Effect of silica coating and laser treatment on the flexural strength, surface characteristics, and bond strength of a dental zirconia.

This study investigated the effect of irradiation with an erbium-doped yttrium aluminium garnet (Er:YAG) laser and coating with silica on the surface characteristics, bond strength, and flexural strength of dental zirconia. Three hundred and forty-three standard zirconia specimens were created, and 49 were assigned to each of seven surface treatment groups: (i) no treatment; Er:YAG laser (80 mJ/2 Hz) with pulse widths of 50 µs (ii), 100 µs (iii), 300 µs (iv), or 600 µs (v); or tribochemical silica coating at the partially sintered stage (vi) or after sintering was complete (vii). All specimens were sintered after the surface treatments, except for the group in which specimens were sintered before treatment. The study outcomes were roughness, surface loss, microshear bond strength (µSBS), and biaxial flexural strength (BFS). Mean roughness and surface loss values were significantly higher in specimens from irradiated groups than in those from silica-coated groups. Regarding µSBS, after aging, specimens from all experimental groups presented very low and similar µSBS values, irrespective of the surface treatment. Silica coating after sintering yielded the highest BFS (1149.5 ± 167.6 MPa), while coating partially sintered specimens with silica resulted a BFS (826.9 ± 60.9 MPa) similar to that of the untreated control group (794.9 ± 101.7 MPa). Laser treatments, irrespective of pulse width used, significantly decreased the BFS. In the group treated with laser at 300 µs pulse width, specimens exhibited the lowest BFS value (514.1 ± 71.5 MPa). Adhesion to zirconia was not stable after aging, regardless of the surface treatment implemented.

In vitro effect of curcumin-mediated antimicrobial photodynamic therapy on fibroblasts: viability and cell signaling for apoptosis.

Although it was demonstrated that curcumin-mediated antimicrobial photodynamic therapy (aPDT) is effective for reducing the viability of microbial cells and the vitality of oral biofilms, the cytotoxicity of this therapeutic approach for host cells has not been yet elucidated. Hence, the aim of this study was to evaluate the cytotoxicity and apoptotic effects of curcumin-mediated aPDT on mouse fibroblasts. Cells were treated with 0.6 or 6 µmol.L-1 curcumin combined with 0.075 or 7.5 J.cm-2 LED at 455 nm. Cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and crystal violet (CV) assays, while quantitative reverse transcriptase-PCR (qRT-PCR) was used to assess the expression of Bax, Bad, Bcl-2, VDAC-1, cytochrome C, and Fas-L genes for apoptosis. The differences between groups were detected by Kruskal-Wallis and post hoc Dunn's tests for MTT and CV assays and by ANOVA and post hoc Tukey test for qRT-PCR (P < 0.05). The effect of 0.6 µmol.L-1 curcumin plus 0.075 J.cm-2 LED (minimum parameter) did not differ statistically from control group; however, the combination of 0.6 µmol.L-1 curcumin plus 7.5 J.cm-2 LED reduced viable cells in 34%, while the combinations of 6 µmol.L-1 curcumin plus 0.075 and 7.5 J.cm-2 LED reduced viable cells in 47% and 99%, respectively. aPDT increased significantly the relative expression of Bax/Bcl-2, cytochrome C, VDAC-1, and Fas-L genes, without influence on the ratio Bad/Bcl-2. Therefore, curcumin-mediated aPDT activated Bcl-2 apoptosis signaling pathways in mouse fibroblasts regarding present conditions, reducing the viability of cells with the increase of curcumin concentrations and light energies.

Pharmacist-Led Medication Evaluation Considering Pharmacogenomics and Drug-Induced Phenoconversion in the Treatment of Multiple Comorbidities: A Case Report.

Pharmacogenomic (PGx) information can guide drug and dose selection, optimize therapy outcomes, and/or decrease the risk of adverse drug events (ADEs). This report demonstrates the impact of a pharmacist-led medication evaluation, with PGx assisted by a clinical decision support system (CDSS), of a patient with multiple comorbidities. Following several sub-optimal pharmacotherapy attempts, PGx testing was recommended. The results were integrated into the CDSS, which supported the identification of clinically significant drug-drug, drug-gene, and drug-drug-gene interactions that led to the phenoconversion of cytochrome P450. The pharmacist evaluated PGx results, concomitant medications, and patient-specific factors to address medication-related problems. The results identified the patient as a CYP2D6 intermediate metabolizer (IM). Duloxetine-mediated competitive inhibition of CYP2D6 resulted in phenoconversion, whereby the patient's CYP2D6 phenotype was converted from IM to poor metabolizer for CYP2D6 co-medication. The medication risk score suggested a high risk of ADEs. Recommendations that accounted for PGx and drug-induced phenoconversion were accepted. After 1.5 months, therapy changes led to improved pain control, depression status, and quality of life, as well as increased heart rate, evidenced by patient-reported improved sleep patterns, movement, and cognition. This case highlights the pharmacist's role in using PGx testing and a CDSS to identify and mitigate medication-related problems to optimize medication regimen and medication safety.

Cannabis Dopaminergic Effects Induce Hallucinations in a Patient with Parkinson's Disease.

Cannabis products that contain the tetrahydrocannabinol (THC) cannabinoid are emerging as promising therapeutic agents for the treatment of medical conditions such as chronic pain. THC elicits psychoactive effects through modulation of dopaminergic neurons, thereby altering levels of dopamine in the brain. This case report highlights the complexity associated with medicinal cannabis and the health risks associated with its use. A 57-year-old male with Parkinson's disease was experiencing worsening tremors and vivid hallucinations despite therapy optimization attempts. It was discovered that the patient took cannabis for chronic back pain, and a pharmacogenomics (PGx) test indicated the presence of variants for the COMT and HTR2A genes. These variants could increase dopamine levels and predispose patients to visual hallucinations. Once the cannabis was discontinued, the patient's hallucinations began to slowly dissipate. Cannabis use continues to expand as it gains more acceptance legally and medicinally, but cannabis can affect the response to drugs. This patient case suggests that cannabis use in combination with dopamine-promoting drugs, especially in a patient with genetic variants, can increase the risk for vivid hallucinations. These conditions support the importance of considering herb-drug interactions and PGx data when performing a medication safety review.

Effect of erosive and abrasive challenges on the glaze layer applied to ceramic materials.

PURPOSE: This study aims to evaluate the effect of erosive, abrasive, and erosive/abrasive challenges on the glaze layer of ceramic materials. METHODS: Ninety-five samples of monolithic zirconia (MZ) (LuxaCam Zircon HT-Plus) and lithium disilicate (LD) (IPS e.max CAD) were divided according to the response variables: Surface roughness and surface loss (n = 10), evaluated with optical profilometry; surface topography, with scanning electron microscopy SEM (n = 3); and biofilm deposition, with microbiological assay (n = 5). The evaluations were performed in three different time evaluations: (a) Sintered, (b) Glaze, and (c) Challenge (Erosion, Abrasion, and Erosion/Abrasion). Erosion consisted in immersing specimens in HCl solution, abrasion was performed with brushing machine, and erosion/abrasion consisted of a combination of the two previous protocols. Data were analyzed with parametric tests (P < 0.05). RESULTS: MZ glaze layer presented significantly higher surface roughness (P = 0.00), surface loss (P = 0.03), and biofilm deposition (P = 0.00) than LD. Abrasion and erosion/abrasion showed similar outcomes, generating significantly higher surface roughness (P = 0.00), surface loss (P = 0.00), and biofilm deposition (P = 0.01) than erosion. CONCLUSIONS: Glaze layer properties were altered by the challenges, with abrasion and erosion/abrasion generating higher surface roughness, surface loss, and biofilm deposition than erosion. A significant correlation was found between the surface roughness and biofilm deposition. CLINICAL SIGNIFICANCE: The glaze layer is susceptible to challenges, especially to abrasion and erosion/abrasion, which generated greater surface roughness and surface loss than erosion. The greater surface roughness lead to a greater biofilm deposition on the glaze layer.

Influence of Er:YAG laser pulse duration on the long-term stability of organic matrix and resin-dentin interface.

The purpose of this study was to explore the influence of Er:YAG laser irradiation with different pulse durations on the organic matrix, micromorphology of the hybrid layer (HL), and bond strength over time. Sixty caries-free human molars were cut to obtain flat dentin surfaces which were randomly divided into 4 groups: control (not irradiated-G1) and laser groups (80 mJ/2 Hz) with pulse duration ranging between 50 (G2), 300 (G3), and 600 µs (G4). A self-etch adhesive system (Universal 3M ESPE) was applied on pre-treated dentin surfaces and cylinders of resin composite were built up and stressed in a universal testing machine (µSBS) at 24 h and after12 months (n = 12). In addition, 3 other dentin-bonded specimens were prepared as previously described for each group with the adhesive doped with 0.1 wt% Rhodamine B to analyze hybrid layer morphology under Confocal Laser Microscope Scanning (CLMS). Organic matrix and collagen fibrils were analyzed by second harmonic generation (SGH). Two-way ANOVA and Tukey's test detected significantly higher µSBS values for the control group, whereas the lower values were observed in all laser groups at 24 h (p < 0.05). Storage in artificial saliva did not reduce µSBS in all groups. The low signal emitted by SHG images below the irradiated area demonstrated thermal damage of the collagen matrix. CLMS images of laser groups exhibited thicker and irregular resin-dentin interfaces than the control group. Regardless of the pulse duration, Er:YAG laser pre-treatment altered the organic matrix and HL formation which resulted in low µSBS values at 24 h. The alterations on dentin's organic structure did not jeopardize the µSBS after 1 year of saliva storage.

Effect of thermal and acid challenges on the surface properties of pink restorative materials.

PURPOSE: To compare the effect of thermal cycling and erosive challenge on color change, surface roughness, surface loss and biofilm deposition of three resin-based composites. METHODS: Three resin-based composites that reproduce the color of gingival tissues [two nanohybrid composites (A and B) and a giomer (C) ] were tested before and after distinct challenges [ thermal cycling (TC) and erosive challenge (EC) ] in regard to its color stability, surface roughness, surface loss and biofilm deposition. Surface roughness and surface loss specimens (n=10) were measured with an optical profilometer and, color stability (n=10) was measured with a spectrophotometer. Biofilm deposition (n=5) was measured after 3 and 24 hours by safranin staining. RESULTS: Two-way ANOVA test was performed to analyze color change, roughness and surface loss. A significant color change was detected for resin-based composites (P< 0.05) and its interaction with tested challenges (P< 0.05). The highest color variation was observed on the giomer after erosive challenge. Surface loss was not different between tested groups (P= 0.708). The roughness was significantly higher in specimens submitted to thermal cycling (P> 0.05). For biofilm quantification, after 3 and 24 hours, ANOVA (3-way) detected significance for the interaction of challenges and resin-based composites (P< 0.05 and P< 0.05, respectively). All resin-based composites presented color changes after challenges; higher roughness was observed after thermal cycling for all resin-based composites tested, without significant surface loss; and higher biofilm deposition was observed on the giomer samples when submitted to erosive challenge after 3 and 24 hours. CLINICAL SIGNIFICANCE: Pink esthetic is as important as dental esthetics and some restorative materials can mimic gingival tissue. However, the tested giomer must be indicated with caution, since it presented significant changes after thermal and acid challenges.

Optical coherence tomography and polarized light microscopy for the evaluation of artificial caries: a preliminary study.

This study was designed to investigate whether there is a correlation between the findings of optical coherence tomography (OCT) and polarized light microscopy (PLM) when these techniques are used to evaluate standard enamel white-spot lesions developed by distinct cariogenic challenges. Bovine enamel fragments (N = 168) were randomly allocated into 6 experimental groups according to the microbiologic model (Streptococcus mutans UA159, Streptococcus sobrinus ATCC 33478, or mixed S mutans and S sobrinus) and carbohydrate sources (1% sucrose or combined 1% sucrose and 1% starch). Specimens were examined by OCT and PLM every day within a period of 7 days. Five measurements of demineralization depth were recorded for each specimen, and means were calculated. Data were analyzed with analysis of variance and Tukey tests (α = 0.05), and a correlation test was performed. All cariogenic challenges created sub-superficial lesions. In both the OCT and PLM analyses, the demineralization depth reached its peak between days 6 and 7 of the cariogenic challenge, except for the group challenged with S sobrinus supplemented with combined sucrose and starch; for that group, demineralization peaked on day 5 in the OCT analysis. There was a significant correlation between OCT and PLM (P = 0.00; r = 0.842). This preliminary study suggests that OCT is a reliable, nondestructive method to measure the demineralization depth of enamel white-spot lesions, which can be useful for the laboratory and has potential for clinical studies. Using the 1% sucrose and S mutans model for 6 days is a simple and effective method to induce enamel caries-like lesions without compromising the depth and morphologic features of the obtained lesions.

Effects of different treatments on chemical and morphological features of eroded dentin.

To evaluate the treatment of eroded dentin (Sensodyne Repair & Protect™, Er:YAG laser and combinations). The occlusal surfaces of 25 third molars were sectioned 1.5 mm in thickness. After an erosion cycle (5 min in demineralizing solution + 3 h in remineralizing solution; six cycles a day for 8 days), the samples were divided into five groups (n = 5): (E) erosion - control; (ES) erosion + Sensodyne Repair & Protect (NovaMin); (EL) erosion + Er:YAG laser (40 mJ, 10 Hz, 0.4 W, 50 µs, 3.1 J/cm2, 63 W/cm2); (ELS) erosion + Er:YAG laser + Sensodyne; and (ESL) erosion + Sensodyne + Er:YAG laser. Following storage in ultrapure water (37 °C/14 days), the Ca/P ratio was evaluated by EDXRF and the morphology surfaces examined in SEM. The percentage of exposed dentin tubules was calculated. One-way analysis of variance and Tukey's test at 5% were used to treat the data. The Ca/P ratio was higher in E and ES groups. More exposed dentin tubules were found in E group and less exposed tubules were found in the ES group (p < 0.0001). When the toothpaste and laser were combined, the number of occluded dentin tubules was higher when laser was performed first (ELS). A positive effect was found when the laser and toothpaste were combined.

"Aroeira" (Myracrodruon urundeuva) methanol extract: the relationship between chemical compounds and cellular effects.

CONTEXT: "Aroeira" [Myracrodruon urundeuva Allemão (Anacardiaceae)] is a tree whose leaves have been studied for therapeutic purposes in medicine and dentistry. OBJECTIVE: The study chemically identifies the leaf extract of aroeira and determines its effect on human gingival fibroblasts. MATERIALS AND METHODS: An 80% methanol leave extract was obtained by maceration and chemically identified through flow-injection analysis-electrospray ionization-ion trap-tandem mass spectrometry (FIA-ESI-IT-MSn). Cytotoxicity of the aroeira's methanol extract was evaluated in lineage of fibroblasts. Adherent cells were treated with different concentrations of aroeira's methanol extract in the medium: 0.1, 1, 10, 100 and 1000 µg/mL. Control cells were cultivated in the medium only. Analyses were done at 24, 48, 72 and 96 h of culture by neutral red assay; and at 24, 48 and 96 h by crystal violet assay. RESULTS: FIA-ESI-IT-MS analysis determined the presence of compounds, for the first time in the species: quercetin-O-glucuronide and quercetin-O-deoxyhexose-O-glucose in the extract. On one hand, neutral red and crystal violet assay showed a reduction (to 50% up until 100%) of cellular viability of groups of 100 and 1000 µg/mL compared with control at 96 h (p < 0.05). On the other hand, lower concentrations (0.1; 1 and 10 µg/mL) of the extract were similar to that of the control at 96 h (p < 0.05), in general. CONCLUSIONS: In view of the results, we can conclude that the extract of aroeira presents tannins and flavonoids. Furthermore, the extract is capable of modulating the viability of human gingival fibroblasts according to its concentration.

Laser phototherapy enhances mesenchymal stem cells survival in response to the dental adhesives.

BACKGROUND: We investigated the influence of laser phototherapy (LPT) on the survival of human mesenchymal stem cells (MSCs) submitted to substances leached from dental adhesives. METHOD: MSCs were isolated and characterized. Oral mucosa fibroblasts and osteoblast-like cells were used as comparative controls. Cultured medium conditioned with two adhesive systems was applied to the cultures. Cell monolayers were exposed or not to LPT. Laser irradiations were performed using a red laser (GaAlAs, 780 nm, 0.04 cm(2), 40 mW, 1 W/cm(2), 0.4 J, 10 seconds, 1 point, 10 J/cm(2)). After 24 h, cell viability was assessed by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide reduction assay. Data were statistically compared by ANOVA followed by Tukey's test (P < 0.05). RESULTS: Different cell types showed different viabilities in response to the same materials. Substances leached from adhesives were less cytotoxic to MSCs than to other cell types. Substances leached from Clearfil SE Bond were highly cytotoxic to all cell types tested, except to the MSCs when applied polymerized and in association with LPT. LPT was unable to significantly increase the cell viability of fibroblasts and osteoblast-like cells submitted to the dental adhesives. CONCLUSION: LPT enhances mesenchymal stem cells survival in response to substances leached from dental adhesives.

Influence of gender, anxiety and depression symptoms, and use of oral contraceptive in color perception.

OBJECTIVE: The color is a psychophysical phenomenon, and much has been studied about its physical components. However, the psychological part is poorly investigated, except for the difference between genders in the literature shows that more men are color deficient than women. Dental students are trained to better understand the differences in color, so we became interested in studying whether psychological variables such as anxiety and depression and use of hormonal contraceptives may interfere with this ability. The aim of this in vitro study was to investigate if factors, such as, hormonal contraceptive use, depressive symptoms, anxiety and quality of life, influence on the ability of color discrimination of dental school students. MATERIALS AND METHODS: Sixty-one subjects participated and the following instruments apply: (1) test that consists in the observation of a set of 25 labels (Pantones) with values of known colors, (2) scales of depression, anxiety, and quality of life assessments, and (3) Ishihara test. RESULTS: No difference was observed between genders as color perception (p = 0.868). Symptoms of anxiety and depression were significantly more frequent in the female population that showed worse quality of life (p < 0.000) but did not interfere with color perception. Women using hormonal contraceptives had lower color perception than men (p = 0.04). CONCLUSION: No difference between the genders in the perception of colors was observed, contrary to common sense that women discriminate more colors than men, but women using hormonal contraceptives showed more difficulty in color perception. CLINICAL SIGNIFICANCE: The ability to understand and distinguish color differences is extremely important in clinical dentistry. There could be differences in color perception between men and women that would influence clinical performance.

Comparison of phenotypic tests for the detection of metallo-beta-lactamases in clinical isolates of Pseudomonas aeruginosa.

Metallo-ß-lactamase (MBL)-producing gram-negative bacteria are an increasing public health concern worldwide. Screening tests for the rapid and specific identification of these pathogens are essential, and should be included among routine diagnostics in laboratories. This study aimed to determine the MBL frequency among carbapenem-resistant Pseudomonas aeruginosa isolates, and to evaluate the accuracy of different tests in screening for MBL production. From January 2001 to December 2008, a total of 142 imipenem-non-susceptible P. aeruginosa strains were isolated from distinct clinical samples from hospitalized patients. These isolates were examined by PCR, MBL E-test, double-disk synergy test (DDST), and combined disk (CD) test. The minimal inhibitory concentration (MIC; µg/mL) was determined by agar dilution, and pulsed field gel electrophoresis (PFGE) was performed on all samples. Sequencing was performed to confirm and define the MBL variant and subtype. Using PCR and DNA sequence analysis, 93 strains were confirmed positive for MBLs, 91 strains for the blaSPM-1 gene, 1 strain for the blaIMP-1 gene, and 1 strain for the blaIMP-16 gene. PFGE displayed a clonal pattern. The sensitivities, specificities, positive and negative predictive values were evaluated for all tests. The DDST assay (CAZ-MPA) was the optimal method for screening MBL production in P. aeruginosa strains. However, the results of the CD assay (IMP/EDTA) showed close agreement with those of the DDST. In addition, the CD assay allowed a more objective interpretation and did not require the use of a toxic substance.

Obtaining artificially caries-affected dentin for in vitro studies.

AIM: This study evaluated and improved a protocol for obtaining standard caries-affected dentin (CAD) by Streptococcus mutans biofilm demineralization process. MATERIALS AND METHODS: Forty-eight human molars were divided in six experimental groups, according to: period of cariogenic challenge (7, 14 or 21 days) and type of dentin (erupted or unerupted teeth). After complete cariogenic challenge sound and CAD dentin were evaluated by: visual inspection (VI), digital radiography (DR), optical coherence tomography (OCT) and laser fluorescence (LF). RESULTS: Visual inspection confirmed the formation of CAD based on tissue yellowing and loss of surface gloss. Digital radiography detected the presence of radiolucent images, suggesting caries. Three calibrated examiners viewed all images obtained by VI and DR and were able to distinguish healthy from CAD. Fisher's exact statistical test (p < 0.05) confirmed no difference between groups by VI (G1/G4: p = 0.6; G2/G5: p = 1; G3/G6: p = 1) or DR (G1/G4: p = 1; G2/G5: p = 1; G3/G6: p = 1). Both LF values and demineralization depth, as determined by OCT, were subjected to ANOVA (p < 0.05). For LF, a statistically significant difference was observed for the type of substrate (p = 0.001). For OCT, no statistically significant differences in the type of substrate (p = 0.163), length of cariogenic challenge (p = 0.512) or interaction between factors (p = 0.148) were observed. Scanning electron micrographs confirmed the presence of CAD; a more uniform demineralization surface was observed in the dentin of unerupted teeth. CONCLUSION: This protocol suggests that standard CAD can be obtained in 7 days of cariogenic challenge using unerupted teeth. Clinical significance: With the new perspective on the clinical treatment of caries lesions, bonding is increasingly performed to demineralize CAD, which is susceptible to remineralization. A useful protocol to standardize the production of CAD, by microbiological cariogenic challenge, would be an important contribution to laboratorial test in the field of operative dentistry.

Comparison of biofilm models for producing artificial active white spot lesions.

OBJECTIVE: This study compared three protocols for developing artificial white spot lesions (WSL) using biofilm models. METHODOLOGY: In total, 45 human enamel specimens were sterilized and allocated into three groups based on the biofilm model: Streptococcus sobrinus and Lactobacillus casei (Ss+Lc), Streptococcus sobrinus (Ss), or Streptococcus mutans (Sm). Specimens were incubated in filter-sterilized human saliva to form the acquired pellicle and then subjected to the biofilm challenge consisting of three days of incubation with bacteria (for demineralization) and one day of remineralization, which was performed once for Ss+Lc (four days total), four times for Ss (16 days total), and three times for Sm (12 days total). After WSL creation, the lesion fluorescence, depth, and chemical composition were assessed using Quantitative Light-induced Fluorescence (QLF), Polarized Light Microscopy (PLM), and Raman Spectroscopy, respectively. Statistical analysis consisted of two-way ANOVA followed by Tukey's post hoc test (α=0.05). WSL created using the Ss+Lc protocol presented statistically significant higher fluorescence loss (ΔF) and integrated fluorescence (ΔQ) in comparison to the other two protocols (p<0.001). RESULTS: In addition, Ss+Lc resulted in significantly deeper WSL (137.5 µm), followed by Ss (84.1 µm) and Sm (54.9 µm) (p<0.001). While high mineral content was observed in sound enamel surrounding the WSL, lesions created with the Ss+Lc protocol showed the highest demineralization level and changes in the mineral content among the three protocols. CONCLUSION: The biofilm model using S. sobrinus and L. casei for four days was the most appropriate and simplified protocol for developing artificial active WSL with lower fluorescence, higher demineralization, and greater depth.

Comparison between a bulk-fill resin-based composite and three luting materials on the cementation of fiberglass-reinforced posts.

Objectives: This study verified the possibility of cementing fiberglass-reinforced posts using a flowable bulk-fill composite (BF), comparing its push-out bond strength and microhardness with these properties of 3 luting materials. Materials and Methods: Sixty endodontically treated bovine roots were used. Posts were cemented using conventional dual-cured cement (CC); self-adhesive cement (SA); dual-cured composite (RC); and BF. Push-out bond strength (n = 10) and microhardness (n = 5) tests were performed after 1 week and 4 months of storage. Two-way repeated measures analysis of variance (ANOVA), 1-way ANOVA, t-test, and Tukey post-hoc tests were applied for the push-out bond strength and microhardness results; and Pearson correlation test was applied to verify the correlation between push-out bond strength and microhardness results (α = 0.05). Results: BF presented higher push-out bond strength than CC and SA in the cervical third before aging (p < 0.01). No differences were found between push-out bond strength before and after aging for all the luting materials (p = 0.84). Regarding hardness, only SA presented higher values measured before than after aging (p < 0.01). RC and BF did not present 80% of the maximum hardness at the apical regions. A strong positive correlation was found between the luting materials' push-out bond strength and microhardness (p < 0.01, R2 = 0.7912). Conclusions: The BF presented comparable or higher push-out bond strength and microhardness than the luting materials, which indicates that it could be used for cementing resin posts in situations where adequate light curing is possible.

The Multifarious Functions of Leukotrienes in Bone Metabolism.

Leukotrienes (LTs) are derived from arachidonic acid metabolism by the 5-lipoxygenase (5-LO) enzyme. The production of LTs is stimulated in the pathogenesis of rheumatoid arthritis (RA), osteoarthritis, and periodontitis, with a relevant contribution to bone resorption. However, its role in bone turnover, particularly the suppression of bone formation by modulating the function of osteoclasts and osteoblasts, remains unclear. We investigated the effects of LTs on bone metabolism and their impact on osteogenic differentiation and osteoclastogenesis using a 5-LO knockout (KO) mouse model. Results from micro-computed tomography (µCT) analysis of femur from 8-week-old 5-LO-deficient mice showed increased cortical bone and medullary region in females and males and decreased trabecular bone in females. In the vertebra, we observed increased marrow area in both females and males 5-LO KO and decreased trabecular bone only in females 5-LO KO. Immunohistochemistry (IHC) analysis showed higher levels of osteogenic markers tissue-nonspecific alkaline phosphatase (TNAP) and osteopontin (OPN) and lower expression of osteoclastogenic marker tartrate-resistant acid phosphatase (TRAP) in the femurs of 5-LO KO mice versus wild-type (WT). Alkaline phosphatase activity and mineralization assay results showed that the 5-LO absence enhances osteoblasts differentiation and mineralization but decreases the proliferation. Alkaline phosphatase (ALP), Bglap, and Sp7 gene expression were higher in 5-LO KO osteoblasts compared to WT cells. Eicosanoids production was higher in 5-LO KO osteoblasts except for thromboxane 2, which was lower in 5-LO-deficient mice. Proteomic analysis identified the downregulation of proteins related to adenosine triphosphate (ATP) metabolism in 5-LO KO osteoblasts, and the upregulation of transcription factors such as the adaptor-related protein complex 1 (AP-1 complex) in long bones from 5-LO KO mice leading to an increased bone formation pattern in 5-LO-deficient mice. We observed enormous differences in the morphology and function of osteoclasts with reduced bone resorption markers and impaired osteoclasts in 5-LO KO compared to WT osteoclasts. Altogether, these results demonstrate that the absence of 5-LO is related to the greater osteogenic profile. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Comparison of chemical aging and water immersion time on durability of resin-dentin interface produced by an etch-and-rinse adhesive.

AIM: The aim of this study was to analyze and compare the influence of short-term NaOCl-storage and long-term water storage on the microtensile bond strength (µTBS) of etch-and-rinse adhesive system to human dentin. MATERIALS AND METHODS: Thirty-six third human molars were randomly divided into 6 groups (n = 6) according to the aging protocol: G1 (water, 24 hours); G2 (water, 6 months); G3 (water, 12 months); G4 (10% sodium hypochlorite--NaOCl, 1 hour); G5 (10% NaOCl, 3 hours) and G6 (10% NaOCl, 5 hours). A two-step etch-and-rinse adhesive (Adper Single Bond 2) was applied according to the manufacturers' instructions. A composite (Filtek Z250) was applied in four horizontal increments and was individually cured. Specimens were cut following the microtensile test technique, submitted to the different aging protocols, and tested in tension. The fracture pattern was observed in a stereomicroscope (40* magnification) and in a scanning electron microscope. The µTBS data were analyzed by ANOVA and Tukey's test (α = 0.05). RESULTS: The effect of storage in 10% NaOCl for 1 or 3 hours was not significantly different from that of aging in distilled water (DW) for 6 or 12 months (p > 0.05). Beams immersed in DW for 24 hours and in 10% NaOCl for 5 hours showed the highest and lowest µTBS values respectively. CONCLUSION: The aging protocols negatively influenced dentin bond strength. Aging specimens in 10% NaOCl for 1 or 3 hours can be an alternative method for long-term water storage (6 or 12 months) bond strength studies. CLINICAL SIGNIFICANCE: This aging protocol allows a quick achievement of longitudinal bond strength data, so that results are available to the professionals in this area while the materials are yet present at the dental market.

The interference of the cleaning procedure of root walls with two different solvents on the adhesion of fiberglass intraradicular posts.

AIM: This study was undertaken to examine the effect of root canal (RT) sealers content and the cleaning procedure of RT walls on bond strength (BS) of a fiber reinforced composite (FRC) post cemented with resin-based or zinc phosphate cement. MATERIALS AND METHODS: Forty bovine roots were divided into 2 groups (n = 20) and obturated with gutta-percha points plus Sealer 26 sealer or gutta-percha points plus N-Rickert sealer. In each group, half (n = 10) of intracanal walls was cleaned with ethanol and the other half with sulfuric ether. In each of these subgroups, half of intracanal posts (n = 5) were cemented with Bistite resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test and tensile force until post dislodgement. The maximum forces required for post removal was expressed in MPa, means were submitted to statistical analysis (Analysis of Variance Test, a = 0.05). RESULTS: Fiber reinforced composite cemented with zinc phosphate were significantly more retentive than those cemented with Bistite (p < 0.05). Regarding the influence of eugenol-based sealer on post retention, there was a statistically significant difference (p < 0.05) only between groups cemented with Bistite, in which canals filled with N-Rickert + gutta-percha showed lower BS than canals filled with Sealer 26 + gutta-percha. CONCLUSION: Despite endodontic cement used, higher pull-out bond strength were obtained when posts were cemented with zinc phosphate. CLINICAL SIGNIFICANCE: The importance of ethanol or sulphuric ether application to properly replace water from intraradicular dentine still requires further investigations, especially to clarify if this technique may reduce the effect of aging and improve the stability of the bond, when used to cement fiber posts into the root canal.