One of the most common things I hear from patients is some version of: “It doesn’t hurt, so I figured it could wait.” And I understand that reasoning — life is busy, dental appointments aren’t anyone’s favorite, and if nothing hurts, it’s easy to push it to the back of the list.
The problem is that cavities don’t hurt until they’ve progressed significantly. By the time a cavity is causing you pain, you’ve already missed the window for the easiest and least expensive treatment. Understanding how tooth decay progresses is one of the most useful things a patient can know — because the difference between a small filling and a root canal or extraction is almost always just time.
A cavity begins with bacteria. Your mouth is home to hundreds of species of bacteria, and some of them — particularly Streptococcus mutans — feed on the sugars in your diet and produce acid as a byproduct. That acid attacks the mineral structure of your enamel, the hard outer layer of your tooth.
In the very early stages, this demineralization can actually be reversed. Fluoride, good saliva flow, and reduced sugar intake can allow the enamel to remineralize before a true cavity forms. This is why early detection matters — a dentist can identify areas of weakened enamel before they become holes.
Once the enamel breaks down enough to form an actual cavity — a physical hole — remineralization is no longer sufficient. The tooth needs to be cleaned and restored.
At this stage, the decay is confined to the enamel. This is the ideal time to treat a cavity. The procedure is simple: remove the decayed material, clean the area, and place a filling. Local anesthetic is usually sufficient. The appointment is short. The cost is low.
There is typically no pain at this stage. The enamel has no nerve endings, so you won’t feel anything. This is why regular X-rays and examinations are essential — this is the stage you want to catch it.
Below the enamel is dentin — a softer, more porous layer that surrounds the nerve of the tooth. Once decay reaches the dentin, it progresses much faster. The tubular structure of dentin allows bacteria to travel more quickly toward the nerve.
At this stage you may begin to notice sensitivity — to cold, to sweets, sometimes to hot. The tooth may be mildly sore when you bite. But many patients still don’t notice anything, or dismiss the sensitivity as something else.
Treatment at this stage is still a filling, but it’s a larger one. The procedure takes longer, costs more, and the proximity to the nerve means there’s a higher chance of sensitivity after the filling is placed. Still, a filling is the right treatment, and outcomes are generally excellent.
As decay continues through the dentin and approaches the pulp — the innermost part of the tooth containing the nerve and blood supply — symptoms usually become more noticeable. You may feel a lingering ache, spontaneous pain that comes and goes, or significant sensitivity to temperature that doesn’t resolve quickly after the stimulus is removed.
At this point, a filling alone may no longer be sufficient. Depending on how close the decay is to the pulp, the dentist may be able to place a deep filling with protective materials, but there’s a real risk that the nerve will become infected or die anyway, requiring further treatment.
The tooth may also have lost enough structure that a crown is now necessary to restore it properly, even if the nerve is still healthy.
When bacteria reach the pulp, infection sets in. The nerve becomes inflamed, dies, and the bacteria begin to colonize the root canals — the narrow channels inside the roots of the tooth.
This is when the serious pain typically begins. Throbbing pain, pain that wakes you up at night, pain that radiates to your jaw or ear. Some patients experience an abscess — a pocket of infection at the tip of the root that causes significant swelling and discomfort.
At this stage, the treatment is a root canal. The infected pulp tissue is removed, the canals are cleaned and shaped, and the tooth is filled and sealed. A crown is almost always required afterward because the tooth has lost significant structure and is now more brittle.
A root canal is a very routine procedure and is not the ordeal its reputation suggests. But it is substantially more involved, more time-consuming, and more expensive than the filling that could have resolved the problem months or years earlier.
If an infected tooth is left untreated long enough, the infection spreads. It can destroy the surrounding bone, involve neighboring teeth, and in severe cases spread beyond the mouth. Dental infections, if left long enough, can become life-threatening — though this is fortunately rare.
At some point, the tooth may be too far gone to save. Extraction becomes the only option. And then you’re back to the situation described in our previous article — a missing tooth, bone loss, and the need for an implant or other replacement.
A small filling might cost a few hundred dollars. A root canal and crown can cost many times that. An extraction followed by an implant can cost significantly more still — and involves a much longer timeline and additional procedures.
The cavity doesn’t get smaller by waiting. It doesn’t get cheaper. It doesn’t get easier to treat. Every week that passes, the decay moves closer to the nerve and your options narrow.
Pain is a late warning sign, not an early one. The absence of pain does not mean a tooth is healthy. It means the decay hasn’t reached the nerve yet.
Regular dental exams — including X-rays — are the only way to catch cavities at the stage where they’re cheap and easy to treat. If you’ve been putting off a visit because nothing hurts, that’s exactly when you should come in.
We’re always straightforward with you about what we find and what it means. Complimentary consultations are available for new patients.
— Dr. Dane Boren
