Influence of Poly(methylmethacrylate) Dopant on Butadiene Derivative Electroluminescence

ＩｎｆｌｕｅｎｃｅｏｆＰｏｌｙ（ｍｅｔｈｙｌｍｅｔｈａｃｒｙｌａｔｅ）ＤｏｐａｎｔｏｎＢｕｔａｄｉｅｎｅＤｅｒｉｖａｔｉｖｅＥｌｅｃｔｒｏｌｕｍｉｎｅｓｃｅｎｃｅＷａｎｇＧｕａｎｇｍｉｎｇ１（王光明）ＷａｎｇＧｕａｎｇｍｉｎ２（王广民）ＹｕａｎＣｈｕ...

A Comparative Assessment of the Surface Roughness of Thermoplastic Denture Base Resins Following Adjustment and Re-Polishing

Purpose: This study assessed the roughness of two injection-molded, thermoplastic materials used for denture bases compared with a polyamide material and compression molded Polymethylmethacrylate (PMMA) after the adjustment and re-polishing with either a laboratory protocol or a chair side protocol. Methods: Forty specimens, each of PMMA, Valplast, DuraFlex, Dura Cetal were fabricated and finished according to individual manufactures’ instructions. These materials were adjusted with tungsten carbide (TC) burs to mimic gross adjustments, and then re-polished either on a lathe or bonded silicon carbide (B-SC). Following instrumentation, the specimens were assessed using contact profilometry and scanning electron microscopy. Two-factor ANOVA was used to determine significant differences in mean surface roughness (Ra and Rmax), with included factors being material type and re-polishing regimen. Results: Mean Ra values ranged from 0.26 (DuraFlex control) to 1.82 (Valplast adjusted with TC burs). Mean Rmax values ranged from 1.88 (Dura Flex control) to 13.76 (Valplast adjusted with TC burs). Two-factor ANOVA revealed that interaction of both factors was significant (p Ra and Rmax. There was a statistically significant increase in both Ra (p Rmax (p < 0.05) for all material types following the gross adjustment. With the exception of DuraFlex, re-polishing of samples that were previously adjusted with TC burs, on the dental lathe produced surfaces that were comparable to control samples. Conclusion: Adjustment of DuraFlex should be kept to a minimum since the adjustment produced the significant surface detriment that could not be corrected with either of the polishing regimens.

Preparation and surface modification of magnetic poly(methyl methacrylate) microspheres

A novel method for preparation of magnetic polymer microspheres by spraying suspension polymerization (SSP) was developed. Relatively uniform magnetic poly(methyl methacrylate) microspheres were prepared by the spraying suspension polymerization (SSP) using methyl methacrylate (MMA) as monomer, divinylbenzene (DVB) as cross-linking agent, benzoyl peroxide (BPO) as initiator and polyvinyl alcohol (PVA) as stabilizer in the presence of hydrophobic Fe3O4 magnetic fluid. The microspheres prepared were modified by surface chemical reaction. The magnetic properties and morphology of the microspheres were examined by SEM and VSM respectively. The active functional groups of microspheres were examined by infrared spectra. The results showed that microspheres with saturation magnetization of 16.8 emu/g showed distinct superparamagnetic characteristics and the magnetic microspheres with a size of 10 μm were relatively uniform.

Fabrication and Characterizations of Metallic Mg Containing PMMA-Based Partially Degradable Composite Bone Cements

Inadequate strength at the bone/cement interface is one of the main drawbacks of poly(methylmethacrylate)(PMMA) bone cement in the current orthopedic surgeries. In the present work, a partially degradable PMMA/Mg composite bone cement (PMC) was developed for enhancing the bone/cement interfacial strength, which is proposed to be accomplished by increasing the osteo-conductivity of PMMA and enhancing the mechanical interlocking between bone tissue and the porous PMMA surface formed by the degradation of Mg on the surface of the cement. PMCs were prepared with various concentrations of Mg particles with different sizes and alloy compositions. The effects of Mg particle size, composition and content on the injectability, mechanical and degradation properties, and biocompatibility of PMCs were evaluated. The results show that these parameters affected the properties of the PMCs simultaneously. The good injectability and compressive strengths of PMMA were preserved, while the compatibility to osteoblasts was enhanced when adding Mg particles in a proper manner. The PMCs degraded at the surface with time and formed porous surface structures in the physiological environment, while maintaining the original compressive strengths. This preliminary study shows that the PMC is promising for minimally invasive orthopedic surgery;however, it still requires to be optimized and evaluated in the future.

Modified poly(methyl methacrylate) bone cement in the treatment of Kümmell disease

Kuümmell disease(KD)causes serious vertebral body collapse in patients.However,only a few case reports have been conducted and the number of patients with KD investigated was limited.Additionally,the frequently used poly(methyl methacrylate)(PMMA)bone cement for KD is limited by excessive modulus and poor biocompatibility.Herein,we aimed to modify PMMA bone cement with mineralized collagen(MC),and compare the clinical effects,image performance and finite ele-ment analysis between the modified bone cement and PMMA bone cement for the treatment of phase I and II KD.Thirty-nine KD patients treated with PMMA bone cement and 40 KD patients treated with MC-modified PMMA bone cement from June 2015 to March 2017 were retrospectively analyzed.The surgical procedure,intraoperative blood loss,hospital stay and complications were compared between different groups.Visual analog scale,Oswestry disability index,anterior verte-bral height,posterior vertebral height,computed tomography value,adjacent vertebral re-fracture,Cobb angle and wedge-shaped correction angle were evaluated.Additionally,the representative sample was selected for finite element analysis.We found that the MC-modified PMMA bone ce-ment could achieve the same effect as that of PMMA bone cement and was associated with better vertebral height restoration in the long term.