The loss of a tooth is relatively common. Whether it is knocked out of the oral cavity by an accident or whether periodontitis has destroyed the periodontium in such a way that it can no longer hold the tooth, both have the consequence that the tooth can no longer remain in the oral cavity. It is also possible that the dentist has to remove the tooth, because even such a deep caries has damaged the tooth substance and possibly the root as well.
In this situation a filling can usually not be made. Either the tooth would have to be filled too much and becomes unstable, or the root of the tooth is destroyed by caries, in which case the tooth must be extracted in almost every case. But what then?
The missing tooth must be replaced somehow. Bridges or crowns are well known, but they cannot be considered the first choice in all cases. Many people are still sceptical about dental implants. Too expensive, what is it, it’s not for me at all – a dentist often hears this when he suggests dental implants as a possible solution to replace a missing tooth. However, dental implants can be very practical
Construction of a dental implant
A dental implant is an “alloplastic prefabricated part” anchored in the jawbone. Alloplastic refers to the material from which the dental implant is made and means that this material does not occur in the human or animal body. It is a foreign body that is made of a different material and then transplanted into the human body.
Alloplastic materials are either made in the laboratory or extracted from nature and then processed in the laboratory. Ready-made means in this context that the screw of the dental implant is not made individually for each patient, but that the dentist has a kind of kit in his practice from which he only selects the appropriate size. To make this easier to understand, one can imagine the different sizes of screws that can be bought in a hardware store.
The craftsman chooses the right screw he needs for his work and does not produce an individual screw every time. So no impression is taken to select the screw size of the dental implant. The field of dentistry that deals with the replacement of natural teeth with implants is called implantology.
Dentists who want to work in implantology should have a special training, because placing implants is not easy and requires great care and knowledge. The “placing of implants” is the technical term used for the insertion of implants into the jawbone. Dental implants usually consist of three parts: In Germany, most implant screws have a rotationally symmetrical shape, i.e. they have a circular diameter and a thread.
The circular diameter makes it easier to drill the hole in the jawbone into which the screw will later be inserted. Thanks to the shape, the hole can now be easily predrilled with a special drill. The thread of the screw provides mechanical hold in the jawbone and thus supports the ingrowth of the screw.
There are also implant screws with a smooth surface, but with these it is very difficult to get a good hold in the bone so that the screw has enough time to grow in. Smooth surfaces have not been proven in practice, so implantology was looking for alternatives. The screw shape seems to be the best alternative.
In the past implants were used that had wings to the right and left so that there was sufficient retention (hold) in the bone. The jawbone had to be opened over a large area to insert the implants. Wound healing with such a large area was naturally more difficult and therefore more prone to complications.
With today’s method of screw implants, the wound area is very small and healing is usually without complications. Nowadays, at least in Germany, the majority of implants are made of titanium. Titanium has already proven itself as a material in orthopedics for many years.
All artificial joints or screws and plates for stabilizing broken bones are made of titanium. It has the advantage that no allergies to this material are known. Any metal that is brought into a moist medium oxidizes.The less noble the metal, the faster and stronger the oxidation.
So why is titanium as a very base metal suitable for implant screws? It forms a very stable oxidation layer, i.e. the metal oxidizes, but ions from the titanium can no longer reach the surrounding tissue because the oxidation layer remains stable. Titanium is very well accepted by the human body and usually grows into the body without complications.
Gold as the most precious metal is absolutely unsuitable for implants. Although it does not oxidize, its consistency is much too soft. It would not withstand the stress of chewing and would bend or eventually break in the jawbone.
The only disadvantage of titanium is that it has a dark color. Especially with very thin crowns, the dark abutment shimmers through and provides a somewhat unsatisfactory esthetic result. Implantology has tried to remedy this situation by developing abutments made of ceramic.
Unfortunately such abutments are not very stable and splinter very easily. For this reason they should only be used in exceptional cases and only for anterior teeth. Implants completely made of ceramic were used by implantologists only for a short time.
Although the implants have excellent properties and are very well accepted by the body so that there is hardly any risk of rejection, they unfortunately splinter very easily under masticatory loading. Removing a splintered implant screw requires a major procedure. Implants completely made of ceramic were taken off the market relatively soon.
- The lowest part is the screw, which is anchored in the jawbone and ideally should grow together with it. The dentist calls this process osseointegration. (Osseointegration means nothing more than that the screw should grow firmly into the bone, i.e. integrate with it).
Dental implants whose screws are not osseointegrated usually have a worse prognosis regarding their life in the mouth.
- The abutment is screwed onto the screw, protrudes into the oral cavity and later wears the crown. In order to anchor a crown in the mouth, a stump is needed that extends into the oral cavity. The crown is glued onto this stump.
In case of natural teeth, the dentist can achieve a suitable stump shape by grinding the tooth. The abutment is already shaped so that the dental technician can make a crown for it that fits well on it and which the dentist can then integrate. To integrate is the technical term for fixing the dental prosthesis (crown, bridge, denture) in the mouth.
- The crown is the third and uppermost part of the implant.
It is the only part that is visible later. Ideally, it is designed to look like the rest of the natural teeth so that no one will notice that there is a crown in the mouth. Under no circumstances should the dental implant be visible as such. Implantology is currently working on how to make implants as invisible as possible, especially in the front tooth region.
