Untreated Discs Research Articles

Evaluation of the immune response of peripheral blood mononuclear cells cultured on Ti6Al4V-ELI polished or etched surfaces.

While titanium and its alloys exhibit excellent biocompatibility and corrosion resistance, their polished surfaces can hinder fast and effective osseointegration and other biological processes, such as angiogenesis, due to their inert and hydrophobic properties. Despite being commonly used for orthopedic implants, research focuses on developing surface treatments to improve osseointegration, promoting cell adhesion and proliferation, as well as increasing protein adsorption capacity. This study explores a chemical treatment intended for titanium-based implants that enhances tissue integration without compromising the mechanical properties of the Ti6Al4V substrate. However, recognizing that inflammation contributes to nearly half of early implant failures, we assessed the impact of this treatment on T-cell viability, cytokine production, and phenotype. Ti6Al4V with extra low interstitial (ELI) content discs were treated with hydrofluoric acid followed by a controlled oxidation step in hydrogen peroxide that creates a complex surface topography with micro- and nano-texture and modifies the chemistry of the surface oxide layer. The acid etched surface contains an abundance of hydroxyl groups, crucial for promoting bone growth and apatite precipitation, while also enabling further functionalization with biomolecules. While cell viability remained high in both groups, untreated discs triggered an increase in Th2 cells and a decrease of the Th17 subset. Furthermore, peripheral blood mononuclear cells exposed to untreated discs displayed a rise in various pro-inflammatory and anti-inflammatory cytokines compared to the control and treated groups. Conversely, the treated discs showed a similar profile to the control, both in terms of immune cell subset frequencies and cytokine secretion. The dysregulation of the cytokine profile upon contact with untreated Ti6Al4V-ELI discs, namely upregulation of IL-2 could be responsible for the decrease in Th17 frequency, and thus might contribute to implant-associated bacterial infection. Interestingly, the chemical treatment restores the immune response to levels comparable to the control condition, suggesting the treatment's potential to mitigate inflammation by enhancing biocompatibility.

Injectable Platelet-Rich Fibrin and Advanced Platelet-Rich Fibrin Demonstrate Enhanced Anti-Biofilm Effect Compared to Enamel Matrix Derivatives on Decontaminated Titanium Surfaces.

The search for effective antimicrobial agents to mitigate peri-implant infections remains a crucial aspect of implant dentistry. This study aimed to evaluate and compare the antimicrobial efficacy of i-PRF, A-PRF+, and enamel matrix derivative (EMD) on decontaminated rough and smooth titanium (Ti) discs. Rough and smooth Ti discs were coated with multispecies biofilm and thoroughly debrided using a chitosan-bristled brush. Subsequently, i-PRF, A-PRF+, and EMD were applied. Untreated discs served as control. Residual adherent bacteria present on the treated Ti discs were visualized by SEM and quantified using culture technique, and colony-forming units (CFUs) were measured after 48 h and 7 days. i-PRF demonstrated better antimicrobial effectiveness on both smooth and rough implant surfaces as compared to A-PRF+ and EMD (p < 0.001). In all the experimental groups, smooth Ti discs displayed a greater reduction in microbes compared to rough Ti discs when treated with the biologics. The major reduction in CFU values was determined after seven days. i-PRF as a regenerative material may also be suitable for decontaminating implant surfaces, which could influence tissue healing and regenerative outcomes positively.

Vacuum Plasma Treatment Device for Enhancing Fibroblast Activity on Machined and Rough Titanium Surfaces.

This study was conducted to compare the effects of an innovative plasma surface treatment device that does not need a gas supply for titanium disks with two different surface topographies: the prototypical machined surface (MAC) and one of the most diffused roughened ones (SL) obtained through grit blasting and acid etching. A total of 200-MAC and 200-SL titanium disks were used. Each group of disks was divided into four sub-groups of 40 samples each that were subjected to five different tests. Among these, 150-MAC and 150-SL were considered the test group, and they were treated with plasma for 15, 30, and 60 s after being removed from the sterile packaging. On the other hand, 50-MAC and 50-SL were considered the control group, and they were only removed from sterile plastic vials. The samples were analyzed to evaluate the capability of the plasma treatment in influencing protein adsorption, cell adhesion, proliferation, and microbial growth on the test group disks when compared to the untreated disks. Protein adsorption was significantly enhanced after 20 min of plasma treatment for 15 and 30 s on the MAC and SL disks. Plasma treatment for 15 and 30 s significantly increased the level of adhesion in both treated samples after 30 min. Furthermore, the MAC samples showed a significant increase in cell adhesion 4 h after plasma treatment for 15 s. The SEM analysis highlighted that, on the treated samples (especially on the MAC disks), the cells with a polygonal and flat shape prevailed, while the fusiform- and globular-shaped cells were rare. The encouraging results obtained further confirm the effectiveness of plasma treatments on cell adhesion and fibroblast activity.

Wettability of Different Zirconia Implant Surfaces after Glycine and Erythritol Treatment.

This in-vitro study aims to investigate whether the wettability of two zirconia implant disk surfaces is affected by glycine and erythritol air-polishing, using saline, bovine serum albumin, bovine thrombin, and bovine artificial blood as the testing mediums. Zirconia disks were provided by two implant companies: SDS. (Swiss Dental Solutions, Plymouth, MA, USA) (n=6) and Patent. (Zircon Medical AG, Altendorf, Switzerland) (n=6). Surface parameters (Sa, Sz, Sdr, Ssk, Sku, and Spd) were measured to determine their initial surface roughness. Air-polishing was completed using glycine or erythritol powders using the AIRFLOW. PERIO device (Manufactured by Electro Medical Systems (EMS)). The wettability of the disk surfaces was evaluated by the contact angle analysis applied on treated and untreated disks using four wetting solutions, saline, bovine serum albumin (BSA), bovine thrombin, and bovine artificial blood. In total, 720 contact angle measurements were completed with n=30 per group. Statistical analysis was performed using the one-way analysis of variance and post-hoc Tukey HSD test. The results indicate SDS. has a greater wettability than Patent. before and after air-polishing. The wettability of surfaces treated with glycine was hydrophobic in some cases. Erythritol increased the surface wettability of zirconia disks compared to glycine. BSA and bovine artificial blood had lower contact angles than saline and bovine thrombin for both untreated disks. The initial wettability of zirconia disks differs between manufacturers, and air-polishing with erythritol powder increases the wettability of zirconia implant disks for saline, bovine serum, bovine thrombin, and bovine artificial blood.

Adherence of Escherichia coli and blood elements in titanium discs submitted to anodic oxidation. In vitro study

Modifications of implants by means of surface treatments are performed to optimize the biochemical interactions of the bone deposition process. However, if on the one hand they favor the adhesion of blood elements, on the other hand they can also enable the formation of biofilm. This study evaluated the adherence of blood cells and Escherichia coli in titanium discs submitted to surface treatments by anodic oxidation (OA), sandblasting followed by acid etching (JAT) compared with untreated discs (Li). To evaluate the adherence of microorganisms were performed: atomic force microscopy; Field Emission Gun Scanning Electron Microscopy (FEG-SEM); biofilm formation was evaluated by spectrophotometer turbidity analysis and colony forming unit (CFU/mL) before and after simulated brushing. For blood cell adherence, the blood collected from a patient was deposited and fixed on the discs and analyzed in the FEG-SEM being classified according to the "Blood Element Adherence Index". The results showed a slight increase in the adhesion of microorganisms in samples treated by anodic oxidation. However, the microorganisms were distributed singly and not in conglomerates, with no biofilm formation unlike the Li group. Regarding the adherence of blood elements, the Li group showed higher adherence and lower amount was found in the JAT group, but there was no statistically significant difference between the groups. The results of this study suggest that anodic oxidation treatment may favor the adherence of blood cells and fibrin mesh, contributing to the early stages of bone deposition.

Tribological behavior of graphene-based friction composite tested on cryogenically treated cast iron

Enhancement of friction and wear performance is the basic requirement of a friction composite material, which primarily relies on the properties of ingredients and the type of counter disc. To meet the superior requirements of the tribological system, a new tribopair between graphene-based friction composite and cryogenic treated grey cast iron disc was designed in this work. Friction composites in the shape of a pin were made from solid lubricants—20 wt.% of molybdenum disulfide, 20 wt.% of graphite, and 10 wt.%, 15 wt.%, and 20 wt.% of graphene nanopowder. The prepared five friction composites are tested on the cryogenic treated grey cast iron disc and untreated disc in a pin-on-disc tribometer under dry state conditions, resulting in 10 different tribopairs. The tribological efficacy of the tribopairs was assessed and finally compared with the tribopair formed from a commercial brake pad. Results proved that the tribological performance of the tribopairs, namely 20 wt. % of graphene nanopowder—cryogenic treated grey cast iron disc and 15 wt.% of graphene nanopowder—cryogenic treated grey cast iron disc was superior compared to the other tribopairs. Thus, the addition of graphene nanopowder in the friction composite and cryogenic treatment of the grey cast iron disc significantly affects the overall friction and wear properties of the tribopairs. Scanning electron microscopy micrographs were used to characterize the friction composites surface and counter disc.

Attachment and Osteogenic Potential of Dental Pulp Stem Cells on Non-Thermal Plasma and UV Light Treated Titanium, Zirconia and Modified PEEK Surfaces.

Ultraviolet (UV) light and non-thermal plasma (NTP) treatment are chairside methods that can efficiently improve the biological aging of implant material surfaces caused by customary storage. However, the behaviors of stem cells on these treated surfaces of the implant are still unclear. This study aimed to investigate the effects of UV light and NTP treated surfaces of titanium, zirconia and modified polyetheretherketone (PEEK, BioHPP) on the attachment and osteogenic potential of human dental pulp stem cells (DPSCs) in vitro. Machined disks were treated using UV light and argon or oxygen NTP for 12 min each. Untreated disks were set as controls. DPSCs were cultured from the wisdom teeth of adults that gave informed consent. After 24 h of incubation, the attachment and viability of cells on surfaces were assessed. Cells were further osteogenically induced, alkaline phosphatase (ALP) activity was detected via a p-Nitrophenyl phosphate assay (day 14 and 21) and mineralization degree was measured using a Calcium Assay kit (day 21). UV light and NTP treated titanium, zirconia and BioHPP surfaces improved the early attachment and viability of DPSCs. ALP activity and mineralization degree of osteoinductive DPSCs were significantly increased on UV light and NTP treated surfaces of titanium, zirconia and also oxygen plasma treated Bio-HPP (p < 0.05). In conclusion, UV light and NTP treatments may improve the attachment of DPSCs on titanium, zirconia and BioHPP surfaces. Osteogenic differentiation of DPSCs can be enhanced on UV light and NTP treated surfaces of titanium and zirconia, as well as on oxygen plasma treated Bio-HPP.

Decontamination of multispecies oral biofilm from rough implant surface by airflow with glycine.

ObjectivesDecontamination of biofilm‐colonized rough implant surfaces remains challenging. We investigated the effect of airflow with glycine powder (AFG) on decontamination of mature oral multispecies biofilm from a sandblasted and acid etched (SLA) titanium surface.Materials and MethodsSubgingival dental plaque was cultured on SLA disks anaerobically for 21 days. AFG with various settings and distances was applied directly on the disks with or without previous rinse of 0.9% NaCl. The specimens were then analyzed through scanning electron microscope and remaining bacteria on the implant surface were quantified and statistically compared.ResultsMature oral biofilm with cocci and rods as major morphotypes, as well as spiral‐ and filamentous‐shaped organisms, was formed on the untreated disks. Saline rinsing removed the thick biofilm layer but left numerous of coccoid bacteria in rough surface pits. AFG effectively removed most of the bacteria from the pits. Both 25% and 50% power settings were equally effective at 3‐mm distance. With 50% power, AFG successfully removed bacteria at both 3‐ and 6‐mm distance. When AFG was applied on native biofilm without prior rinsing with saline, it effectively removed the biofilm including bacteria in the pits.ConclusionApplication of AFG appears effective in removing bacteria from rough implant surfaces.

Next-Generation Dried Blood Spot Samplers for Protein Analysis: Describing Trypsin-Modified Smart Sampling Paper

This paper describes smart sampling paper to be used for bottom-up protein analysis. Four different manners to immobilize trypsin on cellulose were evaluated. Untreated paper, potassium-periodate-functionalized paper (with and without post-immobilization reduction) and 2-hydroxyethyl methacrylate (HEMA)/2-vinyl-4,4-dimethylazlactone (VDM)-functionalized paper were all used to immobilize trypsin. For the evaluation, Coomassie Brilliant Blue staining of proteins on paper and the BAEE trypsin activity assay needed to be modified. These methods allowed, together with data from mass spectrometric analysis of cytochrome C digestions, us to acquire fundamental insight into protein binding, and trypsin action and activity on paper. All functionalized discs bind more protein than the untreated discs. Protein binding to functionalized discs is based on both adsorption and covalent binding. Trypsin immobilized on potassium-periodate-functionalized discs exhibits the highest trypsin activity when using cytochrome C as substrate. It is proven that it is trypsin attached to paper (and not desorbed trypsin) which is responsible for the enzyme activity. The use of discs on complex biological samples shows that all functionalized discs are able to digest diluted serum; for the best-performing disc, HEMA-VDM functionalized, up to 200 high-confidence proteins are qualified, showing its potential.

Influence of Tooth Pigmentation on H2O2 Diffusion and Its Cytotoxicity After In-office Tooth Bleaching.

Pigments in tooth structures affect the diffusion of H2O2 through enamel and dentin. The bleaching methodology can be impacted. Objective: The aim of this study was to evaluate the influence of the presence of pigments in tooth structures on the trans-enamel and trans-dentin diffusion of hydrogen peroxide (H2O2) and its cytotoxicity after carrying out an in-office bleaching therapy.Methods and Materials: A bleaching gel with 35% H2O2 was applied for 45 minutes (three times for 15 minutes) on enamel and dentin discs (n=6), either previously submitted to the intrinsic pigmentation protocol with a concentrated solution of black tea, or not, defining the following groups: G1, unbleached untreated discs (control 1); G2, unbleached pigmented discs (control 2); G3, bleached untreated discs; G4, bleached pigmented discs. The discs were adapted to artificial pulp chambers, which were placed in wells of 24-well plates containing 1 mL culture medium (Dulbecco's modified Eagle's medium [DMEM]). After applying the bleaching gel on enamel, the extracts (DMEM + components of bleaching gel that diffused through the discs) were collected and then applied on the cultured MDPC-23 odontoblast-like cells. Cell viability (methyl tetrazolium assay and Live & Dead, Calcein AM, and ethidium homodimer-1 [EthD-1] probes), the amount of H2O2 that diffused through enamel and dentin (leuco-crystal violet product), and the H2O2-mediated oxidative cell stress (SOx) and components of degradation were assessed (analysis of variance/Tukey; α=0.05).Results: There was no significant difference between the groups G1 and G2 for all the parameters tested (p>0.05). Reduction in the trans-enamel and trans-dentin diffusion of H2O2 occurred for G4 in comparison with G3. Significantly lower cell viability associated with greater oxidative stress was observed for G3 (p<0.05). Therefore, in-office tooth bleaching therapy performed in pigmented samples caused lower cytotoxic effects compared with untreated samples submitted to the same esthetic procedure (p<0.05).Conclusion: According to the methodology used in this investigation, the authors concluded that the presence of pigments in hard tooth structures decreases the trans-enamel and trans-dentin diffusion of H2O2 and the toxicity to pulp cells of an in-office bleaching gel with 35% H2O2.

Combined Nucleus Pulposus Augmentation and Annulus Fibrosus Repair Prevents Intervertebral Disc Degeneration After Discectomy

Abstract INTRODUCTION The objective of the current study is to assess the efficacy of combined annulus fibrosus (AF) using a high-density collagen (HDC) gel and nucleus pulposus (NP) repair using a hyaluronic acid (HA) gel in an in Vivo sheep model. METHODS We performed an anterolateral, retroperitoneal prepsoas approach to access the IVDs L1-6 in a total of 8 skeletally mature Finn sheep. IVDs were randomized into 5 groups: (1) intact, (2) injured via 3 × 10 mm box annulotomy and removal of 200 mg of NP, (3) injury and HDC gel patch for AF repair, (4) injury and injection of a HA gel into the NP, and (5) injury and HDC AF repair and NP HA replacement. At 6 wk postoperatively, sheep were sacrificed and underwent postmortem 3T-MRI scans as well as gross anatomical and histological evaluation. Disc height index (DHI) analysis and Pfirrmann grading (PG) were performed on each segment using MR images. RESULTS Intact control discs were not degenerated and had an average PG of 1 while injured, and untreated discs had a significant degeneration with an average PG of 3. Discs receiving the combined injection and collagen AF patch individually showed fewer signs of degeneration than injured alone, and the combined treatment resulted in the least amount of degeneration with PG not significantly different from the intact controls. DHI confirmed the trends seen in the PG, where injured discs lost 20% of the intact disc height, the individual NP and AF repairs restored 5% to 10% of intact disc height, and the combined repairs preserved 90% of the intact disc height. CONCLUSION PG and DHI results demonstrate that individual NP and AF repairs are able to prevent disc degeneration better than no treatment at all; however, the greatest preservation of disc health was seen with combined AF and NP repairs.

3013 Combined Annulus Fibrosus and Nucleus Pulposus Repair Prevents Degeneration in the Ovine Lumbar Spine

OBJECTIVES/SPECIFIC AIMS: The objective of this study is to assess the efficacy of combined AF and NP repairs to prevent degenerative changes and restore native disc morphology in an in vivo large animal model. We hypothesize that combined repairs will prevent disc degeneration following injury to a greater extent than the individual repairs after 6 weeks in vivo, as demonstrated through disc height measurements and disc morphology. METHODS/STUDY POPULATION: A total of 8 skeletally mature female Finn sheep were used in this study. Following a previously described method, IVDs from L1 to L6 of the lumbar spine were exposed using a lateral access, extraperitoneal approach5. IVDs were randomized into 5 treatment groups: 1) intact discs, 2) discs injured via a 3 cm x 1 cm box annulotomy and partial nucleotomy, 3) injury followed by a high density collagen (HDC) AF patch, 4) injury followed by injection of a modified hyaluronic acid (HA) into the NP, and 5) injury followed by both the HDC AF patch and HA NP injection. The HDC treatment was 15 mg/mL type-I collagen mixed with 0.06mM riboflavin, injected at the defect site and crosslinked in situ with blue light. The NP injection was HA modified with C16 side chains to increase the viscosity of the hydrogel (HYADD 4®)6. At 6 weeks post-operatively, sheep were sacrificed and had 3T magnetic resonance images (MRI) taken of their lumbar spine. Disc height analysis and Pfirrmann grading were performed on each segment using MR images. Additionally, quantitative MRI analyses were performed using a custom MATLAB algorithm that segments NP from the surrounding tissue and directly measures the NP volume. ANOVA with Tukey’s HSD was used to determine statistical significance between groups for disc height and quantitative MRI analyses, and the Kruskal-Wallis test with Mann-Whitney tests was used to statistically analyze Pfirrmann Grades. All animal use followed approved IACUC protocol. RESULTS/ANTICIPATED RESULTS: As shown in axial MR images (Figure 1A), intact discs had hyperintense NP with a distinct border to the AF. The discs receiving injury with no treatment had hypointense NP with no distinct border between the AF and NP. Individual and combined treatment with the HA NP injection and HDC AF patch appeared to preserve the hyperintense NP signal and AF/NP border. Intact control discs were not degenerated and had an average Pfirrmann grade of 1 (Figure 1B), while injured, untreated discs had significant degeneration with an average Pfirrmann grade of 3. Discs receiving the HA NP injection and collagen AF patch individually showed fewer signs of degeneration than the injured alone, and the combined treatment resulted in the least amount of degeneration with Pfirrmann grades not significantly different than the intact controls. Disc height index confirmed the trends seen in the Pfirrmann grades (Figure 1C), where injured discs lost 20% of the intact disc height, the individual NP and AF repairs restored 5-10% of intact disc height, and the combined repairs preserved 90% of the intact disc height. The NP voxel count of all treatment groups were similar to the intact controls (Figure 1D). DISCUSSION/SIGNIFICANCE OF IMPACT: The objective of this study was to determine how combined AF and NP can prevent degenerative changes to the disc in a large animal in vivo model. Pfirrmann grading and disc height index results show that the greatest preservation of disc morphology was seen with combined AF and NP repairs, while the individual strategies prevented degenerative changes better than injury with no treatment. It appears the HA NP injection restores lost water content to the disc following injury, and the AF collagen patch plays a role in maintaining the NP repair within the disc. This is the first study to our knowledge to attempt combined AF and NP repairs in an in vivo large animal model. Combining NP and AF repairs leads to significantly improved outcomes following disc injury, which warrants the translation of combined repairs into the clinic to improve patient outcomes with degenerative disc disease involving NP and AF.

Positive influence of simvastatin used as adjuvant agent for cavity lining.

To assess the biological, antimicrobial, and mechanical effects of the treatment of deep dentin with simvastatin (SV) before application of a glass-ionomer cement (GIC). Dentin discs were adapted to artificial pulp chambers and SV (2.5 or 1.0mg/mL) was applied to the occlusal surface, either previously conditioned or not with EDTA (±EDTA). The extracts (culture medium + SV that diffused through dentin) was obtained and then applied to cultured odontoblast-like MDPC-23 cells. Cell viability, alkaline phosphatase (ALP) activity, and mineralization nodule (MN) deposition were evaluated. Untreated discs were used as control. The antibacterial activity of SV (2.5 or 1.0mg/mL) against Streptococcus mutans and Lactobacillus acidophilus, as well as the bond strength of GIC to dentin in the presence of SV 2.5mg/mL (±EDTA) were also assessed. The data were analyzed by ANOVA/Tukey tests (α = 5%). EDTA + SV 2.5mg/mL significantly enhanced the ALP activity and MN deposition in comparison with the control, without changing in the cell viability (p < 0.05). The association EDTA + SV 2.5mg/mL + GIC determined the highest ALP and MN values (p < 0.05). SV presented intense antimicrobial activity, and the EDTA dentin conditioning followed by SV application increased bond strength values compared with SV treatment alone (p < 0.05). SV presents antimicrobial activity and diffuses across conditioned dentin to biostimulate odontoblast-like pulp cells. The use of SV as adjuvant agent for indirect pulp capping may biostimulate pulp cells thus preserving vitality and function of the pulp-dentin complex.

A laminin-derived functional peptide, PPFEGCIWN, promotes bone formation on sandblasted, large-grit, acid-etched titanium implant surfaces.

This study aimed to investigate the in vitro and in vivo bone-forming potential of a sandblasted, large-grit, acid-etched (SLA) titanium (Ti) surface treated with a laminin-derived functional peptide, PPFEGCIWN (DN3). Human osteoblast-like MG63 cells were cultured with SLA Ti discs untreated or treated with DN3 or a control scrambled peptide (SP). Cell adhesion, spreading, and viability on the discs were tested. Alkaline phosphatase gene expression and enzyme activity were also evaluated. Four DN3-coated SLA Ti implants and four untreated implants were placed into the tibiae of two rabbits (two implants/tibia). Ten days later, the bone-implant interfaces were subjected to histomorphometry to measure the bone response. The surface properties of the discs and implants were determined using scanning electron, widefield confocal, and confocal laser microscopy and x-ray photoelectron spectroscopy. The peptide-treated and untreated discs and implants were similar in terms of physical surface properties, but the peptide-treated surfaces had significantly higher nitrogen levels (P < .05). The DN3 peptide promoted cell adhesion, spreading, and alkaline phosphatase expression and enzyme activity (P < .05). Histomorphometry of the harvested implants showed rapid bone formation and affinity of the motif. This study suggests that treatment with the cell adhesion peptide DN3 promotes bone healing at the SLA Ti surface.

Influence of pH on osteoclasts treated with zoledronate and alendronate.

The objectives of this study were to analyze the effect of pH on the growth and activity of osteoclasts treated with different doses of two nitrogen-containing BPs, zoledronate and alendronate. Murine osteoclasts cultured on dentine disks were treated with zoledronate (50 or 500nM) or alendronate (500 or 5μM) at two different pH values (7.4 or 7.0). Osteoclasts were counted with transmitted light microscopy, apoptosis/necrosis was studied with flow cytometry and confocal microscopy, and resorption pit number and depth were calculated using reflected light and scanning electron microscopy. The osteoclast count on dentine disks was significantly (p < 0.001) reduced by zoledronate or alendronate treatment at pH7.0 in comparison to treatment with the same doses at pH7.4 and untreated disks (controls). The percentage of apoptotic cells was significantly increased by treatment with 500nM zoledronate or 5μM alendronate at pH7.0 in comparison to the same doses at pH7.4. The number and depth of resorption pits were significantly lower in disks treated at each BP dose studied than in untreated controls at pH7.0. Zoledronate and alendronate at therapeutic doses have an adverse effect on the viability and resorptive activity of osteoclasts when the local medium pH is reduced. These findings suggest that periodontal or peri-implant oral cavity infection may be a key trigger of the cascade of events that lead to BRONJ.

Corrosion behavior of erbium chromium-doped yattrium-scandium-gallium-garnet (Er,Cr:YSGG 2780 nm) laser-treated titanium alloy used for dental applications at different pH conditions (in vitro study)

Titanium alloys are most often used in the design of dental implants. Although these biomaterials have good mechanical and biological properties, their corrosion resistance is still critical for the overall success of the treatment procedure. Implant failure is more likely to occur in inflammatory diseases related to low pH levels. Er,Cr:YSGG laser is most often used in implant dentistry. The aim of the this study was to assess the effect of Er,Cr:YSGG laser surface treatment on the corrosion behavior of titanium alloy (Ti–6Al–4V) at different pH. A total of 40 discs were used. Twenty discs were irradiated with Er,Cr:YSGG laser, which was operating in a normal room atmosphere and temperature at power 2 W. The corrosion behavior was investigated in simulated body fluid at pH of 7.40 and 5.20. At each pH, corrosion behavior was studied for up to 864 h at 192, 360, 696, and 864 h intervals using potentiodynamic polarization test and electrochemical impedance spectroscopy. The laser-treated and -untreated discs were examined with scanning electron microscope before and after the electrochemical tests. Laser treatment significantly improves the corrosion resistance compared to the untreated group. Immersion time and pH also significantly affect the corrosion behavior. The acidity yielded more aggressive changes on the untreated titanium alloy. Er,Cr:YSGG laser could improve the corrosion resistance of Ti–6Al–4V.

Does an Annular Puncture Influence the Herniation Path?: An In Vitro Mechanical and Structural Investigation.

A study of mechanically induced herniation in punctured ovine discs followed by structural analysis. To investigate whether an annular puncture influences the path that herniation takes by providing direct passage for nucleus through the annulus and therefore whether it increases the risk of acute herniation from overload at the site of damage independent of any longer-term degeneration. Ten years after treatment with discography both degenerative changes and frequency of herniation have been shown to increase compared to untreated discs. Although the effect of an annular puncture over time has been widely investigated the question of whether it increases the risk of acute herniation has not been resolved. The posterolateral annuli of healthy ovine lumbar discs were punctured with either a 25-gauge (n = 8) or a larger 18-gauge (n = 8) needle and then compressed in a flexed posture of 10° until initial indications of failure. The entire volume of the disc was visually assessed for structural damage by obtaining progressive, full transverse cross-sections of its entire height thus exposing all regions of the disc. There was no association between the 25-gauge puncture and disc disruption and herniation. In contrast, nuclear material was observed to migrate through the 18-gauge needle puncture. Disruption of the lateral inner annulus was observed in 12 out of the 16 discs tested. The risk of acute herniation through the puncture site is dependent on the needle diameter used. Under the conditions employed the lateral inner annulus remains the site most vulnerable to disruption independent of the presence of a posterolateral puncture. N /A.

Acaricidal activity and sublethal effects of the microbial pesticide spinosad on Tetranychus urticae (Acari: Tetranychidae)

Laboratory bioassays were conducted to evaluate the toxicity of the microbial pesticide spinosad to different life stages of the two-spotted spider mite, Tetranychus urticae Koch, as well as its sublethal effects on reproduction and population growth of this important mite pest. The biopesticide was applied to bean primary leaves or leaf discs carrying spider mites using a Potter spray tower (2.7 mg/cm2 aqueous deposit). The following LC50 and LC90 (mg/L) estimates for motile stages were obtained in acute toxicity bioassays: 27.52 and 116.72 (larvae), 36.55 and 136.20 (protonymphs), 82.76 and 721.28 (female deutonymphs), and 61.47 and 457.21 (adult females). Spinosad showed no significant ovicidal action: toxic effect observed after spraying eggs (LC50 = 105.78 mg/L, LC90 = 596.95 mg/L) was the result of its residual action on larvae that hatched from the treated eggs. The effects of spinosad on life history traits and population growth of adult female survivors from treatments with 240, 120 and 60 mg/L were evaluated in two successive 7-day bioassays on untreated leaf discs. In the first bioassay, females that survived treatments as 24 h old eggs and completed their juvenile development on treated leaves had significantly lower gross fecundity, net fecundity and instantaneous rate of increase (ri) but the reduction was merely 4–6%, 9–11%, and 2–3%, respectively. Female longevity was significantly reduced (approximately by half a day) only after treatment with 240 mg/L. In the second bioassay, in which females were treated during their pre-ovipositional period, the treatments with 240 and 120 mg/L significantly reduced their gross fecundity (16–17%), net fecundity (28–31%), ri values (8–9%) and female longevity (approximately by one day). Spinosad effects on the intrinsic rate of increase (rm) and other demographic parameters were evaluated in two successive bioassays in which life tables were constructed for females that survived treatment with 120 mg/L at the egg stage (first demographic bioassay) or pre-ovipositional period (second demographic bioassay). In the first bioassay, the intrinsic rate of increase was significantly higher in treated (rm = 0.278) than control mites (rm = 0.267) as a result of higher net fertility at the beginning of reproduction of treated females. In the second bioassay, treated females had significantly lower rm than control females (0.254 and 0.283, respectively). The results obtained in this study indicate that spinosad, applied against insect pests (at field relevant rates of 60–240 mg/L), could eliminate a part of T. urticae population as well, but survivors would retain a significant potential for population recovery.

Effect of running-in for delamination and friction properties of self-mating diamond-like carbon coatings in water

Two running-in processes, i.e., polishing a diamond-like carbon (DLC) coated disk and pre-sliding in ambient air, were suggested as a delamination suppression method for self-mating DLC coatings in water, and the effects of these methods were verified using a ball-on-disk tribometer. An a-C:H-type DLC coating was deposited on SUJ2 bearing steel balls and disks using plasma chemical vapor deposition. It was confirmed that delamination of DLC coatings was suppressed because microcracks were not generated by removing droplets on the DLC coated disk using the polishing process. The friction coefficient in that condition was reduced to about one-fifth of that of the untreated disk. The running-in process of pre-sliding in ambient air also suppressed delamination of DLC coatings. Moreover, the friction coefficient after this process was reduced to half of that with the other polishing process in the boundary lubrication condition. It was found that these effects have a relationship with surface smoothness and hydrophilicity.

Characterization of Ti-6Al-4V Tribopairs: Effect of Thermal Oxidation Treatment

This paper deals with the study of the influence of the thermal oxidation (TO) treatment on the tribological properties of Ti-6Al-4V tribopairs. A detailed experimental campaign, including tribological tests, microgeometrical measurements, microhardness tests and phase composition analyses, was carried out on both treated and untreated components. The tribological behavior was studied through the pin-on-disk tests in four different contact conditions: treated disk coupled with untreated pin, untreated disk coupled with treated pin, both treated and both untreated. The effectiveness of the treatment in enhancing the tribological properties of the Ti-6Al-4V alloy sheets was found. In particular, the thermal oxidation treatment, promoting hardness enhancement and the formation of a superficial rutile layer, changed the wear mechanism of the titanium alloy, passing from adhesive wear type, for the untreated case, to abrasive wear, in the treated one.