS: The present review followed PRISMA 2020 guidelines. A systematic advanced electronic search was performed in five databases (Medline (via PubMed), Scopus, Embase, Cochrane, and Lilacs) in June-July 2022. Studies that assessed the volumetric changes of paranasal sinuses with age were eligible for inclusion. A qualitative synthesis of the methodology and results of the included studies was performed. Quality assessment was performed using the NIH quality assessment tool. RESULTS: A total of 38 studies were included in the qualitative synthesis. Most authors who studied the maxillary and ethmoidal sinuses concluded that it begins its development from birth until the maximum peak of growth, from which it begins to decrease in volume with age. Results regarding the volumetric changes of the frontal and sphenoidal sinuses are mixed. CONCLUSIONS: Based on the results of the studies included in the present review, it can be concluded that the volume of the maxillary and ethmoidal sinus appears to decrease with age. Conclusions on the volumetric changes of the sphenoidal and frontal sinuses require further evidence.

Calcium Silicate-Based Sealer Dentinal Tubule Penetration-A Systematic Review of In Vitro Studies.

The aim of this systematic review was to perform a qualitative synthesis of in vitro studies which evaluate and compare the penetration of calcium silicate-based sealers into dentinal tubules. A systematic advanced search was performed in Scopus, Embase, Medline (via PubMed), Web of Science, and Cochrane databases on the 1 December 2022. In vitro studies that compared the tubular penetration of at least two calcium silicate-based sealers in extracted human teeth were eligible. PRILE 2021 guidelines were used for the assessment of the risk of bias included studies. The search identified a total of 680 preliminary records, among which 12 studies were eligible for review. The most used methodology to evaluate sealer penetration was the use of a fluorochrome together with the tested sealers and the analysis of their penetration under confocal laser microscopy. Regarding the results of the included studies, calcium silicate-based sealers exhibit a favorable dentinal tubule penetration. Tubular penetration, however, can be affected by factors such as the irrigation protocol, sealer activation, the filling method used, and root canal morphology. EndoSequence BC Sealer showed the highest sealer penetration among the tested sealers. The influence of different fluorochromes on the results of dentinal tubule penetration studies should also be further explored. The in vitro nature of the included studies limits the applicability of the results into the clinical setting. Prospero registration: CRD42022383896.

Symbiosis between Cretaceous dinosaurs and feather-feeding beetles.

Extant terrestrial vertebrates, including birds, have a panoply of symbiotic relationships with many insects and arachnids, such as parasitism or mutualism. Yet, identifying arthropod-vertebrate symbioses in the fossil record has been based largely on indirect evidence; findings of direct association between arthropod guests and dinosaur host remains are exceedingly scarce. Here, we present direct and indirect evidence demonstrating that beetle larvae fed on feathers from an undetermined theropod host (avian or nonavian) 105 million y ago. An exceptional amber assemblage is reported of larval molts (exuviae) intimately associated with plumulaceous feather and other remains, as well as three additional amber pieces preserving isolated conspecific exuviae. Samples were found in the roughly coeval Spanish amber deposits of El Soplao, San Just, and Peñacerrada I. Integration of the morphological, systematic, and taphonomic data shows that the beetle larval exuviae, belonging to three developmental stages, are most consistent with skin/hide beetles (family Dermestidae), an ecologically important group with extant keratophagous species that commonly inhabit bird and mammal nests. These findings show that a symbiotic relationship involving keratophagy comparable to that of beetles and birds in current ecosystems existed between their Early Cretaceous relatives.

Remineralization Potential of Three Restorative Glass Ionomer Cements: An In Vitro Study.

The aim of this in vitro study was to evaluate the remineralizing ability of three glass ionomers on demineralized dentin with different thicknesses and time periods. Fifty third molars were obtained and were sectioned into 1-, 2-, and 3-mm thick slices (n = 36 for each thickness). The specimens were demineralized with 18% EDTA for 2 h. From the glass ionomer cements (GICs) under study (Ketac Molar Aplicap, Equia Forte, or Riva Light Cure), 1 mm was placed over each slice, set, and preserved in PBS until observation after 1, 7, 14, and 28 days after placement. For each material, thickness, and time, three samples were prepared. Using Fourier Transform Infrared Spectrometry (FTIR), apatite formation was determined on the side opposite to that on which the material had been placed. By means of Energy Dispersive Spectroscopy (EDX), the changes in the Calcium/Phosphate (Ca/P) ratio were evaluated. These changes were compared between the different materials by means of a two-way ANOVA test, considering time and dentin thickness, for a significance level of p < 0.05. Results: FTIR showed a peak at 1420 cm-1, evidencing the presence of carbonated hydroxyapatite in all the materials after 14 days, which indicates that a remineralization process occurred. Riva Light Cure showed the most homogeneous results at all depths at 28 days. The Ca/P ratio was maximum at 7 days in 2 mm of dentin for Riva Light Cure and Equia Forte HT (3.16 and 3.07; respectively) and for Ketac Molar at 14 days in 1 mm (3.67). All materials induced remineralization. Equia Forte achieved the greatest effect at 2 mm and Ketac Molar at 1 mm, whereas Riva Light Cure showed similar results at all depths. In terms of Ca/P ratio, Equia Forte and Riva Light Cure remineralized best at 2 mm, whereas for Ketac Molar, it was 1 mm. Carbonate apatite formation was higher at 24 h and 7 days for Ketac Molar, whereas it decreased at 14 days for Ketac Molar and peaked in Riva Light Cure and Equia Forte.

Effect of calcium silicate-based endodontic sealers on tooth color: A 3-year in vitro experimental study.

Objective: To analyze the change in tooth color produced by two hydraulic and one resin-based sealers by means of spectrophotometry for 3 years. Methods: Forty maxillary anterior teeth were selected (n = 10 per group). Root canals were prepared by rotary instrumentation and irrigation was performed with NaOCl, which was also used in the final irrigation, followed by saline and activated with Endoactivator. Root canals were then filled using single cone technique. Negative control (NC): gutta-percha filling; Positive control: gutta-percha and AH Plus; experimental groups: gutta-percha and Bioroot RCS/TotalFill BC Sealer. Gutta-percha was cut 2 mm below the cementoenamel junction, the pulp chamber was sealed with flowable composite. The teeth were kept in PBS. Color was measured in the cervical and incisal halves before root canal treatment (RCT), one and six months after RCT, and after one, two and three years, with the Vita EasyShade spectrophotometer; positioned using an individualized splint. ΔEab and ΔE00 were calculated. Two-way ANOVA repeated measures test followed by Bonferroni post-test were performed to analyze the ΔL, Δa*, Δb*, ΔEab, and ΔE00, considering treatment groups and evaluation periods. Statistical significance was set at p < 0.05. Results: In the incisal half, in decreasing order of darkening, the groups at three years were ordered according to the ΔEab: AH Plus > NC > TotalFill > Bioroot. ΔE00 values were: 1.38 ± 0.61 NC, 2.37 ± 0.70 AH Plus, 1.86 ± 0.60 BioRoot and 1.53 ± 0.85 TotalFill. In the cervical half, the ΔEab values, showed the same descending order, except for Bioroot and TotalFill which alternated the order. The ΔE00 values were 1.86 ± 0.61 NC, 3.01 ± 0.70 AH Plus,1.89 ± 0.58 Bioroot and 1.65 ± 0.41 TotalFill, with no significant differences between groups and times in both locations. Conclusions: All groups presented some degree of discoloration. Lightness and b* component were the most influential. Calcium silicate-based cements (Bioroot RCS and TotalFill BC Sealer) produced acceptable levels of discoloration at the end of follow-up.

Diameter and taper variability of gutta-percha cones adapted to TruNatomyTM and RotateTM rotary file systems.

Background: Evaluate the discrepancy in diameter and taper between adapted gutta-percha cones for TruNatomyTM 26.04 (TRU04), RotateTM 25.04 (ROT04) and 25.06 (ROT06) systems and their reference files. Material and Methods: A sample of 60 gutta-percha cones and 15 rotary files was selected and divided into three groups (TRU04, ROT04, ROT06). Each group consisted of 20 cones and 5 corresponding files. They were observed under an optical microscope at x20 magnification and images of all observations were obtained. Diameters were measured with a digital ruler calibrated at 3 levels: D1, D3, D16 (mm from tip). The taper of each system of cones and files was calculated, The percentage of discrepancy between the taper of each file system and its corresponding gutta-percha cone was calculated. Results: The percentage of discrepancy between the diameter of the tested gutta-percha cones and their corresponding files varied from -7% to 21%. The smallest dimensional discrepancy between gutta-percha cone and corresponding file was found at D16 in TRU04 group. The tapers of the gutta-percha cones vs their respective files were: 2% vs 3% (TRU04), 4% vs 5% (ROT04), and 6% vs 5% (ROT06). The highest discrepancy was observed at D16 in ROT06 group. The global taper discrepancy between gutta-percha cone and its corresponding file was negative in TRU04 and ROT04 groups. Conclusions: The taper and the diameter at D1, D3, and D16 differed between all of the tested gutta-percha cones and their corresponding files. TruNatomy 26.04 files and its adapted gutta-percha cones exhibited the least discrepancy. Key words:Corresponding gutta-percha, rotary file, taper, TruNatomy, Rotate, standardization.

Coupled C, H, N, S and Fe biogeochemical cycles operating in the continental deep subsurface of the Iberian Pyrite Belt.

Microbial activity is a major contributor to the biogeochemical cycles that make up the life support system of planet Earth. A 613 m deep geomicrobiological perforation and a systematic multi-analytical characterization revealed an unexpected diversity associated with the rock matrix microbiome that operates in the subsurface of the Iberian Pyrite Belt (IPB). Members of 1 class and 16 genera were deemed the most representative microorganisms of the IPB deep subsurface and selected for a deeper analysis. The use of fluorescence in situ hybridization allowed not only the identification of microorganisms but also the detection of novel activities in the subsurface such as anaerobic ammonium oxidation (ANAMMOX) and anaerobic methane oxidation, the co-occurrence of microorganisms able to maintain complementary metabolic activities and the existence of biofilms. The use of enrichment cultures sensed the presence of five different complementary metabolic activities along the length of the borehole and isolated 29 bacterial species. Genomic analysis of nine isolates identified the genes involved in the complete operation of the light-independent coupled C, H, N, S and Fe biogeochemical cycles. This study revealed the importance of nitrate reduction microorganisms in the oxidation of iron in the anoxic conditions existing in the subsurface of the IPB.

Effect of highly concentrated bleaching gels on enamel microhardness and superficial morphology, and the recovery action of four remineralizing agents.

BACKGROUND: Dental bleaching is a common clinical practice. The aim of this study is to investigate the effect of 35% hydrogen peroxide (HP) bleaching gel on the morphology and microhardness of enamel, and to analyze the effect of four remineralizing agents. METHODS: One hundred blocks were prepared. The enamel surfaces were bleached with 35% HP in one session. The specimens were divided into four remineralization treatment groups (n = 25). G1: Tooth Mousse, G2: Remin-Pro, G3: Colgate Pro-Relif, G4: Mirafluor. The remineralizing protocol was applied 3 min per day for one week. Vickers microhardness (HV) measurements and SEM observations were performed at baseline, after bleaching, and after remineralizing treatment in all groups. Statistical analyses were performed using the paired t-test and ANOVA. RESULTS: After bleaching, SEM showed an increase of irregularities on the surface of the samples. Enamel microhardness decreased a mean of 47.7 HV, equivalent to a mean decrease of 18.3% (p < 0.05). After remineralization, the HV increased in all groups between 16 and 33% (p < 0.01), recovering the initial microhardness of enamel samples. SEM images revealed a higher quantity of superficial mineral deposits in groups 1 and 2 compared to the rest of the groups. CONCLUSIONS: The application of remineralizing products generates a significant increase in enamel microhardness. Tooth Mousse-treated samples showed a greater microhardness recovery, followed by Remin Pro. The superficial morphology of the samples reflects the results obtained in the HV tests.

Tooth Bleaching of Discolorations Caused by Hydraulic Cements in Regenerative Endodontic Treatment: A 3-Year In Vitro Study.

This study aimed to evaluate the color change caused by hydraulic cements after 3 years in vitro by simulating their use in regenerative endodontic treatment (RET) and to quantify the color change after external bleaching with 40% hydrogen peroxide at 1, 6, and 12 months of follow-up. Fifty teeth were treated simulating RET. Samples were distributed according to the hydraulic cement to be used (n = 10 per group): negative control (no cement), ProRoot-MTA, MM-MTA, TotalFill BC-RRM, or Biodentine. Three years after RET, two sessions of external bleaching with Opalescence Boost were performed. The color was measured in the cervical and incisal halves of the teeth at different time points: baseline, 3 years after performing RET, and after 1, 6, and 12 months after bleaching. The ΔL, Δa, and Δb were determined. A generalized linear model was used to compare color considering group and time. The ΔEab and the ΔE00 were calculated and the acceptability in color change was determined. Three years after RET, a reduction in lightness (negative ΔL values) was found in all groups. These values significantly increased 1 month after bleaching in all groups (p < 0.05) and reversed at 6 months. One month after bleaching, ΔE00 values (color difference tolerance (CIEDE2000)) ranged from very good (>3.6 ≤ 5.4) to excellent (>5.4). One year after bleaching, the color reverted to values similar to those found 3 years after RET. All groups became darker after RET. The color recovered and even improved compared with the baseline measurement after one month of bleaching but did not remain stable over time.

Are Endodontic Solvents Cytotoxic? An In Vitro Study on Human Periodontal Ligament Stem Cells.

The aim of this study was to assess the influence of eucalyptol, chloroform, and Endosolv on the proliferative capability, cell viability, and migration rates of human periodontal ligament stem cells (hPDLSCs) in vitro. Solvent eluates were formulated following ISO 10993-5 guidelines, and 1%, 0.25%, and 0.1% dilutions were prepared. The HPDLSCs were isolated from the extracted third molars of healthy donors. The following parameters were assessed: cell viability via trypan blue and IC50 assays, cell migration via horizontal wound healing assay, cell morphology via cell cytoskeleton staining (phalloidin labeling), and cell oxidative stress via reactive oxygen species assay. The data were analyzed using one-way ANOVA and Tukey's posthoc tests, and their significance was established at p < 0.05. Chloroform and eucalyptol exhibited significantly higher cytotoxicity on the hPDLSCs in vitro compared to the control group, as shown by the cell viability, migration, morphology, and reactive oxygen species release assays. Alternatively, Endosolv showed adequate cytotoxicity levels comparable to those of the control group. The cytotoxicity of the tested endodontic solvents increased in a dose-dependent manner. The results from the present study highlight the cytotoxicity of chloroform and eucalyptol. Thus, their limited and cautious use is recommended, avoiding solvent extrusion.