Clinical and histopathological study of a hollow and posteriorly multiperforated polymethylmethacrylate implant in eviscerated rabbit eyes / Análise clínica e histopatológica de um implante de polimetilmetacrilato oco e multiperfurado em sua porção posterior em olhos eviscerados de coelhos

ABSTRACT Purpose: The study aimed to evaluate the clinical and tissue response to a hollow polymethylmethacrylate orbital implant with a multiperforated posterior surface in an animal model after evisceration. Methods: Sixteen New Zealand rabbits had their right eye eviscerated. All animals received a hollow polymethylmethacrylate implant 12 mm in diameter that is multiperforated in its posterior hemisphere. The animals were divided into four groups, and each one had the eye exenterated at 7, 30, 90, and 180 days post-evisceration. Clinical signs were assessed daily for 14 days post-evisceration and then every 7 days until 180 days. Inflammatory pattern, collagen structure, and degree of neovascularization generated with implant placement were analyzed with hematoxylin-eosin, picrosirius red, and immunohistochemistry staining. Results: There were no signs of infection, conjunctival or scleral thinning, or implant exposure or extrusion in any animal during the study. On day 7, the new tissue migrated into the implant and formed a fibrovascular network through the posterior channels. Inflammatory response reduced over time, and no multinuclea­ted giant cells were found at any time. Conclusion: Hollow polymethylmethacrylate orbital implants with a multiperforated posterior surface enable rapid integration with orbital tissues by fibrovascular ingrowth. We believe that this orbital implant model can be used in research on humans.

RESUMO Objetivo: Avaliar a resposta tecidual e clínica a um implante orbitário de polimetilmetacrilato, oco e multiperfu­rado em sua porção posterior em modelo animal após evisceração. Métodos: Dezesseis coelhos da raça Nova Zelândia foram submetidos à evisceração do globo ocular direito. Todos receberam implante oco de polimetilmetacrilato de 12 mm de diâmetro, multiperfurado em sua semiesfera posterior. O estudo foi dividido em avaliação clínica e histopatológica. A avaliação clínica foi diária até 14 dias pós-evisceração e, a cada sete dias, até completar 180 dias. Os animais foram divididos em grupos de quatro animais e cada um foi submetido à exenteração com 07, 30, 90 e 180 dias e depois à eutanásia. A análise histopatológica teve por fim caracterizar o padrão inflamatório, a estrutura do colágeno e o grau de neovascularização. Para isso, além da tradicional coloração pela hematoxilina-eosina, utilizou-se o corante Picrosirius Red (PSR) e imuno-histoquímica com o marcador CD 34. Resultados: Não houve sinais de infecção, afinamento conjuntival ou escleral, exposição ou extrusão do implante em nenhum animal durante o estudo. Já no sétimo dia, o tecido neoformado migrou para dentro do implante formando uma rede fibrovascular através dos canais posteriores. A resposta inflamatória diminuiu ao longo do tempo avaliado e não foram encontradas células gigantes multinucleadas. Conclusão: O implante analisado permite a sua integração aos tecidos orbitários pelo crescimento fibrovascular em seu interior. Os autores acreditam que este modelo de implante orbital pode fazer parte de testes com humanos.

Integration of heterologous bone matrix associated with polymethylmethacrylate in induced tibial bone defects. An experimental study in rabbits

ABSTRACT Purpose To analyze and compare the reactions at the interface between the composite, composed of fragmented heterologous mineralized bone matrix (MOMHF) and polymethylmethacrylate (PMMA), and the rabbit's tibias, through macroscopic evaluation and scanning electron microscopy (SEM) in different periods. Methods In this study, 12 New Zealand adult rabbits were used (E1: n = 3, E2: n = 3, E3: n = 3 and E4: n = 3). They had the right tibial defects filled with composite and were evaluated immediately after surgery and at 30, 60, 90, and 120 days. Results The composites were incorporated and integrated into the recipient beds in 100% of the cases, defined by the MOMHF osseointegration and the PMMA fibrointegration, with no sign of infection, migration, or rejection. Conclusions The behavior of the composites in the recipient beds demonstrates that these biomaterials have the potential to be used in bone defect repairs, offering, thus, better quality of life to the orthopedic patient.

Analysis of the association of parameters in the formation of ultrafine fibers from PEI and PMMA / Análise da associação de parâmetros na formação de fibras ultrafinas de PEI e PMMA

Objective: The aim of the study was to fabricate and morphologically characterize ultrafine Polyetherimide fibers (PEI) associated with Polymethylmethacrylate (PMMA) ­ PP (group formed by the association of PEI with PMMA), produced by the electrospinning process. Material and Methods: A solution of PEI (0.562 g) + PMMA (0.377 g) dissolved in 2.5 mL of chloroform, 0.85 mL of Dimethylformamide (DMF) and 0.85 mL of 1.1.2.2 Tetrachloroethane (TCE) was prepared. For the electrospinning process, different continuous voltages (10 to 18 kV) and two different distances (8 and 12 cm) between the needle tip and the collecting apparatus were used, giving rise to 6 distinct groups of ultrafine fibers (PP 1 to 6) that were observed in Scanning Electron Microscopy to check for defects and calculate the average diameter of the fibers. Results: The best parameter, the parameter that was most effective for the production of fibers, observed was subjected to Energy Dispersion X-ray Spectroscopy (EDS), X-ray Diffraction (XRD) and Contact Angle Analysis tests. The data were analyzed using the ANOVA and Tukey test (p <0.05). From the comparative analysis of the pre-established parameters, the pattern of PP4 ultrafine fibers was shown to be more effective. Conclusion: The PP4 standard (13 kV ­ 12 cm) had an average diameter of 0.37 µm. An adequate parameter to electrospinning was able to produce ultrafine fibers of PMMA/PEI (AU)

Introdução: O objetivo do estudo foi sintetizar e caracterizar morfologicamente fibras ultrafinas de Polieterimida (PEI) associadas ao Polimetilmetacrilato (PMMA) - PP (grupo formado pela associação de PEI com PMMA), produzidas pelo processo de eletrofiação. Material e Métodos: Foi preparada uma solução de PEI (0,562 g) + PMMA (0,377 g) dissolvido em 2,5 mL de clorofórmio, 0,85 mL de Dimetilformamida (DMF) e 0,85 mL de 1.1.2.2 Tetracloroetano (TCE). Para o processo de eletrofiação, foram utilizadas diferentes tensões contínuas (10 a 18 kV) e duas distâncias diferentes (8 e 12 cm) entre a ponta da agulha e o aparelho coletor, dando origem a 6 grupos distintos de fibras ultrafinas (PP 1 a 6) que foram observados em Microscopia Eletrônica de Varredura para verificar defeitos e calcular o diâmetro médio das fibras. Resultados: O melhor parâmetro, o parâmetro mais eficaz para a produção de fibras, observado foi submetido aos testes de Espectroscopia de Dispersão de Energia (EDS), Difração de Raios X (DRX) e Análise do Ângulo de Contato. Os dados foram analisados pela ANOVA e teste de Tukey (p <0,05). A partir da análise comparativa dos parâmetros pré-estabelecidos, o padrão das fibras ultrafinas PP4 mostrou-se mais eficaz. Conclusão: O padrão PP4 (13 kV - 12 cm) apresentou diâmetro médio de 0,37 µm. Um parâmetro adequado para eletrofiação foi capaz de produzir fibras ultrafinas de PMMA / PEI. (AU)

Síndrome da embolia gordurosa secundária ao uso de polimetilmetacrilato na bioplastia: uma revisão sistemática / Fat embolism syndrome secondary to the use of polymethylmethacrylate in bioplasty: a systematic review

A síndrome da embolia gordurosa (SEG) é definida como a presença de êmbolos gordurosos, não apenas no sistema pulmonar, como também na circulação sistêmica, com manifestações inflamatórias, neurológicas e cutâneas. Na cirurgia estética, atualmente, o material polimetilmetacrilato (PMMA) apresenta indicação para técnicas de preenchimento cutâneo, utilizado na forma injetável em pequenos procedimentos estéticos não incisionais, conhecidos como bioplastia. O presente estudo teve como objetivo fazer uma revisão sistemática de literatura para mostrar estudos clínicos que abordassem a ocorrência de síndrome da embolia gordurosa em pacientes que se submeteram a infiltração de PMMA (polimetilmetacrilato) na bioplastia. Mesmo com esgotamento de fontes e ampliação da pesquisa sistemática que seguiu os preceitos do protocolo PRISMA, a resposta foi de apenas um artigo que foi adicionado ao presente estudo. Infelizmente não há revisões ou estudos experimentais que contemplem a SEG na infiltração com PMMA. A maioria dos relatos disponibilizados é proveniente de lipoaspiração e correlacionados ao trauma ósseo quando citado o uso de PMMA. Esta revisão serve de alerta para os estudos e relatos não científicos sobre os riscos da utilização de PMMA na bioplastia, mas não se obteve relatos ou relacionados com a embolia gordurosa, potencialmente fatal.

Fat embolism syndrome (FES) is defined as the presence of fatty emboli, not only in the pulmonary system, but also in the systemic circulation, with inflammatory, neurological and cutaneous manifestations. Currently, in cosmetic surgery, the polymethylmethacrylate (PMMA) material is indicated for skin filling techniques used in injectable form in small non-incisional aesthetic procedures, known as bioplasty. The objective of this study was to carry out a systematic review of the literature to show clinical studies that addressed the appearance of fat embolism syndrome in patients who underwent PMMA (polymethylmethacrylate) infiltration in bioplasty. Even with the exhaustion of sources and the expansion of systematic research that followed the precepts of the PRISMA protocol, the answer was only one article that was added to the present study. Unfortunately, no reviews or experimental studies are looking at FES in PMMA infiltration. Most of the available reports are about liposuction and correlate with bone trauma when PMMA use is mentioned. This review serves as a wake-up call for nonscientific studies and reports on the risks of using PMMA in bioplasty, but no reports or articles were obtained related to life-threatening fat embolism.

Effect of Addition of Graphene and Carbon Nanotubes on Flexural Strength of Polymethylmethacrylate- A Comparative In-Vitro Study.

Heat polymerized denture base resins are a popular choice in prosthodontics for fabrication of partial or complete dentures, cranioplasts, hybrid implant prosthesis, and maxillofacial prosthetics. The wide utility of these materials can be attributed to their favourable mechanical properties. Despite the popularity gained by them, clinicians often encounter suboptimal flexural strength resulting in frequent fracture of the fabricated prosthesis. The purpose of this study was to compare the flexural strength (FS) of Polymethylmethacrylate (PMMA) modified using micro-additions of Multi-Walled Carbon Nanotubes (MWCNT) and Graphene Oxide (GO) as fillers respectively with PMMA having no micro-additions.METHODSThis is an in-vitro comparative study. Sixty samples of PMMA were divided in three groups of 20 each containing: Group 1: no micro additions (control group), Group 2: 0.5 wt% MWCNT in monomer of PMMA resin, Group 3: 0.5 wt% GO in monomer of PMMA resin. MWCNT and Graphene oxide were dispersed in Methylmethacrylate (monomer) respectively by ultrasonic agitation. Monomer and polymer were mixed in the ratio of 1:3. The samples were heat polymerised. Finished samples were subjected to 3-point bending test for checking their flexural strength. The results were statistically compared using one-way ANOVA followed by post hoc Bonferroni corrected paired T test for inter-group comparisons.RESULTSThe highest mean Flexural Strength of 36.5 MPa was recorded in Group 2 (MWCNT) followed by 31.55 MPa in Group 1 (control) and the least 29.72 MPa in Group 3 (Graphene Oxide) respectively. Intergroup comparisons revealed significant difference between Group 1 (control) & Group 2 (MWCNT) with “p=0.011” and between Group 2 (MWCNT) & Group 3 (Graphene Oxide) with “p<0.001”. However, no significant difference was found between Group 1 (control) and Group 3 (Graphene Oxide) with “p= 0.803”.CONCLUSIONSThe addition of 0.5 wt% MWCNT to PMMA is an easy, effective and economical step towards increasing the flexural strength and thus, decreasing the incidence of prosthesis fracture, when compared to 0.5 wt% graphene oxide or no micro additions.

Presencia de Bacilos Gram-negativos y Candida albicans en provisionales de polimetilmetacrilato (PMM)en pacientes de Clínica Integrada de la Universidad Autónoma de Asunción / Presence of Gram-negative bacilli and Candida albicans in provisional polymethylmethacrylate in patients of the Integrated Clinic of the Autonomous University of Asunción

Las resinas a base de polimetilmetacrilato (PMM) son una solución para la reposición de estructuras dentarias. Este material ha sido muy utilizado debido a su buena estética, pero las rugosidades, grietas y defectos de este material son propicios para la proliferación de microrganismos que podrían constituir un riesgo para la salud de los pacientes. Estudio observacional descriptivo de corte transversal, donde se tomaron muestras de provisorios de PMM de 20 pacientes de la cátedra de Clínica Integrada de Odontología de la Universidad Autónoma de Asunción. Los datos sobre el crecimiento de los microorganismos fueron anotados en planillas Excel para análisis estadísticos. De los 20 pacientes que participaron en esta investigación, 50% fueron de sexo femenino y 50% masculino, el promedio de edad fue de 32,35 años (DE±11,94). Se analizaron un total de 7 pónticos (6 pónticos de 3 piezas y 1 de 6 piezas) y 19 coronas unitarias, el tiempo de permanencia en boca fue de entre 4 a 20 semanas con una media de 8,6 semanas. El 65% de las muestras dio positivo al cultivo microbiológico. En algunas muestras se aislaron más de un género de microorganismos. Se aislaron 5 especies de bacterias Gram-negativas, la más frecuente fue K. pneumoniae con un 40%. Se aisló C. albicans en un 10% de las muestras. En el proceso de elección de los materiales para rehabilitación es fundamental considerar la situación global de cada paciente, pues exponerlos a un material con grandes capacidades retentivas de microrganismos conlleva un peligro

Polymethylmethacrylate (PMM) based resins are a solution for the replacement of dental structures. This material has been widely used due to its good aesthetics, but the roughness, cracks and defects of this material are propitious for the proliferation of microorganisms that could constitute a risk to the health of patients. This was a descriptive cross-sectional observational study, where samples of PMM provisionals were taken from 20 patients of the Department of Integrated Dental Clinic of the Autonomous University of Asunción. Data on the growth of microorganisms were recorded in Excel spreadsheets for statistical analysis. Of the 20 patients who participated in this research, 50% was female and 50% male, and the average age was 32.35 years (SD±11.94). Seven pontics (6 pontics of 3 pieces and 1 of 6 pieces) and 19 unit crowns were analyzed, the time spent in the mouth was between 4 to 20 weeks with an average of 8.6 weeks. Sixty-five percent of the samples tested positive in the microbiological culture. In some samples, more than one genus of microorganisms was isolated. Five species of Gram-negative bacteria were isolated, the most frequent was Klebsiella pneumoniae with 40%. Candida albicans was isolated in 10% of the samples. In the process of choosing materials for rehabilitation, it is essential to consider the overall situation of each patient, since exposing them to a material with high retention capacities of microorganisms carries a danger

Transpedicular Percutaneous Vertebroplasty in Management of Osteoporotic Vertebral Compression Fractures Assessment of Clinical Outcome: A Study of 21 Procedures

Introduction: Osteoporotic vertebral fractures that produce increased morbidity, persistent back pain, risk of collapse with time, and increased fracture risk. Subsequently, these vertebral fractures produce kyphotic deformity and effect on lung capacity. In our study purpose is to assess the clinical outcome, safety, and efficacy of transpedicular percutaneous vertebroplasty in osteoporotic vertebral compression fractures (VCFs). Methodology: The study done between December 2017 and December 2019 at our institute. Atotal of 10 patients with 21 vertebral body collapse in that 13 dorsal vertebra and 8 lumbar vertebral body included in the study in neurologically intact individuals. Patients are considered for treatment, those with chronic pain refractory to medical therapy and bracing and those with severe disabling pain caused by fractures. Severe cardiopulmonary disease, coagulopathy, and cord compression are contraindications to vertebroplasty. Severe vertebral compression may also be a contraindication to treatment, because the vertebra may be compressed to such a degree that needle placement and cement injection become impossible. After treatment, they selected one of three possible responses for each: Significantly improved, worse, or approximately the same. As an overall assessment analgesic requirement, visual analog scale, grading of subjective satisfaction score, sleep, and ambulation improvement assessed. To ensure uniformity despite the variable follow-up period, patients were instructed to indicate their status at 2 weeks after the procedure, 6 months, and 1-year follow-up. Results: Both pain and functional outcome improved significantly in immediate post-procedure at 2 weeks, 6 months, and 1 year. The majority (70%) of the patients were treated for 2 levels while 2 patients were treated for 3 levels and 1 patient was treated for 1 level. Visual analog scale (VAS) in the pre-procedure period is 8.3 which decrease in the post-procedure period at 2 weeks and 6 months is 2.6 and 3.6 subsequently and at 1-year average VAS score is 4. Mobility and sleep pattern is significantly improved in 8 patients (80%) at 1-year follow-up whereas remain same in 2 patients. Conclusion: Significant relief in pain in the post-procedure period with minimum risk noticed for VCFs.

Photodynamic antimicrobial chemotherapy for repairing a rabbit model of osteomyelitis / 中国组织工程研究

BACKGROUND: Photodynamic antimicrobial chemotherapy holds broad-spectrum antibacterial ability, fast onset of action and non-resistance, which has been extensively applied in the treatment of superficial localized infection. OBJECTIVE: To explore the efficacy of photodynamic antimicrobial chemotherapy for treating osteomyelitis. METHODS: Thirty-six New Zealand white rabbits (provided by Laboratory Animal Center of Academy of Military Medical Sciences) were selected, and a left tibia osteomyelitis model was established. At 28 days after modeling, rabbit models were randomly divided into three groups: Blank group (tibia debridement only), control group (vancomycin/polymethylmethacrylate bone cement was filled into the intramedullary cavity of the infectious tibia after debridement), and experimental group (intramedullary treatment of photodynamic antimicrobial chemotherapy after debridement). The gross observation, imaging examination and bacterial culture were performed at 4, 8, and 12 weeks after surgery. The study was approved by the Ethical Committee of Affiliated Hospital of Logistics College of CAPF, with the approval No. (2015)-0002. RESULTS AND CONCLUSION: (1) Appearance of the skin: Purulent secretion was observed in the blank group, but disappeared in the control and experimental groups where the skin healed well. (2) X-ray examination: With time going, the osteomyelitis aggravated in the blank group. The bone destruction was reduced gradually in the control and experimental groups, and the bone defects healed gradually. There was no significant difference between control and experimental groups at different time points after surgery. (3) Bacterial culture: With time increasing, the bacterial positive rate showed no significant change in the blank group. The bacterial positive rate in the control and experimental groups was on a decline, which showed no significant difference between control and experimental groups at different time points after surgery (P > 0.05). (4) These results indicate that photodynamic antimicrobial chemotherapy is a new treatment for osteomyelitis to effectively control infection, providing experimental basis in clinical practice.

Effects of changes in surface morphology of bone cement spacer on the expression of bone growth factor in induced membrane / 中国组织工程研究

BACKGROUND: At present, scholars at home and abroad try to promote the growth of bone graft by changing the types and morphology of implant materials, and improving the thickness and smoothness of induced membrane. OBJECTIVE; To compare the degree of vascularization and the expression of some osteogenic factors in the polymethylmethacrylate bone cement membrane with different surface roughness degrees at different femoral bone defects in rats. METHODS: Forty-eight male Sprague-Dawley rats (purchased from the Experimental Animal Center of Guangzhou University of Chinese Medicine) were used to establish rat models of critical-size femur defect. These rat modes were then randomly divided into groups A, B, C and D. Polymethylmethacrylate bone cement occupiers with surface roughness 0.05). Immunohistochemical staining revealed that the positive expression of bone morphogenetic protein 2, transforming growth factor (31 and vascular endothelial growth factor protein was similar among four groups (P>0.05). These findings suggest that the change of surface roughness of bone cement has no significant effect on the histomorphological structure of induced membrane and the expression of bone morphogenetic protein 2, transforming growth factor pi and vascular endothelial growth factor in induced membrane at 6 weeks after implantation of bone cement spacer.

Comparisons of induced membrane vascularization and osteogenic factor expression in different tissue sites / 中国组织工程研究

BACKGROUND: Studies have found that polymethylmethacrylate bone cement implanted in the subcutaneous region, muscle and other parts can form induced membrane. The induced membrane favors vascularization and secretes multiple osteogenic factors. OBJECTIVE: To investigate the differences in the level of vascularization and the expression of osteogenic factors in the induced membrane among subcutaneous region, muscle and femoral bone defects. METHODS: Thirty-six male SD rats (purchased from the Experimental Animal Center of Guangzhou University of Chinese Medicine) were randomly divided into three groups (n=12/group). Polymethylmethacrylate antibiotic cement spacers were implanted in the subcutaneous tissue, muscle and femoral bone defects of the hind limbs. At 6 weeks after implantation, the induced membrane around the bone cement was removed. The change in membrane morphology was observed by hematoxylin-eosin staining. Expression of bone morphogenetic protein-2, transforming growth factor-31 and vascular endothelial growth factor in the induced membrane was detected by western blot, RT-qPCR and immunohistochemistry. This study was approved by Animal Ethics Committee, Guangzhou University of Chinese Medicine, China (approval No. 20181101006). RESULTS AND CONCLUSION: Hematoxylin-eosin staining showed that induced membrane formed in each group. The number of vessels in the outer layer of the membrane tissue section was higher in the femoral bone defect groups than that in the muscle and subcutaneous tissue group. The number of fibroblasts and myofibroblasts in the inner layer close to the bone cement was higher in the femoral bone defect group than in the muscle and subcutaneous tissue groups. Immunohistochemical staining revealed that bone morphogenetic protein-2, transforming growth factor-31 and vascular endothelial growth factor expression levels were highest in the femoral bone defect group and lowest in the subcutaneous tissue group. Western blot and RT-qPCR showed that bone morphogenetic protein 2, transforming growth factor 31 and vascular endothelial growth factor expression levels were significantly higher in the femoral bone defect group than in the muscle and subcutaneous tissue groups (P < 0.001). These findings suggest that different surrounding tissue conditions have different important influences on tissue structure and osteogenic factor expression in the induced membrane. Polymethylmethacrylate bone cement implanted in the femoral bone defects can improve the quality of induced membrane formation, lead to a larger amount of newly formed vessels and higher osteogenic factor expression in the induced membrane.

Craneoplastía con implante de polimetilmetacrilato (PMMA)para corregir secuela de trauma. Reporte de caso / Craneoplasty with a polymethylmethacrylate (PMMA) Implant to correct trauma sequel. A case report

Introducción: los defectos del cráneo y las anomalías del hueso craneofacial que requie-ren reconstrucción son comunes en una variedad de procedimientos neuroquirúrgicos. Después de una craniectomía o de fracturas craneofaciales posteriores a traumatismos cráneoencefálicos, los pacientes pueden desarrollar defectos cosméticos importantes. Algunos de estos son la depresión de la piel y un defecto de hundimiento que lleva a una apariencia asimétrica de la cabeza, sin dejar de lado las repercusiones físicas, neu-rológicas y psicológicas que estas lesiones conllevan. La reconstrucción craneofacial y la craneoplastía tienen una larga historia, pero las nuevas técnicas quirúrgicas y una multitud de opciones de materiales han impulsado recientemente el avance en esta área. Los implantes de polimetilmetacrilato (PMMA) han demostrado ser estables, bio-compatibles, no conductores, radiotransparentes y de bajo costo. Es así que se pueden colocar y modificar fácilmente, con lo que se elimina la morbilidad del sitio donante. Presentación del caso: en este artículo presentamos un caso de craneoplastía de defec-to frontal, posterior a traumatismo, cuya reconstrucción fue realizada mediante una prótesis de polimetilmetacrilato (PMMA) en el Hospital General Xoco de la Cuidad de México. Conclusión: se reporta la reducción del tiempo quirúrgico, además de un costo de la prótesis accesible para el paciente; de esta manera, se obtuvieron resultados sa-tisfactorios y mejoras en el contorno estético facial, en tanto se permitió cobertura y protección para el tejido encefálico.

Introduction: Skull defects and craniofacial bone abnormalities that require reconstruction are common in a variety of neurosurgical procedures. After craniectomy or craniofacial fractures following cranioencephalic trauma, patients can develop important cosmetic defects, such as depression of the skin and a sunken flap that can lead to an asymmetrical appearance of the head, without neglecting the physical and psychological repercussions. neurological that these injuries carry. Craniofacial reconstruction and cranioplasty have a long history, but new surgical techniques and a multitude of material options have recently fueled progress in this area. Polymethylmethacrylate (PMMA) implants have proven to be stable, biocompatible, non-conductive, radiolucent, and inexpensive. They can be easily placed and modified and the morbidity of the donor site is eliminated. Clinical case: In this article, we present a case of frontal defect cranioplasty after trauma performed using a polymethylmethacrylate (PMMA) prosthesis at the General Hospital Xoco in Mexico City. Conslusion: The surgical time could be reduced, in addition to the cost of the prosthesis. It was accessible to the patient and obtained satisfactory results such as improvements in the facial aesthetic contour and obtained coverage and protection for the brain tissue.

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.

Hydroalcoholic Extract of Eugenia uniflora as Denture Disinfectant: Antimicrobial Activity and Effect on the Physical Properties of Polymethylmethacrylate

Abstract To the moment, there is no ideal substance for home-based denture disinfection. This study assessed in vitro the antimicrobial effect of the hydroalcoholic extract of Eugenia uniflora and the effect on the physical properties of denture polymethylmethacrylate (PMMA). Candida albicans, Staphylococcus aureus, and Klebsiella oxytoca were isolated from samples of saliva collected from denture wearers. The extracts were produced in three concentrations, according to the Brazilian Pharmacopeia. One hundred eighty-eight disc-shaped specimens of thermopolymerizable PMMA were prepared and randomly allocated to five treatment groups: sterile saline solution (0.85%; control); chlorhexidine digluconate (0.2%); and hydroalcoholic extract of E. uniflora (0.2%, 0.8%, and 1.16%). The specimens were disinfected for 8 hours/day for 30 days. Adherence of microorganisms to the surface, PMMA surface roughness, and color stability were assessed. Inferential statistics were performed with one- and two-way ANOVA/Tukey test, and Kruskal Wallis, Mann-Whitney U, and paired t-tests, at α=0.05. The extract of E. uniflora at 0.2% and 1.16% reduced the microbial load of K. oxytoca, while chlorhexidine digluconate significantly reduced microbial load of all microrganisms. Microbial adherence at day 10 was reduced by all experimental substances (p<0.001). Surface roughness was not affected by the disinfecting substances (p>0.05). Nevertheless, all experimental groups produced unacceptable color change at the end of the disinfection protocol (p<0.001). The non-adherent potential against microorganisms isolated from the oral cavity confirm the potential of use of the hydroalcoholic extract of E. uniflora as a denture disinfectant. Yet, unacceptable color changes may occur, regardless of extract concentration.

Biomechanical Test after Hip Cannulated Screw Removal (in vitro Analysis) / Ensaio biomecânico após retirada de parafusos canulados do fêmur proximal (análise in vitro)

Abstract Objective This study aims to evaluate, through biomechanical tests, the resistance and energy required for proximal femoral fracture in synthetic bones after removing cannulated screws shaped as an inverted triangle, comparing the obtained results to those of a reinforcement technique with polymethylmethacrylate (PMMA) as bone cement. Methods Twenty synthetic bones were used: 10 units for the control group (CG), 5 units for the test group without reinforcement (TGW/O), and 5 units for the test group using a reinforcement technique with PMMA (TGW). The biomechanical analysis simulated a fall on the large trochanter using a servo-hydraulic machine. Results All TGW/O and CG specimens had a basicervical fracture. Three TGW specimens presented a basicervical fracture, and two suffered a fracture near the fixation point of the device (femoral diaphyseal region), with one of thembeing associated with a femoral neck fracture. A mean PMMA volume of 8.2 mL was used to fill the 3 screw holes in the TGWgroup. According to the one-way analysis of variance (ANOVA) and the Tukey multiple comparisons tests at a 5% level, the TGW presented a statistically significant difference when compared with the other groups in all parameters: maximal load (p = 0.001) and energy until fracture (p = 0.0001). Conclusion The simple removal of the cannulated screws did not reduce significantly the maximum load and energy for fracture occurrence, but the proximal femoral reinforcement with PMMA significantly increased these parameters, modifying the fracture pattern.

Resumo Objetivo Avaliar, pormeio de ensaio biomecânico, a resistência e a energia necessária para ocorrência de fratura do fêmur proximal em osso sintético após retirada de parafusos canulados em forma de triângulo invertido e comparar os resultados obtidos com técnica de reforço utilizando polimetilmetacrilato (PMMA). Métodos Foramutilizados 20 ossos sintéticos: 10 unidades para o grupo controle; 5 o grupo teste sem reforço, sem preenchimento após a retirada dos parafusos canulados, e 5 o para grupo teste com reforço com PMMA. A análise biomecânica foi realizada simulando queda sobre o grande trocânter utilizando máquina servo-hidráulica. Resultados Todos os corpos de prova dos grupos controle e sem cimento apresentaram fratura baso-cervical. No grupo teste com preechimento, três corpos de prova apresentaram fratura baso-cervical, enquanto que dois deles apresentaram fratura na parte próxima ao ponto de fixação no dispositivo (região diafisária do fêmur), sendo um deles associado a fratura do colo femoral. Foi utilizada uma média de 8.2 ml de polimetilmetacrilato no preenchimento dos três pertuitos do grupo com preenchimento. Segundo a análise de variância (ANOVA, na sigla em inglês) para um fator e o teste de comparações múltiplas de Tukey, ao nível de 5%, o grupo com cimento apresentou diferença significativa em relação aos outros grupos em todos os parâmetros. Conclusão A simples retirada dos parafusos canulados não apresentou redução significativa da carga máxima e da energia necessárias para a ocorrência de fratura; porém, o reforço do fêmur proximal com polimetilmetacrilato aumentou significativamente esses parâmetros, causando mudanças no padrão fraturário.

Mechanical Characteristics of (TiO2-ZnO)/PMMA Nanocomposites for Dentures

Mechanical properties (impact strength, compressive strength and flexural strength) have been studied for (Polymethyl-methacrylate (PMMA)) polymer reinforced with nano (TiO2+ZnO) (0 v%, 1 v%, 2 v%, 3 v%, 4 v% and 5 v%). Ultrasonic dispersion technique was used to prepare the nanocomposites samples, follow with cold casting technique using Teflon molds standard conditions. Charpy impact instrument was used to measure the impact strength, the compressive strength of each sample which was tested in newton units using digital compression tester (TinusOlsen: H50KT, England), while flexural strength can be found from mathematical formulas which depend on the impact strength, compressive strength and flexural strength. Results show that values increase in 1 v%, then decrease alternately by (2 v%, 3 v%, 4 v%, and 5 v%), while 0 v% is the less value of volume fraction of fillers. Young modules values increase alternately by the volume fraction of fillers until 2 v%, while if it is higher and lower than 2 v% it decreases the modulus of elasticity.

Complicação grave do uso irregular do PMMA: relato de caso e a situação brasileira atual / Severe complication due to inappropriate use of polymethylmethacrylate: a case report and current status in Brazil

Introdução: Os preenchedores permanentes, apesar de resultados duradouros, são verdadeiros problemas quando causam complicações. No Brasil, o PMMA é um produto aprovado pela Anvisa, mas seu uso extrapola suas indicações, levando a complicações graves. Há mais de uma década, existem recomendações sobre sua restrição, mas casos com consequências graves do seu uso irresponsável são atuais. Objetivo: Relatar complicação grave do uso irregular do PMMA e discutir a realidade brasileira atual baseado em determinações das entidades médicas, assim como dos órgãos reguladores. Métodos: É relatado um caso de necrose extensa da região glútea após a injeção de PMMA por profissional não qualificado e discutida a situação brasileira atual do produto com base nas entidades médicas e revisão da literatura do Brasil. Discussão: Apesar do esforço das entidades médicas, são inúmeros os casos de complicações agudas e crônicas relatados na literatura brasileira. No ano de 2016, foram registradas mais de 17 mil complicações relacionadas ao PMMA, mesmo assim, é difícil estabelecer dados epidemiológicos confiáveis, pois não há controle do número de aplicações, da qualidade do produto utilizado e da capacitação dos profissionais que o utilizam. Conclusão: No Brasil, há um número expressivo de procedimentos reparadores para correção de complicações decorrentes do uso do PMMA. A gravidade do caso relatado traz à tona a necessidade de combate à má prática por profissionais não capacitados, assim como um controle mais rigoroso da comercialização do produto por entidades reguladoras.(AU)

Introduction: Use of permanent fillers can lead to significant complications. In Brazil, polymethylmethacrylate (PMMA) is a product approved by the Agência Nacional de Vigilância Sanitária (ANVISA), but its use exceeds its indications, leading to serious complications. Recommendations for restricted use have been in place for more than a decade, but cases with serious consequences due to inappropriate use are still seen. Objective: To report a serious complication due to inappropriate use of PMMA and discuss the current status of PMMA use in Brazil based on recommendations of medical societies and regulatory agencies. Methods: This report describes a case of extensive necrosis of the gluteal region after injection of PMMA by a non-qualified practitioner; the report also reviews the literature on the current status of PMMA use in Brazil. Discussion: Despite the efforts of medical societies, acute and chronic complications are still reported in the Brazilian literature. In 2016, more than 17,000 PMMArelated complications were reported; nevertheless, reliable epidemiological data remain unavailable because the number of treatments, the quality of the product, and the training of practitioners remain unregulated. Conclusion: A significant number of repair procedures are performed in Brazil to correct complications resulting from the use of PMMA. The severity of the reported case highlights the need to combat bad practice by untrained professionals, as well as the need for greater control of PMMA marketing by regulatory agencies.(AU)

Color alterations of a PMMA resin for fixed interim prostheses reinforced with silica nanoparticles

PURPOSE: The aim of the present study was to evaluate the color changes of an autopolymerizing PMMA resin used for interim fixed restorations, reinforced with SiO2 nanoparticles. MATERIALS AND METHODS: Silica nanoparticles were blended with the PMMA resin powder through high-energy ball milling. Four shades of PMMA resin were used (A3, B3, C3, D3) and total color differences were calculated through the equations ΔEab= [(ΔL*)2 + (Δa*)2 + (Δb*)2]½ and Δ E 00 = [ Δ L ′ K L S L 2 + Δ C ′ K C S C 2 + Δ H ′ K H S H 2 + R T Δ C ′ K C S C Δ H ′ K H S H ] 1 / 2 . Statistically significant differences between ΔEab and the clinically acceptable values of 3.3 and 2.7 and those between ΔE00 and the clinically acceptable value of 1.8 were evaluated with one sample t-test (P<.05). Differences among the different shades were assessed through One-Way ANOVA and Bonferroni multiple comparison tests. RESULTS: Significantly lower values were detected for all groups concerning ΔEab compared to the intraorally clinical acceptable values of 3.3 and 2.7. Significantly lower mean values were detected for groups B3, C3, and D3, concerning ΔE00 compared to the intraorally clinical acceptant value of 1.8. Color pigments in red-brown (A3) and red-grey (D3) shades affect the total color change to a greater extent after the reinforcement with SiO2 nanoparticles compared to the red-yellow (B3) shade. CONCLUSION: Within the limitations of this in vitro study, it can be suggested that reinforcing PMMA with SiO2 nanoparticles at 0.25 wt% slightly affects the optical properties of the PMMA resin without being clinically perceivable.

Surgical Treatment of Osteoporotic Vertebral Compression Fractures at Thoraco-Lumbar Levels: Only Pedicle Screw Constructs with Polymethylmethacrylate Augmentation / 대한정형외과학회잡지

PURPOSE: To investigate the radiological efficacy of polymethylmethacrylate (PMMA) augmentation of pedicle screw operation in osteoporotic vertebral compression fractures (OVCF) patients. MATERIALS AND METHODS: Twenty OVCF patients, who underwent only posterior fusion using pedicle screws with PMMA augmentation, were included in the study. The mean follow-up period was 15.6 months. The demographic data, bone mineral density (BMD), fusion segments, number of pedicle screws, and amount of PMMA were reviewed as medical records. To analyze the radiological outcomes, the radiologic parameters were measured as the time serial follow-up (preoperation, immediately postoperation, postoperation 6 weeks, 3, 6 months, and 1 year follow-up). RESULTS: A total of 20 patients were examined (16 females [80.0%]; mean age, 69.1±8.9 years). The average BMD was −2.5±0.9 g/cm2. The average cement volume per vertebral body was 6.3 ml. The mean preoperative Cobb angle of focal kyphosis was 32.7°±7.0° and was improved significantly to 8.7°±6.9° postoperatively (p<0.001), with maintenance of the correction at the serial follow-up, postoperatively. The Cobb angle of instrumented kyphosis, wedge angle, and sagittal index showed similar patterns. In addition, the anterior part of fractured vertebral body height averaged 11.0±5.0 mm and was improved to 18.5±5.7 mm postoperatively (p=0.006), with maintenance of the improvement at the 3-month, 6-month, and 1-year follow-up. CONCLUSION: The reinforcement of pedicle screws using PMMA augmentation may be a feasible surgical technique for OVCF. Moreover, it appears to be appropriate for improving the focal thoracolumbar/lumbar kyphosis and is maintained well after surgery.

Cranioplasty using Polymethylmethacrylate (PMMA) self-curing by the conventional casting process: clinical case report / Cranioplastia com uso do Polimetilmetacrilato (PMMA) autopolimerizável pelo processo de moldagem convencional: relato de caso clínico

ABSTRACT Cranioencephalic trauma which results in extensive edema and / or bruising usually requires surgical treatment through a greater withdrawal of the bone portion. Thus, the absence of bone tissue implies the lack of protection of the brain tissue or even compromises the esthetics especially when located in the frontal or frontoparietal region. The purpose of this case report is to describe a treatment option for head trauma, through the prefabricated part by obtaining the skull model. These bone faults can be reconstructed either by the direct method using polymethylmethacrylate directly on the defects or by means of pre-made pieces such as prototyping or from the skull model. Although other techniques have many good points, some show certain drawbacks, from storage conditions below abdominal fat, preheating due to the release of heat during the high polymerization reaction or the high cost when they are prototyped. The technique described in this work reports its simple performance, eliminating the risk of local heating, allows prior sterilization in autoclave, it is biocompatible, allows perfect anatomical recovery, easy placement, low cost, also highlighs the advantage of the bucomaxillofacial surgeon's performance due to the familiarization with the relevant head and neck procedures. Clinical and tomographic examination after 24 months of treatment showed stability of the polymethylmethacrylate plate, adhesions to the bone margins, and absence of tissue alterations.

RESUMO Os traumatismos cranioencefálicos que resultam em extensos edemas e ou hematomas normalmente, requerem tratamentos cirúrgicos por meio de uma retirada maior de porção óssea. Deste modo, a ausência do tecido ósseo implica na falta de proteção do tecido cerebral ou até mesmo comprometer a estética especialmente, quando localizadas na região frontal ou frontoparietal. O objetivo deste relato de caso é descrever uma opção de tratamento para os traumatismos cranioencefálicos, por meio da peça pré-fabricada mediante a obtenção do modelo do crânio. Estas falhas ósseas podem ser reconstruídas tanto pelo método direto utilizando o polimetilmetacrilato diretamente sobre as falhas ou por meio das peças pré-confeccionadas como a prototipagem ou a partir do modelo do crânio. Embora outras técnicas apresentem muitos pontos positivos, algumas mostram determinados inconvenientes, desde condição de armazenamento abaixo da gordura abdominal, aquecimento prévio devido a liberação de calor durante a reação de alto polimerização ou o alto custo quando são prototipadas. A técnica neste trabalho descrita relata sua facilidade de execução, elimina o risco do aquecimento local, permite a prévia esterilização em autoclave, é biocompatível, permite a perfeita recuperação anatômica, fácil colocação, baixo custo, ressaltando ainda a vantagem da atuação do cirurgião bucomaxilofacial devido sua familiarização com os procedimentos pertinentes a cabeça e pescoço. Em exame clínico e tomográfico após 24 meses do tratamento, observa-se estabilidade da placa de polimetilmetacrilato, aderências às margens ósseas, e ausência de alterações tissulares.

Preliminary mechanical test of proximal femur reinforcement with cemented x-shaped pmma / Ensaio mecânico preliminar do reforço femoral proximal com cimento ósseo em forma de "x"

ABSTRACT Objective: To evaluate the mechanical behavior of the proximal end of the femur submitted to the X-shaped polymethylmethacrylate (PMMA) reinforcement technique. Methods: Fifteen synthetic femurs, with a Nacional® density of 10 PCF, were divided into two groups: the DX group, with 5 units that were submitted to PMMA reinforcement, and the DP group, with 10 units, which were evaluated intact. The volume of PMMA required, the maximum load, and the absorbed energy to fracture were analyzed by means of a static mechanical bending test simulating a fall on the greater trochanter. Results: A mean of 6 ml of PMMA was used to model the X-reinforcement; it was observed that the DX group presented significantly higher maximum load (median = 1553 N, p = 0.005) and absorbed energy to fracture (median = 9.7 J; p = 0.050) than the DP group (median = 905 N and 6.6 J). Conclusion: X-reinforcement of the proximal end of synthetic femurs showed a statistically significant increase in the maximum load and absorbed energy to fracture in the mechanical assay when compared to the control group. Level of Evidence III, Experimental study.

RESUMO Objetivo: Avaliar o comportamento mecânico da extremidade proximal do fêmur submetido à técnica de reforço com polimetilmetacrilato (PMMA) em forma de X. Métodos: Foram utilizados 15 fêmures sintéticos, com densidade de 10 PCF da Nacional®, divididos nos grupos DX, com 5 unidades submetidas ao reforço com PMMA, e DP com 10 unidades, avaliados com sua integridade intacta. Foram analisados o volume de PMMA necessário, os valores da carga máxima e a energia absorvida até a fratura por meio de ensaio mecânico estático de flexão, simulando queda sobre o trocanter maior. Resultados: Foram usados em média 6 ml de PMMA para a modelagem do reforço em X e observou-se que o grupo DX apresentou carga máxima (mediana = 1553 N; p = 0,005) e energia absorvida até fratura (mediana = 9,7 J; p = 0,050) significativamente maior que o grupo DP (mediana = 905 N e 6,6 J). Conclusão: O reforço em X da extremidade proximal de fêmures sintéticos apresentou incremento estatisticamente significativo da carga máxima e energia absorvida até a fratura no ensaio mecânico em comparação com o grupo controle. Nível de evidência III, Estudo experimental.