The answer to those questions is no, and no.
This does not mean, however, that there is no place for mini-implants for some people or for some applications.
What IS the difference? Why “mini”? Mini-implants are not the same as full-sized dental implants. An arbitrary mark has been picked: if smaller than 3 mm in diameter (you can look on a ruler, it is pretty small!) the screw or pin is called a mini-implant. If 3 mm in diameter or more then it deserves the designation of “implant”. Somewhat subjective, but you get the idea.
Are mini-implants “as good”? Of course not. All else equal, a full-sized implant should pretty much always be used when possible. If one has to hold a heavy frame on the wall, one uses solid, large nails or screws in general...It is certainly safer for the frame! Could a lot of small nails be used to hold the frame? Possibly, as long as nobody cares too much about the frame or how long it will stay up!
It has been said that “oral surgeons and periodontists do not like mini-implants”, while other dentists much more limited in surgical training like to use them. This is a warning in itself, and it is when the time comes to be careful. Full-size implants are more demanding technique-wise for placement and their size by itself may ask for some enhancements of the areas where they are to be inserted (each implant size asks for a certain amount of bone to surround it and hold it properly, and obviously the larger the implant, the more the bone needed). Surgical limitations of the operators should not in general determine the proper or best treatment plan for a patient, unless there is no possibility for that person to have access to someone more qualified. For example, I remember a friend (from another dental specialty) to whom I asked: “What do you tell someone who consults you for implants, who does not have enough bone in the back of the lower jaw?” His answer was “I simply tell them they are NOT an implant candidate”. The right answer should have been: “I cannot help you, this goes beyond my level of surgical care...But I can refer you to someone who can certainly get it done for you”. Professional pride kept him from doing that...But that would have been the proper thing to do for the patient. As an oral and maxillofacial surgeon, I do see cases (of disease or pathology mostly) that I refer to academic-based colleagues, because of extra experience they have or the environment they have to work in (help from residents, special tools, low-cost cases done for teaching, etc.) There is no shame in that, and it is a better service to the patient. All this is to point out that mini-implants have a role in dentistry, but somewhat limited in my opinion...And they should certainly not be used for applications for which real implants would do better, only because of the surgical limitations of the operator.
Some reviewers have been very drastic about mini-implants: “They always fail”, “they are too small to osseointegrate” (i.e. “fuse to bone”), “they are not FDA approved”, etc. On the matter of failure, I can certainly concur: A lot of them just appear “wedged in place”, and fail early in the game. As for being too small to integrate, I have not seen scientific reasons why it would be so, and I have myself been unable on occasion to unscrew titanium screws (about the size of mini-implants or even smaller) that had been used to fix a fracture when it was decided to remove them - for some reason or other - after months of healing. I believe the main limitations of mini-implants are basic physics: small diameter means smaller outside surface area, therefore less surface of contact with the bone. Bone is also know to resorb when undergoing pressure (it helps the orthodontist move your teeth around, but is an eventual disaster under a denture!); if undergoing a given force, the smaller area of the mini-implant will concentrate more forces on smaller area of bone and most likely favor resorption of the bone, and eventual looseness of the mini-implant. Mini-implants are also usually used “immediately”, without any time left alone for possible osseointegration (the same is often done with full-size implants, however, but they probably benefit from less focused forces spread over a larger bone area).
So we are back to the comparison of the frame in the wall. All else equal, for long-term result with as little hassle or risk of losing the frame as possible, one must favor a full-size screw or nail (or implant!) For bigger jobs, several large screws or nails may be needed. But probably not a ton of small pins…
So again, is there a role for mini-implants in dentistry? Sure. They are actually FDA-approved for some uses. I have used them, for example, to hold a denture or bridge while “real implants” were left to heal in peace. Denture retention is mostly how they have been used by dentists, usually for those stated reasons: Patient too ill for extensive bone augmentation procedures (I obviously agree with that), insufficient bone for implant placement (I will say it depends on the specific case, and may be an appropriate treatment or not), decrease cost of the procedure (hopefully true). Dr. Gordon Christensen (a guru of dentistry, if not surgery) has been teaching dentists to insert mini-implants for a long time...And it is hard to argue with a Guru! But I still believe that they do not have a role in holding crowns (except for a mini-tooth?) or bridges, since the forces on those is too high for long-term success (the physics are just really bad). In cases where multiple small pins can work as a team to hold a denture undergoing smaller forces (no natural teeth left in upper and lower jaw, no clenching or grinding habit, soft diet in general), then sure...But a smaller number of real implants would still be better as a rule. For a debilitated patient who cannot hold a denture in, for someone with limited life expectancy, for someone who would need extensive surgeries and cannot deal with it or afford it...Then sure, again one can make a good argument in favor of them. A solution limited in time is better than no solution at all!
Part of our issue with mini-implants is the tremendous success and longevity of most of what we do in general. I have seen over the years a lot of 30+ year old silver fillings (amalgams), crowns and even bridges (unfortunately, also a few dentures that age!) Given the rather intense conditions found in the mouth (humidity, heat, cold, acids, bases, abrasives, bacteria, intense pressures, etc.) the longevity of what we do is (with exceptions) amazing. Dentists are not used to redo things all the time. Our success rate is great, and we like it like that. Yes, dentures should be replaced every 5-6 years, but this is for health and bone-maintenance reasons, rarely because the denture is broken or unusable. Nobody is surprised when replacing glasses every year or two, and the optometrist is not blamed for it...But this type of repeated short-term replacement is not expected at the dentist's office. I like to give the statistics for “real” implants: 98%+ success rate at healing, 95%+ still in place after 10 years, 90%+ still in place after 15 years in longer term studies...Although still not perfect, these are the type of numbers we like. And as much as I have seen it prove itself with real implants, I sure do not expect the same from mini-implants.
Conclusion? If at all possible, and except for rare specific cases, always use full-size (“real”) implants. To support crowns and bridges long-term, use real implants. To stabilize a denture (especially if opposed by real dentition) use real implants if at all possible. For a young person, use real implants except for extremely rare cases. If one is too weak or sick or has limited life expectancy, or would need extensive bone reconstruction that is undesired or undoable, by all means consider mini-implants. If financials are a terminally limiting factor, consider mini-implants to improve denture retention and quality of life, but make sure that it REALLY is cheaper (I have been surprised by what some people end up paying for mini-implants…and watch out for ongoing “repair and replacements”) and understand that just like glasses, it will probably require regular repairs and replacements.
I hope this helps, and let us know if you have any questions about implants!
Bertrand Sorel, DMD, MD