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Medical Forum / General / Dentistry / October 2006query re: impression materials
For years I have used Coe Flex polysulfide as my impression material for partials--with good results. Recently there was a change in the formulation--the color has been changed from a lovely brown to a cheery aquamarine-like light blue. The package signals this change of formulation with words something like : "NEW--LEAD-FREE FORMULA!!!" (which kinda raises the issue...) Anyhow, this new formulation seems to be a bust. I've taken a couple of impressions and while it seems to set up OK in the mouth, the surface detail (esp. of the soft tissue) on withdrawal has a wrinkled appearance. The lab surmised that the material didn't "set right". We've also gotten back one frame that didn't fit, and one that did. Wondering if anyone else out there uses polysulfide, or if most of you are using Impregum or some other polyether or PVS material. Impregum seems a bit heavy to me and I'm concerned it might displace tissues more than I'd like. Steve > For years I have used Coe Flex polysulfide as my impression material > for partials--with good results. [quoted text clipped - 13 lines] > > Steve Maybe you just have a bad batch? Regards, George >>For years I have used Coe Flex polysulfide as my impression material >>for partials--with good results. [quoted text clipped - 18 lines] > Regards, > George Possible, of course. I've been through a couple of boxes though. Certainly not outdated--I probably threw out at least the first box. I should probably check the lot numbers on the boxes I have left. Steve In that case, you probably need to find a way to put the lead back in... maybe sprinkle it with some pencil shavings? Seriously I can't help you... I used PVS in school, alginate now. Kerr makes an alginate alternative called Alginot, maybe you wanna give it a try? Regards, George > In that case, you probably need to find a way to put the lead back > in... maybe sprinkle it with some pencil shavings? [quoted text clipped - 4 lines] > Regards, > George After failing twice with Coe Flex, I used alginate in a custom perforated tray with Hold adhesive. I prefer not to pour my own impressions though. The frame from the alginate impression was fine. Steve > After failing twice with Coe Flex, I used alginate in a custom > perforated tray with Hold adhesive. I prefer not to pour my own > impressions though. The frame from the alginate impression was fine. > > Steve Back in school we always used alginate for partial impressions. Worked fine, but you do have to pour it in a reasonable period of time to avoid distortion. I still use it as I pour my own impressions. I used Coe Flex, and Permlastic for years too. They worked fine and allowed extra time for transport to the laboratory for pouring, which is hard to do with alginate. I didn't know that Coe had changed the formula. PVS also works fine, and I have been using it for ten years or so for full denture impressions. It will work fine for partials, but since there are so many different formulations of PVS material, you have to find one that works in your own technique. I like regular set instead of fast set as that gives more time to be sure the tray is loaded correctly and inserted without too much stress. I also like the light-body or the universal-body, as the heavier body material seems to give too much resistance upon seating, and in my hands, seems to tend to make folds in the heavy material. A lot of dentists like the medium body, but it's really too thick for my own preferences. I like the light body or the "universal" body in PVS. Your own preferences may vary! Best regards, - dentaldoc >> After failing twice with Coe Flex, I used alginate in a custom >>perforated tray with Hold adhesive. I prefer not to pour my own [quoted text clipped - 28 lines] > Best regards, > - dentaldoc Thanks Bill. I use light body Coe Flex, so that's probably what I'd try first with the PVS. Steve >> In that case, you probably need to find a way to put the lead back >> in... maybe sprinkle it with some pencil shavings? [quoted text clipped - 10 lines] > >Steve A good trick if you are not going to pour, is to heat seal in a Nyclave tubing 'bag' with a damp cotton roll. I double seal on both ends and haven't had a problem in years. Am also using stock trays perf or rim-lock. >>>In that case, you probably need to find a way to put the lead back >>>in... maybe sprinkle it with some pencil shavings? [quoted text clipped - 15 lines] > and haven't had a problem in years. Am also using stock trays > perf or rim-lock. For steel frames? You mean what they taught us ain't true??!! Steve >> A good trick if you are not going to pour, is to heat seal in a Nyclave >> tubing 'bag' with a damp cotton roll. I double seal on both ends [quoted text clipped - 4 lines] > >Steve Well, Ticonium frames at least <hehe>. Yep, in effect this creates a 'humidor'. In a pinch then seal the 'bag' in an air tight container with a damp paper towel. Have done this a few times over a weekend with no ill effects. > Well, Ticonium frames at least <hehe>. > [quoted text clipped - 3 lines] > Have done this a few times over a weekend > with no ill effects. I'm referring to the process I remember being called "syneresis" (do I have that right?) whereby there was dimensional distortion even if the impression is kept wet. In any case, I'm obviously not as brave as you, and if I use alginate I'll pour immediately like the nice boy I am. Perusing the Schein catalog, it seems the options for polysulfide rubber have gotten very thin lately--that may be telling me something. In any case, it looks like PVS materials may be no more expensive than the few polysulfides remaining, so I may switch to that. Steve  SignatureMark & Steven Bornfeld DDS http://www.dentaltwins.com Brooklyn, NY 718-258-5001 >> Well, Ticonium frames at least <hehe>. >> [quoted text clipped - 15 lines] > >Steve IIRC syneresis was adsorption of water by the alginate, irreversible hydrocolliod. Note, I don't *ever* wrap an alginate in a wet paper towel. Just a damp cotton roll or corner of paper towel sealed in the bag, not touching the impression material. It works, have been doing this for years. > For years I have used Coe Flex polysulfide as my impression material >for partials--with good results. [quoted text clipped - 13 lines] > >Steve Is that new formula like lead free gasoline ? Just doesn't work as well. I still use good ole alginate (Jeltrate Plus), but must admit that my lab tech will only accept them from me. Others are required to use a custom tray and VPS. You might look into some of the products from parkell since the volume of material needed may make some of the other materials cost prohibitive. For C&B am using Exaflex heavy and light. The heavy is siff on setting but doesn't seem to displace tissue. >> For years I have used Coe Flex polysulfide as my impression material >>for partials--with good results. [quoted text clipped - 27 lines] > For C&B am using Exaflex heavy and light. The heavy is > siff on setting but doesn't seem to displace tissue. Thanks, I will. I use PVS for crown and bridge, but it's a bit pricey for denture impressions. I have to compare to polyether vol/vol price for comparison--might be a bit less. But Parkell is probably a good place to look. Steve |
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