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Thursday, May 20, 2010

Platform Switching and the Kai Foo's Three Critical Margins of Dental Implants

  • K. F. Chow BDS., FDSRCS May 20th, 2010
    The term “platform switching” may be a misnomer. Misnomer means using the wrong word to describe something. The platform that we are referring to is the round surface area on top of the fixture in which the screw hole for the abutment is located. Branemark set the trend by making sure that the abutment fits exactly over the top-surface of fixture, with the periphery flush with each other……which is a logical decision at the time….and everyone copied him…….which always resulted in a “normal” resorption of the bone away from the junction.
    The advantage of “platform switching” was discovered when a dentist did not have the right sized abutment to fit flush with the fixture and inserted an abutment whose circumference/undersurface area was smaller than the platform/topsurface area of the fixture. This happily and unintentionally took the junction/microgap/microorganisms away from the bone and thus to the pleasant astonishment of the dentist after reviewing the xray, showed that the so-called acceptable normal resorption of the bone away from the implant ceased!!
    Thus “platform switching/shifting” was born. The platform however remained the same and was never switched or shifted. That is why i think that it is a misnomer, i.e. wrong word. What changed was the circumferential size of the abutment. An abutment with a smaller circumference than that of the fixture was then resting on the top-surface of the fixture.
    Maybe the right term should be “abutment downsizing” or “footprint reduction” or just simply “platform mismatch” or “margin shifting” or “green technology” or …”gum friendly”…or “shy margins”…….. oh hack…just call it “platform switching” to comply with the aura of mystery and awe that implant dentistry should continue to have for old times sake!!!!!!
    If you understand the concept, then you can easily see which implant system is platform switching and which is not.
    There are 3 critical margins in implant dentistry. I call them "Kai Foo's Three Critical Margins". The abutment-fixture margin, the crown-abutment margin and the emergence margin…altogether is found within the transmucosal passage of the implant.
    Platform switching has solved the problem of the abutment-fixture margin. Most savvy manufacturers are all moving towards this design. The crown-abutment margin is still unresolved whether you screw or cement, it still poses an inflammatory problem.
    As for the emergence margin… solution may be to reduce the circumference by reducing the diameter of the emerging dental implant. But with our emphasis on the “emergence profile” for the sake of aesthetics, it is unlikely to be practiced widely. As the Chinese have a saying..”Oi lang…Ng moi mang”…which translates as wanting beauty even at the expense of life and health.
    ‘Nuff said.

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