Do you have a amalgam metal fillings? Have you thought about replacing them with white fillings
? If so, it is worth reading this article written by Dr Nissit Patel.What is amalgam?
Amalgam is a combination of metals that has been the most common filling material used in dentistry for the last 150 years. Although it sometimes is called "silver amalgam," amalgam actually consists of a combination of metals. These include silver, mercury, tin and copper. Small amounts of zinc, indium or palladium also may be used.
Mercury is a metal that occurs naturally in the environment. Mercury can exist as a liquid at room temperature . When heated, it becomes a gas.
Everyone is exposed to mercury through air, drinking water, soil and food. Concerns have been raised, for instance, about the amount of mercury building up in fish as a result of pollution. Mercury enters the air from industries that burn mercury-containing fuels. Mercury from all sources can build up in body organs.
As with most substances, the degree of harm caused by mercury in the body is related to the amount. Very low levels are not thought to cause any ill effects, although there is wide disagreement on this.
At higher levels — for instance, when workers are exposed to mercury through their jobs — mercury can cause several symptoms. These include anxiety, irritability, memory loss, headaches and fatigue. There have been some links to systemic disease as well although there is no 'gold' standard evidence that proves this.
The controversy over amalgam really focuses on how much mercury is released from amalgam fillings and how much the body absorbs. In the past, amalgam fillings were thought to be stable and inert. Hence, the thinking was that no mercury was released from the fillings.However, modern day testing has proven this to be incorrect. Very small amounts of mercury vapor is released during everyday function, natural wear and tear and especially from bruxism (tooth grinding).
The European Parliament agreed on 14 March 2017 to the final version of its Regulation on Mercury. The Regulation is the EU's instrument to ratify the Minamata Treaty of 2013.
The Minamata Treaty is a global environmental treaty aimed at reducing the release of mercury into the environment. The EU's Mercury Regulation has the same aim for the territory of the European Union. Both documents prescribe a phase-down of the use of dental amalgam for environmental reasons.
Therefore, the use of amalgam is to drastically reduced over the coming years and the use in dentistry has therefore to be questioned. I have not placed an amalgam filling in over a decade and simply cannot see the benefit of them apart from a cost saving point of view. In this respect, the material is cheap and placing amalgam is simple and less time consuming than placing white fillings.What is a white filling?
A composite 'white' tooth filling is typically made of powdered glass and acrylic resin. It is hardened by the use of a light at a certain wavelength that sets off an addition cured reaction. The material is very sensitive to water and hence a dry field is required for placing white fillings. This is not so easy when the mouth is covered in saliva!
There is also a shrinkage rate involved when the material is set. This means that the filling has to be placed in increments to minimise the stress placed on the tooth during this shrinkage phase. Over the years, manufactures have worked hard to reduce the amount of shrinkage and there are now 'bulk' fill materials which can be placed in thicker increments.
Obviously, the big advantage of a composite white filling is that it is tooth coloured and hence looks like a tooth rather than amalgam which is metal.The white filling process
Here are the steps involved in placing a white filling. As you will see, it is not easy and requires a number of steps and patience.
- Obviously, the first step is a full clinical examination with x rays. Often, tooth decay cannot be seen by eye and an x ray is required to check underneath the top layer of the tooth, in between the teeth or underneath existing fillings.
- The tooth is numbed using local anaesthetic. I advocate using a numbing gel first and then slowly placing the anaesthetic. Pushing the liquid in very fast can be extremely painful- there is simply no need for this. In most cases, there is minimal pain whatsoever.
- The tooth should be tested to ensure adequate anaesthesia. A test cavity is very useful. If there is no sensation at all, we can begin.
- Rubber dam should be placed. What is rubber dam I hear you ask? Well, in simple terms it is a non latex 'drape' for your tooth/ teeth that provides isolation. It keeps the tongue, lip, cheek and saliva out of the way making our life a lot easier and the treatment more comfortable for you. Medium and large composite fillings should NOT be placed without rubber dam.
- The decay is removed and the cavity is shaped. Lots of water should be used to keep the tooth nice and cool to avoid overheating. Temperature rises within a tooth will cause the pulp (nerve and blood supply) to become very sensitive and inflamed. This could lead to the death of the pulp and the need for root canal treatment. Water is a good thing!
- At this stage I tend to clean the surface with chlorhexidine or Corsodyl mouthwash.
- Now is the time for the matrix. Again, what is this I hear you ask. Simply, a matrix allows us to re create the normal anatomy of the tooth when a wall has been lost due to decay. In most cases, a matrix will be used to allow us to replace a missing side wall called the interproximal area. We do not need a matrix if the filling is on the biting surface of the tooth. I tend to use a V ring matrix system originally by a company called TrioDent, with a dedicated wedge.
- What is a wedge is the next logical question! Well this used in between the tooth being treated and the adjacent tooth, to push the matrix up tight against the tooth and create a good seal between the filling and the tooth. Failure to use a wedge can result in the filling material 'overhanging' between the teeth. This is hard to clean and can attract plaque leading to gum issues.
- The tooth is now prepared in a certain way. Firstly, I will etch the enamel with 37% phosphoric acid, wash for a good 10 seconds and then dry. It is important not to dry too hard as this can lead to collapse of the collagen layer which is essential for bonding. I then use Scotchbond Universal on the enamel and dentine of the tooth, which is the inside aspect. This is a dental adhesive and acts as the link between the tooth and the composite filling material. This layer is air dried carefully. Again, it is important not to dry too hard.
- A light cure is used to harden the bond. We use LED light cures at the practice which emits light intensity at over 1000mW/cm2.
- Depending on the size of the cavity, I tend to place a very non viscous layer called flowable composite on the base and ascending walls of the cavity. This helps to block out any undercut and prevents any voids when placing the more harder composite material. This is light cured to set.
- The harder composite is then placed in 2-5mm increments. This does depend on the type of composite being used. For example, Filtek One is a bulk fill material and large increments can be used in one go up to 5mm. Conventional composites will allow up to 2mm in general. Ask your dentist which composite they are using.
- The cavity is then built up in layers to replicate the tooth anatomy as best as possible. I tend to over build slightly which will give me room to adjust and create some anatomy whilst polishing.
- The matrix is removed and the contouring and polishing begins. The rubber dam should remain in place for the initial adjustments and is then removed so that the bite can be checked.
- The bite can feel strange at this stage as you have been open for a while and the tooth/teeth are numb. Do not worry. We will ensure the contacts on the teeth and adjacent teeth are sound.
- Final polishing and checks are made. I tend to use Shofu points, discs, Enhance points and Super Di Glaze paste. This gives a lovely smooth surface.
- The contact points are checked with floss and the embrasure space is checked. This is the space at the gum level between the teeth which is triangular shaped. It is this area that can be cleaned using an inter dental brush which is a little like a bottle brush.
- Final instructions are given. This will include:
- Soft food for a few days
- Avoid the extremes of hot and cold to prevent causing any sensitivity
- Use of a sensitive tooth paste around the tooth at night for a few days
- Cleaning advice
Here is an example of recent case that I treated involving the replacement of an amalgam filling:
Fractured metal filling with decay underneath
Amalgam has been removed and decay is present. The opaque white, brown and orange colours are not healthy tooth substance
Sectional matrix in place with a V ring and wedge. Not so simple hey? This is extremely important to re create the lost wall of the tooth.
The final filling. Tooth coloured, super smooth and life like.
There you have it. The white filling process in complete detail. As you can see, the process is not simple. There are many steps to follow. Typically, we need a full 45 minutes for this type of filling. Our fees range from £150-230 for a white filling that involves a lost wall. I think this is incredibly reasonable!
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Thanks for reading.