The most important problem in the transplantation of artificial cornea is the extrusion of keratoprosthesis. So we performed this study to know the conditions to keep the keratoprosthesis as long as possible after animal experiment with experimental keratoprosthesis of various material and structure. We concluded from the results that silicone barrier could not prevent the retroprosthetic membrane, and fluorosilicone was not adequate material as an optic. And the following conditions are required to maintain keratoprosthesis as long as possible; optic made of PMMA, retention plate made of PTFE with 0.6 mm thick, anterior direction of optic, large optic, intralamellar suture technique. Furthermore we postulated that enzymatic theory is more appropriate than aseptic necrosis theory about the extrusion of keratoprosthesis.
Animals ; *Cornea/pathology ; Corneal Transplantation ; Methylmethacrylate ; *Methylmethacrylates ; *Polytetrafluoroethylene ; *Prostheses and Implants ; Prosthesis Design ; Rabbits

Insertion of methyl methacrylate polymer into newly reamed bony cavities has sometimes resulted in profound hypotension, cardiac arrest, or sudden death which are more common in patients with hemodynamic instability or hypovolemia. In paralysis agitans(Parkinson's disease), dramatic worsening of the disease often occurs when another illness or trauma accompanies it. And it is possible that chronic medication with levodopa can cause the loss of ability to support blood pressure. So, it involves some risk to use methyl methacrylate in chronic levodopa-treated paralysis agitans. We present a case of paralysis agitans who demonstrated profound hypotension immediately following insertion of methyl methacrylate polymer in spite of normovolemia and proper anesthetic management.
Aged ; Case Report ; Hip Prosthesis/adverse effects ; Human ; Hypotension/*etiology ; Levodopa/therapeutic use ; Male ; Methylmethacrylate ; Methylmethacrylates/*adverse effects ; Parkinson Disease/*drug therapy

No abstract available.
Herpes Simplex ; Herpes Zoster ; Humans ; Methylmethacrylates ; Polystyrenes

As a benign adnexal tumor, steatocystoma usually occurs as an autosomal dominant condition known as steatocystoma multiplex. Steatocystoma simplex, the noninherited solitary counterpart of steatocystoma multiplex,was first described by Brownstein in 1982, and is exceedingly rare. We report a case of steatocystoma simplex in a 27-years-old female, who presented with an asymptomatic soft, oval shaped mass on the lower anterior neck. The lesion was completely excised and confirmed as steatocystoma simplex on histopathological examination.
Female ; Humans ; Methylmethacrylates ; Neck ; Polystyrenes ; Steatocystoma Multiplex

The postoperative results of 77 paients:(82 eyes) who had undergone phacoemulsification with implantation of oval optic poly methylmethacrylate (PMMA) introoular intraowlar lens (IOL) (5 X 6mm) were evaluated retrospectively. Scleral pocket incision was done tangentially at the point 2mm. apart from the surgical limbus and 5mm in length. No suture in the group 1 (30 eyes), single horizontal suture in the group 2 (31 eyes) and single X suture in the group 3 (21 eyes) were used for the closure method. Average uncorrected visual acuity at postoperative one week was 0.5 or better in each group and there was no statistically significant difference among three groups (p>0.05). The change in mean keratometric astigmatism from postoperative one to eight weeks turned out to be less than 1 diopter (D) in each group and there was no statistically significant difference among three groups (p>0.05). When the diameter of continuous cirular capsulorhexis (CCC) was greater than 5mm or the position of CCC was decentered, it was found that optic was partially escaped form the bag due to adhesion between the remained anterior and posterior capsular structure. It could be suggested that oval optic PMMA IOL showes early visual recovery with less astigmatism regardless of the suture method and in order to place the optic of IOL properly in the bag postoperatively, the diameter of CCC should be less than 5mm and the position of CCC should be centered.
Astigmatism ; Capsulorhexis ; Lenses, Intraocular* ; Methylmethacrylate ; Phacoemulsification ; Polymethyl Methacrylate ; Retrospective Studies ; Sutures ; United Nations ; Visual Acuity

No abstract available.
Encephalitis, Herpes Simplex ; Herpes Simplex ; Methylmethacrylates ; Neurosyphilis ; Polystyrenes

STATEMENT OF PROBLEM: Volume stability, microstructure reproducibility and fluidity along with compatibility with dental stone must be in consideration in order to use tissue conditioner as a material for functional impression. There are few studies concerning the influence of time factor in oral condition on surface roughness of the stone and optimal retention period in the oral cavity considering such changes in surface roughness. PURPOSE: The purpose of this study was to find out the influence of various kinds of tissue conditioner, its powder/liquid ratio and immersion time on surface roughness of the stone. MATERIAL AND METHODS: Materials used in this study were the three kinds of tissue conditioners (Coe-Comfort, Visco-Gel, Soft-Liner) and were grouped into three: group R - mixed with standard powder/liquid ratio that was recommended by the manufacturers, group M - mixed with 20% more powder, group L - mixed with 20% less powder. Specimens were made with the size of 20 mm diameter and 2 mm width. Each tissue conditioner specimens were subdivided into 5 groups according to the immersion time (0 hour, 1 day, 3 days, 5 days, 7 days), completely immersed into artificial saliva and were stored under 37degrees C. Specimens of which the given immersion time elapsed were taken out and were poured with improved stone, making the stone specimens. Surface roughness of the stone specimens was measured by a profilometer. RESULTS: Within the limitation of this study, the following results were drawn. 1. Major influencing factor on surface roughness of the stone model made from tissue conditioner was the retention period (contribution ratio (rho) = 62.86%, P < .05) of the tissue conditioner in oral cavity to make functional impression. 2. In case of Coe-Comfort, higher mean surface roughness value of the stone model with statistical significance was observed compared to that of Soft-Liner and Visco-Gel as immersion time changes (P < .05). 3. In case of group L (less), higher mean surface roughness value of the stone model with statistical significance was observed compared to that of R (recommended) and M (more) group as immersion time changes (P < .05). CONCLUSION: We may conclude that as the retention period of time in oral cavity influences surface roughness of the stone model the most and as the kind of tissue conditioner and its P/L ratio may influence also, clinician should well understand the optimal retention period in oral cavity and choose the right tissue conditioner for the functional impression, thus making the functional impression with tissue conditioner usefully.
Immersion ; Methylmethacrylates ; Mouth ; Retention (Psychology) ; Saliva, Artificial ; Time Factors

Steatocystoma is a benign adnexal tumor originating from the pilosebaceous duct junction which can be classified into two groups (steatocystoma simplex and steatocystoma multiplex). Steatocystoma simplex, which presents as a solitary lesion, is very rare. Steatocystoma simplex occurs most commonly on the face and the case reported herein involving the scalp is extremely rare. A 49-year-old man presented for evaluation and treatment of a solitary papule on the right parietal scalp which had persisted for a period of 1 year. The histopathologic examination revealed a thin-walled cyst consisting of stratified squamous epithelium with hyaline cuticle that lacked a stratum granulosum. Based on clinical and histologic findings, we diagnosed this case as steatocystoma simplex of the scalp and report this rare case.
Epithelium ; Humans ; Hyalin ; Methylmethacrylates ; Middle Aged ; Polystyrenes ; Scalp

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

PURPOSE: The aim of this study was to evaluate the effect of delayed time, surface treatment, and repair materials on repair of bisacryl composite resin through comparison of shear bond strength and to evaluate the utility of bis-acryl composite resin repair using polymethyl methacrylate resin. MATERIALS AND METHODS: A total of 90 bis-acryl composite resin specimens were fabricated and classified into 9 test groups, each of 10 pieces according to delayed time, surface treatment and repair material. The shear bond strength of each specimen was measured using a universal testing machine immediately after fabrication and analyzed using a statistical analysis program (IBM SPSS statistics 20). After the shear bond strength measurement, the fracture surface of the specimen was observed. RESULTS: The highest shear bond strength (17.54 ± 3.14 MPa) was observed in the experimental group bonded immediately with a light-curing flowable composite resin using a bonding agent. CONCLUSION: When repairing bis-acryl composite resin, it is necessary to consider whether to remake according to the delayed time. For effective repair, it is desirable to consider appropriate materials and surface treatment methods according to the site or purpose of use.
Polymethyl Methacrylate