Fillings are primarily used to treat cavities but can also be used to repair cracked or broken teeth.

Filling a cavity
Once a tooth has a cavity (or has decayed), the process cannot be stopped and the damage will increase. The only way to stop the decay is to completely remove the decayed part of the tooth and to replace it with a filling.

Removing the decay can be painful. For this reason, your dentist will give you a local anaesthetic to ensure that you don’t feel pain during the procedure. He or she will have to use drills to remove the rotten part of the tooth. In some cases, lasers or air abrasion instruments will be used.

When the decay has been entirely removed, the tooth can be filled using a tooth-coloured composite filling (typically made of powdered glass and acrylic resin). This isn’t a simple process, as the tooth must be completely dry for the filling to be bonded.

Depending on the size of the cavity, your dentist may have to fill it incrementally, taking care to set each layer of the filling with a curing light. The filling can also be glazed and stained, depending on the desired cosmetic effect.

The process of filling a tooth can be summarised as follows:

  • Complete removal of all the decay.
  • Etch the tooth, using an etching gel (the rougher surface helps the bonding agent to bond to the tooth).
  • Wash all the acid etch off and dry the tooth.
  • Apply a bonding agent.
  • Set the bonding agent, using a curing light.
  • Shape, place, contour and polish the filling, so that it fits the shape of the tooth and doesn’t change the biting position of the teeth.

If the hole in the tooth is very deep – i.e. if the decay has progressed and the pulp chamber (i.e. the nerve and blood supply) is in close proximity to the floor of the cavity – the nerve may become inflamed. If there’s an abscess, you may require root canal therapy. In severe cases, extraction of the tooth may be necessary.

How to take care of teeth with fillings
Once a tooth has been filled, the natural integrity of the tooth has been compromised, making it more vulnerable to fracture and secondary decay. The interface between the repaired tooth and the filling also often breaks down, allowing for secondary decay to start up again. For this reason, it’s important to have your dentist check your fillings at least twice a year. Don’t wait for pain.

Regular checks at the dentist also makes it possible to detect problems early, which often allows for less costly interventions. A small cavity is better treated early. By the time you feel pain, larger, more complicated and more expensive treatments are indicated.

Of course, the first prize is to prevent tooth decay. Apart from regularly checking in with your dentist, it’s important to:

  • Brush your teeth twice a day for three minutes at a time and to really focus on what you’re doing.
  • Use dental floss at least once a day before bedtime.
  • Rinse your mouth regularly. If mouth rinse isn’t easily accessible, water is a good second choice.
  • Avoid sugar as far as possible. Remember that sugar is disguised in many foods and beverages, including energy drinks, fizzy drinks, fruit juices, and dried fruit. If you’re running a marathon and you require sugar, try to rinse your mouth with water after you’ve had your energy drink or sachet (which is filled with concentrated sugar).

A note on amalgam fillings
Silver amalgam fillings contain elemental mercury, which is toxic. This is why they aren’t used in dentistry anymore.

But dentists and patients often face a dilemma: should these fillings be removed, resulting in a significant dose of mercury entering the bloodstream in one go, or should they be left intact, releasing lower amounts of mercury over time?

In many instances, amalgam fillings cannot be replaced with composite fillings because of their size. Instead, very large amalgam fillings need to be replaced with cast restorations, i.e. inlays, onlays and crowns or caps, which are much more expensive than fillings.

Amalgam fillings also place a different kind of stress on the tooth (when compared to composite fillings), often resulting in complications and pain in a tooth that hasn’t given any problems while being filled with amalgam. So, the decision to replace these fillings can be complex.

Amalgam fillings do, however, tend to last a long time before needing replacement. But, like all dental procedures, they break down eventually.

When replacing amalgam fillings, it’s best not to use amalgam again because of the mercury risk. Check with your dentist which kind of filling would be right for you.

Written by dentist Dr Lance Videtzky of City Dental Care, Cape Town. (B.D.S.) Rand. February 2019.

Read more:

- Crowns

- Dental X-rays

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