why is it that you can break a piece of a tooth and it doesn’t need fixing, but if you have the tiniest cavity it has to get filled ASAP?



why is it that you can break a piece of a tooth and it doesn’t need fixing, but if you have the tiniest cavity it has to get filled ASAP?

In: Biology


A cavity is decay-it is dead and dying areas with bacteria, and can spread if not taken care of. A cracked broken piece of tooth, depending on how deep the break is, won’t cause increasing problems over time.

Dentin, the inner layer of tooth underneath the enamel,, is much softer than enamel.
If a cracked or broken tooth is not broken into the dentin of the tooth, it may be stable, and in, there’s not an increased chance of it developing decay.
If even a small cavity reaches the dentin, the bacteria causing the decay can make the cavity grow very quickly.

Breaking a tooth isn’t a problem in itself, but more than likely the jagged surface of newly broken tooth is a better landscape for bacteria to nestle and grow compared to smooth enamel. That’s why a broken tooth should really be repaired.

For cavities, once bacteria reaches your pulp, that’s when toothaches become unbearable.

There’s two layers surrounding the pulp of the tooth: the outer hard enamel layer and the inner soft dentin layer. When cavities are only in the enamel layer, you can stop the further decay and promote re-mineralization by brushing and flossing away any ‘loose’ bacteria after a day’s worth of eating food. But once bacteria penetrates the dentin layer, it has a much higher chance of becoming its own little bubble that protects itself from your efforts to brush. This enables it to burrow deeper and eventually reach your pulp .

To add to above – bacteria in the dentine induce a reaction in the pulp once they are near it (don’t have to be in it). Inflammation of pulp is painful. Infection in pulp means Root Canal Treatment or Extraction.

Broken teeth, especially if only enamel, tend not to be painful, maybe just a bit jaggy or sensitive, as no inflammation/infection.

Source – I am a Dentist.

Looking at the answers so far; they’re good answers but some still seem a little technical for ELI5. Think of it like a car. If your car gets a little dent because something hit it, it shouldn’t dent more on its own. If there is rust on the car, it’ll slowly eat away at that area until it’s taken care of properly. The rust is like a cavity and the dent is a tooth chip.

Where on the tooth?

The biting surfaces are typically much thicker than the sides, and generally experience more tooth-on-tooth and toothbrush contact that keeps plaque from accumulating. You can still get cavities in crevices along the biting surface.

The sides of teeth (especially the sides between adjoining teeth) are easily covered in plaque, or even hard tartar if your brushing is poor. Toothbrush bristles will not be able to reach into the cavity, allowing bacteria and food to remain lodged.

The harder enamel can also [conceal damage](https://www.reddit.com/r/ThingsCutInHalfPorn/comments/7x209y/cross_section_of_a_molar_with_tooth_decay_800x1128/) to the less-sturdy dentin beneath it. From outside, it would just look like a small crack with maybe some dark discoloration. The crungy stuff in the upper half should normally be brighter white dentin.


If you slice a piece of bread, the rest of the bread is okay to eat. If bread gets apple juice on it that part becomes soggy apple juice bread that doesn’t taste good.

You have to cut out the wet part or the apple juice will spread and more of the loaf will be soggy apple juice bread that you can’t eat.

chip on a tooth is fine, as long as it’s not too big. problem with cavity is that it goes deep, where the nerves are.


The issue with a cavity is that it becomes a pocket that shelters bacteria from brushing and from your saliva. Saliva itself will help kill harmful bacteria, but the deeper a cavity gets, the more safe that harmful bacteria will be from any preventative measures.

Additionally, a cavity means that the bacteria has worn through the enamel of your tooth (the protective layer) and into the softer material. At this point, the cavity will progress much faster, getting deeper and creating more area for the bacteria to work its way not only deeper but wider into your teeth.

I work reception at a dental office.

Ideally, you should get both fixed ASAP. With breakage, it can depend on how much of the protective enamel has broken and whether the nerve is exposed. If it’s just a slight chip, the dentist may mark it as something “to watch”- aka to be re-evaluated at your next check up. But if the bottom part of the tooth is just hanging off and the nerve is exposed, you will likely need an extraction.

Cavities are active decay that have infiltrated the protective enamel surrounding your teeth. Teeth are basically bones- the protective structure on the outside does not grow back once decay has infiltrated, and once it reaches the inner nerve(s) of the tooth there is then a risk of a blood infection forming within the jaw, and that could eventually cause issues elsewhere in the body.

Also, the longer you leave a cavity, the more expensive potential treatments could become. If a nerve or 2 dies inside of the tooth because the filling was put off, that could turn into a root canal AND a filling, which at the clinic I work at can be around $1200 compared to the $150 for the filling alone. And then because of the weakened state of the tooth post-root canal, most dentists will recommend a crown (think of it as a protective hat for your tooth that is cemented into place.) That can be an additional $1500.

So when you look at the cost of dealing with a small cavity ASAP ($150) vs. dealing with it when the pain is no longer tolerable ($2850), the answer is a no brainer.

Cracked tooth is already broken and the bottom of the remaining tooth is similar to the bottom of a fixed tooth when it comes to bacterial breeding grounds. A little cavity can grow and ultimately destroy an otherwise good/living tooth, not to mention a little nook can allow bacterial growth that wont constantly be slapped silly with saliva, tongues, food, and might allow for some nasty bugs to get a firm footing.

Most of your tooth doesn’t have nerves in it. If you chip it without getting deep enough to hit the nerve, it’s kind of like clipping your nails and you won’t deal with too much pain, if any. Getting a cavity is like slicing open the nail bed and letting it get infected. The pain can range from very little to mind-numbing, and can take several forms. Sharp, dull constant, throbbing. Sometimes killing the bacteria will end the toothache, other times the nerve is exposed and everything causes it to hurt.

Source: lost most of my teeth through a combination of poor genetics and tons of energy drinks and unfortunately have a lot of experience with both cavities and broken teeth.

Because the cavity is growing but the chip is not. It’s all about preserving the function of your teeth.

If your teeth can function with a chip, and it doesn’t look like overtime this chip will turn into something bigger, your teeth are working fine with it and you don’t need one.

If your teeth are working fine with a cavity, you still need a filling. Because the cavity is tooth decay which means it eats away at your teeth. Eventually, your teeth will succumb to the cavity, and if you don’t treat it soon enough the whole tooth will be gone.

For the record, tiny cavities *can* be left alone. It depends on what your dentist prefers, but if they notice a small amount of tooth decay, that has not grown because of flossing and brushing, they can leave it alone. That being said, the bigger the cavity the more difficult it is to fill.

So short andwer is you can leave tiny cavities. But the principle is that it’s a waiting game of when your tooth will succumb to the cavity. It’s an inevitable threat. Whereas certain breaks do not get bigger, so if they aren’t a problem now, they likely won’t be a problem a few months from now.

Think of it as a banana- if you cut it in half, it will heal over(this would be a chip). But a disease that rots the banana will spread until the banana is gone or it is stopped(this would be the cavity)

Many dentists will use language that minimizes the severity of the issue to keep the patient from either feeling like shit or hating the dentist because they “have perfect teeth”. The choice of words isn’t helpful for either party. A cavity is decay and a chip is a chip. All decay needs to be repaired or it grows. Not all chips are a problem.

A cracked tooth is like decent sized cut in your arm. It’s a risk factor and the safe choice is get it looked at just in case, but lots of people deal with themselves and turn out fine.

A cavity is like if the cut gets all swollen and full of pus. There’s an active infection, and it will almost always only get worse if you don’t go to a professional

This won’t be 5 yo level, but it is an important aspect that I haven’t seen anyone explain (or I missed it)

Cavities usually form in places where there is no or not enough self-cleaning (by the tongue or saliva) or mechanical cleaning (by toothbrush, floss). For example the back teeth’s grooves (not sure of exact english terminology), or between two teeth, and so the bacteria can be there for a long time without you cleaning it off, and slowly eat away the enamel, then the dentine until it reaches the pulp (the inside of a tooth that contains nerves and etc.), and you will likely need a root canal treatment (killing the tooth essentially). Fillings in due time can stop this process, still in the enamel if caught early, so the bacteria do not reach the pulp, and the decay is stopped.

Chipping and other trauma damage is usually at the fronts and on surfaces that are self-cleaning and/or are easy to clean mechanically. For example the incisal part of your first teeth. In these places the bacteria do not have enough time to eat through your tooth because you are cleaning them off twice a day (hopefully). Now, this varies based on the amount of damage, if the chip is deep and reaches the dentine, the bacteria have a highway to reach the pulp, and you can’t clean it effectively, so if it is not filled and treated soon, it will be the same as a cavity.
If it is just a millimiter off the top, that is still in the enamel, which is good at stopping bacteria, so that tooth may never have problems.
Although in case of trauma it is always a good idea to go for a checkup, because there could be damage to other parts around your teeth that could lead to the need to extract that or other teeth.

Hope this helped, let me know if I can help explain any more.