Syringate cements

All these vanillate and syringate cements are about as strong as those of EBA-eugenol. 

Syringate cements possess similar advantages to the vanillate cements. In addition, syringic acid possesses cariostatic properties, so syringates may inhibit the development of caries (dental decay). Again these advantages need to be confirmed. 

This type of cement has been further improved by the substitution of -hexyl van ill ate [84375-71-3] and similar esters of vanillic acid [121 -34-6] and/or syringic acid [530-57 ] for eugenol (93—95). These substituted cements are strong, resistant to dissolution, and, unlike ZOE and EBA cements, do not inhibit the polymerization of resin-base materials. Noneugenol cements based on the acid—base reaction of zinc and similar oxides with carboxyhc acids have been investigated, and several promising types have been developed based on dimer and trimer acids (82). 

All cements that contain eugenol inhibit the polymerization of acrylates, and those of EBA-eugenol are no exception. In order to remedy this and other defects, Brauer and his coworkers examined alternatives to eugenol (Figure 9.7). These included the esters of vanillic acid (3-methoxy-4-hydroxybenzoic acid, HV) and syringic acid (3,5-dimethoxy-4-hydroxy-benzoic acid). Both are 3-methoxy-4-hydroxy compounds and are thus chemically related to eugenol and guaiacol. Both are solids and have to be dissolved in EBA where they form satisfactory cements with EBA zinc oxide powder. The vanillate (EBA-HV) cements are the more important. 

The best formulation proved to be one based on a liquid containing 88 % EBA, 5% n-ethylhexyl syringate and 7% n-hexyl vanillate. Cements prepared from these liquids set in 5-5 to 6-5 minutes with a compressive strength of 66 MPa and tensile strength of 6 to 7 MPa. 

Brauer, G. M. Stansbury, J. W. (1984a). Cements containing syringic acid ester-o-ethoxybenzoic acid and zinc oxide. Journal of Dental Research, 63, 137 0. 

Brauer, G. M., Stansbury, J. W. Flowers, D. (1986). Modification of cements containing vanillate or syringate esters. Dental Materials, 2, 21-7. 

To obtain reproducible results, it was necessary always to use the same syringe, because although any particular syringe can deliver a reproducible amount, apparently similar syringes deliver considerably different amounts. It was also found necessary to use a syringe with a needle cemented in place with epoxy resin (Araldite) because syringes with detachable needles delivered different amounts at different times for no obvious... 

The solvent cement is generally applied to the substrate with a syringe or brush. In some cases, the surface can be immersed in the solvent. After the area to be bonded softens, the parts are mated and held under pressure until dry. Pressure should be low and uniform so that the finished joint will not be stressed. After the joint hardens, the pressure is released, and an elevated temperature cure may be necessary, depending on the plastic and desired joint strength. The bonded part should not be packaged or stressed until the solvent has adequate time to escape from the joint. 

For the administration of cement into the vertebral body, a dedicated screw-like injection set, provided by several manufactures, is usually employed. The advantage to using a dedicated set instead of a 2-cc Luer lock syringe is that the cement can be administered with continuous flow and minimal effort for the treating interventional radiologist. Furthermore, if a leak is noticed, the pressure can be stopped and reversed immediately. 

Blood bags and intravenous solution bags, one-way articles, gloves, band aids Syringes, hoses, packaging material, needles, sewing material Bone cement, intraocular and hard contact lenses, tooth filler material, artificial teeth, joint replacement... 

Experiments to measure distribution and recovery of -hydrocarbons were performed with a 10-mL gastight syringe (Hamilton Company, Reno, NV). The syringe was equipped with a fixed, epoxy-cemented 304 stainless steel needle [0.028 in outer diameter (o.d.), 0.016 in inner diameter (i.d), point style 2]. Sampling and delivery were done with an infusion pump (Sage Instruments, Cambridge, MA). The sampling and delivery rates were fixed... 

Note As an alternative to constructing a humidified denaturation chamber, seal the coverslip to the slide with a gasket of rubber cement, most easily applied using a syringe with a wide-bore needle. Allow the rubber cement to dry, and then denature the slide directly on a heat block at 94< C. 

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