Dental Filling

(Direct Restoration)

In this section, we will cover: 

1. What is a dental filling?
2. What are the different types of filling materials? 
3. What are the advantages and disadvantages of each material?
4. What does the procedure involve?
5. What should I expect after having a filling?

What are the different types?

There are three main types of dental fillings: 

1. Amalgam
   This is a silver filling made up of lots of different metals including silver, tin and copper. It also contains a small amount of mercury - but don't worry, research has shown amalgam fillings are safe. In fact, most of the mercury is released (in tiny amounts) when the filling is being placed or removed. For this reason, unless your silver filling(s) is failing or the appearance is a big concern for you, it is not advised that you have them replaced with tooth coloured fillings. If you do decide to have them replaced, it should be done under rubber dam (a rubber sheet used to isolate the tooth/teeth, a bit like a raincoat) and suction. 
   
   Although amalgam fillings have been shown as safe to use in the mouth, there is concern regarding the effect of mercury on the environment when amalgam is being disposed of. Due to this, the use of dental amalgam is being phased out in the UK as part of the Minamata Treaty of 2013. Since 2018, amalgam fillings have been banned for use in children under 15 years and in pregnant or breastfeeding women. The aim is to phase out the use of dental amalgam by 2030. 
   
   
2. Composite 
   This is a tooth-coloured filling made of resin and glass. It is extremely sensitive to moisture (i.e. saliva) so it will usually be placed under rubber dam to keep the area as dry as possible. If the decay extends under the gum or your gums bleed a lot, it won't be possible to keep the area dry and a composite filling may not be suitable. It is commonly used for restorations at the front of your mouth, whether due to tooth decay or dental trauma - this is often referred to as "composite bonding". It can also be used for fillings in your back teeth if you want them to be (almost) invisible.
   
   
3. Glass Ionomer
   This is a temporary filling which releases fluoride (a protective chemical) over time. It is made of powdered glass mixed with water. They are a great option in certain situations, such as if you have:
   

• multiple teeth with decay where your dentist needs to stabilise the mouth before moving on to more definitive treatment 
• teeth with large holes where your dentist is concerned about the nerve 
• sensitive teeth due to exposed dentine/root surfaces which need covering 
• in an emergency appointment if there is not enough time to place a definitive filling (composite or amalgam)
• in between root canal treatment appointments so you aren't left with a gaping hole in your tooth through which bacteria can enter and cause further infection (commonly a different temporary material called Intermediate Restorative Material, or IRM, is used for this)

Each type of filling material has its own advantages and disadvantages which are outlined below. 

Sometimes the choice of material will be based solely on your personal preferences (what it looks like, how much it costs, how long it is likely to last), but in some cases a material might not be suitable for your tooth. For example, your dentist won't be able to reliably place a composite filling in a tooth with a hole which goes below the gum. 

Your dentist can help you choose which filling material is best for you. 

What is the procedure?

There are many stages involved in placing a dental filling. The time taken to place a filling depends on: 

• How large the hole is 
• What type of filling is being placed 
  A composite filling will take longer to place than amalgam or glass ionomer as it must be done in multiple stages
• Your dentist's experience
• If the tooth is at the front or back of the mouth 
• How wide you can open your mouth 
  The wider you can open your mouth, the easier it is to place the filling
• How long you can keep your mouth open for
  The dentist can place a plastic block between the teeth called a "mouth prop" - this helps to keep the mouth open for longer and is more comfortable for you

A simple filling will usually take about 20 minutes to place. 

So what are the stages?

1. Local anaesthetic
   A dental filling is most commonly done under local anaesthetic. This means your gum and tooth will be numb so the procedure is more comfortable but you will still be awake. This numb feeling will last about 2-3 hours.
   
   Cases where you may not need any anaesthetic include:
   - if a filling has fallen out and the cavity is clean (so your dentist just needs to put a new one in without any tooth preparation)  
   - if the tooth has had root canal treatment 
   - if the cavity is very shallow 
   
   If you are extremely anxious and unable to tolerate treatment under local anaesthetic, there are other options, such as sedation (LINK), which may be available to you. This will generally require a referral to a community or hospital dentist. There are some dentists, who have had further training in sedation, who can offer this service privately in general practice. 
   
   
2. Isolation (keeping the tooth dry)
   If placing a composite filling, your dentist will place either cotton wool roll or a rubber dam around the tooth being filled to keep it dry. They may choose to do this even when using a different material if the filling needed is quite large/complex as it helps to keep your cheeks and tongue out of the way. 
   
   
3. Removal of tooth decay
   The decay (rotten part of the tooth) is removed using a fast and slow dental handpiece (commonly referred to as a "dental drill"). The fast handpiece is used to remove the hard enamel armour covering the decay in the middle layer of the tooth. The slow handpiece is used to remove the soft decay in the dentine layer. This is to avoid removing healthy tooth close to the nerve.
   
   Sometimes, even if the xray doesn't show the decay has spread into the nerve, we can find a different picture when we go into the tooth. If the decay extends deep into the tooth but not into the nerve, your dentist may decide to place a thin cavity lining material to protect the nerve before placing the filling. A common cavity lining material is calcium hydroxide (Dycal) which is antibacterial so can help to kill off any bacteria which may remain close to the nerve. If there is concern the nerve may die, your dentist may decide to place a temporary filling and monitor the tooth. If the decay extends into the nerve, your tooth will need a root canal treatment (LINK) to save it.  
   
   Many people do not like the vibration or the sound of the handpiece. It can be useful to take a pair of headphones to your appointment so you can listen to music to drown out the sound.
   
   
4. Filling the tooth 
   If the cavity involved the sides of the teeth (as many do), the dentist will place a metal ring (called a matrix band) around the tooth which helps to keep the correct shape and stop the material from flowing out of the cavity and sticking to the tooth next to it. A small wooden wedge is placed between the teeth to help keep the filling material in the cavity. The matrix band and wooden wedge are removed after the filling has been placed.
   
   Amalgam
   If the tooth is being filled with amalgam, the nurse will mix the capsule containing the amalgam and pass it to your dentist. This material is then placed in the cavity and packed tightly with special instruments to make sure the cavity is completely filled. 
   
   Composite
   If the tooth is being filled with composite, you will likely have helped to choose the right shade of composite to match your natural tooth before treatment started. There's a huge range to choose from - some shades are whiter, whilst others are more yellow or grey or brown. It is important not to just choose the whitest shade as if it doesn't match your tooth, the filling will look extremely obvious. 
   
   Before the filling can be placed, the tooth surface must be prepared in 3 stages: etch, prime and bond. Etching the tooth uses an acid which creates small holes or indentations at a microscopic level in the cavity which helps to keep the filling in place. This acid is then washed off and the tooth is dried. Priming the tooth uses a "water chaser" which gets rid of as much fluid as possible which is stuck inside the dentine (as I mentioned before, composite is very sensitive to moisture). This helps the bond to penetrate the indentations and adhere to the tooth. The bond layers allows the composite filling to stick to the tooth. Some practices now use a two-bottle system where they etch the tooth first and then the prime/bond stages are done in one step. The tooth is now ready to be filled. 
   
   The nurse will either pass the dentist a special "gun" with composite in it which can be squeezed directly into the cavity, or place some on a pad of paper which the dentist can pick up with a special instrument and place in the cavity. 
   
   The composite is placed in the tooth in small layers and "light cured" (hardened) with a blue light for 20-40 seconds. This blue light is not good for your eyes so the dentist or nurse will place an orange shield over your mouth and may ask you to close your eyes. It make take many layers and light cures before the cavity is filled. 
   
   Glass Ionomer 
   Before placing glass ionomer, the tooth is conditioned with acid to remove any bits of debris. Your dentist will usually do this whilst the nurse is mixing the glass ionomer - either by hand or in a capsule. Again, depending on which type of glass ionomer your dentist is using, your dentist may use a "gun" to place it in the tooth or pick it up from a pad of paper with a special instrument. Once the tooth is cleaned and the glass ionomer mixed, it can be placed directly into the cavity where it bonds to the tooth. Some glass ionomers harden by themselves, whilst others need to be hardened with a blue light, as with a composite filling. 
   
   
5. Shaping and polishing the final filling
   Once the tooth has been filled, your dentist needs to make sure it's the right shape and that it isn't interfering with the way your teeth bite together. A lot of the shaping will have been done before the filling has hardened but normally some fine-tuning is needed to get it exactly right. 
   
   The dentist will check your bite by placing a small piece of paper between your teeth and asking you to bite down. This will show if the filling is too high as the paper will tear through or the rest of your teeth will not be able to touch meet. You can often tell if the filling is very high.
   
   A range of hand instruments and burs (used in a handpiece) are used to adjust the filling. Hand instruments are used for an amalgam, whilst burs are used for composite. It can take a few attempts of adjusting and polishing before your bite is just right. It can take a few days for you to grow accustomed to your new filling.