Introduction
Caries is widespread and almost everyone has had a carious tooth at some time or another. Either in the front or on the large molars – caries attacks and decomposes the hard tooth substance. Thus the bacteria succeed in penetrating further and further into the inside of the tooth.
The only way to remove the caries and thus protect the tooth from further damage is to go to the dentist. There the caries is removed and a hole remains which cannot be left like this. A filling is needed to close the hole.
There are different materials to choose from, like amalgam, composite or a filling with a special cement. But what exactly is this and how does the cement filling differ from the others? The classic and most famous filling is an amalgam filling.
Silver amalgam is made of mercury, tin, copper and silver. Due to its properties, it is easily deformable and expands after being placed in the cavity, so that it can completely seal the hole and no substances from the outside can penetrate it. Where large chewing forces occur, such as on the large molars, it is still the means of choice.
Amalgam fillings have come under criticism in recent years due to fears that the mercury they contain could be harmful to health. However, the dose is so low that this is not true. The latest means used are the so-called composites.
A composite consists of 80% of the salt of silicic acid and 20% of plastic. The big advantage is that it is tooth-colored and can therefore also be used optimally for fillings in the anterior region. It is also possible to use a special coloring technique to adapt the resin optimally to the remaining tooth color in the dentition.
Composites are durable and retain their shape so that they can be used in the posterior region in addition to the anterior region. A mixture of a composite and a glass ionomer cement is called a compomer. However, these still require some research and further investigation, because the agents currently available on the market are only suitable for fillings in the cervical area, on milk teeth or for a transitional period.
A filling on chewed surfaces is currently not yet possible. Gold hammer fillings, where a thin gold foil is “tapped” into the hole, are hardly ever used. The filling would be clearly visible, but has a good durability.
Another possibility to fill a tooth is to use a cement. If one wants to fill a tooth, one does not simply speak of a “cement”, but rather calls it more closely to glass ionomer cement (GIZ for short). In this way one escapes confusion, since the “cements” used in dentistry are otherwise used to fix a crown.
One can distinguish between 3 basic types of cements: Before taking a closer look at the glass ionomer cement, it is important to consider the properties required of such a cement. It must be biocompatible, not too thick and easy to process. In addition, it must hold well, allow light to pass through, resist high compressive and tensile forces and be able to be loaded quickly.
Not every cement can meet all these requirements 100%. The glass ionomer cement used for filling therapy is used for saliva-tight, temporary fillings, such as those used in emergency dental services when there is no time for a more complex filling. It is not used for permanent fillings, but is placed in the tooth for a certain period of time.
The detailed name for a glass ionomer cement is: glass-polyalkenoate cement and consists of a powder and a liquid that are mixed together. The liquid consists of 48% polyacrylic-itaconic acid copolymer, 5% tartaric acid and 47% water. The powdery component consists of 100% aluminium silicate glass with fluorides and calcium.
This also addresses a special feature of this type of cement, because it releases fluoride and calcium. After it has been added, fluoride, which is also present in toothpaste, is released in small quantities to the tooth. This is supposed to counteract a new caries at the filling edges.
In addition, possible bacteria are killed and the enamel is strengthened. If the two components are mixed together shortly before application, a chemical setting reaction occurs.The acid contained in the liquid attacks the glass parts and metal ions are released. These free metal ions can now migrate so that a rearrangement of the atoms takes place.
A gel-like mass is formed, which sets and hardens as the process continues. When the dentist fills the existing hole with this mass, it adheres to the untreated enamel and dentin by chemically binding the polyacrylic acid to the calcium of the tooth enamel. Thus the bonding is given for a certain time.
- Filling cements, like the glass ionomer cement just mentioned
- Retention cements, which are used to attach a denture, such as a crown or a temporary denture, either permanently or provisionally to the tooth
- Underfilling cements, e.g. for fissure sealants
As mentioned above, this mineral cement is only intended for temporary filling therapy and is otherwise more likely to be used for luting dental prostheses. In addition to temporary fillings, it is also used to treat carious defects in milk teeth. Smaller defects of the neck of the tooth can also be treated with it, but must be checked for durability at regular intervals.
A temporary filling makes sense as soon as a permanent filling is not yet indicated. This would be the case if a caries was already dangerously close to the tooth nerve and it is not yet certain whether the nerve might have been damaged. A definitive filling should not be chosen for a critical tooth because they are more complicated and expensive and the work is in vain if it turns out that the nerve has to be removed or even the whole tooth has to be extracted.
So it can also be used after a root canal treatment until the therapy shows success. In all these cases, temporary treatment makes more sense for the time being to save unnecessary costs and effort. In terms of color, it shows a matte, light-colored surface after curing. However, the color does not quite match the natural tooth color and is therefore recognizable as a filling.
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