Platform switching (sometimes called platform shifting… same thing) has evolved from theory to common practice when restoring dental implants. Companies have modified their product designs to naturally incorporate a platform switch. So what is all the hype about?
Quite simply, a platform switch is whenever we use an abutment that is a smaller diameter than the implant.
Okay, terrific. So what? Well it turns out that several studies have shown that crestal bone around the implant responds more favorably to implant restorations that have been platform switched than those that have been restored with matching diameter abutments and implants.
It has long been accepted that an implant can lose about 1.5 to 2 millimeters of bone vertically (roughly to the area of the first thread) and about 1.4 millimeters of bone horizontally after the abutment and restoration have been placed. There were several theories as to why this might be, including bio-mechanics and stress. But another theory had to do with bugs.
The junction between the implant platform and the abutment (implant-abutment junction, or IAJ), is, of course, not hermetically sealed. There’s a very small gap; a microgap. This microgap is a lovely place for bacteria to hang out and have a party. The body hates when bacteria have a party, so they try to break it up with inflammation. In 1995, Ericsson et al, described evidence of inflammatory cell infiltrate up to 1.5 millimeters around the IAJ. Could this be the reason that we see crestal bone remodeling? The bone could be retreating from the inflammation to a safe distance! That makes sense.
In 2006 Lazzara and Porter wrote one of the first papers describing the curious phenomena whereby less crestal bone remodeling occurs when smaller diameter abutments are used on larger implant platforms. They hypothesized that this occurs because the zone of inflammatory cell infiltrate is being shifted towards the center of the implant and away from the surrounding crestal bone.
I spoke with Dr. David Gardner (www.northshorerid.com) who wrote one of the first papers on platform switching back in 2005 and has lectured extensively on the subject:
“The dynamics involved when an implant is placed are now understood. The crestal bone changes that occur can have a profound effect on treatment outcome and will influence implant location, design, and manufacturer. In addition, restorative options for osseointegrated implants will be greatly influenced by these crestal bone changes. Platform Switching is a way in which the harmful effects of bone remodeling can be decreased and help to ascertain a more predictable outcome thereby improving esthetic expectations.”
Dr. Gardner is highlighting the two major advantages of platform switching:
(1) Esthetics. If we can better preserve the crestal bone around an implant, then we can better preserve the gingiva as well. Healthy and plump gingiva, especially papilla, will give us a cosmetic advantage for the final restoration.
(2) Implant Placement Flexibility. Traditionally implants had to be placed 1.5 millimeters from a natural tooth, 3 millimeters from another implant, and 2 millimeters from the buccal plate in order to compensate for the expected crestal bone loss. Platform switching preserves bone in all three dimensions: apical-coronal, buccal-lingual, and mesial-distal. This can give us more flexibility with our implant placement.
So does it work? Yes. Numerous papers have been published on platform switching and the results have been confirmed. Here’s a list of just a few:
Becker J, Ferrari D, Herten M, Kirsch A, Schaer A, Schwartz F. Influence of platform switching on crestal bone changes at non-submerged titanium implants: A histomorphometrical study in dogs. J Clin Periodontal 2007;34:1089-1096.
Vigolo, P, Givani A. Platform-switched restorations on wide-diameter implants: A 5-year clinical prospective study. Int J Oral Maxillofac Implants 2009;24:103-109.
Fickl S, Zuhr O, Stein JM, Hurzeler MB. Peri-implant bone level around implants with platform-switched abutments. Int J Oral Maxillofac Implants 2010;25:577-581.
Here is an example of a Nobel Active implant replacing an upper right second premolar:
I’m routinely using platform switching in my restorations, especially in the anterior where cosmetics are king. If you’re interested in trying this out, make sure you are working with a company that allows for platform switching. You can’t just take a small diameter abutment and expect it to correctly fit a larger diameter implant. Nobel Biocare and Neoss are two implant companies that I use that have embraced this philosophy.