Bisphenol A release from CAD/CAM splint materials.

This study aimed to investigate the bisphenol A (BPA) release from four CAD/CAM splint materials: three polycarbonate-based (DD BioSplint C, Splint Plus Biostar, Temp Premium Flexible) and one polymethylmethacrylate-based (Temp Basic) material. From each material, ten cylindrical samples (n = 40) were immersed in high-performance liquid chromatography (HPLC) grade water following ISO 10993-12 and incubated for 24 h in an incubation shaker at 37°C and 112 rpm. Following BPA derivatization, analysis was performed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). After 24 h of incubation, all investigated materials released significant amounts of BPA compared to water blanks. The material-dependent elution increased in the following order: DD BioSplint C < Splint Plus Biostar < Temp Basic < Temp Premium Flexible. Subtracting extraneous BPA, the concentrations ranged between 2.27 ng/mL and 12.65 ng/mL. After extrapolating the concentrations in relation to the average surface area of occlusal splints, the amount of BPA per mL exceeded the Tolerable Daily Intake (TDI) set by the European Union for a person weighing 70 kg by 1.32-6.16 times. Contrary to the release from previously investigated materials, BPA elution from CAD/CAM splint materials was highly elevated. Considering the increasing adaptation of CAD/CAM techniques, elution from them may represent a relevant BPA source in daily dental practice.

COVID-19: The Dysregulated Response to Infection - Why Consider Polymethylmethacrylate Membrane in Hemodialysis Patients?

Since SARS-CoV-2 spread through China at the end of 2019, COVID-19 has been probably the most difficult challenge in the last decades for healthcare systems all around the world, still representing a danger for fragile patients with different comorbidities. Chronic dialysis patients affected by COVID-19 experienced severe disease with a higher mortality rate compared to the general population. Morbidity and mortality of this severe acute respiratory syndrome depend on both acute respiratory failure and systemic immunological involvement with consequent inflammation-mediated injury. Indeed, the most important determining factor of COVID-19 severity is the strength of the so-called "cytokine storm" associated with SARS-CoV-2 infection. Therefore, this severe infection varies clinically from an asymptomatic condition to a generalized and violent inflammatory response and acute respiratory distress syndrome, with consequent pulmonary interstitial edema and a high risk of multi-organ failure. The use of extracorporeal therapies targeting cytokine clearance to improve patients' outcomes has been widely debated, especially in end-stage kidney disease's patients on maintenance dialysis or in individuals affected by acute kidney injury admitted to intensive care units. Different studies were conducted to demonstrate how specific dialyzers could decrease the COVID-19 inflammatory state. The aim of this narrative review was to summarize main studies about this topic, focusing primarily on the role of polymethylmethacrylate dialyzer and underlining pros and cons of this sorbent.

Removal of α1-Microglobulin Using Post-Dilution Online Hemodiafiltration with Polymethylmethacrylate Membrane: An Open-Label, Single-Arm Study.

INTRODUCTION: The removal of low- and medium-molecular-weight proteins has been improved with online hemodiafiltration (OL-HDF) and hemodialysis using high-flux membranes; however, the outcomes of patients with end-stage kidney disease (ESKD) undergoing dialysis treatment are still worse than in the general population. α1-Microglobulin (α1-m), with a molecular weight of 33,000 Da, may contribute to dialysis-related disorders and mortality. However, the removal is insufficient even with current OL-HDF using the polysulfone (PS) membrane, which is common in Japan. Polymethylmethacrylate (PMMA) membranes can remove medium- to high-molecular-weight proteins by adsorption. This study aimed to assess the efficacy of removing medium- to high-molecular-weight proteins, such as α1-m and ß2-microglobulin (ß2-m), through post-dilution OL-HDF with PMMA (Post-PMMA). The assessment was conducted in comparison to pre-dilution OL-HDF with PS (Pre-PS), using an open-label, single-arm study. METHODS: Seven patients with ESKD on Pre-PS underwent Post-PMMA with replacement volume of 30 mL/min (low flow) and 50 mL/min (high flow). Clearance and removal rates of α1-m, ß2-m, small molecules, inflammatory cytokines, and albumin were measured at 60 and 240 min of treatment. RESULTS: Clearance rates of α1-m at 60 min were -2.8 ± 5.2 mL/min with Pre-PS, -0.4 ± 2.6 mL/min with Post-PMMA (low), and 0.6 ± 3.4 mL/min with Post-PMMA (high). The removal rate of α1-m was higher in Post-PMMA than that in Pre-HDF-PS (Post-PMMA [high] 17.7 ± 5.9%, Post-PMMA [low] 15.0 ± 5.6%, and Pre-PS 4.1 ± 5.5%). Adsorption clearance of ß2-m was increased with Post-PMMA. Albumin leakage in Post-PMMA was not higher than that in Pre-PS. CONCLUSION: The removal rate of α1-m with Post-PMMA was higher than that with Pre-PS. The PMMA membrane adsorbed ß2-m, suggesting the removal effect of medium- to high-molecular-weight proteins by the adsorption method. Since Post-PMMA effectively removes α1-m without excessive albumin leakage, it will be useful for patients with ESKD, especially those with a poor nutritional status.

The Pregnant Arthroplasty Surgeon: A Women in Arthroplasty Committee Editorial.

BACKGROUND: Women orthopaedic surgeons face unique challenges during their careers. There are extremely low numbers of women in the field, particularly in the specialty of adult reconstruction. Factors contributing to low numbers of women entering this subspecialty include increased perceived physical demand relative to other fields, occupational hazards during pregnancy such as exposure to radiation and polymethylmethacrylate bone cement, concerns for work-life balance, and limited number of women within the subspecialty. The following editorial provides a framework to understand and manage the potential occupational hazards to pregnant and lactating surgeons, parental leave, and postpartum return to work. We aim to dispel any unfounded myths and provide evidence-based education that may help overcome these barriers. In doing so, we hope to encourage more women to consider adult reconstruction as a potential career. METHODS: Our primary method consisted of completing an extensive literature review on the past and current articles about the aforementioned barriers which may contribute to the low number of women entering adult reconstruction. After this literature search was completed, we composed a comprehensive editorial that provided evidence-based education and recommendations for medical professionals. CONCLUSIONS: Issues pertaining to parenthood, pregnancy, and lactation pose barriers to success for women in orthopedic surgery. These concerns may dissuade talented women from pursuing a rewarding career in adult reconstruction. Education on these issues is needed to help our early-career colleagues plan and care for their families. Clearly stated and published policies should be made available in all training programs, fellowships, and clinical practices to allow understanding and unbiased implementation. By being more inclusive, adult reconstruction will have access to the best possible surgeons, which will benefit not only patients but the field as a whole.

Effect of milling procedures in CAD-CAM systems on the color changes of CAD-CAM polymethyl methacrylate resin material as interim material.

PURPOSE: This study aimed to investigate the effects of new and used burs on CAD-CAM PMMA resin color changes following thermocycling. MATERIALS AND METHODS: Twenty disk-shaped specimens (10 × 2 mm) were made using a single brand of CAD-CAM polymethyl methacrylate resin (Polident) for the color test. Group N consisted of half of the specimens that were machined using the new tungsten carbide bur set, and Group U consisted of the specimens that were milled using the used bur set (500 machining time). A color test was performed on the specimens both before and after thermocycling. For the statistical analysis, the Kruskal-Wallis and Dunn Pairwise Comparison tests were employed. RESULTS: The ∆E* value of specimens (2.057) milled with the used bur was higher than those of specimens milled with the new bur (0.340), but this value is within clinically acceptable limits. After thermocycling, specimens milled with the utilized burs had the greatest L* (93.850) and b* (5.000) values. After thermocycling, statistically significant differences were discovered between Group N and Group U as well as between specimens milled with the utilized bur before and after thermocycling. CONCLUSION: Thermocycling process have an effect on the mean ∆E values of specimens milled with the used carbide bur, but these ∆E* values were not statistically significant. CLINICAL SIGNIFICANCE: The color and clinical performance of CAD-CAM restorations may be affected by variations in CAD-CAM milling bur properties, particularly those related to their frequent use.

Effect of intraoral scanning distance on the marginal discrepancy of milled interim crowns.

PURPOSE: To compare the marginal discrepancy between milled interim crowns fabricated using intraoral digital scans acquired at different scanning distances. MATERIALS AND METHODS: Ten acrylic typodont teeth were prepared for interim crowns. Three different resin frames of 2.5-, 5-, and 7.5-mm heights were fabricated and attached to an intraoral scanner (Omnicam). Three groups were created based on the different scanning distances tested: 2.5 mm (Group A), 5 mm (Group B), and 7.5 mm (Group C). Intraoral digital scans were performed on four tooth surfaces: mesial, distal, buccal, and lingual (n = 10). Each experimental scan was used to design and fabricate a milled polymethylmethacrylate anatomically contoured crown. Vinyl polyether silicone was used three times to assess the marginal discrepancy of the specimens by measuring five marginal points on digital photographs. One-way analysis of variance test was used to analyze the data, followed by Tukey's honestly significant difference test (α = 0.05). RESULTS: The mean marginal discrepancy values in Group C were significantly higher than those in Groups A (p ≤ 0.000) and B (p = 0.001). There was no significant difference between Groups A and B (p = 0.702). There were no significant differences among the four surfaces in any of the scanning distance groups (p1  = 0.583, p2  = 0.390, and p3  = 0.135; p > 0.05). CONCLUSIONS: The interim crowns fabricated with a scanning distance of 7.5 mm showed the greatest marginal discrepancy when compared with crowns fabricated using 2.5- and 5-mm scanning distances.

Effects of aging on attachment of Candida albicans to conventional heat-polymerized, CAD-CAM milled, and CAD-CAM 3D-printed acrylic resin bases.

PURPOSE: The aim of this study was to assess Candida albicans attachment on conventionally fabricated (polymethylmethacrylate, PMMA), CAD-CAM milled, and 3D-printed acrylic resin bases pre- and post-simulated thermal aging, along with examining material surface changes after aging. MATERIALS AND METHODS: Forty-six samples (10 mm × 10 mm × 2 mm) for each of four material groups (conventional heat-polymerized PMMA, CAD-CAM milled acrylic resin base, CAD-CAM 3D-printed methacrylate resin base, CAD-CAM 3D-printed urethane methacrylate resin base) were subjected to 0, 1, or 2 years of simulated thermal aging. Microscopic images were taken before and after aging, and C. albicans attachment was quantified using cell proliferation assay (XTT). Statistical analysis employed analysis of variance (α = 0.05). RESULTS: Two-way factorial analysis showed no significant differences based on acrylic resin type or thermal aging (p = 0.344 and p = 0.091 respectively). However, C. albicans attachment significantly differed between 0- and 2-year thermally aged groups (p = 0.004), mainly due to elevated initial attachments on CAD-CAM milled acrylic resin base and CAD-CAM 3D-printed urethane methacrylate resin base. CONCLUSIONS: Regardless of the fabrication technique and material combination, no significant differences were found in C. albicans adhesion pre- or post- thermal aging. Milled and 3D-printed bases compared favorably with heat- polymerized PMMA in their affinity for C. albicans attachment and surface characteristics after aging. These findings indicate that the risk of patients developing denture stomatitis might not be linked to the type of acrylic resin or fabrication method used.

Visible Light Induced Degradation of Poly(methyl methacrylate-co-methyl α-chloro acrylate) Copolymer at Ambient Temperature.

Poly(methyl methacrylate) (PMMA) is a well-known and widely used commodity plastic. High production amount of PMMA causes excessive waste creation that highlights the necessity of recycling. Conventional recycling methods require elevated temperatures to induce degradation or depolymerization. In this work, visible light induced photodegradation system by using dimanganese decacarbonyl (Mn2 (CO)10 ) with high halogen affinity is reported. Halide functional photodegradable polymers are prepared by copolymerization of methyl methacrylate and methyl α-chloroacrylate by conventional reversible addition-fragmentation chain-transfer polymerization. Synthesized copolymers are efficiently degraded to low molecular weight oligomers under visible light irradiation in the presence of Mn2 (CO)10 . Characteristics of precursors, degraded polymers, and kinetics of depolymerization are investigated by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourrier transform infrared (FTIR), and proton nuclear magnetic resonance (1 H-NMR) spectroscopies. The reported approach is expected to trigger further development of more environmentally friendly recycling techniques in the near future as we  are moving toward a greener and more sustainable world.

In vitro analysis of factors affecting the continuous hemodiafiltration clearance of teicoplanin.

BACKGROUND: In the treatment of sepsis, continuous hemodiafiltration (CHDF) and the administration of antibiotics such as teicoplanin (TEIC) are frequently performed in parallel. We aimed to clarify the factors influencing the CHDF clearance (CLCHDF ) of TEIC using a polymethylmethacrylate (PMMA) membrane or a polyacrylonitrile and sodium methallyl sulfonate copolymer membrane coated with polyethylenimine (AN69ST). We also investigated whether the adsorption of TEIC onto the hemofilters inhibits the adsorption of interleukin (IL)-6 onto the membranes. METHODS: TEIC, human serum albumin (HSA), and IL-6 were incubated with pieces of hemofilter membranes and adsorption rates were calculated. The CLCHDF , diafiltration rate, and adsorption rate of TEIC were calculated using an in vitro CHDF circuit model. RESULTS: The adsorption rates of TEIC onto the pieces of PMMA and AN69ST membranes ranged from 15.0% to 100% and from -10% to 5%, respectively. The adsorption rate of IL-6 was similar with or without TEIC. The CLCHDF and adsorption rate of TEIC under PMMA-CHDF depended on HSA, but not on effluent flow rate (Qe). The CLCHDF under AN69ST-CHDF depended on HSA and Qe. The observed CLCHDF under AN69ST-CHDF was similar to the predicted value (the product of Qe and the plasma unbound fraction). The observed CLCHDF under PMMA-CHDF was 2.0-7.8 times greater than the predicted value. CONCLUSIONS: Adsorption mainly contributes to the CLCHDF of TEIC using PMMA membranes, whereas diafiltration mainly contributes to the CLCHDF of TEIC using AN69ST membranes. TEIC adsorption might not affect the adsorption of IL-6 onto PMMA membrane.

Anti-Inflammatory Approach in Chronic Dialysis Patients with SARS-CoV-2: ATA or PMMA Dialyzers?

INTRODUCTION: High-flux hemodialysis membranes may modulate the cytokine storm of SARS-CoV-2, but their impact on chronic hemodialysis (CHD) patients is unknown. The aim of the study was the evaluation of asymmetric cellulose triacetate (ATA) and polymethylmethacrylate (PMMA) dialyzers on inflammatory markers and clinical outcomes in CHD patients with SARS-CoV-2. METHODS: A prospective, observational study on CHD patients with SARS-CoV-2 was carried out. Patients were enrolled from March 2020 to May 2021. Pre- and postdialysis C-reactive protein (CRP), procalcitonin (PCT), and interleukin-6 (IL-6) were determined at each session. Patients who underwent on-line hemodiafiltration (OLHDF) with a PMMA dialyzer were compared with those treated with OLHDF with a ATA dialyzer. The primary endpoint was the differences in the reduction ratio per session (RR) of CRP, PCT, IL-6, and IL-6 RR >25%. RESULTS: We consecutively enrolled 74 CHD patients with COVID-19, 48 were treated with ATA membrane, and 26 with PMMA. Median IL-6 RR was higher in the ATA group compared to PMMA (17.08%, IQR -9.0 to 40.0 vs. 2.95%, IQR -34.63 to 27.32). Median CRP RR was 7.77% (IQR 2.47-13.77) in the ATA group versus 4.8% (IQR -2.65 to 11.38) in the PMMA group (p = 0.0017). Median PCT-RR% was 77.38% (IQR 70.92-82.97) in ATA group versus 54.59% (IQR 42.62-63.16) in the PMMA group (p < 0.0001). A multiple logistic regression analysis with IL-6 RR >25% as the outcome including the membrane employed, pre-dialysis IL-6, CRP, PCT, and ferritin showed that ATA led to a higher probability to reach the outcome (OR 1.891, 95% CI 1.273-2.840, p = 0.0018) while higher CRP favors the risk of lower IL-6 RR values (OR 0.910, 95% CI 0.868-0.949, p ≤ 0.0001). CONCLUSIONS: In SARS-CoV-2 CHD patients treated with OLHDF, ATA showed a better anti-inflammatory profile, regarding IL-6 RR, compared to PMMA.

New Frontiers in Sepsis-Induced Acute Kidney Injury and Blood Purification Therapies: The Role of Polymethylmethacrylate Membrane Hemofilter.

Acute kidney injury (AKI) is a common consequence of sepsis with a mortality rate of up to 40%. The pathogenesis of septic AKI is complex and involves several mechanisms leading to exacerbated inflammatory response associated with renal injury. A large body of evidence suggests that inflammation is tightly linked to AKI through bidirectional interaction between renal and immune cells. Preclinical data from our and other laboratories have identified in complement system activation a crucial mediator of AKI. Partial recovery following AKI could lead to long-term consequences that predispose to chronic dysfunction and may also accelerate the progression of preexisting chronic kidney disease. Recent findings have revealed striking morphological and functional changes in renal parenchymal cells induced by mitochondrial dysfunction, cell cycle arrest via the activation of signaling pathways involved in aging process, microvascular rarefaction, and early fibrosis. Although major advances have been made in our understanding of the pathophysiology of AKI, there are no available preventive and therapeutic strategies in this field. The identification of ideal clinical biomarkers for AKI enables prompt and effective therapeutic strategy that could prevent the progression of renal injury and promote repair process. Therefore, the use of novel biomarkers associated with clinical and functional criteria could provide early interventions and better outcome. Several new drugs for AKI are currently being investigated; however, the complexity of this disease might explain the failure of pharmacological intervention targeting just one of the many systems involved. The hypothesis that blood purification could improve the outcome of septic AKI has attracted much attention. New relevant findings on the role of polymethylmethacrylate-based continuous veno-venous hemofiltration in septic AKI have been reported. Herein, we provide a comprehensive literature review on advances in the pathophysiology of septic AKI and potential therapeutic approaches in this field.

Varying degrees of spontaneous osteogenesis of Masquelet's induced membrane: experimental and clinical observations.

BACKGROUND: Masquelet's induced membrane (IM) has osteogenesis activity, but IM spontaneous osteogenesis (SO) has not been described previously. OBJECTIVES: To report on varying degrees of IMSO and analyze its possible causes. METHODS: Twelve eight-week-old male Sprague-Dawley rats with 10 mm right femoral bone defects who received the first stage of IM technique (IMT) were used to observe the SO. In addition, clinical data from patients with bone defects who received the first stage of IMT with an interval of > 2 months post-operatively and exhibited SO between January 2012 and June 2020 were retrospectively analyzed. The SO was divided into four grades according to the amount and characteristics of the new bone formation. RESULTS: At twelve weeks, grade II SO was observed in all rats, and more new bone was formed in the IM near the bone end forming an uneven margin. Histology revealed bone and cartilage foci in the new bone. Four of the 98 patients treated with the first stage of IMT exhibited IMSO, including one female and three males with a median age of 40.5 years (range 29-52 years). The bone defects were caused by severe fractures and infection in two cases and by infection or tumor in one case each. Partial or segmental defects occurred in two cases. The time interval between inserting a cement spacer and diagnosis of SO ranged from six months to nine years. Two cases were grade I, and one case each of grades III and IV. CONCLUSION: Varying degrees of SO confirm the existence of the IMSO phenomenon. Bioactive bone tissue or local inflammation and a long time interval are the primary reasons underlying enhancement of the osteogenic activity of IM and leading to SO, which tends to take place as endochondral osteogenesis.

Polymethylmethacrylate-induced foreign body reaction presenting as bilateral parotid lesions: A case report of dermal filler adverse reaction diagnosed on fine needle aspiration.

BACKGROUND: Dermal filler injections are being increasingly used as a non-surgical option for facial cosmetic procedures. However, their use has been implicated in multiple adverse events including immediate, early onset, and late onset complications. AIM: We present a case of dermal filler-induced foreign body reaction presenting as bilateral parotid lesions and diagnosed using fine needle aspiration. CONCLUSION: This case elucidate the risk of delayed adverse events in patients with dermal filler injections and stresses the importance of awareness by patients and providers for such events.

Preparation of silver nanoparticles/polymethylmethacrylate/cellulose acetate film and its inhibitory effect on Cronobacter sakazakii in infant formula milk.

Cronobacter sakazakii is a harmful foodborne pathogen, and its contaminated food will pose a huge threat to human health. Prevention of C. sakazakii contamination of food is valuable for food safety as well as for human health. In this study, silver nanoparticles (AgNP) were successfully immobilized on the surface of cellulose acetate (CA) and polymethylmethacrylate (PMMA) composite to obtain AgNP/PMMA/CA film. Through the inhibition zone and growth curve experiments, we found that AgNP/PMMA/CA films has excellent antibacterial activity on C. sakazakii. The AgNP/PMMA/CA film can prolong the lag phase of the growth curve of C. sakazakii from 2 to 8 h. The antibacterial films were found to reduce the survival of C. sakazakii in Luria-Bertani and infant formula by combining it with a mild heat treatment (45°C, 50°C, and 55°C). The AgNP/PMMA/CA film combined with 55°C water bath can completely inactivate C. sakazakii in infant formula within 120 min. Finally, the potential mechanism by which AgNP/PMMA/CA films reduce the heat tolerance of C. sakazakii was investigated by quantitative real-time PCR. The results showed that AgNP/PMMA/CA films could reduce the expression of environmental tolerance-related genes in C. sakazakii. The current research shows that AgNP/PMMA/CA film has strong antibacterial activity, and the antibacterial film combined with mild heat treatment can accelerate the inactivation of C. sakazakii and effectively reduce the harm of foodborne pathogens. The AgNP/PMMA/CA film can be used as a potential packaging material or antibacterial surface coating.

Polymethylmethacrylate Microspheres are Immunologically Inert in Mouse Tissues.

Nowadays, aesthetic concerns have gained attention, especially by patients looking for a less invasive alternative to minor facial corrections. Polymethylmethacrylate (PMMA) is widely used as a soft tissue filler; the demand for this polymer has increased, and along with it, there are some reports of adverse reactions. Such adverse reactions stem from consequences of immune and inflammatory reactions to PMMA. Some animal models have been used to unravel the causes of these reactions, among other factors involving the management of PMMA. The aim of this study was to determine the immunogenic profile of PMMA implantation in different anatomical planes of mice, over up to 360 experimental days. In this study, BALB/c mice were divided into 30 groups for immune evaluation of the interaction between the organism and the polymer; 2% PMMA was implanted subcutaneously, 10% intramuscularly and 30% in periosteal juxtaposition and followed during five experimental days (7, 30, 90, 180 and 360 days after implantation-DAI). Pro- and anti-inflammatory cytokines (IL-2, IL-4, IL-6, IFN-gamma, TNF, IL-17A, IL-10 and TGF-beta) were quantified in all experimental days. There was no statistical difference between the groups analyzed considering the evaluated parameters. Therefore, at all implanted depths, PMMA behaved inertly in a murine model.No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Safety and Efficiency of Minimally Invasive Buttock Augmentation: A Review.

BACKGROUND: Volume restoration and enhancement of the gluteal region appearance has become nowadays a popular concern in particular for many women. Several options are available, none however are without complications and side effects. Volume enhancement with soft tissue fillers of the gluteal region is emerging as a highly attractive minimally invasive modality. It has led unfortunately to more unlicensed, nonmedical practitioners administering illicitly injections for buttock augmentation at relatively low costs. MATERIALS AND METHODS: To determine safety, efficacy, and cost effectiveness of mostly used soft-tissue fillers for buttock augmentation, a systematic literature search of PubMed, Medline, and Embase was conducted to identify the mostly used fillers for gluteal augmentation. It was complemented by searching for each of the identified filler material separately to retrieve any missed reports. References of clinical studies and trials, reviews, and consensus reports were reviewed as well for the same objective. RESULTS: In the final analysis 12, mostly strongly biased clinical reports providing a low level of evidence, were identified for inclusion in the review. Two studies involved Polymethylmethacrylate (PMMA), 5 Poly-L-lactic acid, 1 Calcium hydroxyapatite and 4 hyaluronic acid filler injection. No studies were identified involving liquid silicone or Polyacrylamide hydrogel. The little available evidence provided by this review indicates that a specific brand of PMMA in Brazil has a demonstrable relatively good safety, efficiency, and cost-effectiveness record superior to surgical alloplastic gluteal augmentation or to lipofilling only when injected by experts. CONCLUSION: Gluteal augmentation with soft tissue fillers is not as simple and innocuous as advertised. Serious complications may occur. Moreover, optimal buttock contouring entails not only volume augmentation but also volume removal; thus, volume augmentation with soft tissue fillers may not be ideal. Popularizing this modality must also be approached with great care. Serious complications do occur; they become inevitable when performed illegally by non-specialized, non-authorized, and unscrupulous practitioners in non-accredited facilities. Patients must be warned that adherence to regulations is critical and that only well-trained certified experts practicing legally in accredited facilities can address safely and efficiently their concerns. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Tissue Remodeling After Implantation with Polymethylmethacrylate: An Experimental Study in Mice.

Polymethylmethacrylate (PMMA) is a filler used for aesthetic and/or repair purposes. The response to the implantation of biomaterials varies according to factors related to the patient, the professional responsible for the application and the material used. In vitro and in vivo experimental models have been used to study aspects such as the organism/biomaterial interface and the role of macrophages, dendritic cells and neutrophils. This study aimed to characterize the inflammatory reactions related to polymer concentration, implantation depth and exposure time. Different concentrations of PMMA were implanted in different anatomical planes in mice. The consequences of contact with PMMA, from structural changes to the inflammatory characteristic of tissue damage, were histologically evaluated. The implantation interfered in the morphological structure of the region where it was implanted, expanding it and due to the inflammatory reaction generated, by the presence of the vehicle in the initial phase and by the collagen produced in the chronic phase. The 30% concentration of PMMA induced a greater presence of foreign body giant cells both subcutaneously, at 7, 30 and 90 days after implantation (DAI), and intramuscular at 30DAI. Tissue remodeling was more expressive in the subcutaneous region with significant density of the extracellular matrix at 90DAI. In conclusion, the foreign body reaction resulting from the implantation process acquires different characteristics depending on the anatomical plane and the concentration of implanted product, where the more superficial the implantation plane, the greater the inflammatory reaction. Moreover, PMMA concentration and the depth of implantation did not influence the collagen production.No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors https://www.springer.com/00266.

Polymer Chemical Identity as a Key Factor in Microplastic-Insecticide Antagonistic Effects during Embryogenesis of Sea Urchin Arbacia lixula.

As a proxy for pollutants that may be simultaneously present in urban wastewater streams, the effects of two microplastics-polystyrene (PS; 10, 80 and 230 µm diameter) and polymethylmethacrylate (PMMA; 10 and 50 µm diameter)-on fertilisation and embryogenesis in the sea urchin Arbacia lixula with co-exposure to the pyrethroid insecticide cypermethrin were investigated. Synergistic or additive effects were not seen for plastic microparticles (50 mg L-1) in combination with cypermethrin (10 and 1000 µg L-1) based on evaluation of skeletal abnormalities or arrested development and death of significant numbers of larvae during the embryotoxicity assay. This behaviour was also apparent for male gametes pretreated with PS and PMMA microplastics and cypermethrin, where a reduction in sperm fertilisation ability was not evidenced. However, a modest reduction in the quality of the offspring was noted, suggesting that there may be some transmissible damage to the zygotes. PMMA microparticles were more readily taken up than PS microparticles, which could suggest surface chemical identity as potentially modulating the affinity of larvae for specific plastics. In contrast, significantly reduced toxicity was noted for the combination of PMMA microparticles and cypermethrin (100 µg L-1), and may be related to less ready desorption of the pyrethroid than PS, as well as cypermethrin activating mechanisms that result in reduced feeding and hence decreased ingestion of microparticles.

Effects of Different Surface Treatments of Woven Glass Fibers on Mechanical Properties of an Acrylic Denture Base Material.

Silanized glass fibers are popular reinforcements of acrylic denture base materials. To increase the number of surface hydroxyl groups and to improve interfacial adhesion between the matrix and reinforcements, acid or base treatments of glass fibers are commonly performed before the silanization. However, limited data are available on the effect of these treatments on the mechanical properties of acrylic matrix composite materials used for denture base applications. In this work, before the silanization of a woven glass fiber fabric (GF) with 3-(trimethoxysilyl) propyl methacrylate, activation pretreatments using HCl and NH4OH aqueous solutions have been performed. To characterize the glass surface, FTIR spectroscopy was used. Specimens of cured acrylic denture base resin and composites were divided into five groups: (1) cured acrylic denture base resin-control group; (2) composite with non-silanized GF; (3) composite with silanized GF; (4) composite with NH4OH activated and silanized GF; (5) composite with HCl activated and silanized GF. The flexural and impact properties of specimens were evaluated by means of three-point-bending tests and Charpy impact testing, respectively. The residual reactivity of the samples was analyzed using differential scanning calorimetry. The results of mechanical testing showed that acid and base pretreatments of the glass fabric had a positive effect on the flexural modulus of prepared composites but a negative effect on their impact strength. Possible interfacial adhesion mechanisms and the diffusion control of isothermal cure reactions due to vitrification have been discussed.

A Comparison of the Surface and Mechanical Properties of 3D Printable Denture-Base Resin Material and Conventional Polymethylmethacrylate (PMMA).

PURPOSE: To study the surface and mechanical properties of 3D printed denture-base resin materials and compare them with conventional heat-cured polymethylmethacrylate (PMMA). MATERIALS AND METHODS: Three brands of 3D printed denture-base resin materials and one conventional heat-cured PMMA were tested in this study: NextDent 3D printed resin, Dentona 3D printed resin, ASIGA 3D printed resin, and Meliodent conventional PMMA. Sixty specimens (25 × 25 × 3 mm) were fabricated (n=15 per group) to perform the following tests: wettability, surface roughness, and microhardness. One hundred twenty specimens (65 × 10 × 3 mm) were fabricated (n=30 per group) and stored in distilled water at (37 ±1°C) for 7 days. Specimens (N = 15) in each group were subjected to the three-point bending test and impact strength test, employing the Charpy configuration on un-notched specimens. The morphology of the fractured specimens was studied under scanning electron microscope (SEM). Statistical analysis was performed using one-way ANOVA and Tukey-pairwise multiple comparisons with 95% confidence interval. P-values of ≤0.05 were considered significant. RESULTS: The conventional heat-cured specimens demonstrated the highest means of surface roughness (0.23 ± 0.07 µm), Vickers hardness number (18.11 ±0.65) and flexural strength (92.44 ±7.91 MPa), and the lowest mean of contact angle (66.71° ±3.38°). ASIGA group showed the highest mean of contact angle (73.44° ±2.74°) and the lowest mean of surface roughness (0.19 ±0.03 µm). The highest mean of impact strength was recorded in the Dentona group (17.98 ±1.76 kg/m2 ). NextDent specimens showed the lowest means of Vickers hardness number (16.20 ±0.93), flexural strength (74.89 ±8.44 MPa), impact strength (15.20 ±0.69 kg/m2 ), and recorded the highest mean of bending modulus (2,115.80 ±178.95 MPa). CONCLUSIONS: 3D printed resin exhibited noticeable differences in surface and mechanical properties between different brands and with conventional heat-polymerized PMMA.