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Comment by sandworm101 | Hacker News Reader

Why grow new biological teeth? We have the material to create and implant fake teeth that are better in every way. The real question should be when will it become more practical to simply replace a tooth rather than fill/cap/drill to save the biological tooth.

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This is simply not true. Composites of today are still more brittle and fragile than human teeth. Also when implants are placed you're removing bone in order to place them. This can, and often does, weaken the placement region. Finally you're at higher risk of sinus perforation during extractions among other, generally permanent, complications. My SO is a DSS who does all of this and if you can keep your real teeth, they're almost always superior. Dr. Seuss had it right.

>>> Also when implants are placed you're removing bone in order to place them.

Read up on dental technology. Implants are not the cutting edge of anything. The modern trend it towards 3d printing the entire tooth, roots and all. Within a few years there will be no need to anchor to bone. Furthermore, steel is pretty strong. It doesn't shatter. A solid steel (or other metal) tooth, with composite/ceramic root structure, would last more than a lifetime.

Why on earth would you want a tooth made of steel? Steel is extremely dense and heavy; you don't want something that heavy in your mouth.

There's multiple reasons that implants today are made of titanium. Biocompatibility is one reason, but low weight is a nice bonus. Titanium isn't as hard as steel, though, but that shouldn't matter for fake teeth: it would likely be coated with a ceramic anyway, because no one wants gray-metal teeth unless they're trying to look like a Terminator. I'm pretty sure this is already how crowns are generally made today.

AFAICT, artificial teeth should outperform natural ones in every way, except one very important one: how it interfaces with the rest of the body. And that's probably the biggest reason there's research on growing replacements in-situ like this. It's like this for every kind of implant I think.

Like I said, my SO is a DSS and we get have copious literature on the topic lying around the house. All of the things you've outlined don't exist or are not widely 1) accepted and/or 2) not approved for use. And even if you can print an entire tooth including root structure placing these printed teeth is a challenge. I've seen crazy root structures my SO has shown me. Often times teeth need to be sectioned for removal of them which basically makes replacement impossible. With regard to steel with a composite on-lay, this is exactly what I'm talking about. While steel may last the composite on-lay will not. You're ignoring the difference in forces different teeth are subject to. Front teeth are cutting teeth and need longitudal strength. Ceramic is no comparison to the versatile strength of your original tooth which is why you'll often see total failure of an implant far more often than a shattered real tooth. While I realize you may have read a few things on the topic your comments showcase a lack of domain expertise, so kindly heed your own advice before positing inaccuracies.

Problem with implants is that they cause compressive stress to the bone, which causes bone to deteriorate. Teeth are held by https://en.wikipedia.org/wiki/Sharpey%27s_fibres. This converts the forces acting on the tooth to tensile stress on the bone, which causes it to grow more dense.

Implants are only one way of replacing teeth, anchoring replacements to bone. They are not the only method. 3d-printed replacements, with roots, are in development. They would be slotted into the hole left by a pulled tooth.

I have trouble believing that. New teeth would have nerves, for one.

Nerves in teeth could be considered a bug and not a feature. The sensations you want (chewing food) transmit mechanically through the jaw. The sensations that the tooth's nerve generate are unpleasant ones - extreme heat, cold, pain, sensitivity.

The pain part can be useful: if you have a tooth infection, that nerve tells you before the infection spreads to your brain.

The heat and cold sensations aren't terribly useful though.

Do you have implants?

I have a lot! They are more durable than biological teeth, the main drawback is that I need to be a bit more careful flossing.

Honestly, I'm not sure what's better, in the long run: An implant or regrowing a tooth. I guess it will really just come down to what's cheaper.

Dentists in my area have been told by insurance companies to pitch whole-tooth replacements instead of root canals. The failure rate at 10/15 years for root canals is higher than for implants. So it makes financial sense to just pull and replace rather than extensively repair a bad tooth.

I completely agree, I had a tooth pulled two weeks ago because it cracked after a root canal.

Prior to the root canal, I had a gum graft... I vaguely remember asking the surgeon if I should just have the tooth removed.

It would have been a lot cheaper, and simpler, to just pull the tooth in the beginning. It was in the back of my mouth, with no tooth below it.

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