So what’s new? I’ve just finished reading a book by Thailand’s Dr Death (Porntip Rojanasunand). More about it at Dewdrop Notes.
While I was checking my mail on Thursday, I came across a strange-looking brochure. It’s actually some sort of a circular discrediting another member of my profession. The brochure was printed in colour and on glossy paper to boot. The artwork is not very sophisticated, but the print resolution for the text is definitely higher than standard laser printing. Normally, only businesses would take the trouble and spend the money on this sort of printing to promote their products or services. This guy has probably spent a bomb printing a brochure which discredits a dentist who has done mini implants for him! Though I generally don’t use mini implants myself, I’m glad that he’s not my patient. And instead of achieving his intended objective of warning the public about this dentist, he has probably delivered a stronger warning to dentists not to see patients like him.
Actually, this gentleman’s main complaint is that the immediately loaded temporary crowns of his came off twice. I suspect that if that didn’t happen, he wouldn’t have complained about the dental clinic looking like a “marketplace”, the “unnecessary” extraction, the dentist failing to attend to him quickly, attending to two patients at one time, the assistant not knowing how to use the xray machine ….
The “brochure” also carried pictures taken of the implants in his mouth. He even had the xray printed on it. It seemed to me that the mini implants have not failed and were just doing what they are supposed or able to do. I have no comments with regards to the dentist’s treatment plan, techniques and choice of implants, but I think there is a need for the general public to be educated on the complexities, the limitations and shortcomings of all implant systems. Yes, the manufacturers advertise that their implants are manufactured with cutting edge technology, but the trouble with new technologies is, everyone is still at the learning stage.
Warning. I was never academically inclined, but the rest of this blog entry is going to sound pretty technical.
Dental implants used to be huge frameworks for patients with no teeth at all. The design of mini dental implants is not new. Years ago, when the first individual near-tooth-shaped implants were first introduced, all dental implants were one-piece systems. Like a tooth, the roughened surface acts as the root, engaging the patient’s jaw bone. The polished segment protrudes from the gums so that crowns can be fabricated and cemented on them. The biggest advantage of one-piece systems is that they are completely “straightforward” and “solid”. In other words, there is no weak connection at the neck.
This is a standard (not mini) one-piece implant
2-piece systems came later. These implant systems are separated into the fixture – the part that goes beneath the bone and the abutment and the part that protrudes from the gums. The two components are held together with a tiny screw. A multitude of problems can arise with this 2-piece system. The screw can come loose, it can even break. If there are microgaps between the fixture and the abutment, chronic infection and bone loss can occur.
In view of these disadvantages, why are 2-piece implants still so popular? Before we come to that we must first understand the importance of placing the hook in the correct position on the wall so that a picture hangs where we want it to. Same with implants. If the fixture is placed out of position, the final crown will be out of position. Unlike the one who hangs the picture, the dentist does not have an entire wall to work on. In most cases, he only has a narrow ridge of bone to place the implant. There really isn’t much choice of implant positions. If the bone is there, the implant has to be there and nowhere else.
With a one-piece system, the abutment will be slanted if the implant is placed slanted. If aesthetics are a concern and the remaining bone in the jaw prevents an ideal angle of placement, then the results of using a one-piece system can be disastrous. A 2-piece system allows any slant in implant position dictated by bone limitations to be corrected with the attachment of an abutment that slants in the opposite direction.
More often than not, implant positioning will not be ideal because of bone limitations. With a second piece that can correct this alignment, a major hurdle to restoration can be cleared. On the other hand, one-piece systems are safe and easy to use only when the bone condition is ideal. I would not hesitate to use a one-piece system if I have 10mm of bone in every direction. In the real world, such cases are rare.
Another advantage is the possibility of making screw-retained instead of cemented crowns. I can’t show you pictures of my cases as some people in the profession must be reading this and looking for an excuse to complain against me again. These crowns are bonded to the abutment and screwed directly into the fixtures. They can be unscrewed and screwed back during maintenance. Cemented crowns may be to be destroyed if anything goes wrong with them. That’s why, where possible, I would always try to do screw-retained implant crowns.
Now, what about mini implants? They are always one-piece and unlike the one-piece standard implant you see above, they are far narrower and often longer. The advantages? Well, they are cheap and they are quite easy to place with minimal drilling. They can even be placed in narrow bone. With standard implants, bone grafting will be required. These are probably the considerations that helped Mr Brochure decide to have mini implants. If bone grafting sounded scary to him and if he has been willing to accept compromises, then there is really no reason to complain.
But there’s always a catch somewhere. Mini implants are weaker than their standard counterparts. From my own experience, they tend to break and come loose more easily. I’ve already mentioned that being “straightforward” and one-piece, there is no margin even for “forced errors”. They can still be used, but only in special cases where there is little biting force or where slightly slanted abutment positions are of little consequence. Interestingly, there is one Korean implant manufacturer that came up with an ingenious idea – one-piece mini implant with bendable abutment.
I actually have this system in my clinic and I’ve used it several times though I had only needed to bend the abutment in a few cases, so it’s difficult to tell if it will work for the majority of patients. If I really have to use a one-piece mini implant system, this is probably the only one I’ll use.
The silver “knob” that the surgeon attached to the abutment portion of the one-piece implant can be used to bend that portion if the implant position is somewhat out.
