Understanding Dental Fillings and When They Are Needed

What a Filling Actually Does

A filling is a repair job. When decay has eaten into the hard outer layers of a tooth, your dentist removes the softened, bacteria-laden tissue and rebuilds the missing structure with a durable material. The aim is twofold: to stop the decay progressing and to restore the tooth's shape so you can bite, chew and clean it properly again.

Decay develops when plaque bacteria feed on sugary and starchy foods and produce acid. Over time that acid dissolves enamel, the tooth's protective shell. Once decay passes through the enamel into the softer dentine beneath, it spreads more quickly and the tooth cannot repair itself. That is usually the point at which a filling becomes necessary.

It is worth knowing that not every dark spot is a cavity. Early decay can sometimes be halted with fluoride varnish, better brushing and a few diet changes rather than drilling. Your dentist will assess whether a lesion is active or arrested before deciding on treatment.

Signs You May Need a Filling

• Sharp or lingering sensitivity to hot, cold or sweet foods and drinks
• A dull ache or throbbing in one tooth, often worse at night
• A visible hole, dark patch or rough edge you can feel with your tongue
• Food repeatedly catching in the same spot between two teeth
• A cracked or chipped tooth, or an old filling that has come loose

Many cavities cause no symptoms at all in their early stages, which is precisely why regular check-ups matter. A small filling is quicker, cheaper and kinder to the tooth than a large one, and your dentist can often spot trouble on an x-ray long before you feel anything.

The Main Filling Materials

Composite resin is the most commonly used filling in the UK today. It is a tooth-coloured mixture of resin and fine glass particles, placed in layers and hardened with a bright curing light, then shaped and polished. It bonds directly to the tooth and can be shade-matched, which makes it ideal for front teeth and anywhere visible. It is slightly less hard-wearing than amalgam in heavily loaded back teeth and can pick up staining from tea, coffee and red wine over time.

Amalgam is the silver-grey material made from a mix of metals. It is very strong and long-lasting, and traditionally cheaper. Its use has been phased down in recent years so it is offered far less often, though it may still be appropriate for certain back teeth in specific circumstances.

Glass ionomer releases fluoride, which helps protect the surrounding tooth. It is softer and less durable, so it tends to be used for small fillings near the gum line, temporary repairs and children's teeth.

Ceramic or gold inlays and onlays are made to measure in a laboratory for larger areas of damage. They are strong, precise and long-lasting, but cost more and usually need two visits.

On the NHS in England, most fillings fall under Band 2. Tooth-coloured fillings are generally available on the NHS for front teeth, while white fillings on back teeth may be offered privately — your dentist should explain the options and costs clearly before starting.

What Happens at the Appointment

A straightforward filling usually takes around 20 to 40 minutes. Here is the typical sequence:

• Examination and, if needed, an x-ray to judge the depth of decay
• Local anaesthetic, often with a numbing gel applied first so the injection is barely felt
• Isolation of the tooth with cotton rolls or a rubber dam to keep the area dry
• Removal of decay using a drill, air abrasion or hand instruments
• Shaping and cleaning the cavity; for composite, the surface is etched and bonded
• Placing the material in layers and setting it — composite is hardened with a blue light
• Checking your bite with coloured paper, adjusting the height, then polishing

If you feel anxious, say so. You can agree a hand signal to pause at any point, and most dentists are happy to work at your pace. If decay has reached the nerve, a filling alone will not solve the problem and you may need root canal treatment or a crown instead.

Afterwards: What to Expect and How to Make Fillings Last

Mild sensitivity to hot, cold or pressure for a few days, sometimes a couple of weeks, is normal as the tooth settles. Avoid chewing on that side until the numbness has fully worn off, as it is easy to bite your cheek or tongue without noticing. A sensitive toothpaste used consistently can help, and it is wise to go easy on very hot and very cold drinks for a few days.

Contact your dentist if the pain is severe, lasts beyond two weeks, or your bite feels uneven — a quick adjustment usually sorts it.

To get the longest life from your fillings:

• Brush twice daily with a fluoride toothpaste and spit rather than rinse
• Clean between your teeth daily with floss or interdental brushes
• Cut down on how often you eat sugary foods and drinks — frequency matters more than quantity
• Wear a night guard if you grind your teeth
• Keep your check-ups so failing fillings are caught before decay creeps underneath

Fillings do not last forever. Composite typically manages seven to ten years, amalgam rather longer, and some last far beyond that with good care. Replacing them when they are worn, cracked or leaking is far simpler than treating a tooth that has quietly decayed beneath one. Looking after your teeth now really is the cheapest dentistry you will ever buy.