Dental Adhesives.

[MWParticipant @mw27036]

Just throwing an idea out there.

I happened to be wondering once about the sort of adhesives used by either dentists for fillings or dental fixtures for dentures or tooth repair, what sort of adhesives are they? It's an interesting question because so many adhesives are biologically harmful, how could you have one that was constantly in contact with you all the time and potentially getting into what you eat and drink?

So, i have no idea how they managed to come up with one that was safe, But what sort of potential could said adhesives have in a workshop enviroment? Say you were making something for a disabled person or repairing ceramics/other materials that will be in contact with food and drink? I think it could have some interesting applications simply because it's adapted for biological contact.

Michael W

[MWParticipant @mw27036]

[Michael GilliganParticipant @michaelgilligan61133]

Going by smell … I think they are Acrylics

Logically, they are probably 'Toughened Acrylics'.

MichaelG.

[Enough!Participant @enough]

Good in shear; relatively weak in tension (like many other adhesives actually). A lot (most?) are UV cured.

As for the biological harm – it would be reasonable to assume that, giver the oral use, they have that one covered. Then again, in the days of amalgam fillings they said (words to the effect of): "sure we know it contains mercury but it's all locked up – don't worry about it". But they sure got rid of that material and replaced existing fillings in a hurry when better (and probably safer ) materials became available. At least, around here they did.

[Neil WyattModerator @neilwyatt]

Posted by Bandersnatch on 05/07/2016 21:51:46:

At least, around here they did.

The NHS still give you amalgam for your back teeth.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Michael,

I've just found this excellent paper anout Toughened Dental Acrylic

… Much easier than me trying to explain.

MichaelG.

[pgk pgkParticipant @pgkpgk17461]

The early ones were 'glass ionomers' the later generation are light set acrylics. CA type adhesives are used as tissue glues and I've known dentists use ordinary CA to temporarily bond crowns back ( because I happened to have a tube in my pocket and he borrowed it for a different paient).

I don't pretend to know the actual glue compositions but for deep thermal lining or to plug a pulp cavity then it's stuff called dycal (some sort of di-Calcium Phosphate mix sets in about 5mins) Enamel is etched with phosphoric acid gel then a liquid light set layer followed by packing with the light-set paste. NHS dentist are often lazy about thorough sanding of the fillings. For my (animal) patients I tried to let the final layer of paste form a meniscal type skin before setting (dentists don't wait)…. that was then very shiny and smooth and bypassed the need for sanding. However when the shape of repair didn't allow that then place and set the paste, shape and work down through the grades of grits. Shofu brand of discs were my choice if anyone has need to really polish up tiny items with dental handpieces.

Ocasionally we needed to reinforce the repair with some pins prior to filling over tem. Dentists have some neat little threaded studs on the handpiece shank that snap off once screwed in far enough.. could also be handy for some weird hobby applications

[KWILParticipant @kwil]

Those dental studs are tough. I once lost a filling on the day I was going away, it left the stud protruding. Tough little *****s to cut and I finished it off with the hand held diamond file!!

There must be a better modern material that stays in place longer than the infamous amalgam?

[Simon CollierParticipant @simoncollier74340]

I have some neat little threaded things that snap off when they are in the work too; they are called 8 BA taps.

[AjohnwParticipant @ajohnw51620]

Amalgam – I think the comments on this page are correct. It's best used for back teeth.

**LINK**

John

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[pgk pgkParticipant @pgkpgk17461]

I'm not sure why anyone uses amalgam still.. apart from trying to con folk into paying extra for a 'white filling'. Amalgam totally depends on a retentive shaped cavity to hold it in (or pins) and the only benefit i can see is that you can tamp the stuff in firmly and really remove any deadspace. The acryllic paste is softer to work and move about more but with etch and prep of the enamel it will stick as such. It's quicker to use, Doesn't involve mercuric fumes or another little machine to grind/mix and you don't get the ocassional poor devil picking up radio on their teeth or that nasty electric shock when a piece of foil wrapper gets chomped. It's not even that expensive (those extra charges are a con IMO). I didn't have that much dental work to do involving repairs and used to buy the demo kits that came with a whole colour range so i could really match them up for invisible repairs. Shelf life can be extended by keeping the kit in the fridge.

On the one ocassion the setting lamp failed while patient was on the table we set the paste using a fibre light guide from the endoscopy system… only took a few seconds longer.

[Peter G. ShawParticipant @peterg-shaw75338]

As has been mentioned, the NHS still use amalgam fillings for repairs which can't normally be seen. For repairs which can be seen, then white fillings are used. However, if you request it, NHS dentists will use white material instead of amalgam, but you have to pay extra – £50 or so on top of whatever the NHS charge would have been.

My wife and I have been requesting this for a long time now, say around 15 or more years – we are happy to take the financial hit rather than have fresh amalgam used on our teeth. Any existing amalgam is left in situ until it fails as apparently the problems occur when the amalgam is disturbed, eg when removing or being inserted. Please note I used the word "apparently" – I have no actual knowledge other than what I have picked up over the years.

FWIW, I had such a repair done only three weeks ago, had to remind the dentist about not using amalgam, and told him that I knew about and accepted the extra charge. He was a new dentist to me, so didn't know my requirements.

Peter G. Shaw

[Steve WithnellParticipant @stevewithnell34426]

Amalgam is better than the white material in a least three specific instances:

1. Molar teeth – something to do with the grinding motion of the rear teeth, makes amalgam a better choice.

2. Teeth that have had root canal treatment. Amalgam seals the tooth better than the white composite and improves the prognosis. Its better at keeping bacteria out.

3. Large fillings. The white composite is more difficult to form into a natural shape and produce a good biting surface and is harder then amalgam, which means machining it is harder to do, so you can end up with a less effective tooth.

It's worth challenging your dentist if they propose composite over amalgam for a filling and definitely in the case of a tooth with a root canal treatment.

I'm not a dentist – but I've spent too much time with three different dentists over the last 18 months in two different practices and the above is the consistent message I 've had from them.

Steve

[Mike PooleParticipant @mikepoole82104]

Using my teeth as wire strippers I split a lower incisor and later when biting into something the entire front of the tooth broke off. My dentist used a white type filling to repair the tooth, he did not hold high hopes of the durability of this repair but 18 months later it is holding up well and looking in the mirror I struggle to see which tooth it was. I suspect the future will require a much more expensive repair but so far am really impressed. I also now look a bit harder for the wire strippers.

Mike

[pgk pgkParticipant @pgkpgk17461]

I don't read human dental stats so not in a position to argue over details. I did make the point that amalgam can be tamped in harder to reduce dead space. However on a root canal which traditionally was cleaned out to healthy dry dentine filings (often over more than one session in people but since my work was under g/a we tried to get the job done in one long session) then again following tradition packed with zinc oxide and eugenol paste.. although newer antibacterial materials are often used now. The next layer is nearly always the dycal liner.. as mentioned before particularly with amalgam you want a thermal barrier and while the zinc ox/eugenol stays pasty the dycal dries to a firm but carvable barrier so you can reshape the liner with hand tools for best retention. The dead space issue with composites is aleviated by starting with a settable liquid.. place on a cotton swab, blow off excess with air and set.. repeat if necessary before staring the paste. And the paste can be applied in layers so you can push it about to try and deal with deadspace as well as building up your shape – which is where the artistry and aesthetics and patient comfort come from.

Apart from the deaspace arguement I actually expect (but again don't read human stats) that the edges bonded to etched enamel with composites might well seal against new bacterial tracking better than a firm plug.

Way back in history I had work done by a mate who was a dental student. At that time any suggestion of opening a pulp chamber and it was mandatory to place a rubber dam around the tooth and isolate from the mouth to keep things clean. I've never seen a qualified dentist do that… it's hassle and more awkward to work around. NHS guys work at production rates and speeds with a mandate only for 'reasonably dentally fit'

A few years ago I lost a bit of molar side wall and the ancient root-canal pinned chem-set filling came out with 'the pins. We'd just moved here and the NHS dentist i went to took one look and called for extraction tools. She seemed incapable of any technical discussion as to why it had to be removed rather than repaired apart from 'it won't work'.

I walked out and went to a private chap who sensibly agreed there was nothing to lose by trying to salvage the tooth and rebuild the whole thing with modern composites. He guessed it might be good for a couple of years and it's now 5yrs and counting.

Of course there are other factors that come into this.. state of gums and bone density would be right up there. Sadly for us for NHS dentists it's often speed/their cost for the set fee that decides the route they take.

[Neil WyattModerator @neilwyatt]

Posted by Michael Poole on 06/07/2016 22:12:22:

Using my teeth as wire strippers I split a lower incisor and later when biting into something the entire front of the tooth broke off. My dentist used a white type filling to repair the tooth, he did not hold high hopes of the durability of this repair but 18 months later it is holding up well and looking in the mirror I struggle to see which tooth it was. I suspect the future will require a much more expensive repair but so far am really impressed. I also now look a bit harder for the wire strippers.

Mike

I have a a white filling repair to a small chip on a lower incisor. Several dentists had put on a small blob which lasted days, but this one drill;ed a tiny hole and touch wood, it's lasted many years.

Neil

[AjohnwParticipant @ajohnw51620]

I had amalgam replaced with the most suitable white stuff on one back tooth. No extra charge at all. Problem. The tooth broke not long after and had to come out. It put the dentist off using it for back teeth. Actually I think that the NHS point out that amalgam need not be used now but point out that it more robust.

My memory from years ago tells me that the used something referred to as compo under amalgam. I think they still do.

I also had a crown come off. I expected the dentist to stick it back on. He drilled more away and built up some sort of UV compound and then shaped it with the drill asking me to check for roughness. No peg in it either. It just sits on top of a flattened molar. Charge – as per a filling. It's still ok 3 years later but I still think I would have preferred the crown.

A dental nurse once told me that the treatment people get is very dependent on where the dentist was trained. The practice has several from different areas of the country.

I seem to have less problems with ones trained in B'ham.

John

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[mechman48Participant @mechman48]

I've resolved my teeth probs… had them all out bar two top molars to clip the dentures to,

George.

[Steve WithnellParticipant @stevewithnell34426]

Posted by pgk pgk on 06/07/2016 23:04:51:

Way back in history I had work done by a mate who was a dental student. At that time any suggestion of opening a pulp chamber and it was mandatory to place a rubber dam around the tooth and isolate from the mouth to keep things clean. I've never seen a qualified dentist do that…

The last root canal treatment I had was done by an Endontologist at huge expense (more than I paid Ketan for my C6!) he used a rubber dam, wondered what it was for!

Steve

[pgk pgkParticipant @pgkpgk17461]

Posted by Steve Withnell on 07/07/2016 19:48:15:

The last root canal treatment I had was done by an Endontologist at huge expense (more than I paid Ketan for my C6!) he used a rubber dam, wondered what it was for!

Steve

Done 'by the book' it' an involved process and if he was really well equipped with the latest gadgets then likely had fibreoptic lights and a camera in the dental drill and certainly digital x-rays for progress checks.

The other end of the scale is a US vet i knew that fixed a canine tooth on a tiger… using a makita cordless and a 5/8 drill to ream the pulp chamber. You start mixing materials by the oz instead of a few drops for that.

Before i was fully kitted out with dental supplies i had a German Shepherd canine root canal to do. I borrowed pastes from my own local dentist and later bitched at him that he was so mean I'd only just managed with the supplies he gave me. His answer was that he'd given me enough for 6+ people teeth

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