Tooth Filling

A tooth filling is a dental treatment that restores a tooth damaged by decay, a crack, or a chip by packing it with a material that hardens in place and protects what remains of the tooth.

When decay (the breakdown of tooth structure caused by bacteria and acid) eats into a tooth, it leaves a cavity (a hole). The dentist removes the decayed material, cleans the space, and fills it with a chosen material — such as composite resin (a tooth-coloured plastic-based substance), amalgam (a silver-coloured metal alloy), glass ionomer (a cement-like material that releases fluoride), or porcelain. The filling seals the cavity so bacteria cannot re-enter, restores the tooth's shape, and allows normal biting and chewing.

A tooth filling is used whenever a tooth has lost structure that needs to be rebuilt to keep the tooth functional and prevent further damage. The most common reason is dental caries (tooth decay), but fillings are also used in other situations.

• Dental caries (cavities) at any stage that has not yet reached the pulp (the inner living tissue of the tooth containing nerves and blood vessels).
• A cracked or chipped tooth where the break is not deep enough to require a crown (a full cap over the tooth).
• Worn-down teeth caused by bruxism (teeth grinding) or erosion from acidic foods and drinks.
• A broken or worn-out old filling that needs to be replaced.
• Tooth sensitivity caused by exposed dentine (the layer beneath the hard outer enamel) due to gum recession.

A filling is usually not suitable when the damage to the tooth is too extensive. In those cases, the dentist will discuss other options.

• Decay that has reached or infected the pulp — this typically requires root canal treatment (removal of the infected inner tissue) first.
• A tooth that is too severely broken or weakened to hold a filling reliably — a crown or, in the worst case, extraction may be needed.
• An active dental abscess (a pocket of pus caused by infection) that must be treated before any filling is placed.

A tooth filling is a routine, low-risk procedure, but like any dental treatment it can have side effects or complications. Most resolve on their own within days.

• Tooth sensitivity to hot, cold, or pressure after the filling — this is the most common side effect and usually fades within a few weeks.
• Short-term soreness or numbness in the gum or cheek from the local anaesthetic (the injection that numbs the area).
• Pain when biting if the filling sits slightly too high — the dentist can adjust this quickly at a follow-up visit.
• Cracking or fracture of the filled tooth if the cavity was large or the tooth was already weakened.
• The filling coming loose, falling out, or wearing down over time, requiring replacement.
• An allergic reaction to the filling material — rare, but possible, particularly with amalgam (metal alloy) fillings.
• Secondary decay (new decay forming around the edges of the filling) if oral hygiene is not maintained.
• In very rare cases, damage to the pulp (inner nerve tissue) during decay removal, which may later require root canal treatment.

A tooth filling generally requires very little preparation compared with surgical procedures, but there are a few things a patient can do beforehand to help the appointment go smoothly.

Eating and drinking is usually allowed right up until the appointment because fasting is not required for this procedure. However, arriving with a very full stomach can occasionally make some patients feel uncomfortable when reclining in the dental chair, so a light meal is reasonable. There is no need to pause most regular medications, but the dentist should be told about any blood thinners (medications that reduce clotting), bisphosphonates (drugs used for bone conditions), or immunosuppressants (medications that lower the immune system's activity) as these can affect healing. Smoking and alcohol do not need to be stopped in advance, though quitting or reducing smoking supports better healing of gum tissue in general.

Before the filling is placed, the dentist will carry out an assessment that may include the following:

• A visual examination of the tooth and surrounding gum.
• Dental X-rays (radiographs) to see the extent of the decay, especially between teeth or beneath the gum line.
• A sensitivity test using cold air or a small instrument tapped against the tooth, to check whether the pulp (inner nerve tissue) is still healthy.
• In some cases, a dental probe (a fine pointed instrument) to measure the depth of the cavity.

During the procedure itself, the steps typically follow this order, though the exact sequence and time taken can vary depending on how large and deep the cavity is:

• 1. The dentist administers a local anaesthetic injection into the gum near the tooth so the area becomes numb.
• 2. Once the area is numb, a dental drill, laser, or air abrasion tool is used to remove all decayed tooth material.
• 3. The cleaned cavity is shaped so the filling material can bond and hold securely.
• 4. If a tooth-coloured composite resin is used, a mild acid gel (etching agent) is applied briefly to help the material stick, then rinsed away.
• 5. The filling material is placed in layers and shaped to match the natural contours of the tooth.
• 6. For composite resin fillings, a special blue curing light is shone on the material to harden each layer.
• 7. The dentist checks the patient's bite by asking them to bite down on special paper that marks any high spots.
• 8. Any high spots are smoothed down and the surface is polished.

Recovery after a tooth filling is usually quick. Most people leave the clinic and return to normal activities the same day, though the mouth may remain numb for a couple of hours after the local anaesthetic wears off — during this time it is easy to accidentally bite the cheek or tongue without feeling it, so eating is best avoided until full sensation returns.

• Avoid chewing on the filled side for at least a few hours after the appointment, or until any numbness has fully gone.
• For amalgam (metal alloy) fillings, your dentist may advise avoiding hard or sticky foods for 24 hours while the material fully hardens.
• Mild sensitivity to hot, cold, or sweet foods and drinks is normal for the first few days to weeks; if it worsens or lasts longer than a few weeks, inform your dentist.
• Take any pain relief medication recommended by your dentist if sensitivity or soreness is uncomfortable — no specific dose or brand will be suggested here, as your dentist will advise.
• Brush gently around the filled tooth from the first night; this does not harm the filling and prevents secondary decay (new decay forming at the edges).
• Floss daily, including around the new filling, once the dentist confirms the filling margins are smooth.
• Attend the follow-up appointment your dentist schedules — this allows the bite to be re-checked and any sensitivity to be assessed.
• Routine dental check-ups, usually every six to twelve months, help the dentist monitor the filling and catch any new decay early.
• If the filling feels high when biting, falls out, cracks, or the tooth develops severe pain or swelling at any point, contact your dentist promptly rather than waiting for a routine appointment.