THE INCI-DENTAL BLOG

When I left dental school I had made 12 sets of complete dentures. 3 years out and I must’ve made 250+ by now, maybe 2 a day on the go currently (what can i say where I’ve worked there are lots of edentulous post-pyorea 80-somethings). I don’t claim to be an expert, far from it, but I’ve tried and experimented with a few techniques some of which seem to work for me but only after messing around and repeatedly re-doing things until correct. You learn most from what doesn’t work.

First of all, the dental hospital teach a fairly out-dated technique as most prosthodontists now use A- silicones of a medium consistency in an appropriately-spaced tray. However the thing is, greenstick/zoe technique works! I think results with greenstick come as a result of practice and a little tweaking of the taught technique.

I think the think the place to start is by looking at the ridges and categorise the case as difficult or routine depending on the amount of ridge and it’s thickness, dimensions and sulcus depth and WIDTH. And remember, where indicated, the copy technique is the best method to do because assuming the patient used to like their old denture you can’t really make it worse. The lab will have copyboxes even though some technicians use putty and stock trays. Copy boxes work a treat and you can even do this technique easily on the floor of a retirement home if you have to!

If the patient has good ridges it will be possible to make a reasonable set of C/C with alginate imps as a secondary imp material (but remember the perforations needed in the tray). I think what’s more important than the imps is the reg and occlusion since the adhesion/cohesion, and stability are all better if this is bang on. In my experience alginate imps for dentures nearly always ends up in underextended dentures being made but not massively underextended. Using this method the overflowing alginate is often unsupported, thin and the flanges are also narrow. Most patients manage just fine but you’re always going to be able to remove these completes easily – muscle adaptation rather than a seal is what keeps ‘alginate dentures in’. There is some thought out there that upper denture flanges should be finished to a knife-edge!

Now the difficult case… When I’ve figured this I’ll let you know… ha.

Honestly, I think you can get away with any impression material for a well-formed ridge in the upper complete as long as the alginate is fairly runny (which most practice nurses can’t mix because their bosses have taught them to make it set as quickly as possible). However, I’m dubious regarding the lower completes in most cases; although in a routine case with good ridges I admit alginate seems to do the job ok. It’s the difficult cases where greenstick and ZOE come in useful and I have to admit I use the techniques that I was taught at dental school probably more than the alginate ones.

The reason I used alginate in the first place was the labs ability to give a perforated heavily-spaced tray even when asked for a ZOE-spaced special tray with no perforations. You often do what you can when the lab mess up! Guess what? I started to get reasonable results. At my practice I am the only dentist

who uses greenstick, compound and ZnOxEugenol routinely but I think I’m the one with the greatest number of free sample packs of Fixodent left at the end of the year! So make of that what you will. I think it’s knowing when alginate just won’t do a good enough job.

What I learnt by trial and error and a few courses/seminars:
1) compound in green stick form is at it’s best when used to capture the width of the sulcus, not the depth, as taught in school. If the depth is captured (in my hands) this gives overextended completes that ‘pop’ out when gently tugging at the patient’s cheeks. Greenstick should be placed along the buccal peripheral border of the tray and border moulded accordingly. This is never achieved first time so then I find the best think to do is use a chef’s torch to heat the greenstick locally, temper in warm water, then remould. Suction should be achieved before zinc oxide is used. Postdam has to be spot on for best retention.

2) Greensticking all around the lower denture means a bulky lower will result. I find that most people already have underextended completes and making it too bulky will not work as they will not tolerate it in the slightest. What I read about and concentrate on is getting greenstick around the retromolar/pear-shaped pad areas bringing it is far forward as the 6, 7 areas buccally and lingually. I also find placing it labially and a small amount in the lingual anterior helps with the stability. I then do the zinc oxide imp but use possibly a little too much so that when vigorously border moulding it displaces onto the side of the trays. I find the resulting denture isn’t overextended because greenstick use was minimal yet adaptation is good.

Also, it’s worth paying the extra lab bill for permanent bases as the retention is easily assessed early on (at reg and try in) and relines can be done if the denture is not up to scratch at try in. I think it’s important to stand back and assess how the dentures are going at each stage, rectifying problems early on.

Does anyone else find that after going through all the trouble of registering properly that the lab hand-articulate NHS work and so the occlusion can be off?

Another useful tip which I figured out when doing dentures on domiciliary visits is that there is no better special tray than the tried-in permanent base itself. What I mean is… Do primary imps in compound, then use these (which are usually overextended) to make the permanent bases. After removing the overextension at registration by trimming to about 2mm short of the buccal sulcus you can do the reg and pick shade. This misses out the major imps all together. What is this here? It’s a special tray! You can then do the zinc oxide impressions after the try-in via a closed mouth technique. The added advantages are that it saves a visit and you also get a ‘functional’ occlusion by using the closed-mouth impression technique thereby meaning there should be no cock up by the lab in getting a good even occlusion because it’s already been done and any slight (and i mean only slight) errors in occlusion are ironed out by doing the imps in this way. I find no occlusal grinding is needed at Insert. As I said this is unneccessary normally but very good when you’re using your own petrol as VT/GPT to go to nursing homes to make dentures and you want to get a good result quickly. There is no reason why this can’t be done in the surgery though. I use it when doing C/C overdentures because these often need relining over the abutments anyway. The only disadvantage I can think of is that the denture base may end up getting a millimetre or so too thick but no more so than when doing copy dentures as this is a cross between the two
techniques. It might poosibly increase the weight of an unretentive upper denture.

You are only as good as your technician though I’ve discovered, so ring up the lab and let the angry man out by giving them an earful! Also the worst bit is remembering the embarassment of explaining to a patient why your denture is crap if you don’t doit properly.