Everything you need to know about cavities
A cavity is a hole, and holes do not heal. But the stage before the hole can still be turned around, which is the whole reason check-ups exist. Here is how decay actually works.
A cavity is a hole in a tooth. That is all the word means.
The useful part is what happens before the hole, because that stage is reversible and the hole is not. Almost everything worth knowing about decay follows from that one distinction.
How a cavity actually forms
Your mouth is full of bacteria, which is normal and cannot be changed. Some of those bacteria live on sugar and starch, and what they produce is acid.
That acid sits against the enamel and pulls minerals out of it. Between meals, saliva does the opposite job, washing acid away and putting minerals back. All day, every day, your teeth are losing minerals and regaining them.
A cavity is simply what happens when the losing side wins for long enough.
The first stage is a softened, chalky patch on the enamel. There is no hole yet. Give that patch fluoride, keep it clean, and stop feeding it acid several times a day, and it can harden back up. This is the only point at which decay can be undone.
If it keeps going, the surface collapses and you have a hole. Enamel has no blood supply and no cells to rebuild itself, so from that moment it cannot heal. It can only be repaired, and it only gets bigger.
Where they start
Two places account for most of them.
The grooves on the back teeth, which are deep, narrow and often narrower than a toothbrush bristle.
Between the teeth, at the points where two teeth touch. This is the one people miss, because no brush on earth can reach there. That is what floss and interdental brushes are for, and it is why "I brush really well" is not on its own a defence against decay.
Gum recession adds a third site later in life, because the root surface it exposes is softer than enamel and decays faster.
Why it usually does not hurt
Enamel has no nerves in it. Neither does the early part of the layer beneath.
So decay can travel a surprising distance into a tooth without producing any sensation at all. Pain arrives when it gets close to the nerve in the middle, and that is late. By that point the conversation has often moved from a filling to root canal treatment.
This is the whole argument for check-ups, and it is not a sales argument. It is that the only reliable way to catch decay early is to have somebody look, with a light and an x-ray, before your body has any reason to tell you about it.
Signs worth acting on, none of which are pain:
- A tooth that has become sensitive to cold or to sweet things
- A visible dark spot, chalky patch or rough edge
- Food that keeps packing into the same gap
- A filling that feels different, or an edge that catches floss
Frequency beats quantity
This is the single most useful thing on this page.
Every time you eat or drink something sugary, acid production starts, and it takes a while for saliva to bring things back to normal. One chocolate bar eaten in one sitting is one acid attack. The same chocolate bar picked at over three hours is many attacks, and your teeth never get back to neutral in between.
The same logic makes a sipped soft drink, a sports drink at your desk, or a coffee with sugar topped up all afternoon much worse than they look on a nutrition label.
Practical version: keep sweet things to mealtimes, drink water in between, and let your mouth have long stretches of nothing.
What treatment involves
For a hole, a filling. The area is numbed, the decay is cleaned out, and the space is rebuilt with tooth-coloured composite that bonds to the tooth and is shaded to match it. Twenty minutes to half an hour, and then a check of your bite before you leave.
If the tooth has lost too much structure for a filling to be sensible, a porcelain inlay or onlay or a crown restores the shape properly and lasts far longer. Where a crown is needed, ours are made in our own lab at Southport rather than posted offshore.
If the decay has reached the nerve, root canal treatment saves the tooth. If it has gone further than that, removal becomes the last option.
Notice the direction of that list. Every step is bigger, longer and more expensive than the one before it, and every step was once the step before it.
If it is the dentist rather than the cavity that is putting you off
That is extremely common and it is worth saying out loud rather than waiting.
Tell us when you book. There is a lot we can do, from simply explaining every step before it happens through to sedation options for people who need them.
Read more: Scared of the dentist? It is not the pain you are afraid of
The bottom line
Decay is reversible right up until it is a hole, and it almost never hurts until it is deep.
Those two facts together mean the same thing: the only way to catch a cavity cheaply is to look for it before you can feel it.
A full check-up and clean is a fixed $249, which covers the exam, the scale and clean, fluoride and any bitewing x-rays you need, with your health fund claimed on the spot.
Preventive care FAQ
Can a cavity heal on its own?
The earliest stage can. When enamel has only started to soften and lose minerals, fluoride, better cleaning and cutting down on how often you eat sugar can harden it back up. Once an actual hole has formed, it cannot heal, because enamel has no blood supply and no way to rebuild itself. That is the whole reason for finding decay early.
Why does my tooth not hurt if I have a cavity?
Because decay starts in enamel, which has no nerves in it. Pain only arrives when the decay gets close to the nerve in the centre of the tooth, and by then it is much deeper. Waiting for pain is waiting for a small filling to become a root canal.
Does sugar cause cavities, or acid?
Acid does the damage, and sugar is what the bacteria turn into acid. What matters most is how often you eat it rather than how much. Sipping a sweet drink through the afternoon keeps your teeth under acid attack for hours, which is worse than the same amount of sugar eaten in one go with a meal.
Does getting a filling hurt?
The area is numbed first, so you should not feel pain during it. Most fillings take about twenty minutes to half an hour. If you are anxious, tell us when you book, because there is a great deal we can do to make it easier, including sedation options.
What are fillings made of?
We use tooth-coloured composite for most fillings, which bonds to the tooth and is shaded to match it. For larger repairs where a filling would be doing too much work, a porcelain inlay or onlay, or a crown, gives a stronger and longer-lasting result.
