What is an implant?
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Different types of titanium screw implants
A dental implant integrated into the bone. The post screwed into the head of the implant protrudes through the gum tissue and acts as a support for the ceramic crown.
A dental implant is an artificial tooth root made from a biocompatible (tissue-friendly) material that is inserted operatively into the jawbone to replace one or more missing teeth. Standard implants today are screw-shaped or cylindrical and made from pure titanium. Titanium is a unique metal: it fuses directly with the bone without an intermediate layer. This intimate contact between the bone and titanium is called osseointegration. Pure titanium is so tissue-friendly that it is not rejected by the body and does not trigger allergic reactions or inflammation of the gums. On account of its excellent biocompatibility, this hard and durable metal is widely used for other medical implants, too, e.g. for artificial hip joints, cardiac pacemakers etc. The titanium surface of dental implants is roughened by special processes in order to facilitate attachment of the bone cells and accelerate incorporation into bone.
The dental implants used today are usually cylindrical or slightly conical screws (the shape of the tooth root) and normally 6-18 mm long and 3-6 mm in diameter. In the head of the implant is a small internal screw thread for attachment of the support post (known as the abutment). Depending on the use (crowns, bridges, dentures) there are various kinds of abutments.
Osseointegration under the microscope.
Left: cross section through an implant integrated into the bone.
Right: a bone cell sitting directly on the roughened titanium surface.
There are innumerable implant manufacturers on the market but only few systems are supported by scientific studies and long-term results. In our practice we use implants from the following manufacturers:
These manufacturers are market leaders with decades of experience and continuously improved systems backed by excellent long-term results.
Recently ceramic implants are often promoted as an alternative to titanium. In contrast to titanium implants they are white, but in our opinion this is not a relevant advantage since the implant is placed inside the bone anyway and is therefore not visible.
A disadvantage, however, is that for reasons of stability ceramic implants can currently often only be made in one piece. This means that it is not possible to work with angulated abutments, which can lead to cosmetic and functional problems in the prosthetic treatment. The excellent biocompatibility of ceramic is another argument put forward in favour of this material. However, as pure titanium is also extremely biocompatible and there have been no reports of titanium allergy anywhere in the world, we do not see this as a relevant advantage of ceramic either. Moreover, ceramic implants are usually considerably more expensive than titanium ones. However, the chief reason why we do not currently use ceramic implants is the absence of reliable long-term scientific studies on fracture strength, behaviour in the bone etc. As we do not want to use our patients as "guinea pigs" for materials which have not been sufficiently tested, we will for the time being continue to use the titanium screw implants which have proved themselves millions of times over.
We also refrain from using other alternative implant forms such as leaf implants or BOI implants (basal osseointegration implants) for the same reasons. Most professional associations do not recommend these implants either.
How is an implant placed?
Careful planning is the first step preceding an implant operation. The examination of the patient begins with careful inspection of the oral cavity and palpation of the jawbones. X-rays are taken to determine the available height of the bone. In straightforward cases it is sufficient to take a panoramic X-ray of the entire mouth (orthopantomogram, abbreviated OPG or OPT), possibly complemented by small dental X-rays taken inside the mouth.
In more difficult cases in which the amount of available bone is limited and we have to operate in the proximity of sensory nerves, for example, we have a computed tomographic (CT) scan of the jaw done. Cone beam volumetric tomography (CBVT or DVT) is a new type of computed tomography which has been developed specially for the head region. In comparison to normal computed tomography CBVT involves up to 80% less radiation exposure. The radiation dose of CBVT is therefore approximately the same as that of a normal panoramic X-ray (OPG). You can find further information on CBVT at Volumen Tomografie Zentrum Luzern.
Implant planning with three-dimensional CT images.
Computed tomography or cone beam volumetric tomography produces precise three-dimensional images of the jawbone on a 1:1 scale and permits optimal planning of the implant operation. The three-dimensional imaging permits exact measurement of the amount of available bone. The optimal positioning, length and diameter of the implants can now be planned on the basis of the available bone, as well as any necessary bone augmentation. The images also give us information about the quality of the bone (solid or porous). The CT or CBVT images also show the exact position of the nerves running through the bone as well as other structures which we must be careful to avoid injuring during the operation. This means considerable extra safety for the patient.
A further use of the three-dimensional images is for computer guided implantation, which is the safest and least traumatic method of all for the patient.
The placement of dental implants is a surgical intervention performed under sterile conditions. The operation takes between about 30 and 60 minutes depending on the complexity, possibly longer if several implants are placed in one session. It is normally done under local anaesthesia and is absolutely painless. However, we know that even though there is no pain, many patients find such procedures stressful. Therefore in our practice we often use sedation, e.g. with laughing gas (nitrous oxide) or other sedatives, in addition to the local anaesthetic. The benefit of this is that the patient feels fully relaxed and comfortable throughout the procedure.
Another option, particularly for larger operations such as bone augmentation or full-mouth reconstruction, is treatment under general anaesthesia. Treatment under general anaesthesia can be performed in our own operation theatre, in which case we call in an experienced team of anaesthesiologists.
From left to right:
1. Drilling the pilot hole in the bone
2. The implant has been inserted and the gum tissue repositioned over the implant and secured with sutures
3. At the end of the healing phase (osseointegration), the gum tissue is opened again, an impression is taken and a healing screw inserted
4. The finished crown on the implant
As soon as the local anaesthetic has taken effect the gum is carefully opened. With a sequence of calibrated burs, the implant bed in the bone is prepared. To prevent overheating of the bone, preparation is done with sterile water cooling. The suitable implant is chosen and carefully inserted. The gum tissue is replaced over the implant and secured with sutures (stitches) and a provisional denture or bridge is fitted. In the case of template guided implantation the operation can be even performed as a closed procedure, that means without cutting open the gum tissue at all.
Unncovering the implant
Normally dental implants should be left to heal for 6-12 weeks without beeing loaded, except in the case of what is known as immediate loading. After the healing phase, a small procedure is performed to uncover the head of the implant. We often do this by laser because this guarantees particularly good wound healing and is painless for the patient. After uncovering the implant head we take an impression and send it to the dental laboratory where the reconstructions (bridge, crown or dentures) are fabricated. There are also open healing implants known as transgingival implants (e.g. some Straumann implants), in which surgical exposure is not necessary. We use these implants particularly in the region of the back teeth.
Chapter overview: Implants
- What is an implant?
- Single-tooth implant
- Implants in the toothless jaw
- Bone augmentation
- New surgical procedures
- Immediate implants
- Risks and complications of dental implants
- Costs and guarantee of implant treatment
- Questions and answers about dental implants
Download the entire illustrated text Better Quality of Life with Dental Implants:
Better Quality of Life with Dental Implants (pdf 2 MB, possibly long download time)