Assembling a Tooth

[RABaker96]

I was out hunting shark teeth after the latest rain here in Central Texas, and came across something a bit more interesting, but in several pieces. I have seen the concerns and recomendations for elmers glue or for higher-end paleo adhesives, and was wondering if there is a readily available compromise to help piece this back together, or should I wait and order the paleo glues?

Pictures include the main pieces held together, and the unfortunate condition of the tooth in its natural, broken, form. As for location, this came out of the Del Rio claystones (Washita group), which were quite soggy, and this tooth fell apart as it slipped out of the matrix.

thanks

[JohnJ]

You'll want to use an acetone soluble adhesive for that meticulous of a reconstruction. I've done some about that bad; you'll need to do it under magnification.

I wouldn't be surprised if that was pliosaur or plesiosaur. Really nice finds.

[TNCollector]

I use super-glue to reassemble broken fossils. I like the gel kind specifically, as it fills in the cracks and pores and creates a better hold.

[Runner64]

Without a complete tooth it's hard to say what it's from. Pliosaur and plesiosaur are plausible and is a possibility as to what it came from.

[LordTrilobite]

You might find this useful. Personally, I use cyanoacrylate for my preps.

Edited November 4, 2015 by LordTrilobite

[Ptychodus04]

I have pieced together some dinosaur teeth for clients that were in rougher shape than this. I like the high viscosity Paleobond (750cps or 1500cps) for these jobs. There's even one that is 80,000cps. It is great for filling really bad, ill-fitting, cracks. Beware, the high viscosity cyanoacrylates can take a while to set without an activator.

[Troodon]

I like a cyanoacrylate adhesive for teeth. Paleobond is my choice and the viscosity is dependent on how bad the cracks are.

[Harry Pristis]

First, consolidate the pieces with an acetone/plastic solution. Then assemble the pieces with any sort of glue you prefer, even white glue. Fill in gaps with black epoxy putty.

[Ptychodus04]

My experience with Texas reptile teeth has been that consolidation with PVA or Butvar is not beneficial. The solution does not readily penetrate the fossil except for in the most weathered specimens. The plastic just sits on the surface.

[Harry Pristis]

My experience with Texas reptile teeth has been that consolidation with PVA or Butvar is not beneficial. The solution does not readily penetrate the fossil except for in the most weathered specimens. The plastic just sits on the surface.

If the tooth were intact, maybe no consolidation would be necessary (though my advice always is to consolidate. Better safe than sorry). Since the tooth is falling apart, I speculate that there are further micro-cracks in the tooth parts. Consolidation in this case would serve to bind the tooth parts together by penetrating those micro-cracks.

[Troodon]

My experience on assembling dinosaur teeth is that an initial coating on the pieces is not beneficial since its not absorbed and you wind up with a fit problem. However once the tooth is assembled a very light coating is necessary to take care of those micro cracks.

[Doctor Mud]

Good luck with the tooth surgery!

Some great advice as usual from the TFF crew.

Things maybe worth thinking about:

Adhesive: I think JohnJ's suggestion is great. You'll at least want time to position the fragments as they look crumbly. Even when they are solid and you can practice there always seems to be the "adhesive anxiety" effect. "Gotta get this in position quick before the glue sets" and it never seems to go as smoothly once adhesive is involved :-0

Something that sets quickly but is reversible is useful. You can roughly position fragments and then add a drop of acetone to dissolve the glue and reposition. You can also use the pva (or other acetone based solution) to pick up fragments and handle them with a brush.

Dip your brush in the solution then pick of the fragment. Have a second brush you can dip in acetone or pva to release from the brush.

As others have said consolidation may or may not benefit. Depends on whether it will penetrate and if the bits are likely to fall to pieces when handling them. Maybe try out on the bigger fragment first? It's always reversible.

Good luck!

[JohnJ]

Good luck with the tooth surgery!

Some great advice as usual from the TFF crew.

Things maybe worth thinking about:

Adhesive: I think JohnJ's suggestion is great. You'll at least want time to position the fragments as they look crumbly. Even when they are solid and you can practice there always seems to be the "adhesive anxiety" effect. "Gotta get this in position quick before the glue sets" and it never seems to go as smoothly once adhesive is involved :-0

Something that sets quickly but is reversible is useful. You can roughly position fragments and then add a drop of acetone to dissolve the glue and reposition. You can also use the pva (or other acetone based solution) to pick up fragments and handle them with a brush.

Dip your brush in the solution then pick of the fragment. Have a second brush you can dip in acetone or pva to release from the brush.

As others have said consolidation may or may not benefit. Depends on whether it will penetrate and if the bits are likely to fall to pieces when handling them. Maybe try out on the bigger fragment first? It's always reversible.

Good luck!

Precisely the problem. With these teeth, you are dealing with fragments so small that positioning will not always happen as fast as cyanoacrylate drying. A combination of tactics might come into play in this situation. This is all best done under high magnification.

[Doctor Mud]

Well put JohnJ,

A combination of tactics :-)

It can seem like a little battle to reassemble teeth.

I should say that I've never worked on reptile teeth, but these tactics worked on shark teeth. I was dissolving brittle teeth out of matrix and they needed to be pieced back together. I did it under a dissecting scope.

You can pick up fragments with a brush dipped in water too, but I preferred acetone or pva as it dries quickly. A dry brush can send little fragments flying away! Keep a clean workspace just in case :-)

[Harry Pristis]

"Coating" is not what consolidation is about; coating is for surface treatment. Consolidation is about penetration, which requires inundation.

[LordTrilobite]

Hm, in my previous post I tried to post this picture. But it seems something whent wrong. So here it is again.

This should be useful.

[Ptychodus04]

If the tooth were intact, maybe no consolidation would be necessary (though my advice always is to consolidate. Better safe than sorry). Since the tooth is falling apart, I speculate that there are further micro-cracks in the tooth parts. Consolidation in this case would serve to bind the tooth parts together by penetrating those micro-cracks.

I agree that a final consolidation is in order once the tooth has been repaired. I was just saying that consolidating individual bits prior to assembly is not beneficial on these things. As Troodon said, it causes fit problems on these teeth.

I also don't worry about fitting every microscopic fragment in its place. Often, these little fragments are impossible to properly fit. Typically, the tooth will require some restoration anyway.

[Auspex]

I think one of the factors for the general admonition to consolidate fragments before re-assembly is that (in the case of porous bone, anyway) flooding with consolidant after gluing can undo the gluing (since the solvents are often universal).

[Ptychodus04]

I think one of the factors for the general admonition to consolidate fragments before re-assembly is that (in the case of porous bone, anyway) flooding with consolidant after gluing can undo the gluing (since the solvents are often universal).

Agreed. In the case of nonporous tooth enamel, this practice (in most cases) is detrimental rather than beneficial to the repair process.

When repairing fossil bone, I always consolidate prior to reassembly. This greatly improves the adhesive bonding and prevents the scenario you are describing.

[Auspex]

I did have the sense that non-porous enamel is a different deal altogether, and could be the exception that proofs the rule.

[Ptychodus04]

I did have the sense that non-porous enamel is a different deal altogether, and could be the exception that proofs the rule.

I honestly hate repairing/restoring teeth for this very reason, not to mention the fact that the adhesives don't readily penetrate the enamel either. You wind up with a fairly weak bond no matter what you do.

[Harry Pristis]

Well, Chas, if you were dealing only with enamel, consolidation before assembly might be optional. As it is, tooth enamel is typically bonded to dentin which is frangible and permeable. It is the dentin that should be consolidated.

And, Kris, enamel is not the prime target of consolidation; the prime target is the dentin with the secondary (but critical) purpose of binding unseen micro-fractures in the tooth, including the enamel.

Try the fit of the consolidated pieces. If consolidation plastic interferes with tight joints upon reassembly of the tooth, the consolidant solution might be too thick. The fix in that case is to remove the plastic on the join edges with acetone on a cotton swab. Trying the fit and cleaning the join edges is possible because the tooth parts are consolidated and sturdy.

Adhesive bond is not so much dependent on penetration as on surface area of the bond. A rough surface offers much greater surface area than does a smooth surface. The joins even with white glue on a reassembled tooth are likely to be stronger than the unbroken areas of the tooth, if the joins are of a sufficient surface area.