Prognosis of Final Restoration when Using Shorter Dental Implants?

The longer the implant has no relation to success rate but wider implants have more stability,bone condition is also very important in your case because of d4 bone quality and 4.5 milimeter of diameter of bone in area of 17 it is a good policy to use the hard cortical bone floor of sinus as a reinforcement for retention of implant,i really want to know the height of bone to the floor of sinus.if it is about 7 mm you can penetrate safely 3 millimeter in sinus. Best Regards Dr.Hajiheshmati Implantologist

I need to make a correction, the third implant 3.7X13mm would be placed in the area of #4, not 5.

Dr. Hajiheshmati, the 4.5mm you are referring to is the height of available bone, not the width. The width of available bone in the area 2-3 is: 7.5-8mm.

Dr. M, The design of an implant can allow a short implant to have as much suface area as a much longer threaded implant. The reasearch on the Bicon.com site shows greater success with shorter implants in many situations. Bicon has circumferential "landings", or "fins", instead of threads. You can do successful molar replacement with implants as short as 5, 6 and 8 mm. They now have a specially designed placement instrument which engages (locks into) the special sinus lift abutment (a T shaped, sub-periostal, healing abutment which helps to prevent accidental dislodgement into the sinus. Even if the implant went into the sinus, it is locked onto this new instrument handle which allows simple, safe retrieval. It is not yet in the catalogs, but you can order it. Try viewing some of their online webcast replays as well as the reviews and research on short implants (less than 8 mm long) John

Also, Bicon implants adapt well to immediate grafts and there are several webcast replays on that subject on the Bicon site. I think you will find the shown Bicon options to be less traumatic and less demanding of existing structures than would a lateral sinus lift graft and placement procedure. John

Also note that Bicon has had a locking placement tool for years which engaged the implant well directly. What is new is a placement instrument which will lock on the Sinus Lift Abutment so you place the implant with the abutment atop and locked onto the implant, but lock the placement instrument into the abutment, not the implant as before.

Most of the articles in the literature conclude that osteotome sinus lifts should only be done if you have at least 5-6 mm of vertical height below the sinus. I am familiar with the use of short implants, most notably Bicon. However, much of the current literature is strongly suggesting that there is an increasingly alarming high rate of failures with short implants, especially in type D4 bone, and in the position of the maxillary second molar. I would definitely re-think placing a short implant in the area of the second molar.

Have you seen research done on the Bicon short implants which shows decreased lift success with sinus floors less than 5 mm? The papers I've seen show higher success rate or equal success rates. If you had 5 mm of bone, you may not need to lift the sinus when using Bicon. I wonder if the literature to which you allude have evaluated this "plateau" style implant design, or the more common threaded designs. The Bicon plateau design implants are integrated via Haversian Bone, similar to Cortical Bone after having been placed passively. They have as much surface area in an 8 mm implant as does a 14 mm long threaded implant, and begin immediate integration with no primary resorption as is common with pressure fitted or threaded implant designs. Case studies shown on Bicon site routinely show long term success with Floor Transports at 2 mm or Sommer's Lifts at 3 mm floor depths. John

Thanks for the very interesting comments on the Bicon short implants. I am curious, when you say that "case studies" show routinely success with these short fixtures, how many cases are they referring to, and over how long a period of time?

I used to do a lot of Bicon implants (originally were Stryker). I quit when I had two that would not keep the abutment in place (morse taper fit). When I called the company they said they had never heard of this happening. I had two. When a company that sells all over the world tells me that I am the only one experiencing an issue with their product, I tend to walk away for good. Has the design been improved?

Dr. H: - And before Stryker they were Driscoll (designed by an engineer with that name I believe.) Problems with the system include occasional fracture of the original 2mm dia. post abutments and repeated loosening of the morse taper abutments in the maxillary anterior. Company has always stated that these were problems that could be alleviated by "proper" occlusal adjustment. Maybe true, maybe not! They came out with the 3mm dia. post abutments around year 2000 and they now make 2.5mm post abutments for the larger diameter implants. Still a good system "when used in the appropriate location scenario" with >2mm dia. post abutments. Please see Dr. Manuel's comments above. I have placed many of these circa 1990/later and have had excellent success in the posterior maxilla and anywhere in the mandible. Still place a few in "selected" cases currently - actually have some referrals that prefer and ask for them. It certainly seems that all systems have their weak and strong points. - Dr. No

I agree that the lateral window would be the best option. However, in my hands, 8-10 mm implants have never been a problem if I had primary stability during placement. for that matter, many 6 mm implants that I have placed have worked out well for me. As a disclaimer, however, those 6 mm implants were placed on the posterior mandible where I had type 1 and 2 bone. If I ever had to resort to a 6mm implant, it was the Straumann. Bottom line is primary stability. If you are going to use a wide 5x8 for example in type 4 bone, as you know, underprep your osteotomy by 1 mm or more before placing the implant.

Great discussion here. You can write a full review of Bicon Short Implants and rate the system at: http://www.osseonews.com/products/bicon-short-dental-implants-review/ - and you can rate and review any implant system by visiting our new Implant System Rating and Review section at: http://www.osseonews.com/dental-implant-systems-reviews/

Re: past problems with abutment loosening or breakage. This was a problem with the smaller implants with 2 mm wells and posts. It mainly arose in cantilevered, off center occlusal relationships, or when the patient could hook the lower anterior teeth against the Labial surface of the upper anteriors and pull back. As with most implant component breakage, high and off-axis occlusal forces seem to have played a major role in that problem. No such problem has been seen on the 3.0 nor 2.5 mm abutments. Last year they came out with a more parallel, 2.5 mm post abutment which not only eliminates this problem on anteriors, but is so tight that removing it is extremely difficult. We are now using some 2.5 well implants posteriorly, when balanced function is possible. When it comes to reliable answers, I usually refer to Dr. Shadi Daher. There are some new, young researchers who also seem to be measured and accurate about these important questions. John

Re: Sinus lifts Whether I've done the graft myself or sent to the specialist, all sinus grafts I've seen "feel" softer than normal bone to me. There is a lot of hand prep possible with the Bicons and that allows a bit better "feel" of the situation. By alternating reaming with the gentle tappiing of an expander in each size, some greater density can be achieved prior to the final, passive implant placement. Re: Research vs. Case Studies The Bicon site has a number of long term case studies listed, several videos of research presentation from past conferences. The most impressive research I've seen recently was done by Dr. Rainier Urdeneta, a young prosthodontist from Harvard, who has completed some long term, retrospective, cohort studies identifying the 5 - 10 most significant factors in bone growth and implant success. That study showed that shorter implants are more likely to experience bone growth than longer implants. What I really enjoyed about his presentation in Boston in mid August, 2011, was the great many factors which we worry about that seem to have little or no effect on the long term success of implants. This team has made several very interesting, significant discoveries which are to be published this Fall, I believe. For one, they found that bone can be loaded and stimulated to grow vertiallly THROUGH fibrous tissues. For another, they arrived at a specific ratio, a specific measurement of the circulating tissue base which will reliably result in normal interdental papilla growth. i.e., it does not matter how skillful an operator is at grafting, unless this specific Biologic Base Proportion (similar to the Biologic Width principle) is present, sustained papilla formation and maintenance is not possible. He also, during a 2010 study of "The Effect of Increased Crown-to-Implant Ratio on Single-Tooth Locking-Taper Implants" from the International Journal of Oral and Maxillofacial Implants demonstrated that, as you mention, increased crown-root ratio increased the chances of loosening or breakage in the 2mm implants. BUT he also demonstrated increased bone GROWTH over the abutment/implant connections. Whether Bicon or whatever, it is so very pleasant to see new principles proposed with substantial supporting evidence. John

Dr. John Manuel: - Just a follow-up to the posting on Bicon abutments. The last Bicon stat that I saw on 2mm abutment post fractures (a couple years ago) was a 0.14% incidence. To qualify that, those are just formally reported complaints (i.e. paperwork submitted) and probably do not represent the total actually experienced. Although I don't restore implants, I have seen fractured abutments in several cases that were not cantilevered or otherwise restoratively abused (i.e. single unit maxillary and mandibular bicuspids w/o off axis loading, prematurities or etc.) As far as I am aware, there has never been a reported case of a fracture with a 2.5 or 3mm abutment post. - As for abutment loosening, this was much more prevalent with the original 2mm well implants requiring a 2mm post abutment. In the maxillary anterior, I know for a fact that there have been reported complaints with the 3mm posts as well (I have lodged some.) This despite what I would consider good placement position, restoration and with no angled abutments in play. By necessity, off axis loading is often at a maximum in the maxillary anterior. If a company markets implants to be used there, they must be designed to handle and actually accommodate that load in long term function. I am not convinced that the 3mm Bicon implants are satisfactorily reliable (for me) in the anterior maxilla. - Also, for consideration is the fact that Bicon did come out recently with the 2.5mm "narrow" well implant/taper post abutment combination to increase retention. Why would they do that and change the morse taper if they were not still experiencing problems that they needed to correct. I do believe that this last change may have eliminated the abutment loosening problem. However, it does come to late to help those with existing 2 and 3mm well implants who have, or will have those problems. - I still stand by my comment that I believe the Bicon to be a very good system and, like all systems, just a work in progress. I have several thousand of these in happy patients with very few exceptions. Lastly, the recent introduction of the 2.5mm post abutment (in conjunction with the 3mm) may have returned it's status, in my mind, to an implant system that may be placed universally. I would still maintain and discourage anyone from utilizing 2mm well Bicon implants anywhere except the mandibular incisor area. I also would not recommend using the 3mm well implants in the anterior maxilla. This is just my personal opinion based on my clinical experience. - John, thanks for your intelligent and insightful postings to this forum - I enjoy reading and learn from them! - Dr. No

Thanks for the perspective, Dr. No. You are definitely correct about the reports of some 3 mm anterior posts loosening. I have not yet seen that in my cases, but I don't have a thousand Bicons under my belt yet. Beginning last year, Bicon is recommending only 2.5 mm posts and wells on anterior locations. You are correct that some problems must have been reported along these lines. As to the earlier report of someone at Bicon stonewalling the problem of 2mm and 3mm posts loosening, that would seem to be a step backward for them. I generally ask questions of the surgeons or those new young researchers, most of whom have given measured, thoughtful responses to my questions. I do not think implant technology and research details should be left to a sales person. John

Will you guys explain to me ,why bicon over Nobel, biohor. , iti, or strauman ? I continue to read about the fractured abutements with the narrower wells , as well as the trouble associated with removing failed wide body implants. My experience with the product is limited , but have removed a few. I do recall some strong data supporting a minimum of 13 mm in the maxilla, and have operated behind that science with great success. Yes it does require the occasional nasal or more commonly the sinus lift,but it seems like God made teeth this long for a reason. Granted our molars are wide and sometimes barely 13 mm at the cej to apices. My biggest issue is after I have taken one of these wide fixtures out , I can't just come back with a wider one. Just trying to augment my surgical knowledge. Bv

Baker: - Not going to tell you anything that you don't already know. Overall, the success rates of the Bicon implant are comparable to other systems "with the same diameter and length". I say that with the qualifications that I had posted above on 9/7/11 at 3:06pm. It is a simpler and cheaper system than many others which has some merit but shouldn't be the sole reason for using it. I do like their slow speed and hand reamers for precise osteotomy control and bone harvesting. The Bicon design and diverse implant size options do have some advantages in certain clinical situations (one example, where a short, very wide implant is a necessity or the most practical choice.) That said, Bicon isn't my first choice for many of my patients but I still utilize them on occasion. - My biggest concern with the short or ultra-short implants is that they are being marketed and probably utilized as a first line treatment option. Why do a sinus lift and utilize a traditionally sized implant when just placing a short will yield the same results - I don't believe that is true and suspect that you feel similarly. On the other hand, doing a nerve transposition to utilize a longer implant may not be patient acceptable or risk indicated either. With proper case selection (i.e. adequate bone density and etc.) I believe that there is a place for these short implants dentistry. But just because there is inadequate vertical height and the operator doesn't yet have the skills to perform a direct sinus lift, doesn't make it a primary indication to place a short implant in D4 bone. But maybe it is a viable alternate consideration in D1 or D2 bone??? - I believe and have said before, bigger is usually always better when it comes to implants, especially in the maxilla. I would like to use 13mm long implants but will consider 12mm (or even 10mm) implants typically when bone density is good and I have enough room for a 4.8 to 6mm diameter implant. Please understand that is not an arbitrary decision but one based on careful individual patient considerations. I rarely use shorter implants - why, guarded long term prognosis on the basis of what I have read, seen and done. As for when wide fixtures fail, traditionally I'm grafting and waiting to replace them anyway. I have seen only a few circumstances where one could follow-up a failed standard with a larger implant. Often those justifications to remove an implant (significant bone loss, mobility and infection) preclude placing another anyway. From what I have seen, failed implants are always a mess. - Baker - sometimes I think that you are just baiting us with some of your queries which I think is just fine. I'm primarily here to learn and in that vein, you come up with the most thought provoking questions, comments and solutions. I don't always agree with everything that you say but I always appreciate a different perspective which allows me to constantly re-evaluate my own. Thanks for your input! - Dr. No

Yes, I agree that comments occasionally come across that way,thanks to the likes of Bruce epker, R.V.Walker,Doug Sinn,and other tough " nuts". It's been engrained in me to challenge but respect. Worst of all was my father, of whom I'm eulogizing tomorrow. Truthfully, the last entry was just a question. Unfortunately ,I spend most of my ce at tumor/ recon and trauma meetings. I am trying to milk this sight, in that implants are probably my favorite facet of what we do, and I'm quickly learning that after 20 years ,I am still learning. Hope non of my comments have offend you,but I consider myself a scientist first then an omfs. I will always question first, maybe will try to be a bit more eloquent in the future. Bvinci

Baker: Sorry about your father! - You are right about challenging me, anyone or anything on this site. If we are bold enough to state our opinions, then we should be able to back them up with, at least, some reasonable explanations or statistics. After all, most advice is worth just what you pay for it. - Implants are also my favorite - OMS is a subtractive profession by nature, it's nice to do something additive every once and awhile. - Why change anything, it works for me and you keep it exciting! - Dr. No

Thanks dr. No,I agree.have good weekend.bv

- Sorry for the late posting which very few may end up seeing. Thought I'd throw a few more items into the mix to at least try and explain why we may have some control in achieving a higher degree of success (then one may otherwise expect) with the short implants in the posterior maxilla. I apologize in advance if my oversimplifications offend. - First, There are two two cortical plates of bone available to us in this area for implant stabilization, one lining the sinus and another lining the oral cavity. For simplicity, I think of the anatomy here being similar to a pie with a variable thickness and denser crust on the top and bottom, a softer variable thickness filling in the center. Implant systems and procedures (i.e. a Summer's Lift or DSL) that allow us to engage both of the crusts would seem to offer more us more implant stability. If only one crust is engaged, research (presented by Misch) indicates that bone in contact with the the occlusal third of the implant surface takes the most stress and is most important in stability. In that light, a system that engages only the inferior maxillary cortex should be more stable than one that only engages the superior sinus cortex. Also consider that many feel that implant diameter is disproportionally more important than length - if true than more than just raw surface area may be in play here. In summary, maximizing cortical engagement with an implant system and procedure, increasing implant diameter (and length) as well as choosing candidates with thicker and denser bone should yield increased stability and longevity. As far as system choice is concerned, I don't believe that all systems or types (i.e. bone level) engage the occlusal cortex equally (or at least the same.) Technique wise, I believe that over seating the implant diminishes occlusal cortical engagement and retention in all systems and types. - Second, we often utilize CT or CBCT scans to help us determine bone density. I watched a webinar recently by Russo (a periodontist with some radiology credentials) who stated that CBCT's yield a "decreased" bone density as compared to densities determined from CT's expressed in HU's. Being that the D1-4 categories defined by Misch are based upon CT data, we may actually be dealing with denser bone than information received from the CBCT data indicates. Russo stated that in some instances, the actual density may be twice the value (in HU's) especially in the D4 range. I am trying to contact him to get a source link for that information and will post it here if he responds. If true, we may be seeing successful outcomes from short implants placed in what we believe to be D4 bone, when actually they exist in D3 bone. - Thanks and hope this of value to some! - Dr. No

- I received Dr. Russo's reply this morning: - "As per the Misch book Contemporary Implant Dentistry, the HU numbers 0-400HU = D4, 400-800=D3 etc. are for “spiral” CT scans (medical scanners). These measurements cannot be translated into CONE BEAM CT scans. I am not aware of any literature correlating clinical bone density as we know it (D1-D4) with cone beam HU measurements. I was speaking from personal experience and simply wanted to point out the difference between spiral and cone beam with regard to bone density readings in HU. If you find something (literature) different, please share with me." - For what it is worth, I tend to agree with his conclusion which would make density determinations from CBCT very arbitrary. - Dr. No

Dr. No and Baker and others - personally, I a glad to see some disagreements amongst experienced clinicians. Regardless of how long we've been active in implantology, or in what area our expertise, we can still learn volumes and hone our judgement through these exchanges. Someone asked , "Why Bicon? Why Short?". I agree that the stats on implant "survival" does not yet show any one clear champion. However, there are some design factors which I believe we'll see more of. For one, the "plateau" or "finned" design, kind of like wider landed threading is already showing up on Nobel designs. MIT grads have done Stress Analysis on Bicon's designs and noted that the rounder, "ball" or "pineapple" shaped implant bodies demonstrate a unique stress dispersion - if you load the top pushing Distally, the forces express to the bone down the Distal, across the bottom and BACK UP the Mesial of the implant, eliminating the "dead loading" spots seen on most cylindrical designs. Wide emerging implant tops interfere with the Bone Platform available to support soft tissues and papillae, so cut back or tapered top designs will probably be increasing in use. By nature all threaded screw attached abutments must have a clearance for the screw to turn, the screw's mating threads always wear and round off over time, bacteria can go up and down that like a spiral staicase. Those joints do not allow bone growth OVER the implant/abutment junction. Fin designs with wide plateaus, vertical slots, and narrow centers allow the maximum circulation around the installed implant and better long term prognosis on all fronts. As in gingival grafts, the body is very efficient and does not want to build circulation around a bulging, intruding root nor implant. Another thing - I totally agree with the "pie crust" analogy. On top of that, the non threaded, plateau designs are invaded by Haversian bone, not the soft, canellous native bone. On the Floor Transports with Bicons, Dr. Daher tries to match the width of the implants with Buccal-Palatal cortical width so you have "crust" on top, bottom, and two sides of the implants. Thanks again, guys, for all the thought and banter! John

Also, while I have never experienced a broken abutment post with a Bicon implant, I have seen case videos on how to handle that situation. Basically, it is just like an Endodontic access prep. You use a small round bur or diamond to cut down the center of the broken post, taking x-rays to document your direction. Once down to the space at the bottom, you switch to a slow speed, #4 round bur and it usually locks up and knocks the broken abutment stub loose rapidly. I have had to recover and repair broken abutments, implants and screws on many other brand name implants and that is ALWAYS a stressful situation. There are only 3 abutment post sizes since the Bicon's design's inception and all three are available anywhere in the world today. Compare that to the thousands of damaged attachment systems implantologists see each year where it is a miracle if you can identify the brand name, the model, the part number, much less even find a source. John

Like I said ,still learning . Good stuff. Cbct's do not represent density well, hence the need in my opinion to own your own machine. The one I have allows you to adjust as you view . Pretty easy to get close. I do about 4-5 a day. Getting better each day. Bv

- Dr's. Vinci and Manuel: - Although you will probably never see this, thought I'd post a few comments. - Baker: Just as you stated in another forum question, there are to many of us answering questions with absolutes (always, never, 100% and etc.) Dentistry is not an absolute science. Each patient deserves and should get our best treatment offering which should be based on our current training, best knowledge and experience as well as being tailored to their individual situation and needs. All of those criteria change almost daily. I don't place implants the same way as I did twenty or even ten years ago. That said, some of what I do routinely today, I thought was garbage then. My point is, we at least need to be open to considering novel or different techniques and approaches, some of which may become the standards of tomorrow. But just like you have said, question everything! - John: As always, good postings above. Wish you were local and available when I had a run of four 2mm post fractures (in different patients) a few years ago! Four different GP's with pretty good knowledge, dexterity and armed with the Bicon info. you mentioned above, could only remove one of the four fractured posts w/o damaging the well. - I know that you are very knowledgeable and experienced with regard to the Bicon system. From my experience, if you had to work with just one system, that is not really a bad choice. However, I do hope that you keep an open mind as far as evaluating and using other systems. There may well be times that another implant design is a better fit for a given patient. Given that, I think that it is better to know how to use one good universal system very well, than to know just a little bit about several. - Nice work guys, I always learn something here every day! - Dr. No