Hi there. You are listening to the Perio Patient Podcast, a podcast for my patients and anyone else who cares to listen. My name is Dr. Ben Young, and I am a periodontist treating patients in my own private practice here in San Antonio, Texas. The title of this podcast is: “About Dental Implants.” Welcome if this is your first time listening.
Recently, a patient came to me referred by an excellent comprehensive dentist friend to evaluate a problem with a loose crown/abutment over a dental implant. The implant was placed 7-10 years ago by another dentist entirely.
About two years ago or so, the crown became loose. This crown is the replacement for a lower first molar and he or she (I don’t want to give any personal details here) is missing the two molars behind this one.
So, let’s talk about this problem as a way of talking about one of the most interesting and transformative developments within my career as a dentist.
When I graduated from dental school many moons ago, dental implants were unpredictable and frankly thought of as experimental and fringe dentistry. Then something remarkable happened in the mid-80’s. A new dental implant along with new surgical methods of placement fundamentally transformed dentistry for everyone.
Before the discovery of how the body can integrate or grow to accept titanium (we call this osseo – meaning bone – integration, osseointegration), and before we knew that if we heated the bone up too much during implant placement resulting in cell death and implant failure, and also before a new simpler implant design had been developed the survival rate for most of the implants placed was less than five years.
After these new techniques and dental implants became commercially available, the success rate for dental implants shot up and became so good that now the dental implant is considered the most successful and predictable dental restoration available.
Its survival rate is better than crowns, bridges and fillings of all kinds.
Having said all of this, dental implant systems can run into problems for three basic reasons – and you – if you have dental implants or may need their service in the future – aught to know about them.
The first one has to do with the bone/implant connection and the second one has to do with chewing or biting forces and the third has to do with the same potential chronic infections that affect the teeth. Instead of periodontitis, we call a similar process affecting the dental implant as peri-implantitis.
So let’s talk about each potential problem.
If a dental implant has problems, say, within the first six months or so, it is likely due to a bone/implant connection failure. Adequate osseointegration was not achieved. The body’s bone cells did not grow and essentially stick to the specially designed implant surface, at least in enough quantity to cause the implant to become, what they normally become – ten times stronger or more capable of handling loads compared with natural teeth.
These problems can be significantly reduced by not pushing the healing envelope after the implant is surgically placed. In other words, sometimes it is acceptable, even smart to extract a tooth and place an implant immediately. At other times it is better to stage things so the implant rests within the bone and heals before its top is exposed and the parts are then placed that puts this implant into chewing service.
There are a lot of things we could get into on this topic, but let’s move on for sake of brevity at this point. I try never to talk about teeth-in-a-day as having anything to do with dental implants. If you have any questions about all of this and want me to talk more on that particular topic, let me know. Moving on.
After the implant has healed past six months and there are no signs of problems, it is likely that osseointegration has been achieved. Now the greater concern has to do with loading.
To explain the difference between how dental implants take forces and how teeth take forces, let’s review the four parts of the tooth. Enamel, dentin, pulp and the least known, but most important when it comes to periodontal disease – cementum and the little fibers that project from it called periodontal fibers. These act as sort of the shock absorber of the tooth. When a tooth is overloaded it compresses these fibers – which does two things. First it allows the tooth to move and in moving absorb some of the force of the load. Teeth can get loose and then tighten up again thanks to the activities going on with the periodontal fibers – also called ligaments. The principles of moving teeth with orthodontics involve this process as well. The second way these fibers help when teeth are overloaded is due to the nerves that fire and send a message to the brain with not only the pain information but also the location of the problem. This ability to tell the brain locations of where the different parts of the body are relative to one another is called proprioception. This is what gives you the ability to touch the first fingers of your two hands together even while blindfolded. Proprioception allows you to eat food and not bite your tongue and cheek at the same time.
But what about dental implants? First they do not have a fiber system surrounding them. They are fused directly to bone. This means they do not have the same proprioceptive ability. Because they osseointegrate directly to bone they resist forces better than teeth can. However, if the forces become more excessive, and the brain is not aware this is happening, then eventually there can be microfracture of the implant/bone interface. If this happens then the implant will become loose and eventually fall out. Another possibility with excessive forces is fatigue of the metal which then results in a fracture or fractures within the implant. Unfortunately, this is what we discovered with the loose crown/abutment problem I started this podcast describing. Once the crown/abutment had been removed – which required drilling a hole through the crown to get access to the small set screw inside that holds the parts together – it was then possible to look at the top of the implant and for the first time see that the implant walls were fractured.
Once the implant has fractured, it cannot be repaired. So this required the removal of the implant body with grafting of the bone defect created with its removal. Now we have to wait for the area to heal and then rescan to make sure the healing is completed and to plan for the next dental implant to be placed.
And finally, just like periodontal disease, infections can occur around dental implants. These begin as bleeding and bone can be lost as pockets around implants deepen.
So, what might have given us a better outcome?
First, it is critical that dental implants be checked annually.
Every year it is a good idea to take a dental x-ray to make sure the bone levels are good and that there is no evidence that something has become loose.
The second step is to check the bite forces over dental implant crowns. This is accomplished by biting on a colored marking paper and also using a thin silver looking very thin mylar strip called shim stock. Ideally initial contact forces when you bite down are between teeth first. Once all the teeth are contacting, then the implant crown should contact. The shim stock helps show which contacts are hitting first. Another way to think of this is to understand that the thickness of the shim stock represents the thickness of the periodontal ligament space.
Finally, if something feels loose, do not wait to see if it gets better. It won’t get better and if perhaps if you are seen soon enough the implant may still be useable.
Also, even if you have only dental implants, you may have escaped from tooth decay, but not the chronic infections like periodontal disease. Check ups and cleanings are still important.
Well, that’s enough to chew on for now. This has been The Perio Patient Podcast and I am still Dr. Ben Young. Thanks for listening. If you have questions or comments, please send them to me. Have a great day. Bye for now.