THE INCI-DENTAL BLOG

Apologise if this sounds a bit like a recipe book I’ll have to try to get some photos or a video on here eventually. The technique described below is my own to my knowledge but is an amalgamation of what I’ve picked up from books, hundreds of conversations with SHO’s, Consultants and VT’s. I have picked up much from carefully watching consultants working and trial and (mainly) error.

I don’t claim to be any kind of expert in denture making. This technique is not from any book i’ve seen and is probably not the textbook method. I’m also sure this technique will continue to evolve (hopefully with the help of your comments) as i gain more experience. However I would love it if anyone can profit from it, maybe even give it a go and who knows make a great pair of dentures.

Primary impressions: Currently I’ve been using compound when working in hospital and alginate in practice. I’ve not noticed much difference in the quality of special trays but i find compound slightly easier to use and i think patients prefer it (especially those with gag reflex). I prescribe a zinc oxide eugenol tray (single spaced)

Upper denture: I always start with this tray as lets be honest lower complete dentures are just not as satisfying!

Trimming tray: Hold tray against ridge with left hand and pull right cheek out as far as possible then down. Does the tray drop? If it does note where the muscle attachments are pressing on the tray. Remove tray and relieve this area. replace and repeat until tray does not drop. If it continues to drop but the muscle attachments are not catching then check the other extensions it’s usually the buccal flange in the first molar area pressing too deep.

Repeat on the left side and then repeat the sequence for the anterior frenal attachment and labial sulcus. It’s a little harder to manipulate the tissues in the anterior region so you have to work slightly by eye.

Applying Greenstick: Carefully heat the greenstick through. I find this is best done slowly dipping it in and out the flame and rotating. I think it’s very easy to melt a small section of greenstick so that it drips without it really being soft. Run along a section of the tray I try to do mine in 4 sections: right side, post dam and hamulus, left hand side and anterior region.

Think about how much greenstick you really need. If you have taken a good primary impression and trimmed your special tray carefully then only the thinnest layer should be required. This will just create that roll at the sulcus and definition of the muscle attachments which will make the denture comfortable to wear. I place a thin layer over the allotted section and go to a hot running tap. I wet my fingers (gloved before I get struck off) and make the greenstick into a fin. This is so that: 1) i know the material was hot enough as the fin will become compressed 2) The greenstick is itself more flowable in a thin section. Remember the greenstick needs to be really quite warm to flow effectively, you have to work quick.

Border moulding: I’m fairly enthusistic with my border moulding and i think you have to be. Greenstick really isn’t that flowable. I use a similar technique as i do for checking my tray extensions. pulling cheeks out and down as far as possible. When doing the post dam and hamulus you really need to press hard to define your post dam and get the patient to swing their jaw side to side to stop over extensions in this area.

Once the greenstick is completed the tray should be retained in the patients mouth hands free. It should also stay in place if you complete your border moulding movements. If it’s dropping then the greenstick is likely to be overextended and should be adjusted by heating with a pin flame or hot wax knife and reinserting. Obviously their comes a point when you have to be pragmatic if your not getting this retention but i find this is achievable with a bit of effort!

Zinc Oxide and Eugenol: The impression technique is fairly standard but should use all the same border moulding procedures as before. When the impression is removed it should be with great difficulty (get the patient to puff out their cheeks with their mouths closed if your really struggling). I would consider a good impression to have a shine through of greenstick on the borders this is because the zinc oxide should be incredibly thin in this area.

Lower tray: The lower tray is completed in much the same way but with the following alterations

Trimming tray: place the tray in position and hold back the cheeks on both sides. Does it jump up in the mouth? if so it is overextended lingually. The tray should only jump up if the patient raises their tongue high. To reduce the lingual extension run your finger along the lingual aspect of the patients ridge and feel for the Mylohyoid Ridge. The tray should finish just short of this. Feel for the ridge with the tray in the mouth with your finger under the tray and slowly raise the tray up until you can feel the ridge. This gives you a good estimation of how much the tray should be reduced.

Do this for both sides then look at the anterior lingual aspect. This is always difficult to judge how much to reduce but if the tongue catches the tray straight away as it lifts its usually because of over-extension in this area. I always think the the reduction needed in this area is counter intuitive as you need to thin the tray more often than you need to reduce it in height but eventually the tray will seat with the buccal mucosa retracted.

The next step is to let the right mucosa go when the tray is seated and see if the tray lifts, also check by pulling the cheeks out and upwards. If the tray is lifting adjust where the muscle attachments etc. Repeat this stage with the left buccal mucosa.

Applying greenstick: Once the tray is trimmed apply greenstick as before. The only difference is that if the ridge is very atrophic then i don’t greenstick in all areas.  Especially in the lingual area if i have just carefully reduced the tray to avoid overextensions. I think this is because the greenstick is so difficult to apply to the lingual flange that by the time you seat it, it is often too firm to flow and you create overextensions and roughness on the fitting surface of the tray.

Border moulding: When border moulding lingually i get the patient to raise their tongue as high as possible move it left and right firmly and push forward. I border mould the buccal sulcus as i do for the upper tray.

Zinc Oxide and Eugenol: Much the same as an upper tray but i find on occasions during the impression the patient may feel a rough area. Looking at the impression this always corresponds to a bit of greenstick which has found its way onto the fitting surface. I remove with a burr and tidy with wax knife and take a second impression in this area using “kelly’s paste “if available.

That’s it! phew! If you’ve read this far you officially love greenstick and can become a member of my I love greenstick club. Congratulations! Comments criticisms and advice are more than welcome

Good luck with your dentures

Chris