Balanced Salt Solution Research Articles

Impact of a handpiece with a built-in fluidics pressure sensor on phacoemulsification: a multicentre prospective comparative study

ObjectiveWe assessed whether the immediate pressure adjustments provided by a phacoemulsification handpiece with a built-in pressure sensor (Active Sentry, AS) could decrease the amount of energy delivered in the eye...

Effects of surface treatments of bioactive tricalcium silicate-based restorative material on the bond strength to resin composite

ObjectivesThis study aimed to enhance the bond strength between Biodentine™ (BD), a bioactive tricalcium silicate (C3S) based material, and resin composite through various surface treatments. MethodologyBD samples were immersed in either double distilled water or Hank's Balanced Salt Solution and analyzed using X-ray Diffraction (XRD). Shear bond strength (SBS) evaluations of BD were performed using Prime & Bond™ NT (PNT), Single Bond Universal (SBU), Xeno V (Xeno), and glass ionomer cement (GIC) following various etching durations (0 s/ 15 s/ 30 s/ 60 s with 37.5% phosphoric acid). Two primers, RelyX™ Ceramic Primer (RCP) and Monobond ™ Plus (MBP), were chosen to prime BD for SBS enhancement. Fractography and bonding interfaces were examined with energy dispersive X-ray spectroscopy (EDS)/ scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). ResultsXRD confirmed BD’s main compositions as C3S, Ca(OH)2, CaCO3 and ZrO2 after 14 days crystal maturation. Etched BD did not improve SBS. GIC exhibited the lowest SBS (p < 0.05) among all adhesives, regardless of the etching mode (all < 1 MPa). The highest SBS (17.5 ± 3.6 MPa, p < 0.05) was achieved when BD primed with MBP followed by SBU application. FTIR and EDS showed γ-MPTS and10-MDP within the MBP primer interacted with C3S and ZrO2 of BD, achieving enhanced SBS. Most specimens exhibited mixed or cohesive failure modes.SignificanceBD’s subpar mechanical properties and texture may contribute to its poor adhesion to resin composite. Pretreating BD with MBP primer, followed by SBU adhesive is recommended for improving bond strength.

Corrosion behavior and microstructure of the surface corrosion film of biodegradable WE43 and ZX21 Mg alloys in Hanks’ balanced salt solution

In this study, the corrosion behavior and microstructure of the surface corrosion film of WE43 (Mg-4 wt%Y-3 wt%RE) and ZX21 (Mg-2 wt%Zn-1 wt%Ca) Mg alloys immersed in Hanks’ balanced salt solution (HBSS) at 37 °C are investigated. Through cross-sectional transmission electron microscopy (TEM) analysis, the surface corrosion films formed on both alloys after immersion in HBSS for 24 h are mainly a mixture of magnesium hydroxide (Mg(OH)2) and dicalcium phosphate dihydrate (DCPD) (CaHPO4·2H2O). Nevertheless, the surface corrosion film on WE43 alloy is only 114 ± 17 nm with Ca and P enriched in the outer portion of the film, while the surface corrosion film on ZX21 alloy is thicker (406 ± 50 nm) with some scattered hollow corrosion products on top of the film. The difference in the surface corrosion film thickness and microstructure is because of the faster corrosion rate of the ZX21 alloy, which resulted from the occurrence of localized corrosion on the alloy surface.

A novel approach for 25-gauge transconjunctival sutureless vitrectomy to evaluate vitreous substitutes in rabbits.

To improve the standard three-port vitrectomy for establishing and evaluating an endotamponade model in rabbits. Three ports were prepared near the third eyelid of rabbits, and the infusion port was placed at the inferior nasal quadrant with the inserted cannula linking with a self-designed handheld rigid infusion catheter. All right eyes of rabbits underwent a modified 25-gauge vitrectomy and were subsequently filled with balanced salt solution, silicone oil, and eight-arm polyethylene glycols (8-arm PEGs) hydrogel separately for comparison. Ophthalmic examinations were performed regularly to record the changes after the surgery. Successful vitrectomy was achieved among 44 chinchilla rabbits. The mean operation time was 4.51±1.25min. Four eyes (9.1%) presented limited lens touch and two eyes (4.5%) showed retinal touch during surgery. Incision leakage was found in three eyes (6.8%) after surgery. There was no endophthalmitis, hemorrhage, or retinal detachment during the observation period and ophthalmic examinations after the implantation of vitreous substitutes. The modified technique of the standard vitrectomy applied in the endotamponade model in rabbits shows excellent safety and practicality.

Guttapercha Improves In Vitro Bioactivity and Dentin Remineralization Ability of a Bioglass Containing Polydimethylsiloxane-Based Root Canal Sealer.

Guttapercha (GP, trans-1,4-polyisoprene) is the most used tooth root filling material, and it must be used with an appropriate cement (typically a polydimethylsiloxane (PDMS)-based sealer) to ensure an adequate canal obturation. This study aimed to assess the bioactivity and dentin remineralization ability of a bioglass containing PDMS commercial endodontic sealer, BG-PDMS (GuttaFlow Bioseal), and to evaluate the possible influence of a GP cone (Roeko GP point) on the mineralization process. To this end, BG-PDMS disks were aged alone or in the presence of a GP cone in Hank's Balanced Salt Solution (28 d, 37 °C). Dentin remineralization experiments were carried out under the same conditions. Micro-Raman and IR analyses demonstrated that BG-PDMS is bioactive, thanks to the formation of a silica-rich layer with nucleation sites for B-type carbonated apatite deposition. This phase was thicker when BG-PDMS was aged in the presence of GP. The two materials influenced each other because GP, which alone did not show any bioactivity, nucleated a calcium phosphate phase under these conditions. Analogously, dentin remineralization experiments showed that BG-PDMS is able to remineralize dentin, especially in the presence of GP. Under the experimental conditions, GP acted as a templating agent for calcium phosphate deposition.

Synthesis of Titanium Oxide Nanotubes Loaded with Hydroxyapatite.

A simple method of synthesis of TiO2 nanotubes (TiNT) loaded with hydroxyapatite (HAP) is described. Such nanotubes find wide applications in various fields, including biomedicine, solar cells, and drug delivery, due to their bioactivity and potential for osseointegration. The Cp-Ti substrate was anodized at a constant voltage of 40 V, with the subsequent heat treatment at 450 °C. The resulting TiNT had a diameter of 100.3 ± 2.8 nm and a length of 3.5 ± 0.04 μm. The best result of the growth rate of HAP in Hanks' balanced salt solution (Hanks' BSS) was obtained in calcium glycerophosphate (CG = 0.1 g/L) when precipitates formed on the bottom and walls of the nanotubes. Structural properties, surface wettability, corrosion resistance, and growth rate of HAP as an indicator of the bioactivity of the coating have been studied. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), potentiodynamic polarization test (PPC), electrochemical impedance spectroscopy (EIS), and contact angle (CA) measurements were used to characterize HAP-loaded nanotubes (HAP-TiNT). The CA, also serving as an indirect indicator of bioactivity, was 30.4 ± 1.1° for the TiNT not containing HAP. The contact angle value for HAP-TiNT produced in 0.1 g/L CG was 18.2 ± 1.2°, and for HAP-TiNT exposed to Hanks' BSS for 7 days, the CA was 7.2 ± 0.5°. The corrosion studies and measurement of HAP growth rates after a 7-day exposure to Hanks' BSS confirmed the result that TiNT processed in 0.1 g/L of CG exhibited the most significant capacity for HAP formation compared to the other tested samples.

Multisine impedimetric monitoring with an in-depth distribution of relaxation times analysis of WE43 and AZ31 magnesium alloys corrosion

This research aims to develop and utilize an impedance-based tool for monitoring non-stationary electrochemical processes, coupling the multisinusoidal perturbation signal approach and distribution of relaxation times (DRT) analysis for the first time. The approach was used to distinguish independent processes occurring at the surface of AZ31 and WE43 Mg alloys undergoing corrosion in Hank’s Balanced Salt Solution at 37 °C. We highlighted two common processes related to corrosion product layer formation. Detailed DEIS-DRT analysis was capable of real-time identification of a unique third process for the WE43 alloy, resulting from a spatially localized filiform corrosion attack in the vicinity of intermetallic particles. The proposed tool proved to be highly efficient in terms of studying non-stationary processes, while the DRT analysis allowed for an in-depth and precise localization of the number and the kinetics of the ongoing processes. The corrosion mechanism description was supported by numerous microscopic and spectroscopic tools.

Minimal Posterior Pole Vitrectomy and Fixing the Inverted Internal Limiting Membrane Flap with DisCoVisc for Macular Hole: No Gas or Air Tamponade.

To investigate an alternative surgical method for macular hole repair without fluid-air exchange, gas tamponade, and prone positioning. Eighteen eyes of 17 patients with macular holes underwent minimal posterior pole vitrectomy with an inverted internal limiting membrane flap technique. Ophthalmic viscosurgical device was used to fix the inverted internal limiting membrane flap in the balanced salt solution. No fluid-air exchange, gas tamponade, or prone positioning was needed. Follow-ups were performed at 1 day, 1 week, and the last visit (ranging from 3 to 6 months) after surgery. Optical coherence tomography examination, intraocular pressure, and best-corrected visual acuity measurements were performed preoperatively and at every follow-up, postoperatively. Primary closure of the macular hole was observed in all 18 eyes (100%). Optical coherence tomography showed U-type closure in 12 eyes, V-type closure in five eyes, and W-type closure in one eye. Preoperative, postoperative 1 week, and last follow-up best-corrected visual acuity were 0.90 (Snellen equivalent 20/159) ± 0.31 LogMAR, 0.72 (Snellen equivalent 20/105) ± 0.33 LogMAR, and 0.48 (Snellen equivalent 20/60) ± 0.32 LogMAR, respectively. Postoperative visual acuity was significantly improved compared with preoperative values ( F = 19.250, P = 0.000). No significant difference in intraocular pressure was found compared with preoperative values ( F = 1.933, P = 0.168). No significant complications were observed. This surgical method can effectively close macular holes, improve visual acuity, enhance surgical efficiency, reduce surgical complications, and improve patients' postoperative experience without the need for fluid-air exchange, gas tamponade, or prone positioning.

Fluid Supplementation Through Weakened Zonules via Side-Port Incision to Maintain Intraocular Pressure in High Myopic Eyes.

During phacoemulsification, the infusion pressure can cause the liquefied vitreous fluid to escape through the ciliary fiber interspace in highly myopic eyes, leading to reduced vitreous cavity pressure similar to vitrectomized eyes. This study assessed the probability of low intraocular pressure (IOP) in high myopic eyes with different axial length (AL) group undergoing cataract surgery, as well as the impact of balanced salt solution (BSS) supplementation and the optimal IOP value for such supplementation. The control group consisted of cataract eyes with normal AL (group 1: 22mm ≤ AL < 24.5mm), while cataract eyes with high axial myopia were categorized into three groups (group 2: 26mm ≤ AL < 28mm, group 3: 28mm ≤ AL < 30mm, group 4: AL ≥ 30mm). IOP was measured using the iCare pro tonometer intraoperatively. BSS supplementation was performed to raise IOP in cases of low IOP, before intraocular lens (IOL) implantation and before the end of surgery. The probability of low IOP was calculated, and the IOP before and after supplementation were compared. Ninety-five eyes were included. The total probability of low IOP in groups 2, 3, and 4 was 56.52, 62.50, and 70.83%, respectively, significantly higher than that in group 1 (16.67%). Similarly, the probability of low IOP before IOL implantation was significantly higher in groups 2, 3, 4 (43.48, 41.67, and 62.50%) compared to group 1 (4.17%, P < 0.05). The IOP before and after the first BSS supplementation in three high myopia groups were statistically significant (P < 0.05), increasing from 12.10mmHg (range, 6.0-24.9mmHg) to 16.60mmHg (range, 10.2-34.4mmHg). After the second BSS supplementation before the end of surgery, the IOP of high myopia groups increased from 12.60mmHg (range, 7.0-25.3mmHg) to 14.60mmHg (range, 9.8-25.3mmHg). The condition of highly myopic eyes seems more likely to develop low IOP during cataract surgery. There is an observed correlation: as AL increases, the total probability of low IOP rises. In patients with IOP < 9.5mmHg intraoperatively, fluid supplementation via a side-port incision can effectively raise IOP to about 16mmHg before IOL implantation and about 14mmHg after incision sealing, facilitating smoother IOL implantation and reducing the risk of postoperative low IOP. NCT, NCT05201677. Registered 23 November 2021-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05201677 .

Quantification of oral neutrophil counts in periodontal health and disease utilising a standardised oral rinse.

Polymorphonuclear neutrophils are the most abundant leukocytes in humans and are key host cells in defence against invading microorganisms. The oral neutrophil count may be an indicator of the periodontal health status, which correlates with the severity of periodontal disease. This study attempts to quantify orogranulocytes utilising an oral rinse and to assess the usefulness of this method in evaluating the oral inflammatory load much the same way the circulating neutrophils are used to screen for patients with infection in extra-oral sites. A total of 125 participants were divided into five groups with 25 subjects in each group. The groups consisted of healthy, gingivitis, mild periodontitis, moderate periodontitis, and severe periodontitis. Participants were asked to rinse with 10 mL of 0.9% saline for 30 s and to expectorate. Samples were centrifuged at 2000 RPM for 10 min. The supernatant removed was suspended in 5 mL of Hanks's balanced salt solution. One millilitre of this suspension was mixed with 4 μL of acridine orange. A 10 μL aliquot of this suspension was then assessed on a haemocytometer, and the oral PMNs were counted using fluorescence microscopy. The mean number of oral neutrophils (100,000 cells/mL) was the lowest in the healthy group and increased in ascending order across the different groups with the highest for severe periodontitis group. The oral neutrophil counts increased with the severity of periodontal inflammation. This is an easy, safe, reliable, and non-invasive method of quantification of oral neutrophils.

Efficiency of a polymer-coated phacoemulsification tip in cataract surgery.

To determine whether there is a difference in efficiency during phacoemulsification when using the hybrid polymer tip compared with the metal balanced tip, as measured by cumulative dissipated energy (CDE) and total procedure time. John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. Experimental study. Phacoemulsification was performed with the Centurion Vision System and Infiniti OZil handpiece, with a 30-degree bevel metal balanced tip and hybrid polymer tip. The vacuum was set at 500 mm Hg and the aspiration flow rate at 50 mL/min. Power was changed for torsional and longitudinal ultrasound (US) at 20%, 40%, 60%, 80%, and 100%. Hardened porcine lenses were cut into 200 two mm cubes, 10 for each specified tip/power setting. They were placed into an artificial anterior chamber filled with a balanced salt solution, and phacoemulsification was performed. A second observer randomly assigned the US type and power. The same observer timed trials with a stopwatch, and CDE was recorded. There were no significant differences in time or CDE for any power levels or US modes when comparing the 2 tips. No significant difference in efficiency was observed when comparing the metal balanced tip with the hybrid polymer tip. Given the known improved safety profile and the overall equivalent efficiency of the hybrid tip, it could improve the performance of beginning and advanced surgeons in the future. Future study is needed to evaluate other setting combinations and to evaluate the hybrid tip in clinical settings.

Effects of Intra-cameral Dexamethasone after Uncomplicated Phacoemulsification

Purpose: Postoperative inflammation is very common following phacoemulsification. We conducted this study to compare the effectiveness of intra-cameral dexamethasone injection with traditional topical steroids following phacoemulsification. Study Design: Quasi experimental Place and Duration of Study: Jinnah Postgraduate Medical Center, JPMC, Karachi from February 2022 to July 2022. Methods: A total of 60 patients were divided into two equal groups of 30 each. One group was treated with prophylactic intra-cameral dexamethasone at the end of phacoemulsification and the other group was given Balanced Salt Solution in its place. Both the groups were examined at post-operative day 1 and 7 for following parameters; best corrected visual acuity (BCVA), intra-ocular pressures (IOP), anterior chamber cells and flare. Results: The dexamethasone group showed statistically significant improvement in anterior chamber cells and flare as compared to the placebo group at postoperative day 1 and 7 (p-value of 0.042 and 0.029 respectively for cells; p-value of 0.038 and 0.002 respectively for flare). HoweverBCVA and IOP showed no statistically significant differences between the two groups at postoperative day 1 and 7 (p-value 0.67 and 0.46 respectively for BCVA and 0.22 and 0.08 respectively for IOP). Conclusion: Intra-cameral dexamethasone is an effective way to control postoperative inflammation following phacoemulsification with reduced anterior chamber cells and flare. However, its effects on BCVA and IOP were comparable to topical steroids.

Topical Losartan Decreases Myofibroblast Generation But Not Corneal Opacity After Surface Blast-Simulating Irregular PTK in Rabbits.

To evaluate the efficacy of topical losartan after blast injury-simulating irregular phototherapeutic keratectomy (PTK) in rabbits. Twelve NZW rabbits underwent 100 pulse 6.5mm diameter PTK over a metal screen to generate severe surface irregularity and inhibit epithelial basement membrane regeneration. Corneas were treated with 0.8mg/mL losartan in balanced salt solution (BSS) or BSS 50 µL six times per day for six weeks after PTK. All corneas had slit lamp photography, with and without 1% fluorescein at two, four, and six weeks after PTK, and were analyzed using immunohistochemistry for the myofibroblast marker α-smooth muscle actin (α-SMA), keratocyte marker keratocan, mesenchymal cell marker vimentin, transforming growth factor (TGF)-β1, and collagen type IV. Topical 0.8mg/mL losartan six times a day significantly decreased anterior stromal α-SMA intensity units compared to BSS at six weeks after anterior stromal irregularity-inducing screened PTK (P = 0.009). Central corneal opacity, however, was not significantly different between the two groups. Keratocan, vimentin, TGF-β1, or collagen type IV levels in the anterior stroma were not significantly different between the two groups. Topical losartan effectively decreased myofibroblast generation after surface blast simulation irregular PTK. However, these results suggest initial masking-smoothing PTK, along with adjuvant topical losartan therapy, may be needed to decrease corneal stromal opacity after traumatic injuries that produce severe surface irregularity. Topical losartan decreased scar-producing stromal myofibroblasts after irregular PTK over a metal screen but early smoothing of irregularity would also likely be needed to significantly decrease corneal opacity.

Evaluation for endotoxin in intraocular materials used during phacoemulsification surgery using a recombinant factor C assay.

Cataract surgery remains the sole method to resolve blindness secondary to cataract formation. One complication includes fibrin web formation post-operatively. This study aimed to investigate the presence of endotoxin within materials used during cataract surgery as a possible cause of fibrin web phenomenon. Preservative-free epinephrine, heparin, viscoelastic devices, and intraocular lenses were collected for evaluation. Various manufacturers and manufacturing lot numbers were used when available. Viscosity of viscoelastics was reduced by incubating samples with human recombinant hyaluronidase. Intraocular product (IOL) packaging fluid was collected and stored for testing. The IOLs were then washed with a sterile balanced salt solution, incubated at 37°C for 48 h, and then fluid was collected for testing to mimic intraocular placement. Samples were tested using a commercially available rFC kit. Fluorescence was measured at time zero and after 1 h using a fluorescence microplate reader. The change in fluorescence was corrected for blank fluorescence and plotted to a standard curve. Endotoxin levels were below the limit of detection (0.05 EU/mL) in all samples. Incubation of IOLs at intraocular temperature did not increase extraction of endotoxin. Endotoxin was not identified in any tested sample, including those used in cases of fibrin web formation post-phacoemulsification. As fibrin webs are often observed episodically, it is possible that endotoxin levels may vary between batches, or that endotoxin is not related to fibrin formation.

Systemic administration of clinical-grade multilineage-differentiating stress-enduring cells ameliorates hypoxic–ischemic brain injury in neonatal rats

Multilineage-differentiating stress-enduring (Muse) cells are endogenous reparative pluripotent stem cells present in the bone marrow, peripheral blood, and organ connective tissues. We assessed the homing and therapeutic effects of systemically administered nafimestrocel, a clinical-grade human Muse cell-based product, without immunosuppressants in a neonatal hypoxic–ischemic (HI) rat model. HI injury was induced on postnatal day 7 (P7) and was confirmed by T2-weighted magnetic resonance imaging on P10. HI rats received a single dose nafimestrocel (1 × 106 cells/body) or Hank’s balanced salt solution (vehicle group) intravenously at either three days (on P10; M3 group) or seven days (on P14; M7 group) after HI insult. Radioisotope experiment demonstrated the homing of chromium-51-labeled nafimestrocel to the both cerebral hemispheres. The cylinder test (M3 and M7 groups) and open-field test (M7 group) showed significant amelioration of paralysis and hyperactivity at five weeks of age compared with those in the vehicle group. Nafimestrocel did not cause adverse events such as death or pathological changes in the lung at ten weeks in the both groups. Nafimestrocel attenuated the production of tumor necrosis factor-α and inducible nitric oxide synthase from activated cultured microglia in vitro. These results demonstrate the potential therapeutic benefits and safety of nafimestrocel.

Zein-Bioactive Glass nanocomposite Coating on Magnesium Alloy Substrate for Orthopedic Applications

Excellent mechanical strength and biodegradable characteristics of magnesium alloys have sparked considerable interest in orthopedic applications. The utilization of magnesium alloys in orthopedic applications has been restricted due to their brittleness caused by high corrosion rate in biological environments. One of the best techniques for increasing corrosion resistance of these alloys is surface coating. For the first time, the present work aims to dip-coat zein-bioactive glass (BG) nanocomposite on AZ31B magnesium alloy. The alloy surface was also coated by native zein as a control coating. BG nanoparticles required for zein and BG (zein_BG) composite were synthesized by a bio-inspired method using cetyltrimethylammonium bromide (CTAB) as a template. The formation of BG particles was affirmed by FTIR showing characteristic Si-O-Si and Si-O– peaks. Nano-size of BG particles with an average diameter of 6.67 ± 0.06 nm was reported by TEM. SEM micrographs revealed successful deposition of zein and zein_BG coatings on the magnesium alloy surfaces. High-resolution XPS analysis on zein_BG-coated Mg alloy immersed in HBSS revealed the corrosion deposition of Mg(OH)2, MgHPO4.H2O, CaHPO4.H2O, SiO2, MgCO3, and CaCO3 on the substrate surface. More than twofold wettability, 95% adhesion strength and 14-fold increase in surface roughness were reported for zein_BG-coated magnesium alloy compared to the bare surface. Measurements of weight loss in zein and zein_BG-coated alloy substrates in Hanks Balanced Salt Solution (HBSS) for 10 d at 37°C showed a drastic decrease in weight loss of substrates after coating. As a result, zein_BG-coated substrate was observed to possess the maximum protective efficacy (95.99%) against corrosion. Interestingly, electrochemical measurements revealed a vast decrease in corrosion current density (2.41 E−6 A.cm−2) of zein_BG-coated substrate compared to the uncoated substrate (3.04 E−4 A.cm−2). Electrochemical impedance spectra (EIS) confirmed capacitive behavior of zein_BG-coated alloy substrate. These findings demonstrated that simple zein_BG composite dip coating was a successful corrosion-resistant implant coating on magnesium alloy surface for orthopedic applications.

Quantification and comparison of salivary neutrophils in periodontal health and disease.

Neutrophils continuously migrate into the oral cavity from various sources like gingival crevicular fluid and saliva both in health and in inflammation. The migration of the neutrophils into the various tissues and into the oral cavity occurs when the host microbial interplay tips the balance favoring the initiation of the inflammatory and immune reactions which depending on the amount of the microbial load results in the development of acute and chronic infections in the susceptible host. The present study was designed to quantify and compare the oral salivary neutrophil levels in patients with gingivitis and chronic and aggressive periodontitis as well as in healthy controls, before and after scaling and root planing (SRP) and to compare the difference within the selected study groups. Forty subjects were classified into four groups, that is, healthy controls, gingivitis, and chronic and aggressive periodontitis. Oral rinse samples were collected using Hank's balanced salt solution from each patient before and after phase I periodontal therapy. Cells in the rinse samples were stained with Acridine orange, and neutrophil counts were carried out using a fluorescence microscope and a hemocytometer. Baseline oral salivary neutrophil levels were maximum in the chronic periodontitis group followed by the aggressive group and then the gingivitis group. Oral salivary neutrophil levels also positively correlated to probing pocket depth, plaque index, calculus index, and gingival index in all four study groups. Maximum reduction in the oral salivary neutrophil levels after phase I periodontal therapy was seen in the gingivitis group. From our study, we conclude that the oral salivary neutrophil levels decreased significantly after SRP. Estimation of changes in the oral salivary neutrophil levels has the potential to aid in monitoring treatment outcomes. Thus, it suggests that it could be used as a simple, noninvasive laboratory technique to monitor the periodontal status and disease progression.

Contributed Session II: Ex-vivo human crystalline lenses geometrical changes during simulated disaccommodation.

The young crystalline lens changes its shape to focus targets at different distances, a capability (accommodation) that is lost with age. Quantifying crystalline lens morphology during accommodation and aging is essential for understanding basic mechanisms of function and disease (presbyopia and cataract). We studied the geometrical changes of the ex-vivo human crystalline lens while simulating different levels of physiological disaccommodation using a motorized lens-stretcher system designed for this purpose. 14 human lenses (11-54 y/o) from donor eyes were radially stretched mounted in the lens-stretcher and immersed in a cuvette filled with balanced salt solution for preservation purposes. Lens geometry and power were characterized using custom-developed high resolution 3-D optical coherence tomography (OCT) and laser ray tracing system coupled with the OCT. The lens thickness decreased linearly 81 microns/diopter (D) of simulated disaccommodation (-r=0.87, p<0.001), the diameter increased 76 microns/D (r=0.84, p<0.01), the radius of curvature of the anterior surface increased 0.63 mm/D (r=0.92, p<0.001), the lens surface area increased 1.9 mm2/D (r=0.62, p<0.01) and the lens volume remained constant. The same stretching displacement produced larger deformations in younger than in older lenses. Simultaneous high resolution optical and geometrical measurements of stretched lenses therefore match results in vivo and support the Helmholtz theory of accommodation.

Effect of Polydeoxyribonucleotide on Human Periodontal Ligament Cells as a Storage Medium for Avulsed Tooth

Objective: This study aimed to evaluate the suitability of polydeoxyribonucleotides (PDRN) as a storage medium for avulsed teeth.Materials and Methods: The viability of human periodontal ligament (PDL) cells stored in Hank’s balanced salt solution and PDRN solutions (concentrations, 10, 25, 50, and 100 μg/mL) and tap water was measured using the Cell Counting Kit-8 and Live/Dead assays. In addition, Nitric oxide detection and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to evaluate the anti-inflammatory effect of PDRN.Results: The viability of PDL cells stored in a 100 μg/mL PDRN solution was significantly higher than that of cells stored in the other solutions (&lt;i&gt;p&lt;/i&gt; &lt; 0.01). Furthermore, cells stored in 100 μg/mL PDRN solution demonstrated a significantly reduced NO production (&lt;i&gt;p&lt;/i&gt; &lt; 0.0001), and cells stored in 50 and 100 μg/mL PDRN solutions expressed significantly lower levels of tumor necrosis factor α, interleukin (IL) -4, IL-6, and IL-10 (&lt;i&gt;p&lt;/i&gt; &lt; 0.01) compared to cells stored in HBSS.Conclusion: The PDRN solution exhibited cell-preserving and anti-inflammatory effects on the PDL cells. The findings of this study can serve as a basis for further experiments directed at the development of an effective storage medium for avulsed teeth.

Localized Corrosion Behavior and the Relationship to the Second Phases in Biodegradable ZX21 Mg Alloy in Hanks' Balanced Salt Solution

Mg alloys are considered promising biodegradable implant materials owing to their high activity, which makes Mg alloys degradable in the human body and can avoid second removal surgeries. Also, compared with other biodegradable implant materials, Mg alloy has a similar density and Young’s modulus to human bones, which minimizes the stress shielding effect. ZX series Mg alloys, which contain Zn and Ca, are designed to increase the alloy strength but maintain biocompatibility. However, even with all the advantages, the high degradation rate limits the clinical applications of ZX series Mg alloys. With fast degradation, not only the mechanical properties are affected, but also a large amount of hydrogen gas and hydroxide ions would accumulate around the implant in the patient. Therefore, it is essential to investigate the corrosion mechanism of the ZX series Mg alloys to mitigate the degradation rates.Localized corrosion is one of the noticeable features in the corrosion process of ZX series Mg alloys, which is the main reason for the low corrosion resistance and high degradation rate of the alloy. However, the origin and detailed mechanism of the initiation and propagation of localized corrosion on ZX series Mg alloys are still unclear. The second phases, which contain Zn and Ca, play complex roles in the corrosion process owing to the inhomogeneous elemental distribution and different electrochemical potentials with respect to the Mg alloy matrix. Thus, this study aims to investigate the microstructure of the localized corrosion sites and the galvanic effects around the second phases in a ZX series Mg alloy.In this study, an Mg-2 wt%Zn-1 wt%Ca (ZX21) alloy was prepared, and the localized corrosion behavior was investigated in a Hanks’ balanced salt solution (HBSS) at 37°C. By scanning electron microscope (SEM)/focused ion beam (FIB) cross-sectional observations, two kinds of second phases were identified in the ZX21 Mg alloy, one is enriched with Zn and the other is not. After immersion in HBSS, galvanic corrosion sites were found in the Mg alloy matrix next to the second phase enriched with Zn, while the Mg alloy matrix next to the second phase with lower Zn concentration was intact. Furthermore, the second phases in the ZX21 Mg alloy were found to hinder the propagation of localized corrosion. The complex roles of the second phases in the ZX21 Mg alloy on the localized corrosion behavior will be discussed based on electrochemical measurements and microstructure characterizations. Figure 1