Table of Contents
(Note that there are two pages to this section. This page is about the technical aspects of implants themselves. The second page involves the surgical techniques and a general discussion of how much they cost.
In 1952, A Swedish orthopedic surgeon named Per Ingvar Branemark was doing research on the microscopic healing of bony defects. His subjects were rabbits, and he and his team were studying healing bone by using specially designed microscope heads made out of titanium metal with lenses at the tips. These were placed firmly in holes drilled into thighbone of the anesthetized animals, and left in place in order to photograph the microscopic events during healing.
After the experiments, he attempted to retrieve the microscope heads and found that they he could not remove them. Further study convinced him that the titanium metal was biocompatible and had actually integrated into the bone. He called this phenomenon “osseointegration”. He spent the next 25 years trying to convince the scientific community that he had finally discovered a metal that would integrate when implanted in bone, and not be rejected by the body’s immune system.
Today implants have become the most rapidly growing dental service in the world. Properly done, their immediate success rate borders on 100%, and their ten year success rate is about 95%. A tooth with a root canal, post and core and crown has ten year success rate of about 90%. (Unlike natural teeth, implants are not subject to decay, fracture or failed root canals, but like natural teeth, they can still be lost to poor oral hygiene leading to periodontal disease.)
Dental implants can be placed immediately after the extraction of a tooth, and, like the natural teeth they are meant to replace, they preserve the bone height wherever they are placed. They can also be used to retain full dentures in patients who cannot ordinarily wear them due to gagging or because there is not enough bony anatomy to retain them due to severe bone resorption. They can be used to replace individual missing teeth, or serve as abutments for a bridge
Finally, unlike traditional bridges, they have the added advantage of being able to replace a missing natural tooth without damaging adjacent teeth.
When people think of dental implants, they generally are thinking about endosseous rootform implants. Above are images of three different rootform endosseous implants. Endosseous means that this type of implant is actually placed in a hole drilled in the bone and is then allowed to integrate, just as Branemark’s microscope heads integrated into the rabbit bone. The two implants on the left are made of pure titanium. The one furthest left is the one refined by Branemark himself. The implant in the middle has been sandblasted with silicon oxide to produce a rough surface. Sandblasted and etched titanium has become the industry standard. This rough surface has been shown to help in bony integration. The implant on the right is made of zirconium oxide which has been shown to integrate with bone as well as pure titanium. Most dentists work with a specific brand of implant since all the drills and wrenches, as well as the implants themselves are company proprietary.
The image on the right is what the finished case looks like after healing is complete. The image to the left above shows the lab fabricated abutments (top),the screws used to secure them to the implants (middle),and the crowns which are cemented over the abutment after it is screwed firmly into the implant itself. Much more on this process will be found on the next page
Implant retained dentures
As you can see from the Panorex in the upper left image above, the lower jaw can undergo some serious deterioration after the teeth are removed, leaving very little to retain a denture. The image on the lower right shows old style ball abutments placed on a pair of rootform implants can reverse the situation permanently. Below is a Panorex film of a normal jaw for comparison.
Nothing beats a healthy tooth with a live nerve if it surrounded by healthy gums. Natural teeth are meant to last you all your life, especially if you have reasonably good oral hygiene and do not use sugar to excess. Even if the tooth has large fillings, or a well done root canal, it may last for a the rest of your life. For teeth with a root canal, this is true only if it is protected with a post and core followed by a crown.
A fairly intact tooth with a root canal, a post and core and a crown has about a 90% ten year survival rate while an implant has about a 95% ten year survival rate. (These figures are industry standards and were published recently in Dental Economics.) Neither of these statistics takes into account the vast majority in both categories which survive for twenty or more years. In most instances, it is wiser to do the root canal, if necessary, on a good, intact tooth with no gum disease rather than to extract it and replace it with an implant. On the other hand, a patient presenting with a very badly broken down tooth above the gum line, or with a tooth that needs a root canal and also has moderate to severe gum disease, might be wise to extract the tooth and place an immediate implant instead.
When a dentist suggests an extraction followed by an implant rather than repairing the natural tooth, he or she is simply calculating the relative expense vs. the long term prognosis for each option. In other words, twenty years from the day the procedures are finished, the dentist believes the implant tooth is more likely than the natural tooth to be in place and functioning. The implant tooth will never get decay, there is no post and core that may break out, there is no root canal to fail, and, unlike the roots of a natural tooth with a root canal, the implant itself will never fracture. (Unfortunately, poor oral hygiene will cause the implant to fail, just like a natural tooth.)
Finally, the dentist and the patient must consider the expense side of the equation. The implant, along with the abutment and bone grafting that may be necessary will probably cost between 15% and 39% more than repairing the natural tooth with a root canal, post and core and crown, but when you consider the probability of that tooth’s long term survival, the costs even out. Furthermore, there are now many ways to finance even an expensive dental treatment plan. The costs of implants are discussed in more depth on the
next page of this section
Factors that cause implants to fail
A properly done implant is one of the most predictable procedures in dentistry. Unfortunately several health related factors can contribute to peri-implant disease (which is the implant version of periodontal (gum) disease.
- Smoking and smokeless tobacco increase the likelihood of peri-implant disease by a factor of 5. In other words, if you are a smoker, or if you chew or dip tobacco, you are 5 times as likely to lose your implant than persons who do not have these habits.
- Uncontrolled diabetes is a serious risk factor for implant failure. This is not the case for well controlled diabetics who’s success rate with implants is nearly as high as persons without diabetes.
Many dentists will not even consider doing implants on people who smoke or have uncontrolled diabetes.
- Immunosuppressed patients may have a higher risk of implant failure. This does not apply to HIV patients who’s symptoms are in remission during implant surgery and healing.
- Patients on immunosuppressive drugs for cancer should wait until they are they have stopped their therapy and are in remission.
- Patients taking corticosteroids for chronic conditions are more prone to implant failure.
- Patients taking IV bisphosphonates for cancer are poor candidates for implants. Patients taking oral bisphosphonates (Fosamax, Boniva Actonel, etc.) are NOT at risk. See my page on Bisphosphonates for more on this subject.
- Untreated periodontal disease can predict implant failure since the same factors which cause periodontal disease (poor oral hygiene, smoking etc) can cause peri-implant disease. If you want implants, you still have to carefully brush and floss or you can lose them.
Dental Implants vs. Fixed bridges
fixed bridge (fixed partial denture) is the traditional method of replacing one or more missing teeth if there remains at least one healthy natural abutment tooth on either side of the edentulous (empty) space. The dentist prepares (changes the shape of) the remaining natural teeth on either side of the space and takes an impression. The lab returns a bridge, which consists of crowns that replace the anatomy of the abutment teeth with a pontic (false tooth) attached between them.
The cost of doing a three unit bridge is the same as the cost of doing three crowns, which, it turns out is about the same as the cost of doing a single implant with its associated abutment and crown. However, implants have a number of serious advantages over the fixed bridge, and consequently, implants are becoming the tooth replacement of choice. The long term success rate of an implant is, in fact greater than the success rate for a three unit bridge. Implants also prevent the loss of the bone that used to support the extracted tooth, while the bridge does not. Bone continues to disappear under a pontic leaving more and more space between the gums and the false tooth where food can become trapped.
What about Dental implants in patients who have had radiation therapy to the head and neck?
Radiation therapy was originally considered a contraindication (This means that it was considered a bad idea) for installation of dental implants. This is no longer the case. In most cases, patients benefit greatly from dental implants after radiation therapy because;
1) these patients are more likely to loose the remaining teeth due to decay from the dry mouth caused by the radiation therapy,
2) the failure of a dental implant after radiation therapy does not necessarily imply (or cause) osteoradionecrosis, and
3) strategically placed implants can restore the patient’s ability to eat properly, as well as to smile and speak with confidence, both of which are essential to the patients ability to recover from their cancer.
While most dental implants placed in irradiated bone do survive for ten years or more, overall, implants in these patients still have a greater risk for failure. Once again, failure of a dental implant does not necessarily imply osteoradionecrosis, although this can certainly happen. Survival is significantly influenced by the location of the implant (maxilla or mandible, anterior or posterior). In one study;
A total of 48 patients who had prior head and neck radiation had 271 dental implants placed during May 1987 to July 2008. The estimated survival at 1, 5, and 10 years was 98.9%, 89.9%, and 72.3%, respectively. Implants placed in the maxilla were more likely to fail than implants placed in the mandible. There was also a tendency for implants placed in the posterior region to fail compared with those placed in the anterior region. Conclusion: Dental implants placed in irradiated bone have a greater risk for failure. Survival is significantly influenced by the location of the implant (maxilla or mandible, anterior or posterior).
Financing an expensive dental treatment plan
Dentists are not banks. They have no means of checking your credit history, and even if they did, they have no legal status as lenders. They simply cannot finance your dentistry. Until recently, patients either had to pay for their dental plans all at once, or do a little at a time until it was all finished. This often lead to financial hardship, unfinished treatment plans or dental work that never ended.
But things began to change when financiers figured out that patients are customers too. When that patient goes into an automobile dealership and purchases a car, he doesn’t have to pay for it all at once out of pocket. Nor does he make arrangements to drive the car only when he happens to have the cash to pay that month. He makes a financial agreement with a bank or finance company to take a loan. He then gets to pay a fixed amount monthly, the dealer gets his money up front, and the patient/customer gets his new car.
Today we have several finance companies which do the same thing for dentistry that they do for car dealerships. Now, Care Credit, Wells Fargo, Henry Schein and several other large banks will arrange loans that can be used at any medical facility, including physicians, dentists, ophthalmologists, podiatrists and veterinarians. You don’t have to make your own arrangements. The doctor’s staff can apply for you over the internet. The finance company checks the patient’s credit and makes an immediate decision about granting the loan. If the patient is approved, he or she signs an agreement, the money goes immediately to the medical provider, and the patient gets his or her treatment from beginning to end with no waiting or dragging out his or her wallet at each visit. In most instances, the medical provider will even pay the interest on the loan during the first twelve months for the patient.