Implant Sizes: What has the FDA Approved?
Dr. V. asks:
Is there a difference with the terms “narrow diameter implants”, “mini implants” or “small diameter implants”? I’ve heard that FDA approved term for implants 1.8 to 3.0mm in diameter are termed as “narrow diameter implants” and that 3.0 to 3.5 as “Mini implants” and 3.5 to 6.0 mm as regular diameter implants. Is this information authentic? I am having difficulty verifying this information. Also, what are the potential legal implications of using other than conventional implants?
17 Comments on Implant Sizes: What has the FDA Approved?
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Dr HAaold Bergman
Orignally, Nobelpharma sold a threaded implant 3.0 mm in diameter for standard use. They experienced breakages as the narrow part of the thread was much smaller than 3.0 mm but closer to 2.0 mm. As well, Nobelpharma implants are made from C.P. Titanium which is about 60% weaker than 6/4 Titanium alloy. Therefore breakage. The only FDA approved about 20 years ago and still approved implant for standard usage and still available is the Anchor 3.0 mm HA coated implant. FDA removed the approval for the Nobelpharma implant and would not approve of any implant afterwards below 3.25mm diameter due to fear of breakage. "Minis" came on the scene about 15 years ago and were approved only for transitional usage. Therefore the name Mini nd transitional were synonymous. Recently a number of these narrower implants have been approved for limited permanent use. The FDA now wants all implants smaller in diameter than 3.25 mm called "narrow Diameter" to differentiate them from "stanadrd" use implants which are greater in diameter.
In looking a the long term studies, the implant being used to replace a tooth or teeth should approximate the size of the root of the tooth being replaced or have multiple implants to add up to the surface areas.
The total osseointegrated surface area of an implant need not follow the total surface area of the tooth root surface area that it is replacing because the attachment mode is different. Natural teeth are attached to the alveolar bone via the periodontal ligament that acts both as an attachment device as well as a suspensionary device. Osseointegated dental implants are attached to the bone directly via ankylosis which is essentially an attachment device with no suspensory element. Based on this understanding, the osseointegrated surface area of a dental implant need not be equivalent to the surface area of the tooth it is replacing. Arguably,only half the equivalent surface area is sufficient since it is via ankylosis.
I have a question to whom ever would like to answer it (correctly). How does or should I say what is the correct procedure a dentist is supposed to follow to determine the exact size implant to use on a patient. They must have in writing somewhere in the dental manuals how to determine the size implant to use. I am sure that there is more than one determining factor and I would like to know if the size of the jaw of a patient has anything to do with it. thank-you
Dr. Bill Woods
There is no exact size. Period. Every case is different. every patient is different. here are 50+ companies that manufacture hundreds of different implants that work. Size is only one factor. And not just length. Surface area, coating, on and on. And clinicians have variables in their abilities as well. The is no exact in implant dentisty, or dentistry as a whole. Bill
tina to Bill
Okay, thank-you for answering my question but, I would like to know if the jaw is a determining factor. For instance would you put a lumberjack implant into a petite jaw.
Dr. KFChow malaysia
The natural teeth for humans are designed and built to withstand masticatory forces of between 200 to 400 pounds per square in. Any implant that can withstand such forces with about 30% safety margin will be adequate. The implant material per se and the margin of osseointegration between the implant surface and the bone should also be designed to withstand such forces in the mouth over long periods without metal fatigue. As such, titanium alloy implants need not imitate the general size of the teeth roots that they are replacing. Instead, the size of the titanium implant should be designed to achieve enough osseointegration to withstand normal masticatory forces. This usually translates into half or less than the surface area of the tooth the implant is replacing since ankylosis(aka osseointegration) is area for area much more resistant to masticatory forces than the periodontal ligament. That is why the titanium implant need not be the same size as the root that it is replacing but instead be smaller by a half or more. So, Tina, you need not have a lumberjack implant, just a wimpy mini will do for your petite jaw. As for the jaws, it is not the size of the jaws but the density of the bone that is the determining factor. Most people will have sufficiently dense bone. Cheers.
i just want to clarify somepoints.first , load distribution over implant is following the rule:-when two different materials in contact exposed to load,the load well be distributed to the are where they first come in contact, that is why diameter of implant is more importa than the length regarding load distribution. seconed ,calculating load distribution over implant has different concept than the natural teeth,also we should not use the term(ankylosis)to describe implant rigid fixation,cos ankylosis means chemical & mechanical bonds ( in case of dental implant itis only mechanical) finaly it is not only the size of the implant which count in biomechanics for dental implant, other factores like ,bite force ,force direction,nature of the opposing tooth & prosthetic design
I have upper and lower dental implants. They have been in for about 2 years now. I have not had any problems with them, but a short time ago I started noticing that underneath my chin is swelling up. I can put ice on it and it will go down, but the swelling always comes back. I am afraid to go to the dentist because I do not want to loose my lower implants. They are not brothering me. What could be causing this?
According to the mfg they are FDA approved for long term use. I have seen broken minis, minis nit take in the maxilla etc. I think they have limited use.
FDA has cleared mini implants for long term use. The definition of long-term according to the FDA is 18 months. So, the FDA has cleared mini implants for 18 months. I use mini implants in my office as temporaries. Many times these implants stay well integrated and at times they do break or come out. I agree with the statment that they have limited use but used properly they work great.
Ken Clifford, DDS
Ever see a broken conventional implant? If your decision not to use them is based on seeing a broken one, better stop doing implants period.
Ken Clifford, DDS
Same goes for not "taking" in the maxilla. Mini implants are easy to replace with minimal bone loss, what happens when a conventional implant doesn't "take"? And on the subject of forces and stress, natural teeth in the posterior have two or three roots to distribute the forces over different force vectors. Why wouldn't two or three mini implants be better than one massive conventional which can only resist force in the occlusal direction? Just asking.
I have seen the rare broken regular implant. The mini's are ok for a short time. An implant with a robust diameter and length is better. This is just common sense.
Ken Clifford, DDS
Common sense says "do the math". Surface area of a cylinder equals pi (3.14168) times diameter times length. Surface area of a single 5.0mm implant, length 12mm, is 188 sq mm, and that assumes you have enough width in all directions to allow the appropriate clearance on all sides. Surface area of two 2.5mm implants, length 12mm, is 188 sq mm. I usually find I can place longer mini implants than conventionals, and sometimes use three minis for an upper molar, resulting in significantly MORE surface area than I could otherwise achieve. Also note I have only had one mini fracture in function out of over 1000 placed, and that was a rumored fault of an Imtec implant. K Clifford
A wider implant is better for the following reasons: increased width helps reduce the stress transmitted across the crest of the boney ridge thus maintains bone, increased width reduces thepossability of bending fracture by the power of 4. This info came from Misch's text. I use mini's as a transitional only. To rely on them and hinge extensive treatment on them is folly. One should leard several methods like blades, subs etc inaddition to various grafting techniques.
Dr. Gerald Rudick
There is no doubt that mini transitional implants have their place in treatment planning implant dental cases. I would classifiy an implant of 1.8 mm as a mini. If possible, rather than leave a patient edentulous, or having to endure a flipper during the healing and waiting stages of conventional implant sizes, mini implants can be installed between and close to normal size implants and natural teeth; to fasten and secure a fixed temporary prosthesis. I personally feel more secure using mini implants for this purpose rather than place temporary bridges on freshly installed conventional larger diameter implants in anything less than type 1 bone. If a mini implant fails, it leaves very little damage, and the bone will fill in uneventfully. If they fracture, the remaining portion can generally be trephined out....and that will demonstrate the degree of osseointegration.... as you will see in the core sample. Gerald Rudick dds Montreal The advantage of the mini is that it can