Fracture strength of cad-cam milled polyetheretherketone (PEEK) post-cores vs conventional post-cores; an in vitro study.

Background: The aim of this study was to compare the fracture strength and fracture modes of post-cores produced with CAD-CAM from modified polyetheretherketone (PEEK) materials with other custom-produced post-cores. Methods: Sixty human mandibular first premolars with equal root sizes were used. The teeth were divided into six groups (n = 10), and root canal treatment was performed. The teeth were separated from the roots over 2 mm from the cemento-enamel junction. As a result of the decoronation process, a 1 mm wide shoulder line was obtained for all teeth. For the fracture strength test, 10 mm deep post spaces were created on the teeth with a 1.6 mm diameter driller. Post-core groups consisted: everStick® glass fiber post-core (Group GF), zirconia post-core (Group Z), metal (Cr-Co) post-core (Group M), PEEK post-core without filler (Group UP), PEEK post-core with 20% TiO2 Filler (Group TP), and post-core with 20% ceramic filler (Group CP). Following the application of posts to post spaces, copings were created and cemented on the samples. With the universal tester, a force was applied to the long axis of the tooth with a slope of 135°. The mean fracture strength (N) between the groups was statistically evaluated using one-way ANOVA, and pairwise mean differences were detected using post hoc Tukey's HSD test among the groups. Results: According to the results of the statistical analysis, a significant difference was found between the groups in terms of mean fracture resistance (p < 0.05). Group Z (409.34 ± 45.72) was significantly higher than Group UP (286.64 ± 37.79), CP (298.00 ± 72.30), and TP (280.08 ± 67.83). Group M (376.17 ± 73.28) was significantly higher than Group UP (286.64 ± 37.79) and Group TP (280.08 ± 67.83). There were no statistically significant differences between the means of the other groups (p > 0.05). Among all the groups, Group Z exhibited a higher prevalence of repairable failure modes, while the rest of the groups predominantly experienced irreparable failure modes. Conclusion: In our study, zirconia and metal post-core samples showed higher average fracture strength values than PEEK post-cores groups. Repairable failure modes were more common in the zirconia post-cores, whereas the opposite was observed in the other groups. Further experimental and clinical trial studies are needed before PEEK materials can be used as post materials in the clinic.

Effect of micro-arc oxidation coatings with graphene oxide and graphite on osseointegration of titanium implants-an in vivo study.

Background: This in vivo study evaluated the effect of graphene oxide and graphite coatings, coupled with the micro-arc oxidation (MAO) surface roughening technique, known for their mechanical strength, chemical stability, and antibacterial properties. The main objective was to assess the degree of improvement in osseointegration of titanium implants resulting from these interventions. Materials and methods: In this study, 32 female rats were utilized and randomly allocated into four groups (n = 8 each): machined surface titanium implants (control), those roughened by the MAO method, those coated with graphene oxide-doped MAO, and those with a graphite-doped MAO coating. Titanium implants were surgically placed in the right tibia of the rats. Rats undergoing no additional procedures during the 4-week experimental period were sacrificed at the end. Then, the implants and surrounding bone tissues were separated and embedded in acrylic blocks for reverse torque analysis. Using a digital torque device, the rotational force was applied to all samples using a hex driver and racquet until implant separation from the bone occurred, with the corresponding values recorded on the digital display. Then, statistical analysis was performed to analyze the data. Results: No statistically significant difference between the groups was observed in the biomechanical bone-implant connection levels (N/cm) (P = 0.268). Post-hoc tests were not required because no discernible differences were identified between the groups. Conclusion: Within the scope of this study, implants treated with the MAO method, along with those coated with graphene oxide- and graphite-doped MAO method, did not exhibit significant superiority in terms of osseointegration compared to machined surface titanium implants.

Molecular insights into the antioxidative and anti-inflammatory effects of P-coumaric acid against bisphenol A-induced testicular injury: In vivo and in silico studies.

This study investigated the protective effects of p-coumaric acid (PCA) against bisphenol A (BPA)-induced testicular toxicity in male rats. The rats were divided into control, BPA, BPA+PCA50, BPA+PCA100, and PCA100 groups. Following a 14-day treatment period, various analyses were conducted on epididymal sperm quality and testicular tissues. PCA exhibited dose-dependent cytoprotective, antioxidant, and anti-inflammatory effects, ameliorating the decline in sperm quality induced by BPA. The treatment elevated antioxidant enzyme activities (SOD, GPx, CAT) and restored redox homeostasis by increasing cellular glutathione (GSH) and reducing malondialdehyde (MDA) levels. PCA also mitigated BPA-induced proinflammatory responses while reinstating anti-inflammatory IL-10 levels. Apoptotic parameters (p53 and p38-MAPK) were normalized by PCA in BPA-treated testicular tissue. Immunohistochemical and immunofluorescent analyses confirmed the cytoprotective and anti-inflammatory effects of PCA, evidenced by the upregulation of HO-1, Bcl-2, and Nrf-2 and the downregulation of the proapoptotic gene Bax in BPA-induced testicular intoxication. PCA corrected the disturbance in male reproductive hormone levels and reinstated testosterone biosynthetic capacity after BPA-induced testicular insult. In silico analyses suggested PCA's potential modulation of the oxidative stress KEAP1/NRF2/ARE pathway, affirming BPA's inhibitory impact on P450scc. This study elucidates BPA's molecular disruption of testosterone biosynthesis and highlights PCA's therapeutic potential in mitigating BPA's adverse effects on testicular function, showcasing its cytoprotective, anti-inflammatory, and hormone-regulating properties. The integrated in vivo and in silico approach offers a comprehensive understanding of complex mechanisms, paving the way for future research in reproductive health and toxicology, and underscores the importance of employing BPA-free plastic wares in semen handling.

Mitigation of Acute Hepatotoxicity Induced by Cadmium Through Morin: Modulation of Oxidative and Pro-apoptotic Endoplasmic Reticulum Stress and Inflammatory Responses in Rats.

Cadmium (Cd) is a toxic heavy metal with significant environmental health hazards. It enters the body through various routes with tissue accumulation. The relatively longer half-life with slow body clearance significantly results in hepatotoxicity during its liver detoxification. Therefore, researchers are exploring the potential use of herbal-derived phytocomponents to mitigate their toxicity. Here, we investigated, for the first time, the possible ameliorative effect of the phytochemical Morin (3,5,7,29,49-pentahydroxyflavone) against acute Cd-induced hepatotoxicity while resolving its underlying cellular mechanisms in a rat animal model. The study involved 50 adult male Sprague-Dawley rats weighing 200-250 g. The animals were divided into five equal groups: control, Cd, Morin100 + Cd, Morin200 + Cd, and Morin200. The 2nd, 3rd, and 4th groups were intraperitoneally treated with Cd (6.5 mg/kg), while the 3rd, 4th, and 5th groups were orally treated with Morin (100 and 200 mg/kg) for 5 consecutive days. On the 6th day, hepatic function (serum ALT, AST, ALP, LDH enzyme activities, and total bilirubin level) testing, transcriptome analysis, and immunohistochemistry were performed to elucidate the ameliorative effect of Morin on hepatotoxicity. In addition to restoring liver function and tissue injury, Morin alleviated Cd-induced hepatic oxidative/endoplasmic reticulum stress in a dose-dependent manner, as revealed by upregulating the expression of antioxidants (SOD, GSH, Gpx, CAT, and Nrf2) and decreasing the expression of ER stress markers. The expression of the proinflammatory mediators (TNF-α, IL-1-ß, and IL-6) was also downregulated while improving the anti-inflammatory (IL-10 and IL-4) expression levels. Morin further slowed the apoptotic cascades by deregulating the expression of pro-apoptotic Bax and Caspase 12 markers concomitant with an increase in anti-apoptotic Blc2 mRNA expression. Furthermore, Morin restored Cd-induced tissue damage and markedly suppressed the cytoplasmic expression of JNK and p-PERK immunostained proteins. This study demonstrated the dose-dependent antioxidant hepatoprotective effect of Morin against acute hepatic Cd intoxication. This effect is likely linked with the modulation of upstream p-GRP78/PERK/ATF6 pro-apoptotic oxidative/ER stress and the downstream JNK/BAX/caspase 12 apoptotic signaling pathways.

Selenium reduces acrylamide-induced testicular toxicity in rats by regulating HSD17B1, StAR, and CYP17A1 expression, oxidative stress, inflammation, apoptosis, autophagy, and DNA damage.

This study investigated the effects of Selenium (Se) on testis toxicity induced by Acrylamide (ACR) in rats. In our study, 50 male adult rats were used, and the rats were divided into five groups; control, ACR, Se0.5 + ACR, Se1 + ACR, and Se1. Se and ACR treatments were applied for 10 days. On the 11th day of the experimental study, intracardiac blood samples from the rats were taken under anesthesia and euthanized. Sperm motility and morphology were evaluated. Dihydrotestosterone, FSH, and LH levels in sera were analyzed with commercial ELISA kits. MDA, GSH, TNF-α, IL-6, and IL-1ß levels and SOD, GPx, and CAT, activities were measured to detect the level of oxidative stress and inflammation in rat testis tissues. Expression analysis of HSD17B1, StAR, CYP17A1, MAPk14, and P-53 as target mRNA levels were performed with Real Time-PCR System technology for each cDNA sample synthesized from rat testis RNA. Testicular tissues were evaluated by histopathological, immunohistochemical, and immunofluorescent examinations. Serum dihydrotestosterone and FSH levels decreased significantly in the ACR group compared to the control group, while LH levels increased and a high dose of Se prevented these changes caused by ACR. A high dose of Se prevented these changes caused by ACR. ACR-induced testicular oxidative stress, inflammation, apoptosis, changes in the expression of reproductive enzymes, some changes in sperm motility and morphology, DNA, and tissue damage, and Se administration prevented these pathologies caused by ACR. As a result of this study, it was determined that Se prevents oxidative stress, inflammation, apoptosis, autophagy, and DNA damage in testicular toxicity induced by ACR in rats.

Comparative Stress Analysis of Custom-Made PEEK Dental Post-Cores versus Conventional Post-Cores in Incisor Restorations: A Finite Element Study.

BACKGROUND We conducted a finite element analysis to evaluate stress levels in incisor teeth restored with custom polyetheretherketone (PEEK) dental post-cores compared to conventional post-cores. MATERIAL AND METHODS Using micro-computed tomography (µCT) imaging data, a 3D model of a maxillary incisor was created. For each material type, 3D mesh models were developed via specialized software. Two post diameters, 2.5 mm and 3.5 mm, were considered. Five different post materials were examined: Unfilled polyetheretherketone (Group UP); Glass fiber-reinforced polyetheretherketone (Group GP); Carbon fiber-reinforced polyetheretherketone (Group CP); Metal (Group M); and Zirconia ceramic (Group Z). Each model underwent finite element analysis, after which the von Mises equivalent stress values were determined. RESULTS For models involving both wide and narrow diameter posts across the crown, crown cement, post cement, and dentin, PEEK posts (Group UP, GP, and CP) exhibited higher von Mises stress values than Groups Z and M. However, the reverse trend was noticed in the post model itself. In the post cement model, stress values appeared similar only for the narrow-diameter post groups. Notably, results for Groups Z and M were largely consistent with each other. CONCLUSIONS PEEK posts, which have a lower modulus of elasticity, demonstrated different stress values when contrasted with zirconia and metal posts. As the post diameter expanded, the residual dentin decreased, influencing the stress values among various materials. Further in vitro and clinical examinations are essential to comprehensively understand PEEK posts.

A neuroscience-based approach to the assessment of sexual behavior in animals.

Sexual behavior in animals is important in ensuring the continuity of the generation. These behaviors differ in animal species. Sexual behaviors are shaped under the control of the reproductive system. Physiological stimuli produced by the reproductive system find their counterparts in the organism as reproductive activity. Reproductive activity display a critical role by transferring on the genetic heritage of organisms to the next generations. This activity, which is built on delicate balances, is associated with many systems in the organism. Nervous system, hormonal system, and circulatory system are the main ones. The regular formation of the reproductive activity in species is due to the effect of various factors. In domestic mammals, the reproductive activity is regulated by hormones secreted from brain and endocrine glands. Many hormones have duties in terms of the sustainability of reproductive activity. GnRH is the main hormone responsible for initiating this reproductive activity. Gonadotropin-releasing hormone (GnRH), which is a small molecule peptide from certain nerve cells in the nucleus infundibularis region of the hypothalamus and consists of different amino acids, is secreted under the influence of smell, temperature, light, and physical stimulation. Besides, GnRH release is controlled by various neurotransmitters (adrenaline, noradrenaline, dopamine, acetylcholine, serotonin). On the other hand, various genetic factors in secretory glands, gonadal cells, reproductive tissues can lead to significant changes on reproductive activity through specific molecular pathways and mechanisms.

Fracture strength of different veneers on polyetheretherketone (PEEK) frameworks in implant-supported single crowns.

PURPOSE: To evaluate the fracture strength of polyetheretherketone (PEEK) single crowns veneered with different materials produced by computer-aided design (CAD)-computer-aided manufacture (CAM) after aging. METHODS: 60 stainless-steel master dies were prepared with a 1 mm-wide deep chamfer. Sixty PEEK frameworks were produced with a CAD-CAM system for the right maxillary first molar tooth on the dies. PEEK frameworks were divided into six groups (n= 10) according to veneering materials (five CAD-CAM materials and a resin composite). Group ZR: monolithic zirconia (Upcera ST-Color); Group EC: lithium disilicate glass-ceramic (IPS e.max CAD); Group LU: resin nano-ceramic (Lava Ultimate); Group VM: feldspathic ceramic (Vitablocs Mark II); Group VS: zirconia-reinforced lithium silicate glass-ceramic (VITA Suprinity); and Group CR: indirect resin composite (Gradia). All samples were subjected to a fracture strength test in a universal test device after thermo-mechanical aging and then the results were analyzed statistically using one-way ANOVA and Tukey's post hoc test. In addition, post-fracture analyses of all samples were performed with a stereomicroscope. RESULTS: The differences in fracture strength values of different veneer materials in single crowns with a PEEK framework were statistically significant (P< 0.05). Fracture strength was highest in Group ZR (1665 N), followed by Groups LU (1440 N), EC (1249 N), CR (918 N), VS (754 N), and VM (655 N). CLINICAL SIGNIFICANCE: PEEK frameworks may have the potential to be used with many veneer materials of different content and properties in fixed partial prostheses.

Effect of ultrasonic scaling and air polishing on the surface roughness of polyetheretherketone (PEEK) materials.

PURPOSE: To evaluate the effects of ultrasonic scaling (US) and air polishing (AP) on four polyetheretherketone (PEEK) composites. METHODS: One hundred-twenty 15 × 3 mm discs of PEEK specimens were divided into four groups (n=30): Unfilled PEEK(U-PEEK), carbon fiber-reinforced PEEK(CFR-PEEK), glass fiber-reinforced PEEK(GFR-PEEK), and ceramic-filled PEEK(CF-PEEK). Each group was further divided into three subgroups (n = 10): control, US, and AP. Profilometry and scanning electron microscopy were used to analyze and evaluate surface roughness (SR). Statistical analyses of the data obtained were conducted using Shapiro-Wilk, Welch, and Games-Howell tests. RESULTS: When the SR values of the specimens with US cleaning were evaluated, a statistically significant difference was found between the groups (P< 0.05). When the SR values of the specimens with AP cleaning were analyzed, there was a statistically significant difference in the CF-PEEK group (P< 0.05), whereas the other groups were not significantly different (P> 0.05). More studies are needed on CFR-PEEK and GFR-PEEK materials offered as alternatives to CF-PEEK in dentistry. CLINICAL SIGNIFICANCE: Dental instruments affect the different PEEK materials, as well as causing surface roughness in many restorative materials used in dentistry. Surface roughness that occurs in dental restorations can cause bacterial adhesion. It is clinically important to choose the dental instrument according to the type of PEEK used for dental implant or prosthetic restoration in the clinic.

Investigation of the effect of hesperidin on some reproductive parameters in testicular toxicity induced by Bisphenol A.

Bisphenol A (BPA) is one of the chemicals that cause dysfunction and infertility in testicles. Therefore, it is crucial to develop effective treatments against this damage. In this study, the effects of Hesperidin (HESP), a flavonoid in testicular toxicity induced by BPA in rats, on oxidative stress, inflammation, apoptosis, histological damage, spermatogenesis, steroidogenic enzymes and reproductive hormones were investigated. Our study used 52 Sprague Dawley male rats weighing 250-300 g, and four experimental groups were formed. From the experimental groups, 1 ml of olive oil was administered to the control group, HESP at a dose of 50 mg/kg to the HESP group, BPA at a dose of 100 mg/kg to the BPA group, HESP at a dose of 50 mg/kg to the BPA + HESP group and 100 mg/kg BPA was administered intragastrically (ig) for 14 days. We determined that BPA administration causes apoptosis, histological damage, inflammation, oxidative stress and toxic effects on spermatogenesis and steroidogenic enzymes in testicles. We observed that the administration of HESP with BPA attenuated oxidative stress, inflammation and apoptosis resulting in therapeutic effects on both steroidogenic enzymes and spermatogenesis and reproductive hormones (FSH, LH and testosterone). Our findings from this study clearly showed that while HESP treatment alleviates oxidative damage, inflammation and apoptosis in testicles of rats treated with BPA, it has regulatory effects on steroidogenic enzymes, spermatogenesis and serum reproductive hormones.