What is a dental implant?

A gap in your teeth is clouding your smile and your dentist recommends an implant? That's where the money comes in, because implants cost a tidy sum. But what exactly is a dental implant? Here you can find out what you need to know to make a decision!

The condition of your teeth is a status symbol. Nowadays, a flawless smile is as much a part of your image as skillful make-up and well-groomed fingernails. Most people need dentures of some kind for this. It is estimated that German dentists insert at least one million dental implants every year (1). They can last a lifetime - but only with good care.

What is an implant - tooth or tooth root?

For the uninitiated, the word implant initially conjures up images of an artificial tooth. But strictly speaking, the term only refers to the artificial tooth root. During an operation, the dentist drills it into the jawbone like a screw. He later attaches the visible part of the prosthesis, the actual crown, to this root.

Dental implant abutment: Abutment and crown

The entire dental prosthesis consists of three different components:

• Implant - artificial tooth root
• Implant abutment - abutment, intermediate piece to the denture
• Implant crown - superstructure, denture supported by the implant

Implant: shape and material of artificial tooth roots

Implants are good business for everyone involved. That is why manufacturers continue to strive to develop the perfect implant. There is now a huge selection. This means your dentist can choose exactly the right model for you. Screws or pins with a diameter of between three and five millimetres are the most common. The length ranges from seven to 15 millimetres.

Most implants today have the shape of a screw, either cylindrical or conical (2). The dentist will decide which shape is suitable for you. During the preliminary examination, he will take a close look at your jawbone. He must rule out the possibility of inflammation. He must also make sure that there is sufficient bone mass at the site of the implant.

The shape of the implant is important because it influences how it grows into the jawbone (3) (4). This consists of different types of bone. Under a thin layer of cortical bone is the trabecular bone with a spongy structure. Most of the implant must grow into the trabecular bone. The condition of this type of bone and its long-term reaction to the implant determine its durability.

Dental implants: The material - titanium or ceramic

Over time, two materials have emerged as the most commonly used for dental implants:

• Titanium
• Zirconia

Titanium was the first material to make permanent implants possible. It has been used worldwide for 40 years and there are the most studies and experiences with implants made of titanium. It is compatible with the human body and normally grows into the bone without any problems. It is therefore the preferred metal for this task.

However, it is possible that sensitive people may develop allergies to titanium alloy additives (5). In addition, small metal particles may migrate from the titanium implant into the tissue. Macrophages, scavenger cells of the immune system, accumulate around these particles and cause the tissue to become inflamed (6). However, titanium often heals faster than zirconium (7).

In contrast to grayish titanium, implants made of highly crystalline ceramic (zirconia or zirconium oxide) shine wonderfully white. This is particularly important for the front teeth. With titanium implants, a dark shadow can shimmer through the tooth. When it comes to appearance, zirconia beats titanium.

Some people simply don't like metal in their bodies and therefore choose screws made of zirconium oxide. Strictly speaking, this is a metal oxide with ceramic properties. But it looks like ceramic, which is why even experts call it a ceramic material.

Both materials are similarly suitable for implants. However, studies show that zirconia is slightly less elastic than titanium. In rare cases, microcracks may therefore occur (8).

Why is the surface of an implant rough?

The surface of the artificial tooth root is always roughened to facilitate ingrowth into the bone (9). Scientists worldwide have been researching the ideal treatment of the surface for a long time. Three main methods are currently used:

• Etching
• Sandblasting
• Irradiation with titanium

Bone cells need support in order to grow. At the same time, however, pathogens can cling to the rough surface and multiply easily. Careful oral hygiene is therefore crucial for the long-term success of an implant. A regular collagen test shows whether the tissue around the implant is healthy.

Scientists are now experimenting with nanostructures to counteract inflammation, such as the application of titanium dioxide in nanotubes, treatments with fluoride or coatings with peptides (10). However, this research has not yet progressed far enough to be applied to commercial implants.

Implants don't just replace individual teeth

In addition to individual teeth, implants can also supplement shortened rows of teeth. If there are no longer enough teeth in the jaw, implants can hold bridges and even full dentures like supporting pillars. For a full denture, six implants are usually placed in the lower jaw and eight in the upper jaw.

Since 2003, the so-called 'All-on-4' method has also been used in dentistry: full dentures are attached to just four implants. As supporting pillars for bridges and full dentures, dental implants must be particularly stable, as the forces involved in biting can be enormous. Experts estimate that the maximum force during chewing is 390 kilograms.

However, a study in 2014 showed that the average chewing force rarely exceeds 60 kilograms (11). According to the study, men usually chew more vigorously than women. The forces on the molars are around three times greater than the forces on the front teeth.

No grinding required for bridges

This means for implants: Front teeth are the easiest to replace. However, the retaining teeth for bridges and especially for full dentures should be able to withstand extremely heavy loads. This is why implants with a retaining function are usually longer than implants that replace individual teeth (12).

Implants good for free-end situations

Dentures are particularly important in a so-called free-end situation. Free-ended means that several molars on one side of the upper or lower jaw are missing. As a result, those affected can no longer chew properly - which naturally has a significant impact on their quality of life. The solution to this can be either several implants for individual teeth or a bridge that is attached to a natural tooth and an implant.

However, this method is controversial. Like all parts of the body, teeth are movable to a certain extent. However, implants - and the bridges attached to them - are rigidly anchored. According to critics, this can lead to the forces generated during chewing having a negative effect on the tooth or implant. However, a review study from 2017 provided no evidence for this criticism (13). The authors of the study expressly recommend this method as a tooth replacement in free-end situations.

High-risk: All-on-4 solutions

The All-on4 implants are placed in the anterior part of a completely edentulous jaw. The two anterior implants are placed axially, while the two posterior implants are placed at an angle. This inclination makes optimum use of the existing bone material. This enables the attachment of dentures with up to 12 teeth.

It becomes expensive if problems occur with an All-on-4 prosthesis. Providers advertise that the implants can be inserted in just one day. However, the bone substance must be suitable for this. In the case of complete tooth loss, this is usually not the case and the bone must be painstakingly rebuilt before the implants are inserted (14). This can lead to numerous complications. If only one of the four implants is unsuccessful, the full denture must be removed. This means new implants: A new prosthesis must be made.

Contraindications for dental implants

People with severe, chronic illnesses or autoimmune diseases should avoid implants. This includes diabetes mellitus if the medication is not optimally adjusted. Severe cardiovascular disease, kidney damage or osteoporosis are also contraindications. Pathological changes in the oral cavity as well as acute caries and periodontitis also prevent implantation.

Increased risk for smokers
Smokers have a greatly increased risk of peri-implantitis (15). This refers to inflammation of the gums and bone, which often leads to the loss of the implant.

How painful is a dental implant?
There is no general answer to this question. It depends, among other things, on how sensitive you are to pain and how well you respond to painkillers. Placing an implant involves cutting open the gums and drilling into the bone - processes that cause pain for several days. If you are very anxious, this can increase the pain (16).

A bit of history: from gold wire to titanium screw

Magnificent teeth have always been a privilege of the rich and beautiful. Thousands of years ago, people tried to conceal gaps with naturally somewhat primitive bridges (17). The ancient Egyptians fixed loose teeth with gold wire. The Etruscans in Italy were somewhat more resourceful, making replacement teeth from cattle bones.

Modern implantation is the result of many attempts in dentistry. In 1913, the US dentist E. J. Greenfield placed the first artificial tooth root that supported a tooth (18). This implant looked a bit like a basket and was made of a platinum alloy soldered to gold.

Problem: Foreign body in the mouth

Over the course of the 20th century, dentists around the world experimented with different materials and shapes for dental implants. One problem was that the body generally regarded stainless steel and ceramics as foreign bodies. As a result, superfluous connective tissue often formed around these implants.

The Swedish orthopaedic surgeon Per-Ingvar Brånemark was the first to use titanium in 1965. Today, he is considered the father of modern implantology (19). During animal experiments, he discovered that titanium measuring devices had grown firmly into the bone of a rabbit. His first implants in a human accompanied the patient for 40 years until his death.

Erst 1982 fand seine Entdeckung jedoch weltweite Beachtung, als er sie in Toronto präsentierte. Seitdem hat sich im Bereich Zahnimplantate viel ereignet. Die Implantologie gilt heute als wichtiger Teilbereich der Dentistry. Weltweit zählt man rund 80 große Hersteller, die Hunderte verschiedener Implantatformen anbieten.

Conclusion: Prevent complications

After the implant has been placed, perfect dental hygiene is of crucial importance. Due to the structure of the implant, bacteria and other pathogens can penetrate the bone via the abutment. The rough surface of the implant promotes ingrowth into the bone. At the same time, it offers excellent surfaces for germs to attack.

Daily mouthwashes, dental floss and mouthwash help to prevent inflammation. In addition, a collagen test provides information about the condition of an implant. This simple saliva test shows whether there is an increased breakdown of collagen in the oral cavity or on the implant. If inflamed tissue in the area of an implant remains untreated, this often results in its loss.