Comments

You must log in or register to comment.

GeriatricZergling t1_is8krml wrote

Collagenous connective tissue. Basically, each tooth's roots sit in corresponding sockets, and there a thin but very strong layer of fibrous connective tissue connecting the tooth root to the surrounding bone.

This is why teeth can sometimes, but not always, fall out of long-dead skulls. Collagen is really tough stuff, and pretty decay resistant once it dries up, so if the skull is dry, the dried tissue keeps the teeth in. But if the collagen rots, gets wet, or is eaten by something, the teeth just fall out. Bone collecting subreddits are full of laments by people who put a skull in water and Dawn to degrease and all the teeth fell out.

252

Aceticon t1_is9ofpu wrote

I just wanted to aplaud you for your post's wonderful combination of well explained and just the right amount of creepy.

112

Ademoney t1_is9meel wrote

How do braces affect the fibers?

18

Astroglaid92 t1_isad23u wrote

There’s a lot of stuff going on physiologically when you put a constant force on a tooth, but that mostly involves gradually breaking down and rebuilding - or “remodeling” - the tooth socket walls. The periodontal ligament (PDL) fibers don’t do much themselves during tooth movement other than compress or relax and resist displacement of the tooth from the original center of the tooth socket. It’s actually a bit of a problem, because their natural rate of turnover (replacement of old fibers with new fibers) is slow and because tooth movement doesn’t seem to accelerate the rate of turnover for many of the PDL fiber components. That means that the fibers that were stretched during tooth movement will remain stretched and continue to apply a force that would return the tooth to its original position. This is one of the primary reasons for relapse following orthodontic treatment (in addition to continuous forces applied by the cheeks, lips, tongue, and jaws), and it’s why retainers are almost always recommended following orthodontic treatment.

For an idea of the timescale over which PDL and gingival fibers experience turnover, consider that the biological half-life of collagen fibers is about 9 weeks and that the half-life for elastin fibers is over 70 years! Meanwhile, bone can begin remodeling in as little as a week following force application to a tooth.

Interestingly, it’s the most accessible fibers around the neck of the tooth (just under the surface of the gums) that seem to provide the bulk of the relapse force discussed above, while the deeper fibers seem to remodel into more relaxed conformations within several months. So one method to reduce relapse - particularly for previously severely rotated teeth - is to sever those “supracrestal fibers” by cutting straight down through the gingival sulcus (gum pocket) to about the level of bone with either a scalpel or a laser. This is called a circumferential supracrestal gingival fiberotomy.

13

No-Jump-371 t1_isfrl6w wrote

Wow! Crazy interesting. But it also made my teeth hurt just reading about it! Yeooowch!

1

Starstroll t1_is9ndix wrote

That's wild. Have there been any attempts/successes at making new types of adhesives based on similar molecules?

3

GeriatricZergling t1_is9voqz wrote

Not so far as I know. Collagen isn't so much adhesive as it's physically linking things together, like a billion tiny, molecular ropes. Collagen is also present in bones and dentin in teeth, so it's basically tying on to the "rope ends" on each surface.

10

Wahoo017 t1_is92vib wrote

Your teeth are surrounded by bone under the gums. It is this boney support that holds them in place.

They are attached to the bone with very short ligaments. Lots of little fibers connecting root to tooth. These fibers don't flex very much, but it's enough to give you a sensation of biting pressure, and so that your teeth naturally can move just a little.

It is possible for the ligaments connecting your tooth to bone to die and the tooth and bone connect directly together. Hard to remove a tooth like this.

Gum tissue attaches to your teeth as well, and can hold on pretty tight, but this sort of attachment alone isn't enough to keep your teeth from falling out during use.

30

doughy1882 t1_is9u0y6 wrote

Your bottom teeth are constantly pushing your top teeth back into place and vice versa.

There is stuff that holds them in, but over time your body would push the teeth out

I had a top wisdom tooth with nothing below and it eventually starting dropping down.

5

Keyspam102 t1_is9vt7k wrote

Yup this is why it’s important to replace lost teeth, the pressure against the opposite tooth plus the pressure against the jaw is very important to how your mouth/jaw functions over the long term

7

tikkymykk OP t1_is9vcrg wrote

This is the answer that explains it for me. I finally understand. So simple and obvious but never crossed my mind.

3

somebody_DDS t1_isaj3kz wrote

Most of the answers here mention the bone and ligaments holding the teeth in, which is correct, but it’s also worth noting that your other teeth prevent each other from falling out. More specifically, the teeth opposite on the top and bottom of your jaw. When someone has a tooth extracted, it’s common for the tooth opposite to do something called “super erupt.” Super eruption means the tooth essentially grows out of the bone because there is no longer an opposite force keeping it in place. In severe enough cases, when the bone and ligaments around a tooth are also compromised, teeth can spontaneously fall out. This isn’t necessarily rare, but for most people it isn’t a concern.

3