What is a dental implant?
An implant is a titanium screw that is inserted into bone. It is a replacement for the root of a tooth. The bone heals and bonds to the implant in a process called “Osseointegration”. Once integrated, the implant can be used to hold a range of things, such as crowns, bridges and dentures in place. When it is used to replace a single missing tooth, two parts are connected to the implant. The first is the “abutment” and the second is the” crown”.
The abutment is a custom made connecting post that will join the crown to the implant. The whole complex is known as an “implant supported crown”.
Why use an implant to replace a tooth?
A dental implant is used when the tooth is no longer viable or salvageable and cannot be used to hold a filling or crown in a predictable way.
What are the advantages?
The implant is in some ways a “fresh” start. The crown will be put on a new structure that hasn’t been subjected to decades of use and abuse. The implant supported crown process also does not require major modifications to other teeth such as a “bridge” requires. When the implant supported crown requires maintenance, the crown and abutment can usually be unscrewed, modified and then screwed back on. The cost of replacing the abutment and crown is less than other treatments such as a bridge. When other teeth in the mouth change or deteriorate the implant supported crown can be removed and the implant used for a different purpose, e.g. to hold a bridge or denture.
Why not have a dental implant?
Implants are not recommended when there is insufficient bone to safely place the implant. There are some situations where a bone graft can be performed to allow the implant to be placed. However there are occasionally situations when the best treatment may not be with dental implants. There are also individuals who have poor healing. Examples are smokers and uncontrolled diabetics. It has been shown that there are lower success rates in these individuals and more long term maintenance problems. These individuals have to be willing to face the higher risks if they wish to have treatment performed. People who are taking osteoporosis and some cancer medications such as the bisphosphonates have higher failure rates with dental implants. Implants are not generally recommended in young patients as they have a lot of growing to occur.
How long do they last?
Implant supported crowns have been used to replace single teeth since the late 1980’s. Various scientific studies indicate that the vast majority of the implants are still working after 30 years. Most studies have found that the abutment and crown is typically replaced after about 12 to 15 years, which is similar to a crown on a tooth. This is not surprising given that the crown is what is chewed with and subject to the greatest wear and tear. Those same studies show the abutment and crown is replaced for many reasons including fracture of the crown, change in use of the implant, e.g. conversion from a crown to a bridge or surrounding tooth movement. Other maintenance needs can be the periodic tightening of the abutment screw. This is usually required after several years.
What types of crowns for implants are there?
In general there are two different types of crowns, tooth coloured and non-tooth coloured. Tooth coloured crowns have some type of ceramic layer on the surface. It is this layer of ceramic that allows the correct colour to be created. The ceramic is however brittle and can crack and fracture is put under a lot of stress. The non-tooth coloured crowns are made out of metal. The shape is the same as a tooth but the colour is either gold or silver depending on the metal used. While they aren’t as pretty as tooth coloured crowns the metal crowns are substantially stronger and more forgiving. When put under a lot of stress the metal just deforms slightly.
How do I choose which type of crown to use?
The choice is largely dependent on how life-like you want your crown to look and how much stress the crown will be under. In general terms the visible crowns usually have tooth coloured bridges and non-visible crowns have metal.
How do I care for an implant supported crown?
An implant with a crown on it still has to be cleaned with daily brushing and flossing. The implant will not get decay however it has to be checked on a regular basis for gum disease and other complications. The crown should also be checked for cracks or looseness. As with teeth x-rays are needed from time to time to check the bone around the implant.
What is the different between a tooth-supported and an implant-supported crown?
As good as a dental implant is, it is not the same as your teeth. The overall shape of the dental implant supported crown is different to a tooth. This means that you will need to adapt your cleaning methods to the new shape. Food debris and plaque will collect in different areas than your regular teeth necessitating new habits. While the crown will look like a tooth, the gum around the implant can be a subtly different shape and colour. Usually this is not noticeable but for some people who show a lot of their gum, it can be a distraction. The feel when biting on the implant supported crown is also different to the feel of biting on a “normal” tooth. It is sometimes described as “dull” or “wooden” to bite on.
Are all dental implants the same?
Most dental implants are made from commercially pure titanium. There are different grades and they have different properties. Manufacturers of implants also treat the surface of their implants and this varies from company to company. Lastly, implants from different manufacturers vary in their design and how teeth can be connected to them. There is no one universal dental implant that is the best for all situations. We tend to select the implant to be used from one of the 4 major worldwide manufacturers of dental implants.
The reasons for this are:
1) we have a range of options to choose the best implant for you,
2) that there is ample independent research to show that those implants work predictably
3) these companies are not going bankrupt and so parts will be available for a long time
4) parts are also available worldwide in case you happen to move countries. These companies’ products are more expensive but the peace of mind is worth it.
How many visits does it take to have an implant supported crown?
It takes several visits to complete the process. The typical sequence of appointments is:
1. Consultation to determine the appropriate plan
2. Removal of the tooth and placement of the dental implant (if possible) and placement of a temporary tooth (if needed)
3. Test the implant
4. Impression of the implant and teeth
5. Insert the abutment and crown
6. Review after 1 month
This process usually takes 3 to 4 months to complete. If bone grafting is required, the time needed can extend even more. We strive to place implants when teeth are removed (see point 2) as it shortens the treatment time. There are however some instances when this is not physically possible or not recommended as it would compromise the long term outcome. We will not perform treatment for convenience if a better outcome could be obtained using a more measured approach.
There are instances when the colour of the crown is particularly important and you may be required to visit the laboratory technician. This is done between visits 4 and 5.
What can go wrong in the process?
The most significant complication is that the bone fails to integrate with the implant. This is an unusual occurrence and is less than 1% of instances for healthy people. There is usually the chance to try putting the implant in again with a different approach and possibly a different implant design.
Other things you need to know
All people continue to grow and change and so do teeth. Implants however are anchored to the bone and will not change position. This means that as the years pass the teeth will gradually shift position around the implant supported crown. If the difference is noticeable, the abutment/crown may need to be replaced. There are some occasions when the crown is glued on to the abutment. In these instances the crown can’t be simply removed and replaced. The crown would have to be cut off and a new one made.
The pain after an implant is placed is usually surprisingly low, less than a tooth extraction. A variety of pain relievers can be prescribed in case of more intense pain.