No abstract available.
Methylmethacrylate* ; Plagiocephaly*

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.
Anesthesia, Local ; Forehead ; Frontal Bone ; Fungi ; Humans ; Inlays ; Methylmethacrylate ; Polymers ; Scalp ; Surgery, Plastic ; Transplants

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.
Adult ; Aged ; Aged, 80 and over ; Arthroplasty, Replacement, Hip/*instrumentation ; *Coated Materials, Biocompatible ; Equipment Failure Analysis ; Female ; Femur Head Necrosis/diagnosis/surgery ; *Hip Prosthesis ; Humans ; Kaplan-Meier Estimate ; Male ; Methylmethacrylate ; Middle Aged ; Prosthesis Failure ; Retrospective Studies ; Treatment Outcome ; Young Adult

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.
Adult ; Automobiles ; Brain ; Follow-Up Studies ; Frontal Bone ; Fungi ; Humans ; Hypogonadism ; Male ; Methylmethacrylate ; Mitochondrial Diseases ; Ophthalmoplegia ; Polymerization ; Polymers

OBJECTIVE: The prefabrication of customized cranioplastic implants has been introduced to overcome the difficulties of intra-operative implant molding. The authors present a new technique, which consists of the prefabrication of implant molds using three-dimensional (3D) printers and polymethyl-methacrylate (PMMA) casting. METHODS: A total of 16 patients with large skull defects (>100 cm2) underwent cranioplasty between November 2009 and April 2011. For unilateral cranial defects, 3D images of the skull were obtained from preoperative axial 1-mm spiral computed tomography (CT) scans. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of the cranium as a model. For bilateral cranial defects, precraniectomy routine spiral CT scan data were merged with postcraniectomy 3D CT images following a smoothing process. Prefabrication of the mold was performed by the 3D printer. Intraoperatively, the PMMA implant was created with the prefabricated mold, and fit into the cranial defect. RESULTS: The median operation time was 184.36+/-26.07 minutes. Postoperative CT scans showed excellent restoration of the symmetrical contours and curvature of the cranium in all cases. The median follow-up period was 23 months (range, 14-28 months). Postoperative infection was developed in one case (6.2%) who had an open wound defect previously. CONCLUSION: Customized cranioplasty PMMA implants using 3D printer may be a useful technique for the reconstruction of various cranial defects.
Computer-Aided Design ; Decompressive Craniectomy ; Follow-Up Studies ; Fungi ; Humans ; Methylmethacrylate ; Polymethyl Methacrylate ; Reconstructive Surgical Procedures ; Skull ; Tomography, Spiral Computed

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.
Acetylcholine ; Adenylyl Cyclases ; Animals ; Atropine ; Baths ; Calcium ; Carbachol ; Epithelium ; Hip ; Knee ; Methylmethacrylate* ; Muscle, Smooth ; Muscle, Smooth, Vascular ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Nitric Oxide Synthase ; Orthopedic Procedures ; Propranolol ; Rats* ; Receptors, Muscarinic ; Relaxation ; Tetraethylammonium ; Trachea

The purpose of the present study was to evaluate the effects of several implant surface treatments to the bone formation, by placing Machined implants, 75 micrometer Calcium phosphate-blasted implants and Al2O3- blasted and acid-etched implants in rabbit tibia through histomorphometric study. Two animals of each group were sacrificed at 2, 4, 8 weeks. The specimens containing the implants were dehydrated and embedded into hard methylmethacrylate plastic. Thereafter, the sections were ground to 50 micrometer. The specimens were stained with Villanueva bone stain for a light microscopic study. The results were as follows; 1. When the surface roughness of three different implants was measured by Surfcorder, the Ra of the Machined group, the RBM group and the SLA group was 0.16 micrometer, 0.44 micrometer, and 1.08micro meter. 2. When examining the surfaces of the implants in the scanning microscope, Machined implant has the smooth surface with a few scratches, RBM implant has the rough surface with curled ridges and valleys, and SLA implant has the rough surface structures such as sharp protruding parts and micropits measuring 1-2 micrometer in diameter. 3. After 2 weeks of implantation, the percentage of bone-to-implant contact of the Machined group, the RBM group and the SLA group was 26.86%, 35.40% and 45.99%. However, its differences between each group decreased during the healing periods. 4. After 2 weeks of implantation, the percentage of bone area inside the threads of the Machined group, the RBM group and the SLA group were 21.55%, 30.43% and 41.18%. However, its difference of bone area between machined group and surface treatment groups was maintained but the difference within the surface treatment groups decreased during the healing periods. In summary, the amount of bone formation in RBM and SLA group was greater than Machined group in early healing stage. These results suggest that RBM and SLA implants can reduce the healing period for osseointegration and may be suitable for early function.
Animals ; Calcium ; Dental Implants* ; Methylmethacrylate ; Osseointegration ; Osteogenesis ; Plastics ; Tibia*

PURPOSE: Alloplastic implants, such as methylmethacrylate, Teflon, silicone, Supramid are commonly used to cover the floor defect and to prevent reherniation of the displaced orbital tissue in orbital floor fracture. Silicone implant has been used for reconstruction of orbital wall defects because of pliability, advantage of carving and chemically inert nature. However, silicone implant also has complications including infection, extrusion, pain, dystopia and tissue reaction. Cyst formation around the silicone implant is a very rare complication. According to many reports, cysts around alloplastic implant in an orbital area are mostly hemorrhagic cysts consisted of blood breakdown product with fibrous capsule cell in histologic examination. METHODS: The authors report atypical case and successful treatment of intraorbital hemorrhagic cyst around silicone implant of a 37-year-old male patient. RESULTS: Preoperative symptoms of diplopia, exophthalmos, proptosis, vertical dystopia and ectropion of lower eyelid were resolved after surgical removal of implants with surrounding capsule. CONCLUSION: Clinical suspicion of plastic surgeon is important in diagnosis of intraorbital cyst of patients who have history of silicone implantation and computed tomography is the standard tool of diagnosis. During the operation, caution must be taken on delivering the whole capsule of intraorbital cyst along with silicone implant to prevent recurrence of the cyst.
Adult ; Diagnosis ; Diplopia ; Ectropion ; Exophthalmos ; Eyelids ; Humans ; Male ; Methylmethacrylate ; Nylons ; Orbit ; Pliability ; Polytetrafluoroethylene ; Recurrence ; Silicones*

Prepared from 15.3% N-acetylated chitosan (FNC), half N-acetylated chitosan (HNC) possesses a good solubility in a weak basic solution, guaranteeing the formation of microcapsules by the coacervating reaction between HNC and methacrylic acid (MAA)-hydroxyethyl methacrylate (HEMA)-methyl methacrylate (MMA) (MAA-HEMA-MMA) terpolymer under physiological conditions. When hepatocytes were encapsulated in such 3-dimensional microenvironment, as compared to monolayer culture, cell functions, including P450 activity, urea production and albumin release, were well supported. The prepared microcapsules have good mechanical stability and permeability.
Animals ; Capsules ; Cell Culture Techniques ; methods ; Cells, Cultured ; Chitosan ; chemistry ; pharmacology ; Hepatocytes ; cytology ; drug effects ; Male ; Methacrylates ; Methylmethacrylate ; Polymers ; Rats ; Rats, Wistar ; Tissue Engineering ; methods

methylmethacrylate plastic. After grinding to 50micrometer, the specimens were stained with Villanueva bone stain. From each specimen, histomorphometric evaluation and the bone implant contact rate were analysed with optical microscope. The results were as follows; 1. In the scanning electronic microscopic examination, machined surface implant had several shallow and paralleled scratches on plain surface, double acid-etched implant had lots of minute wrinkles, rough valley and also irregularly located craters that looked like waves, anodic oxidized surface implant had porosity that minute holes were wholly distributed on the surface. 2. After 2 weeks of implantation, the percentages of bone-to-implant contact in the machined implant, double acid-etched implant and anodic oxidized implant were 26.85%, 62.64% and 59.82%, after 4 weeks of implantation they were 64.29%, 77.85% and 75.23%, and after 8 weeks they were 82.66%, 85.34% and 86.39%. 3. After 2 weeks of implantation, the percentages of bone area between threads in the machined implant, double acid-etched implant and anodic oxidized implant were 21.55%, 42.81%, and 40.33%, after 4 weeks of implantation they were 49.32%, 62.60% and 75.56%, and after 8 weeks they were 71.62%, 87.73% and 83.94%. In summary, percentages of implant surface contacted to bone trabeculae and bone formation area inside threads in double acid-etched implants and anodic oxidized implants were greater than machined implants in early healing stage. These results suggest that double acid-etched and anodic oxidized surface implants could reduce the healing period for osseointegration and may enable to do early function.]]>
Animals ; Dental Implants ; Humans ; Male ; Methylmethacrylate ; Osseointegration ; Osteogenesis ; Plastics ; Porosity ; Rabbits ; Tibia