Platform Switching: Evidence for this Protocol?

3i has extensive literature on platform switching as does Astra. I can't think of a single reason not to platform switch. There is potential concern that residual cement trapped subgingivally can cause bone loss over the years and some surgeons think the undercut nature of the platform switched abutment may lead to increased cement retention. To combat the cement issue, keep the finish line within 1 mm of the free gingival margin so you can visualize any residual cement. Otherwise, there is ample research and evidence that platform switching works. Platform switching does not protect the implant from bacterial invasion it moves the microgap medially to allow the body to create a soft tissue seal more coronally (generally on top of the platform) that seals the crestal bone from any potential microleakage from the microgap.

Well Said Dr. Johson. I have seen consistent crestal bone presevation with platform switching implants clinicaly... I would not go back to the conventional implant platform.

I agree with the comments. Platform switch works great in a situation where the neck of the implant is below the crest of the bone. Upon exposure of the implant during the second surgery for placement of the healing collar - I can retain the bone around and place the collar/ abutment with out destroying the crestal bone therefore preseve the bone.

Platform shifted implants such as Straumann's , Nobel Active, Astra, 3i, Ankylos, etc and the studies attached to them show bone loss up to 1.2 mm after 9 years. These implants add another dimention by adding two micro gaps instead of the original one. The taper internally varies from 9 degrees to 17 degrees and the higher the degree, the less the stability and the more the possibility of leakage under bruxing forces. Also, lab processing of metal abutments are possibly subject to processing sandblasting which will contribute to leakage at bone level which can cause more bone loss. The ceramic abutments are subject to ceramic glaze overrun at the end of the processing cycle. I personally have seen platform shifted implants that with a metal abutment ( which resembles tissue level collored implants) show thru. The myth that these implants are easier to to place and will give better esthetics is just that. They all work ( platform shifted implants and tissue level implants) and the results are dependant on the surgical placement. At least witrh tissue level implants , you can see the margin (1 microgap versus 2) when it is being placed. The restorative aspect for platform switched implants costs more and takes more labor for tissue development. Studies continue and the future will tell us which will prevail. The two kinds at this point oth have their place in certain casework

It would be beneficial if the periodontist in question could supply us with the recent studies that he is referring to that call this into question . Thanks

Bicon has been platform switching by their inherent design since 1986, I believe. Bill Ingram.

Robert56, perhaps get your laboratory to sandblast with glass beads rather than the sand? Also the use of gold components (gold collar- plastic waxing sleeve) ?

Bill, you are most correct.

IAn Glass beads actually destroy gold even worse and can send micro fractures into Zirconia. I have seen SEM's of this presented in articles Sorry

"A data confirm the important role of the microgap between the implant and abutment in the remodeling of the peri-implant crestal bone. Platform switching seems to reduce peri-implant crestal bone resorption and increase the long-term predictability of implant therapy” [Cappiello M et al. Int J Periodontics Restorative Dent. 2008 Aug;28(4):347-55] The use of Morse taper connection implants represents a successful procedure for the rehabilitation of partially and completely edentulous arches. The absence of an implant-abutment interface (microgap) is associated with minimal crestal bone loss. The high mechanical stability significantly reduces prosthetic complications. [Mangano C et al. Clin Oral Implants Res. 2009 Mar;20(3):254-61 ] I can't imagine working with implants without platform switching and Morse taper connection. I used to use implants with just hex connection and without microgap and my succes rate ( I mean crestal bone preservation) was very low. When I started using AstraTech and Mozograu implants crestal bone preservation is very high, but not 100% as Astra suggests. Regards Michal Fidecki

Platform switching as a term is difficult to understand. I prefer the term abutment downsizing. Basically, the principle involved is to distance the abutment fixture microgap away from the bone as far as possible. This is because the microgap harbours micro-organisms that produce toxins that may cause bone resorption. Some dentists call this microgap a toxin pump because everytime the patient bites on it there is an outflow of toxic products of the micro-organisms and when the patient relaxes his bite, there is a corresponding reverse inflow of nutrients for the bacteria. The Morse taper connection is an engineering principle that closes the gap so tightly that the abutment and fixture behaves like a single piece....called cold welding. There is effectively no more microgap and therefore no more micro-organisms....and it follows therefore no more bone resorption. Another way to get rid of the microgap is not to have it at all which results in the one piece solid implant like the nobel direct and others like it and also the mini/narrow diameter dental implant. No bacteria irritation.....no bone resorption. Platform switching or abutment downsizing works. One piece also works but like all good things, must be used judiciously.

According to Straumann and Astra the micro gap of platform shifted implants is 9 to 11 ums. The ecoli bacteria is around the same micron size. I am proposing that la fabrication is suspect on these types of implants. It all works when the microgap is less than the bacteria and the stability of 10 degrees or less is present. The systems that have this (COLD weld) that is over 11 % is suspect to lateral instability and if the gap is altered in any way from the fabroication of the restorative restoration. It is true that the bone loss around platform shifted implants is better that the old external hex implants but the developments from the 1990,s improved that a bit from certain comapnies. The new stabilised connections that are from some companies give better stability, lower collor heights and benefit of placing the margin at the time of the implant where as the platform shifted implants , the margin is invisible when placing as the abutment has the biological width built in and therefore you cannot see the margin when placing. Both implats worrks and ARE SUBJECT TO PRECISION 3D PLACEMENT. Not one is beter than the other , other than the fact that the platform shifted implants are more costly and need more attention to tissue development. The old standard of 2 -3 mm of bone loss is not accepatble with todays standards and the new designs with better understanding od the biological width and placement procedures allow for better bone preservation around the coronial aspect of the implant as thus that is better for interdental papilla support for long term stability. I prefer a tissue level implant in 90 % of the case work even in the anterior. Also, I have seen Maxilla rebuild that creates vertical esthetic issue with Bone level types so back to the thought that placment is the key to esthetic and not product. A crutch will be a hindrence in the long run.

Bicon is one of the pioneers in platform switching and sooner or later i believe every implant company is going to incorporate this design.Dentist India

Actually Ankolos is the pioneer with Professor Phillipe Ledermann which went on to other ventures.

Ankylos and their "Tissue Care Concept" has been well documented in the literature for numerous years. While i do not have the time to cited every article published, here are a few references. Implant-Abutment Interface- From Mechanical to Biologie View of the Microgap. Weng and Richter. Implantologie 2005; 13(2):125-130 The Ankylos Implant system: Concept and clinical application. Nentwig. J Oral Implantol 2004; 30(3):171-177. Crestal bone loss associated with the Ankylos implant: Loading up to 36 months. Chou, Morris et al. J Oral Implantol 2004;30(3) 134-143. this is a start. Dr Dwayne Karateew DDS, Dip Perio, Dip Prosth

The issue with platform switching is that in many case studies it is not the only variable that could affect cortical bone loss. As the main reason for platform switching is to move the connection, or micro-gap, farther from bone contact it would seem that this is beneficial but as the micr-gap is still present it can not be determined with certainty. Most implants that preach this feature also have mini-threads at the top of the implant to reduce stress, which could also be reason for reduction in bone loss. It would seem that the best option would be to use application specific implants as often as possible, therefore eliminating the micro-gap in which the bacteria breeds.

Have you tried the app. specific line at Implant Direct? Was there a significant difference in ease and initial stability? I have heard great things about them and would like to hear some peer reviews.

The microgap is not the most important variable, because monobody implants or these which have the platform over the gum, both have bone loss. Which is the explanation? Forces? Heat? Periosteal damage?.

This is a good question, worth a dental nobel ;-) Do you mean forces by implant on the bone? To much compression? I think combination of three of theam plus individual patient reaction.

I am agree with dr. Fidecki. I think that the bone responds to the forces until becoming stabilized, like the flying buttresses of the cathedrals. But the cortical bone needs the irrigation from periostial, so major soft tissue, major irrigation. Regards

Mono one piece implants are more critical for placement as 1.the implant Surface 2.Transmucosal dimentions 3.Abutment have to placed simotaniosly which in most cases is not ideal according to design. (Not unlike the scalloped implant or Perfect) The abutment connection then has to have a Margin sealed restorations on it and that is suspect to micron size by the laboratory. Labs are supposed to get that gap down to 25ums but that is still a trap. We need 10ums or less. Two piece implants have the ability to be versitle whereas the one piece implants are already determined and placement, Patient dimentions are variable due to each patient being slightly differant. Two piece implants offer more but now comes the discussion of the micro-gap and stability. I maintain that having two microgaps (bone level)can be suspect to issues and stability in some manufacturers. Transmucosal implants can be favored in most casework. There is a reason that Mono, Direct and others are not common. Loading can and does affect crestal bone preservation but is quite seconadary. Primary is the gap size and the stability of that gap under lateral load of less than 200 ums force. Percolation of that gap and too close to the bone is by design a bone loosr and will result in papillia instability over the long term yeilding esthetic issues if that your gaol. Overdentures, Posterior , Anterior, and Immediates require thinking as to what type of implant is required as does the patient type, load factor and hygenic access.

OK, Robert56. But gap is not the only factor because exists implants with a platform more wide than them and have not bone loss, even they mantain it. The gap is then next to bone and of the second gap (prothesis/abutment? , in Spain we did not use this term, I am mistaken?) is far. In addition, the behavior is very different in bone between implants with natural teeth than implants/implants. I am very happy of being able to discuss this subject and to try to clarify my doubts. Thanks (sorry if I wrote something wrong in english)

According to Thomas Albrekson and Lars Senerby's work with their type of Bone Level implant, They are calling for a new standard of what is acceptable in bone loss to around 1mm. The evedence has been presented that the new platform shifted implants shows that loss after 9 years. The old stan dard that goes all the way back to Albreksons work was with the original external Mark 4 connection implant from Baraemark. Thta showed 3 to 4 mm plus bone loss. The new types of internal connectios that had 1.5mm of transmucosal height showed up to 2 mm of none loss. The ITI had a more stable connection at 2.8mm showed very little remodeling around mthe creastal part but was critiqued for non esthetis reasons and then came the 1.8mm with less than 1mm of bone loss. Others have improved on this with prefered connections and stabilities that are down to 1mm collors with bone loss at bthat 1mm. So in the end, the new platform shifted implants yeild bone loss of up 1.2 mm with rough surface exposed after 9 years. The other collored implants with stability offer the same result with a smooth exposure. Again, placement is thye key. I have seen built up crests that have platform switched implatrs with the abutment margin showing due the the new biological width that is on these implants. That is the same distance as the collored implants. Why incorporate another gap that was originally not there. I agree that some cases with thin soft tisstue need this type but most do not. It is the PLACEMENT that matters. The new types are drivrn by the companies that have found a way to increase fees vis the seconadry part abutment. The old way was well documented and works well if placed well. The new way cost more $ and the money is going to the companies rather than the laboratory. The extra labor for tissue development also need consideration. As for information on the Implant to natural tooth distances, plesae see Denis Tarnow's studies on inter-implant distances. The current studies are not complete and consensus have not been reached for the newly studied platform shifted implants. Certinly the behavior of bone loss is affected by other factors that are still being studied. You wrote: Which is the explanation? Forces? Heat? Periosteal damage?. Micro gap and stability.

It is great to see a discussion on this very popular topic. I was most interested in a study presented at the 2009 AO mtg. in San Diego by Dr. Zipprich. The study analyzed several platform designs and Ankylos and Astra, both deep conical connections, were the only to show no micro-movement. Although these design features do not exist in a vacuum and there are other features and scenarios to consider, I truly believe it is imperative we no longer accept 1mm or more of bone loss. Astra currently is pushing that there are over 40 published studies that show Astra Tech implants provide 0.3mm of bone loss or less in cases of 5+ years. I reviewed many of these studies myself and hope other companies will take note of the design features of Astra and provide further research. From what i understand, this is how the Straumann bone level came to be though not an exact replica. Study can be found online at www.kgu.de/zzmk/werkstoffkunde/index_en.html T. Rely

This study shows what I have been talking about. 200 UMS force. The platform shifted implants that have 9 and 11 degrees show very good stability but the longer term ( 9 year)( I will site the study soon) shows a bit more bone loss than the 5 year. It is true that these are good but we also need to consider at what cost is this development. The prosthetics escalate direct to the companies CAD divisions and the prosthetic flexibility decreases with less than 13 degrees but the instability increases which leads to screw problems and leakage. Most real life casework is off more than 11 degrees and that will increase prosthetic complexity and costs. It is our role to try and decrease treatment costs with new develpoments, not increase it while increasing long term results. Again, standard stable collors that have one microgap and a premier placement will shine and keep costs down which should yeild more case treatments. Both work. Both have issues. Not one is better overall in all cases, but a well placed stable connection implant will provide what we need on most work.( some do not provide stability) The 13 and 15 degree platform shifted implants on the market from major companies provide prosthetic flexibility but at a cost of less stability and still and increased cost of the prosthetic and labor for tissue development so the final result will show in the near future. Heck, as stated before, why not use a solid implant with no connection? (read above). The sucess is in the hands of the operator, not the product. Don't be fooled by claims that provide nothing better and increased costs to the patient. You all should really check the full cost of the Implant, healing abutment, custom tissue former, transfer assembly, analog, and various abutments. You may be shocked that the companies get more than the surgical ands or prosthetic doctor. This is not acceptable imo. The risk/ liability is to the users. The planning is with the same to excell and be most effective, safe and rewarding. Referals are the life blood of the practice.

And why implants without paltform shift not show bone loss? The key to understand the behavior of the osseointegration is the mechanotransduction bone and gingiva. Platform switching can help but not is the final solution. Another question. When we used this abutments smaller, Is not more overload over the screw and the implant connection?.

Transduction would suggest that the forces would impact survivorability. The natural teeth move with the allowance of proprioceptin of the PDL. The most that matters is the connection and the stability. Again. The original ITI at 1.8mm biological width is supportive of the studies that Chochran and associates hacve done. Implants that are below 1.8mm or 2.0mm are subject to bone loss due to the microgap being closser and the ones that are (unstable) as the current leader in implants are suspect to issues. There are ones that take the gap on TL implants closer to the bone that provide stability, tight tolorance connections, and esthetics that are basically hybirds of Tissue level and Bone level implants. Screws become overloaded when 1. Tolorances are too loose 2. Material used for screws is of weaker quality (gold) 3. Bruxing forces are abnormally high ( above 200UMS)4. Whan the cold weld connection is less that stated form the companies at 10 ums or more, the connection is weaker and more suseptable to issues. Most casework has forces that exceed the norm in the real world.

Research has shown the benefit moving the microgap away from the crest of the bone and the reduction of bone loss. Tissue level implants with the 1.8mm collar have only one microgap and it will be 1.8mm away from the crest of the bone if the polished collar is not submerged. Secondly the margin of the crown is on the platform on the implant and therefore it is critical that the placement of the platform be at a level which will allow the margin of your crown to be subgingival. I developed an adjustable depth gauge which will aid in this placement. The problem in my opinion is dentists sink the polished collar rather than reshaping the crest of the ridge. The guage will allow you to adjust the margin of the crown to the tissue BEFORE the osteotomy. In other words adjust the crest first then determine which implant length will allow a crown margin position subgingival with the polished collar ABOVE the crest.

Since the 1.8mm ITI is polished. that is what causes the CUPPING effect od the bone when places sub crestally. There are others that have a collor that are machined that act very differant that the polished ones. Therefore, you sould fine one that has a machined collor that onle has one microgap to worry about. Again, having twp microgaps add to the complexity and cost. One microgap with a pollished surfaced and flared platform causes cupping and the is the issue with why many are looking for stability of bone with out cupping. There are some on the market that provide the best of both worlds? Bone stability thru Microgap stability and very low mm dimentions to get Aesthetics. The new implants offer a true hybird of a result without having to resort to two kinds on implants.

Recently there are more and more studies that support the idea of distancing the microgap from the crestal bone because there is a reduced loss of crestal bone when this system is used. Some of these systems use a conex connector and some do not. Conversly there are a few studies that do not support this theory but the former seem to be outweighing the latter. It is a supposition that the reason for diminished crestal bone loss is because the platform shift reduces the bacterial harbor effect or that the conex connector reduces micromovement which in turn stimulates bone loss. The reality is that we do not know for sure what is behind the problem of crestal bone recession. Historically I have seen many cases even of submerged posilhed collars that do not have any bone loss after 10 or more years. The reason for crestal bone loss most likely has a multifactorial explanation. Notwithstanding, the advantage of a platform shift design seems to be a compelling one which hopefully we will better understand with more time.

Platform switching as a marketing issue was started by 3i when they made wide platform external hex implants to help stabalize the screw loosening but had to use the standard abutments because of product availability. Tarnow then came up with a "theory" that moving the junction away from the bone reduced bone loss do to microgapping but internal connections such as the screw-vent, stay sealed anyway. Internal connections themselves along with torque wrenches stopped the problem but it was such a good marketing story, companies with connical connections like that have inherent medialized connections jumped on the bandwagon claiming superior results and next thing you know everyone wants to say they have platform shifting. The VA study showed bone loss was evident at time of uncovery, before exposure of the junction and before loading, related to how thick the labial bone was at time of implant placement. One piece implants with no micro-gap lose bone just as inevitably with thin ridges as two piece implants.

Jerry Niznick, Good points. I have not bought in to the platform switching concept. I believe it has more to do with microgap and more to occlusal loading.

Long-term radiographic follow-up of these "platform-switched" restored dental implants has demonstrated a smaller than expected vertical change in the crestal bone height around these implants than is typically observed around implants restored conventionally with prosthetic components of matching diameters. Dentist Shimla