胎儿鼻粘膜微血管铸型扫描电镜观察

用８例足月胎儿，通过树脂复型技术，铸造下鼻甲及鼻中隔粘膜微血管结构，进行扫描电镜观察．结果显示鼻粘膜血管呈现清晰的三维构型，可见下列四种血管成份：粘膜固有层毛细血管网、腺体周围毛细血管网、海绵状血窦及位近骨膜的小动、静脉．本研究对于了解鼻粘膜的微循环具有一定价值．     

快速液压热聚合义齿基托材料的实验研究

目的 了解快速液压热聚合义齿基托材料的力学性能。方法 采用自行研制的新型液压自控牙用树脂聚合器和常规水浴两种方法加热固化义齿基托材料，进行挠度、抗弯曲强度、弹性模量、抗冲击强度及硬度的对比分折。结果 快速液压热聚合义齿基托材料的力学性能与水浴法相比无显著性差异，但可以明显缩短热处理时间且全过程自动完成。结论 快速新型液压自控牙用树脂聚合器简化了义齿制作的操作过程，明显缩短了热处理时间，可以准确快速制作出理想的义齿。     

Nd:YAG laser capsulotomy rates following implantation of square-edged intraocular lenses: polymethyl methacrylate versus silicone versus acrylic

Objective: To study the influence of square-edged intraocular lenses (lOLs) on the development of posterior capsule opacification (PCO) and the requirement for laser capsulotomy.Design: Retrospective study.Participants: Three hundred seventy-seven eyes of 377 patients were included.Methods: All these patients underwent phacoemulsification and implantation of square polymethyl methacrylate (PMMA) (Aurolab), silicone (Tecnis Z9000), acrylic hydrophobic (AcrySof MA60AC and Sensar Optiedge), or acrylic hydrophilic (Akreos Adapt) lOLs with a minimum of 2 years’ follow-up. Only those cases in which Nd:YAG laser capsulotomy had been performed for visually significant PCO were evaluated.Results: Three hundred seventy-seven eyes of 377 patients were included in the study. Follow-up duration ranged from 24 to 54 (mean 40.27, SD 8.42) months. The incidence of PCO requiring Nd:YAG laser capsulotomy was found to be significantly less in the silicone lens group: 1.4% as compared with an incidence of 11.7% in the PMMA lens group (p = 0.018). In the square-edged acrylic group, visually significant PCO requiring Nd:YAG laser capsulotomy was observed in 3.6%, 4.8%, and 6.8% of eyes implanted with AcrySof MA60AC, Sensar Optiedge, and Akreos Adapt lOLs, respectively. In 5 of the 7 eyes (71.4%) exhibiting PCO in the PMMA group, the condition developed within the first 6 months. In the silicone and acrylic group, development of PCO was delayed.Conclusions: The rate of visually significant PCO as well as the need for Nd:YAG laser capsulotomy is influenced by IOL biomaterial in addition to square edge. It is significantly delayed with square-edged foldable acrylic and silicone lOLs compared with square-edged PMMA IOLs.     

EVALUATION OF THE BIOCOMPATIBILITY OF ROOT CANAL SEALERS USING SUBCUTANEOUS IMPLANTS

The purpose of this study was to evaluate in vivo the biocompatibility of Endométhasone, Pulp Canal Sealer EWT and AH-Plus root canal sealers after implantation in rat connective tissue. Twenty-four Wistar-Furth rats were used. Polyethylene tubes were filled with the sealers and implanted into specific dorsal subdermal tissue sites of the rats. Implants were removed after 3, 7 and 30 days, fixed and processed for glycol methacrylate-embedding technique to be examined microscopically. On the 3rd day, there was a mild inflammatory reaction to Pulp Canal Sealer EWT implants, but a severe response to the other sealers with presence of acute inflammatory cells. On the 7th day, tissue organization was more evident with attenuation of the inflammatory reaction, especially for the AH-Plus implants. On the 30th day, connective tissue with few inflammatory cells was observed in contact with all sealer implants. In this time interval, the tissue in contact with Pulp Canal Sealer EWT implants was more organized, while the tissue close to Endométhasone and AH-Plus implants showed a mild persistent inflammatory reaction and had similar results to each other. In conclusion, the sealers had a similar pattern of irritation, which was more severe in the beginning and milder with time, in such a way that all sealers showed a persistent mild reaction. Pulp Canal Sealer EWT yielded better tissue organization than Endométhasone and AH-Plus, which, in turn, showed similar results to each other.     

Occupational contact dermatitis in 2 dental technicians

2 dental technicians, both with chronic hand eczema, reported worsening from the use of 2 products containing methyl methacrylate, employed in manufacturing acrylic prostheses. Patch tests in both patients gave positive reactions to methyl methacrylate, ethylene glycol dimethacrylate and products employed in manufacturing acrylic prostheses (2% and 5% pet.). On the basis of results subsequently obtained from patch tests carried out with pieces of glove interposed between the skin and the allergens (methyl methacrylate and products employed), we advised our patients still to use latex gloves during work. Follow-up after 1 year showed complete regression of the dermatitis in 1 case and considerable improvement in the other.     

Biologically active polymers: synthesis and antimicrobial activity of modified glycidyl methacrylate polymers having a quaternary ammonium and phosphonium groups

Polymers with antibacterial activity have been synthesized by chemical modification of poly(glycidyl methacrylate). The glycidyl methacrylate was polymerized by the free radical polymerization technique. The poly(glycidyl methacrylate) was hydrolyzed and was chloroacetylated using chloroacetyl chloride. The chloroacetylated product was modified to yield polymers with either quaternary ammonium or phosphonium salts. The antimicrobial activity of the modified glycidyl methacrylate polymers has been examined against a variety of test microorganisms by the cut plug and the viable cell counting methods using shake flask of ten times diluted nutrient broth medium. All three polymers obtained were inhibitory to the growth of Gram negative bacteria (Escherichia coli, Pseudomones aeruginosa, Shigella sp. and Salmonella typhae) and Gram positive bacteria (Bacillus subtilis and B. cereus) as well as the fungus (Trichophytun rubrum). It was found that the growth inhibitory effect varied according to the structure of the polymer and the composition of the active group and increased with increasing the concentration of the polymer. The tested polymers showed more antimicrobial activity against Gram negative bacteria and the fungus, whereas were less active against Gram positive bacteria.     

Photodeformable Microspheres from Methacrylate‐Based Azo Homopolymers

In this study, two methacrylate‐based azo homopolymers are synthesized and used to fabricate photodeformable microspheres through a self‐assembling approach. The methacrylate‐based azo homopolymer with the narrow molecular weight distribution is synthesized by reversible addition fragmentation chain transfer polymerization, while the other with the relatively broad molecular weight distribution is synthesized by conventional radical polymerization. The azo polymers are characterized by proton nuclear magnetic resonance (¹H‐NMR), Fourier transform infrared spectroscopy (FT‐IR), differential scanning calorimetry (DSC), thermal gravimetric analysis TGA, gel permeation chromatography GPC, and ultraviolet‐visible spectroscopy (UV–vis) m. The colloidal spheres are obtained by gradually adding deionized water into the solutions of the azo polymers in N ,N‐dimethylformamide. Laser light scattering analysis and transmission electron microscopy observations show that although both azo polymers can form uniform colloidal spheres in the dispersions, the molecular weight and its distribution show significant effects on the colloid formation process and the sizes of the colloidal spheres formed in the process. Upon irradiation with a linearly polarized Ar⁺ laser beam for a period of time, the azo polymer microspheres show the elongated deformation along the polarization direction of the actinic light.

     

Polymethyl methacrylate intraocular lens opacification 20 years after cataract surgery: A case report in a tertiary eye hospital in Saudi Arabia

Snowflake degeneration is a slow progressive opacification of polymethyl methacrylate (PMMA) intraocular lenses (IOLs). This late postoperative complication can occur a decade or later after implantation. The deposits are composed of IOL materials that tend to aggregate centrally. There is a relative paucity of the literature on snowflake degeneration of IOLs. Symptoms can range from mild visual disturbance to significant loss of visual acuity. In cases of opacification after IOL implantation, the different diagnosis should include snowflake degeneration to prevent surgical intervention such as lens exchange or explantation unless clinically warranted. We report a case of late optical opacification of a PMMA IOL, the clinical diagnosis and treatment that increased best corrected vision.