Cavity treatment depends entirely on how far the decay has progressed. A cavity caught early, before it breaks through the enamel surface, can sometimes be reversed with fluoride alone. Once decay creates an actual hole in the tooth, a dentist needs to remove the damaged material and restore the tooth with a filling, crown, or in severe cases, a root canal. Here’s what each stage looks like and what to expect.
Early Decay Can Be Reversed Without a Filling
Not every cavity needs a drill. When decay is still in its earliest stage, it shows up as a white spot on the enamel where minerals have been lost. At this point, the tooth hasn’t developed a hole yet, and the damage is reversible. Enamel can actually repair itself using minerals from saliva combined with fluoride from toothpaste, mouth rinses, or professional treatments.
If your dentist spots early demineralization, they may apply a fluoride varnish or gel directly to the tooth surface, prescribe fluoride tablets, or recommend a fluoride mouth rinse. These concentrated fluoride applications help drive minerals back into the weakened enamel, essentially hardening it again before a cavity forms. This is why regular dental checkups matter so much: catching decay at the white-spot stage can save you from needing any restorative work at all.
Silver Diamine Fluoride: A No-Drill Option
Silver diamine fluoride (SDF) is a liquid that a dentist paints onto a decayed tooth to stop the cavity from progressing. The American Dental Association issued its first clinical recommendations for SDF in 2018, and it has become especially popular for treating children. In a large randomized trial of over 7,400 children, SDF performed just as well as dental sealants and traditional restorations at preventing new cavities and managing existing ones.
The main trade-off is cosmetic. SDF permanently stains the treated area black, which makes it less appealing for front teeth. However, when applied to back teeth, studies found no difference in how children perceived their smile compared to those who received traditional treatment. SDF also had no negative impact on oral health-related quality of life in the children studied. For young kids, anxious patients, or anyone who needs a quick way to halt active decay before a more permanent fix, SDF offers a painless alternative that takes seconds to apply.
What Happens When You Get a Filling
Once decay has broken through the enamel and created an actual cavity, the damaged tooth structure needs to be physically removed and replaced. This is the most common cavity treatment. Your dentist numbs the area, removes the decayed material with a drill (or in some cases a laser), and fills the resulting space with a restorative material.
The two most common filling materials are composite resin (tooth-colored) and dental amalgam (silver-colored). Amalgam fillings last longer and cost less than composite resin. In one analysis, composite fillings showed the highest failure rates within the first 36 months, while amalgam demonstrated greater durability beyond that timeframe. Teeth restored with amalgam also tend to need crowns or extractions later in life compared to composite, simply because the restoration holds up longer before problems develop.
Composite resin has become the more popular choice despite its shorter lifespan, largely because it matches the color of your natural teeth. The procedure takes slightly longer than placing an amalgam filling, but the difference in chair time is minimal. Your dentist will recommend one material over the other based on the size and location of the cavity, the amount of chewing force the tooth handles, and your preferences.
Laser Treatment as an Alternative to the Drill
Some dental offices now use erbium lasers to remove decay instead of a traditional high-speed drill. The FDA has cleared this type of laser for removing all classes of decay, shaping the cavity, and preparing the tooth surface for bonding. In clinical trials, the laser performed equal to or better than the drill for these tasks, and patients were consistently treated without anesthesia.
Microscopic analysis of laser-treated teeth showed no microfracturing of the surrounding tooth structure, and tissue samples confirmed the inner pulp of the tooth wasn’t damaged by the procedure. Laser treatment tends to be quieter and vibration-free, which makes it appealing if dental anxiety is a factor. Not every office has the equipment, and it may cost more than conventional drilling, but it’s worth asking about if the sound and sensation of a drill keep you from seeking treatment.
When a Filling Isn’t Enough
Larger cavities that have destroyed a significant portion of the tooth may need a crown rather than a filling. A crown is a custom-made cap that fits over the entire visible portion of the tooth, restoring its shape, strength, and function. Porcelain-fused-to-metal crowns typically cost between $800 and $1,400 per tooth before insurance. The process usually requires two visits: one to prepare the tooth and take impressions, and a second to place the permanent crown.
If decay has reached the innermost part of the tooth, where the nerve and blood supply live, you’ll likely need a root canal. This procedure removes the infected tissue from inside the tooth, cleans and seals the internal channels, and preserves the outer shell. A root canal stops the infection, relieves pain, and prevents bacteria from spreading deeper. In many cases, a crown is placed over the tooth afterward to protect what remains, since a tooth that has had its inner tissue removed becomes more brittle over time.
Why Fillings Fail and What Causes It
Fillings don’t last forever. The leading cause of restoration failure is new decay forming around the edges of an existing filling, which was present in 73.5% of failed restorations in one retrospective study. Microleakage, where tiny gaps develop between the filling and the tooth allowing bacteria to seep in, contributed to over 99% of failures in teeth with living pulps. Bond failure, improper contact points with neighboring teeth, and errors in the original preparation also played roles.
These numbers underscore why oral hygiene after treatment matters just as much as the treatment itself. A filling protects the tooth from further damage, but the junction between filling and natural tooth is a vulnerable spot where plaque and bacteria tend to accumulate. Brushing with fluoride toothpaste, flossing around restored teeth, and keeping up with dental visits are the most effective ways to extend the life of any restoration.
What Recovery Feels Like
Some sensitivity after a filling is normal, particularly to hot, cold, or sweet foods. This typically resolves within two to four weeks as the tooth adjusts to the new material. During that window, you might notice a mild zing when drinking cold water or biting down, which gradually fades.
Sensitivity lasting beyond four weeks is not typical. Throbbing pain that doesn’t subside or gets worse over time, swelling, or redness around the treated tooth can signal an infection in the pulp. If the cavity was deep and close to the nerve, there’s a higher chance the tooth may need additional treatment. Persistent or worsening symptoms after a filling are worth getting checked promptly rather than waiting them out.