Novel Eudragit® -based polymeric nanoparticles for sustained release of simvastatin

This paper reports on the development of nanoparticles aiming at the in vitro controlled release of simvastatin (SVT). The nanoparticles were prepared by the nanoprecipitation method with polymers Eudragit® FS30D (EDGFS) or Eudragit® NE30D (EDGNE). EDGFS+SVT nanoparticles showed mean size of 148.8 nm and entrapment efficiency of 76.4%, whereas EDGNE+SVT nanoparticles showed mean size of 105.0 nm and entrapment efficiency of 103.2%. Infrared absorption spectra demonstrated that SVT incorporated into the polymer matrix, especially EDGNE. Similarly, the differential scanning calorimeter (DSC) curve presented no endothermic peak of fusion, indicating that the system is amorphous and the drug is not in the crystalline state. The maintenance of SVT in the amorphous state may favors its solubilization in the target release sites. In the in vitro dissolution assay, the SVT incorporated into the EDGFS+SVT nanoparticles showed a rapid initial release, which may be related to the pH of the dissolution medium used. Regarding the EDGNE+SVT nanoparticles, the in vitro release occurred in a bimodal behavior, i.e., an initial "burst" followed by a sustained delivery, with the kinetics of drug release following Baker-Lonsdale's mathematical model. All these features suggest the nanoparticulate system's potential to modulate SVT delivery and enhance its bioavailability.

Enzymatically Synthesized Ph-Responsive Ipn For In-Situ Release Of Pantoprazole Sodium

Objective: This study involves the synthesis of Gum tragacanth (gt) based interpenetrating polymer network (ipn) and its utilization for sustained release of anti-ulcerative drug i.e. pantoprazole sodium. Methods: IPN was synthesized from Gum tragacanth, polyacrylic acid (gt-cl-paa) hydrogel. gt-cl-paa was kept in distilled water. Further, acryamide (aam) and methylmethacrylate (mma) was added and then kept for overnight. Later on, lipase and glutaraldehyde were added. Homopolymers and the unreacted monomers were removed using acetone. Synthesized IPN was dried at 50 °C for further study. Synthesized ipn was swelled in water and the drug was added to it. The drug was entrapped in the pores of the synthesized ipn and then drug release behavior was studied using uv-vis spectrophotometer. Results: Gt, paa and mma based crosslinked IPN were synthesized using lipase-glutaraldehyde as initiator-crosslinker system. The synthesized IPN was pH sensitive and possessed the desired swelling capacity required for the controlled and systematic liberation of pantoprazole sodium at 37 °C. The kinetic of drug release was studied and found that lateral diffusion (DL) of drug was higher as compared to the initial diffusion (DI). The prepared IPN can be used as prospective carrier for prolonged drug delivery. Conclusion: A novel pH sensitive and colon targeted IPN was synthesized. It acts as an effective device for the controlled release of drug pantoprazole sodium.

Fabrication of Polymerase Chain Reaction Plastic Lab-on-a-Chip Device for Rapid Molecular Diagnoses / 대한배뇨장애요실금학회지

PURPOSE: We aim to fabricate a thermoplastic poly(methylmethacrylate) (PMMA) Lab-on-a-Chip device to perform continuous- flow polymerase chain reactions (PCRs) for rapid molecular detection of foodborne pathogen bacteria. METHODS: A miniaturized plastic device was fabricated by utilizing PMMA substrates mediated by poly(dimethylsiloxane) interfacial coating, enabling bonding under mild conditions, and thus avoiding the deformation or collapse of microchannels. Surface characterizations were carried out and bond strength was measured. The feasibility of the Lab-on-a-Chip device for performing on-chip PCR utilizing a lab-made, portable dual heater was evaluated. The results were compared with those obtained using a commercially available thermal cycler. RESULTS: A PMMA Lab-on-a-Chip device was designed and fabricated for conducting PCR using foodborne pathogens as sample targets. A robust bond was established between the PMMA substrates, which is essential for performing miniaturized PCR on plastic. The feasibility of on-chip PCR was evaluated using Escherichia coli O157:H7 and Cronobacter condimenti, two worldwide foodborne pathogens, and the target amplicons were successfully amplified within 25 minutes. CONCLUSIONS: In this study, we present a novel design of a low-cost and high-throughput thermoplastic PMMA Lab-on-a-Chip device for conducting microscale PCR, and we enable rapid molecular diagnoses of two important foodborne pathogens in minute resolution using this device. In this regard, the introduced highly portable system design has the potential to enable PCR investigations of many diseases quickly and accurately.

Degradação química e citotoxicidade in vitro de cimentos resinosos fotopolimerizáveis / Chemical degradation and in vitro cytotoxicity of light-cured resin cements

O objetivo deste estudo foi investigar o efeito degradante da saliva artificial e do ácido lático sobre diferentes cimentos resinosos fotopolimerizáveis e avaliar os efeitos citotóxicos dos extratos da degradação em saliva artificial sobre fibroblastos Balb/c 3T3 de ratos. Os cimentos Variolink II (base), AllCem Veneer e RelyX Veneer foram testados. Para caracterização microestrutural destes materiais, análise termogravimétrica (TGA), cálculo do grau de conversão (GC) e análise da distribuição granulométrica das partículas de carga, foram realizados. O GC foi calculado utilizando-se a espectroscopia infravermelha por transformada de Fourier (FTIR). Dez amostras de cada cimento foram construídas em matriz teflon (0,5 mm x 5 mm) e fotoativadas pelo diodo emissor de luz (LED) Elipar S10 (3M ESPE). Após obtenção dos espectros FTIR iniciais (24h após a fotopolimerização), 5 amostras de cada cimento foram, individualmente, imersas em 10 ml de saliva artificial (pH = 7,0) e outras 5 em 10 ml de solução de ácido lático (pH = 4,0), por 18 dias, a 37°C. Depois, as amostras foram submetidas a novas análises espectroscópicas FTIR, sob as mesmas condições iniciais, e posteriormente, seus espectros foram comparados qualitativamente aos obtidos antes do processo de degradação. A viabilidade celular de fibroblastos 3T3, frente aos possíveis efeitos citotóxicos dos resíduos dos cimentos livres na solução de saliva artificial após 18 dias de degradação, foi testada através da redução do brometo de dimetiltiazol-difeniltetrazólico (MTT). As culturas foram expostas aos extratos salivares por 24h e 72h. Células controle foram expostas à solução de saliva artificial pura. Dados foram submetidos a ANOVA e teste Tukey. Os resultados demonstraram maior conteúdo de partículas de carga significante ao cimento Variolink II (65,86%±0,17; p<0,05) quando comparado aos cimentos RelyX Veneer (62,29%±0,30) e AllCem Veneer (62,15%±37,84); distribuição granulométrica trimodal aos cimentos Variolink II (0,2 ­ 3,3µm) e RelyX Veneer (0,6 ­ 29µm), e monomodal ao AllCem Veneer (1 ­ 4,1µm); maior GC ao cimento AllCem Veneer (71,23%±5,53; p<0,05), enquanto RelyX Veneer (66,00%±6,84) e Variolink II (62,24%±2,45) não diferiram entre si (p=0,1306). A solução de ácido lático contribuiu para maiores alterações sobre o conteúdo inorgânico do cimento Variolink II, porém este material demonstrou maior degradação polimérica após imersão em saliva artificial. O cimento RelyX Veneer degradou tanto em saliva artificial quanto em ácido lático, não havendo diferenças em relação à solução degradante. O cimento AllCem Veneer não revelou degradação química após imersão em ambos os meios testados. Em 24h de exposição, os resíduos do cimento AllCem Veneer garantiram a maior viabilidade celular para fibroblastos 3T3 (90,0±6,3), enquanto os do cimento Variolink II a menor (7,43±0,17). Após 72h de exposição, todos os extratos salivares ofereceram citotoxicidades importantes aos fibroblastos. Concluiu-se que os cimentos resinosos avaliados são passíveis de sofrerem degradação em condições que simulam o ambiente oral. Existiu uma relação direta entre degradação química dos cimentos resinosos e efeitos citotóxicos in vitro a fibroblastos 3T3.

The aim of this study was to evaluate the degradation of different light-activated resin cements after aging in artificial saliva and lactic acid solutions, and the in vitro cytotoxicity of salivary extracts obtained from the resin cements degradation on mouse fibroblast (Balb/c 3T3). The resin cements Variolink II, AllCem Veneer and RelyX Veneer were tested. For microstructure characterization, TGA, degree of conversion (DC) and granulometric distribution of filler particles were employed. The DC was calculated from baseline FTIR spectra obtained from uncured and cured samples of each resin cement. These samples were development on teflon mold (0.5 mm x 5.0 mm) and photoactivated by a LED (Elipar S10; 3M ESPE). After baseline FTIR spectra obtaining, 5 samples of each cement were immersed in 10 ml of artificial saliva (pH = 7.0) and the others 5 samples were immersed in 10 ml of lactic acid solution (pH = 4.0), individually, for 18 days, at 37°C. Then, the samples were submitted to new FTIR analyzes, at the same anterior conditions, and their new spectra were compared with the baselines by qualitative FTIR method. The cell viability of 3T3 fibroblast was evaluated of MTT test. The cells were exposed to salivary extracts for 24 h and 72 h. Control cells were exposed to pure artificial saliva solution. The data were submitted to ANOVA and Tukey's test. The results revealed significant higher mass percentage of filler particles for Variolink II (65.86%±0.17; p<0.05) when compared with RelyX Veneer (62.29%±0.30) and AllCem Veneer (62.15%±37.84); trimodal granulometric distribution for Variolink II (0.2 ­ 3.3 µm) and RelyX Veneer (0.6 ­ 29.0 µm), and monomodal distribution for AllCem Veneer (1.0 ­ 4.1 µm); significant higher baseline DC for AllCem Veneer (71.23%; p<0,05), while RelyX Veneer (66.00%±6.84) and Variolink II (62.24%±2.45) were not different from each other (p=0.1306). The lactic acid solution contributed to higher changes of the inorganic matrix for Variolink II cement. However, this cement revealed more polymeric degradation after aging in artificial saliva when compared with lactic acid solution. RelyX Veneer had chemical degradation in both solutions. AllCem Veneer not showed any chemical degradation after aging in both solutions. Within 24 h of exposure, the chemical wastes of the AllCem Veneer cement guaranteed the higher cell viability to 3T3 fibroblasts (90.0±6.30) and there was no difference with the control group (80.3±8.70). The chemical wastes of the Variolink II cement guaranteed the smaller cell viability at the same time (7.43±0.17). After 72 h of exposure, all salivary extracts, except for control group, caused important cytotoxic effects to 3T3 fibroblasts. Then, the resin cements evaluated in this study can suffer chemical degradation under conditions that simulate the oral environment. There was a direct relationship between chemical degradation and in vitro cytotoxicity.

Assessment of Occupational Symptoms and Chemical Exposures for Nail Salon Technicians in Daegu City, Korea / 예방의학회지

OBJECTIVES: This study aimed to evaluate occupational symptoms and chemical exposures of nail salon technicians. METHODS: Work-related symptoms of nail salon technicians in Daegu City were surveyed using a researcher-administered questionnaire, and responses were compared to those of non-exposed office workers as controls. Personal exposure level of airborne volatile organic compounds was also monitored using passive samplers. RESULTS: A total of 159 subjects in 120 salons were interviewed. Average work-shift concentrations of 13 chemicals were measured for 50 workers from 30 salons using personal passive samplers. The most frequently reported respiratory or neurologic symptoms by nail shop technicians compared to controls were nose irritation (odds ratio [OR], 54.0; confidence interval [CI], 21.6 to 134.8), followed by headache (OR, 9.3; CI, 4.7 to 18), and throat irritation (OR, 4.3; CI, 2.2 to 8.5). For eyes and skin, 92% of respondents complained eye irritation (OR, 13.1; CI, 5.7 to 30.1). In musculoskeletal symptoms, workers reported pain or discomfort in shoulders (OR, 20.3; CI, 7.7 to 54) and neck (OR, 19.7; CI, 8.9 to 43.6). From personal measurements, the proportion of exceeding the Korean Occupational Exposure Limit was the highest for acetone with 64%, followed by toluene (50%), butyl acetate (46%), and methyl methacrylate (12%). However, the service was being provided without a proper ventilation system in most surveyed shops. CONCLUSIONS: Based on these findings, it is warranted to have appropriate local exhaust ventilation place to ensure adequate health protection of nail shop technicians as well as customers. At the same time, greater policy interests are warranted in nail care business to protect health of both workers and customers.

Esterilização de guias em resina acrílica por plasma de peróxido de hidrogênio: estudo dimensional linear / Hidrogen peroxide plasma sterilization of surgical acrylic stents: a linear dimensional study

Guias cirúrgicos confeccionados em resina acrílica são dispositivos importantes na transposição de planejamento cirúrgico no transoperatório. É obrigatório a todo dispositivo que entrará em contato direto com a ferida cirúrgica que esteja esterilizado para garantir padrões ideais de assepsia e antissepsia no campo operatório. Equipamentos que empregam o plasma de peróxido de hidrogênio para esterilização estão ganhando cada vez mais as centrais de esterilização dos hospitais. Propusemo-nos a verificar, preliminarmente, em um estudo in vitro, se corpos de prova em resina acrílica em formato similar a guias cirúrgicos odontológicos podem sofrer alteração dimensional linear após processo de esterilização por plasma de peróxido de hidrogênio. 45 corpos de prova foram confeccionados em resina acrílica em três espessuras: 1.5mm, 3.0mm e 5.0mm. Foram submetidos à esterilização por plasma de peróxido de hidrogênio por igual período de tempo e temperatura. Imagens dos corpos de prova antes e após o processo foram obtidas digitalmente e formatadas por meio de um programa de computador que permitiu analisar alterações lineares. Os resultados mostraram que apenas os dispositivos de 1.5mm não sofreram alterações lineares estatisticamente significativas. Nos dispositivos acrílicos mais espessos, as alterações foram mais significativas. Estudos tridimensionais são necessários para verificar se essas interferências podem ter importância clínica.

Resin surgical stent is an important device to transfer pre surgical planning to the operative moment of a dental implant or an orthognatic surgery. To guarantee asepsis and anti sepsis, it is undeniable that, this critical material has to be sterile once it will be directly in contact with surgical wound. Since the nineties, hydrogen peroxide plasma sterilization equipments have gaining hospital centers for sterilization of materials that are sensible to heat but literature is rare about testing the performance of those devices after that sterilization process. The aim of this preliminary in vitro study is to verify if acrylic specimens shaped as dental stents undergo linear dimensions changes after peroxide hydrogen plasma sterilization process. 45 acrylic specimens were made in three different thicknesses: 1.5mm, 3.0mm and 5.0 mm. Specimens underwent sterilization employing peroxide hydrogen plasma for equal time and temperature. Digital images were kept from the specimens before and after the sterilization process and were analyzed by digital software comparing three linear dimensions in each specimen. The results showed that only 1.5mm specimens did not underwent significant linear extent changes. Tridimensional studies are necessary to conclude that those interferences are clinically important.

Avaliação morfológica e por imagem radiográfica da matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato, preservados em glicerina para reparação de falhas ósseas em tíbias de coelhos / Morphological evaluation and radiographic image of fragmented heterolog mineralized bone matrix and methylmethacrylate preserved in glycerin to repair osseous defects in tibias of rabbits

Os traumas que resultam em fraturas ósseas, principalmente as cominutivas, têm uma importância muito grande na rotina clínico-cirúrgica veterinária e humana. Foi realizada falha segmentar de 6mm na região metafisária medial da tíbia esquerda de 12 coelhos, a qual foi preenchida com implante constituído de matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato, preservados em glicerina (98%) para a sua reconstrução. Foi realizada avaliação morfológica e radiológica aos 30, 60, 90 e 120 dias e observou-se a incorporação do implante ao leito receptor, em 100% dos casos, mostrando ser biologicamente compatível, pois promoveu a reparação das falhas ósseas, sem sinais de infecção, migração e/ou rejeição, sendo uma opção de substituto para preencher defeitos ósseos.

The traumas that result in bone fractures, especially comminuted, have high importance in veterinary and human surgical routine. A 6mm of segmental defect was performed at the medial metaphyseal region of the left tibia of 12 rabbits and an association of fragmented heterologue mineralized bone matrix and methylmethacrylate conserved in glycerin (98%) was used as a graft to fill the bone defect. To evaluate the procedure morphological and radiological exams were performed after 30, 60, 90 and 120 days. There was gradual integration of the bone graft in the receptor bed in 100% of the cases showing that the material is biologically compatible as it promotes bone defect reparation without signs of infection, migration and/or rejection and can be considered one more option to be used as a substitute to fill bone defects.

Manejo protésico-quirúrgico del paciente hemimandibulectomizado / Prosthetic and surgical treatment of patient previously subjected to hemi-mandibulectomy

Por lo general las mejores opciones de rehabilitación para el paciente hemimandibulectomizado quedan fuera del alcance del poder adquisitivo de la mayoría de ellos, esto hace que el abordaje reconstructivo protésico- quirúrgico para éstos se tenga que restringir al uso de materiales más accesibles tales como el clavo de Kirschner y las prótesis inmediatas de metilmetacrilato, siendo estas últimas las más recomendables por su bajo costo, fácil manejo, por evitar la rotación mandibular y por prevenir la atrofia de los tejidos blandos. Se reporta el caso clínico de un paciente masculino de 25 años de edad el cual ingreso al Servicio de Oncología del Hospital General de México debido a la presencia de un aumento de volumen en el área correspondiente al ángulo mandibular izquierdo, diagnosticándose microscópicamente como un tumor mixto maligno (diagnóstico histopatológico final). Se decidió hacer la hemimandibulectomía de la zona involucrada, con reconstrucción del segmento óseo perdido mediante la colocación de una prótesis inmediata implantada confeccionada con metilmetacrilato de metilo termocurable, la cual fue fijada con alambre para osteosínteis aproximadamente a 3 y 6 milímetros por arriba de la cortical inferior mandibular en ambos bordes de sección.

In general terms, the best rehabilitation options for patients previously subjected to hemi-mandibulectomy are far beyond their financial possibilities. For this reason surgical-prosthetic reconstructive approach is mainly restricted to the use of more affordable materials such as Kirschner wire and methyl-methacrylate immediate prostheses. The latter are widely recommended due to their low cost, ease of handling, and because they prevent soft tissue atrophy. A clinical case is reported in this article: 25 year old male patient seeking treatment at the Oncology Service of the Hospital General de Mexico (Mexico's General Hospital) due to the presence of a volume increase in the area of the left mandibular angle. Microscopic analysis revealed presence of mixed malign tumor ( final histopathological diagnosis). It was decided to perform hemi-mandibulectomy of involved area, with reconstruction of lost bone segment by means of positioning an immediate methyl methacrylate prosthesis (thermosetting methyl). The prosthesis was fixated with osteosynthesis wire at both resection margins, at 3 mm above the cortex.

Forehead Augmentation with a Methyl Methacrylate Onlay Implant Using an Injection-Molding Technique

BACKGROUND: The forehead, which occupies about one third of the face, is one of the major determinants of a feminine or masculine look. Various methods have been used for the augmentation of the forehead using autologous fat grafts or alloplastic materials. Methylmethacrylate (MMA) is the most appropriate material for augmentation of the forehead, and we have used an injection-molding technique with MMA to achieve satisfactory results. METHODS: Under local anesthesia with intravenous (IV) sedation, an incision was made on the scalp and a meticulous and delicate subperiosteal dissection was then performed. MMA monomers and polymers were mixed, the dough was injected into the space created, and manual molding was performed along with direct inspection. This surgery was indicated for patients who wanted to correct an unattractive appearance by forehead augmentation. Every patient in this study visited our clinics 3 months after surgery to evaluate the results. We judged the postoperative results in terms of re-operation rates caused by the dissatisfaction of the patients and complications. RESULTS: During a 13-year period, 516 patients underwent forehead augmentation with MMA. With the injection-molding technique, the inner surface of the MMA implant is positioned close to the underlying frontal bone, which minimizes the gap between the implant and bone. The borders of the implant should be tapered sufficiently until no longer palpable or visible. Only 28 patients (5.4%) underwent a re-operation due to an undesirable postoperative appearance. CONCLUSIONS: The injection-molding technique using MMA is a simple, safe, and ideal method for the augmentation of the forehead.

Fifteen-year Results of Precoated Femoral Stem in Primary Hybrid Total Hip Arthroplasty

BACKGROUND: There has been controversy whether methylmethacrylate precoating of the cemented femoral stem is a solution for aseptic loosening or rather contributes to increased failure rates in cemented total hip arthroplasties. METHODS: On a retrospective basis, we analyzed 76 primary hybrid total hip arthroplasties from 63 patients with precoated, cemented femoral stems between October 1990 and December 1995. The mean age of the patients was 46.8 years (range, 22 to 77 years) with a minimum follow-up of 14 years (mean, 15.5 years; range, 14 to 19.5 years). Third generation cementing techniques were employed in all cases. RESULTS: Twenty-four out of 76 cases (31.6%) showed aseptic loosening of the femoral stems, of which 23 stems were revised at an average revision time of 8 years (range, 3 to 14.8 years). The main mode of loosening was cement-stem interface failure in 22 hips (91.7%). Twenty-one out of 24 failed hips (87.5%) demonstrated C2 cementing grades (p < 0.001). Kaplan-Meier survivorship analysis using radiographic aseptic loosening of the femoral stem as the endpoint for failure showed survival rates of 76.5% at 10 years (95% confidence interval [CI], 71.4 to 81.6) and 63.2% at 19 years (95% CI, 57.3 to 69.1). CONCLUSIONS: An early failure of the precoated femoral stem in this study was mainly due to an insufficient cementing technique. Achievement of good cement mantle may improve the survival rates.

Easy Molding Technique of Methylmethacrylate Implant Using Plaster and Rapid Prototyping Model in Cranioplasty

PURPOSE: Methylmethacrylate is the most commonly used alloplastic material in cranioplasty. However during the polymerization of methylmethacrylate, a significant exothermic reaction takes place. This reaction may result in thermal injury to the brain tissue and other soft tissues. Also it is difficult to make three-dimensional methylmethacrylate implant that is perfectly matched to the defect during the operation time. We report on the molding technique of methylmethacrylate implant using plaster mold and the rapid prototyping model in cranioplasty. METHODS: A 44-year-old male was referred to the department for severe frontal hollowness. He was involved in an automobile accident resulting in large frontal bone defect with irregular margin. The preformed patient-specific methylmethacrylate implant was made using plaster mold and the rapid prototyping model before the operative day. The methylmethacrylate implant was placed in the frontal defect and rigidly fixed with miniplates and screws on the operative day. RESULTS: The operation was performed in an hour. In the 6 months follow-up period, there were no complications. Patient was satisfied with the results of cranioplasty. CONCLUSION: Safe cranioplasty was performed with the preformed patient-specific methylmethacrylate implant using plaster mold and the rapid prototyping model. The result of this method was satisfactory, aesthetically and functionally.

Effect of leaching residual methyl methacrylate concentrations on in vitro cytotoxicity of heat polymerized denture base acrylic resin processed with different polymerization cycles

OBJECTIVES: Residual methyl methacrylate (MMA) may leach from the acrylic resin denture bases and have adverse effects on the oral mucosa. This in vitro study evaluated and correlated the effect of the leaching residual MMA concentrations ([MMA]r) on in vitro cytotoxicity of L-929 fibroblasts. MATERIAL AND METHODS: A total of 144 heat-polymerized acrylic resin specimens were fabricated using 4 different polymerization cycles: (1) at 74ºC for 9 h, (2) at 74ºC for 9 h and terminal boiling (at 100ºC) for 30 min, (3) at 74ºC for 9 h and terminal boiling for 3 h, (4) at 74ºC for 30 min and terminal boiling for 30 min. Specimens were eluted in a complete cell culture medium at 37ºC for 1, 2, 5 and 7 days. [MMA]r in eluates was measured using high-performance liquid chromatography. In vitro cytotoxicity of eluates on L-929 fibroblasts was evaluated by means of cell proliferation using a tetrazolium salt XTT (sodium 3´-[1-phenyl-aminocarbonyl)-3,4-tetrazolium]bis(4-methoxy-6-nitro)benzenesulphonic acid) assay. Differences in [MMA]r of eluates and cell proliferation values between polymerization cycles were statistically analyzed by Kruskal-Wallis, Friedman and Dunn's multiple comparison tests. The correlation between [MMA]r of eluates and cell proliferation was analyzed by Pearson's correlation test (p<0.05). RESULTS: [MMA]r was significantly (p<0.001) higher in eluates of specimens polymerized with cycle without terminal boiling after elution of 1 and 2 days. Cell proliferation values for all cycles were significantly (p<0.01) lower in eluates of 1 day than those of 2 days. The correlation between [MMA]r and cell proliferation values was negative after all elution periods, showing significance (p<0.05) for elution of 1 and 2 days. MMA continued to leach from acrylic resin throughout 7 days and leaching concentrations markedly reduced after elution of 1 and 2 days. CONCLUSION: Due to reduction of leaching residual MMA concentrations, use of terminal boiling in the polymerization process for at least 30 min and water storage of the heat-polymerized denture bases for at least 1 to 2 days before denture delivery is clinically recommended for minimizing the residual MMA and possible cytotoxic effects.

Artroplastia glenoumeral: resistência do fio de poliéster após contato com o metilmetacrilato / Glenoumeral arthroplasty: polyester properties after methyl methacrylate contact

OBJETIVO: Os autores estudam as características do fio de poliéster (ethibond) após o contato com o metilmetacrilato (cimento ortopédico) no laboratório de resistência de materiais. MÉTODOS: Avaliam a força necessária para a ruptura bem como a elasticidade e a deformidade provocadas durante a tração no aparelho Instron 4482. Realizam análise estatística através do teste "t-student". RESULTADOS: Não encontram diferença estatisticamente significativa entre os grupos estudados. CONCLUSÃO: Concluem que o contato do metilmetacrilato com o poliéster não acarreta mudanças na suas propriedades elásticas e de resistência à tração.

OBJECTIVE: The authors studied the physical properties of polyester thread (ethibond) following methyl methacrylate contact in a biomechanics laboratory. METHODS: Strain at rupture, elasticity and traction deformity were evaluated using an Instron 4482 machine. The student-t test was used for the statistical analysis. RESULTS: There were no statistical differences between the two groups. CONCLUSION: It is concluded that methy metacrylate contact with polyester does not affect its elastic properties and traction resistance.

Residual monomer: effect on tensile bond strength of silicone resilient liners / Monômero residual: o efeito na resistência de união de reembasadores resilientes de silicone

Adhesion failure between silicone resilient liner materials and denture base resin is a common problem found in clinical practice. Bond failure results in localized unhygienic conditions at the debonded regions and causes functional failure of the prosthesis. The aim of this study was to evaluate the tensile bond strength of 2 resilient liners (auto-polymerized silicone - Permafix® and heat-polymerized silicone - Permaflex®) under the influence of a residual monomer methylmethacrylate ([MMA]R) concentration. Two polymethyl methacrylate (PMMA) specimens were prepared by implementing brass dies by means of a 3 mm thick spacer in a denture flask. Specimens (20 X 10 X 3 mm) were made by processing the resilient liners against the polymerized PMMA blocks. After polymerization, the brass spacer was removed from the mold, the PMMAblocks were trimmed, and the bonding surfaces were smoothed. The PMMA blocks were placed back into the molds and resilient liners were packed into the space provided by the brass spacer, followed by trial packing and polymerization according to manufacturer instructions. Twenty specimens...

Falha na união entre reembasadores resilientes de silicone e base acrílica da prótese é um problema encontrado na prática clínica. A falha na união resulta em condições anti-higiênicas localizadas em regiões que apresentam descolamento, além de causar perda de função das próteses. O objetivo deste trabalho foi avaliar a resistência de união de 2 reembasadores resilientes de silicone (autopolimerizável - Permafix® and termopolimerizável - Permaflex®) sob a influência da concentração do monômero residual metilmetacrilato ([MMA]R). Duas amostras de polimetilmetacrilato (PMMA) foram obtidas por meio da inclusão de matrizes metálicas separadas por um espaçador com 3mm de espessura em mufla. As amostras (20 X 10 X 3 mm) foram obtidas processando o material resiliente contra os blocos de PMMA polimerizados. Após a polimerização, removeu-se o espaçador, submeteram-se os blocos ao processo de acabamento, sendo as superfícies de união alisadas. Os blocos foram recolocados no molde e o material resiliente condensado no local...

Effect of Methylmethacrylate Monomer in Isolated Rat Tracheal Rings / 대한마취과학회지

BACKGROUND: Methylmethacrylate monomer (MN) bone cement is commonly employed in orthopedic procedures, particularly total hip and knee replacement, to anchor prosthetic devices to bone. Numerous cardiopulmonary complications can occur just after injection of MN. And MN produces direct relaxation of vascular smooth muscle in vitro. The purpose of this study was to determine if MN could have relaxation effect in tracheal smooth muscle too. METHODS: Each ring of rat trachea was suspended on wire supports in a bath with Tris Tyrode solution. Dose response curves of MN were recorded after contraction of tracheal ring with acethylcholine (Ach) 10(-5) M or cabachol (Cch) 10(-8) M. MN was administered in denuded tracheal rings and compared it's effect with intact tracheal rings to see the effect of epithelium for contraction. And MN dose response curves were recorded after pretreatment of nitric oxide synthase inactivator (L-NAME), muscarinic receptor blocker (atropine), beta-adrenaline receptor blocker (propranolol), adenylyl cyclase inhibitor (SQ22536) respectively. The effects of MN on cellular Ca2+ and K+ migration in rat tracheal preparations were studied. RESULTS: MN significantly inhibited acetylcholine or carbachol induced contractions of tracheal rings dose-dependently (P < 0.05). This relaxation effect of MN was not recovered in denuded tracheal rings. And pretreatment with L-NAME, propranolol, atropine, SQ22536 or tetraethylammonium respectively did not recover the relaxation effect of MN. MN inhibited both intracellular calcium release and extracelluar calcium influx. CONCLUSIONS: The relaxation effects of MN on rat tracheal rings are not related with epithelium, nitric oxide, muscarinic, or beta-adrenergic receptor. Methylmethacrylate monomer inhibits both intracellular calcium release and extracelluar calcium influx.

Rigid Fixation of Methylmethacrylate on Cranioplasty: Internal Screw-Locking Method

Methylmethacrylate has been proven to be successful in craniofacial alloplastic contouring surgery over several decades. Especially, for the patient with only forehead irregularity after the skull trauma, the alloplastic contouring surgery with methylmethacrylate onlay implant is the choice of treatment. The major advantage of methylmethacrylate is that it is completely malleable in the initial stages of hardening, thus permitting an optimal contouring. However, due to its incapability of direct bonding to the surrounding tissues and consequent lack of fixation, additional fixation technique is necessary. Several different methods have been established to prefabricate methylmethacrylate for cranioplasty, but they are complex; no one-stage procedure. In case of forehead irregularity we performed craniofacial contouring using methylmethacrylate and fixation with internal screw-locking method. Firm fixation, molding in situ, and easiness of manipulation are potential advantages over previously established methods.

Application of PMMA artificial eye in ophthalmosteresis / 中华医学美学美容杂志

Objective To evaluate the application of the polymethyl methacrylate (PMMA) artificial eye in acquired ophthalmostewesis. Methods We summarized the experience in the application of PMMA in prosthesis for 8 years. 1155 patients were involved in the artificial eye custom-made program. The artificial eye was individually prepared based on the patient's condition and characters of the healthy eye.Results PMMA artificial eye associated with hydroxyl apatite implantation gave good cosmetic results with good motility, and there was no rejective reaction. The artificial eye was almost same to the real one in color and transparency. Conclusion It is suggested that PMMA is one of the best materials for manufacture of artificial eye at present.

The Direct Myocardial Depressant Effect of Methylmethacrylate Monomer in vitro: Mechanical and Electrophysiological Actions / 대한마취과학회지

BACKGROUND: Methylmethacrylate monomer (MMA) bone cement has been associated with sudden systemic hypotension. The present study was aimed to explore the mechanism of direct myocardial depressant actions of MMA. METHODS: The isometric contraction of isolated guinea pig's right ventricular papillary muscle was measured. Normal and slow action potentials were evaluated by a conventional micro-electrode technique. The effects of MMA on sarcoplasmic reticulum (SR) function were evaluated by its effect on: rapid cooling contractures, rested state contraction of rat papillary muscle in normal Tyrode's solution and of guinea pig's papillary muscle in low Na+ Tyrode's solution. To measure the inward calcium currents (ICa), whole cell patch clamp techniques were applied. RESULTS: MMA caused a dose-dependent depression of the peak force (PF) and maximal rate of peak force (dF/dt-max). About a 30% depression of PF was shown at rested state (RS) contraction in rat myocardium and under low Na+ Tyrode's solution in guinea pig myocardium, respectively. In the 26 mM K+ Tyrode's solution, MMA caused dose-dependent depression of late force development without alteration in early force development. MMA depressed rapid cooling contracture accompanied by prolongation of time to peak contracture. MMA did not alter the amplitude or maximum depolarization rate of normal and slow action potentials. Action potential durations were significantly reduced. In patch clamp studies, MMA reduced ICa in a dose-dependent manner. CONCLUSIONS: MMA depressed cardiac contractility in a dose-dependent manner and may be partly related to the depression of Ca2+ influx through the cardiac membrane. SR Ca2+ release seems to be mildly inhibited by MMA. Based on common clinical concentrations, the direct myocardial depressant effect of MMA may not be a main cause of hypotension during an operation.

Cardiac Arrest During Hip Arthroplasty and Postoperative Delirium in the Elderly Patient: A case report / 대한마취과학회지

An Eighty-year-old female patient was transferred to the operating room for hip arthroplasty under the general anesthesia. Immediately after injection of two units of methylmethacrylate bone cement into the intramedullary canal, systolic blood pressure rapidly decreased and cardiac arrest occurred. The patient was turned to the supine position and was successfully resuscitated with intravenous administration of fluids, injection of epinephrine and external cardiac massage. In the intensive-care unit, she was treated for acute pulmonary edema. Three days later, postoperative delirium was developed. She spoke incoherently, was disoriented, and showed impairment of memory and attention. She was treated with haloperidol, lorazepam and sedative drug, five days later recovered. The patient was discharged to home without any sequelaes, but she died due to pneumonia two months later postoperatively at home.

Cardiac Arrest During Hip Arthroplasty and Postoperative Delirium in the Elderly Patient: A case report / 대한마취과학회지

An Eighty-year-old female patient was transferred to the operating room for hip arthroplasty under the general anesthesia. Immediately after injection of two units of methylmethacrylate bone cement into the intramedullary canal, systolic blood pressure rapidly decreased and cardiac arrest occurred. The patient was turned to the supine position and was successfully resuscitated with intravenous administration of fluids, injection of epinephrine and external cardiac massage. In the intensive-care unit, she was treated for acute pulmonary edema. Three days later, postoperative delirium was developed. She spoke incoherently, was disoriented, and showed impairment of memory and attention. She was treated with haloperidol, lorazepam and sedative drug, five days later recovered. The patient was discharged to home without any sequelaes, but she died due to pneumonia two months later postoperatively at home.