In dentistry, platform switching
is a method used to preserve alveolar bone levels around dental implants. The concept refers to placing restorative abutments of narrower diameter on implants of wider diameter, rather than placing abutments of similar diameters, referred to as platform matching.
Discovered by accident in the late 1980s, the benefits of platform switching have become the focus of implant-related research with increasing frequency. Numerous peer-reviewed articles and recent systematic reviews have revealed that platform switching can be considered a means of preventing initial peri-implant bone loss.



This dental radiograph displays two identical 5.5 mm diameter SLock implants placed into the lower right mandible. The conical post abutments on the posterior implants are platform switched(it shares the same 5.5 mm diameter as the implant platform), while the post abutment on the other side implant is platform switched (it possesses a 5.0 or 6.0 mm diameter).
 


Concept

  After being placed in a surgical procedure, dental implants undergo  osseointegration, during which time the surrounding bone grows into intimate contact with the surface of the implants and the implants become fused to the bone. When this process has been deemed to have occurred to a sufficient extent, the implants are fitted with restorative abutments in order to allow dental restorations (e.g.crownsdentures, etc.) to be cemented on, screwed down or otherwise attached.
Historically, the  diameter of the abutment matched the diameter of the implant platform; for example, a 4.8 mm-wide abutment was placed on a 4.8 mm-wide implant-this can be termed platform-matching.[1]
When  platform switching, a narrower abutment diameter for a given implant platform diameter is used; for example, a 4.8 mm-wide implant may be restored with a 3.8 mm-wide or 4.2 mm-wide abutment.[1]

History


The introduction of wide-diameter dental implants in the late 1980s created a situation in which mismatched standard-diameter abutments were used simply because of the lack of commercial availability of components to match the wide-diameter implants. Serendipitously, it was found that these implants exhibited less-than-expected initial crestal bone loss - the effect of bone modeling at the crest of the alveolar bone into which dental implants are placed - during healing. Several early clinical reports demonstrated enhanced soft (gingiva) and hard (bone) tissue responses to these platform switched implants, leading many implant companies to incorporate platform switching into their implant systems even for narrower-body implants.[2][3]

Rationale


 
It has been observed that some degree of bone resorption occurs at the crest of bone following implant placement. Through extensive investigation, it has been discovered that the extent of bone resorption is related to both the texture of the surfaces of the implant and abutment at and the morphology of the  implant-abutment junction (IAJ). A number of investigators have zeroed in on the proposed inflammatory cell infiltrate that forms a zone around the IAJ.[4] Although not yet fully understood, the current theory of the benefit of platform switching is related to the physical repositioning of the IAJ away from the outer edge of the implant and the surrounding bone, thereby containing the inflammatory infiltrate within the width of the platform switch.[3]
In line with the supposed mechanism of action, it is not merely the introduction of a platform switch, but the  magnitude of the implant-abutment diameter mismatch, that makes a difference. Difference in bone levels became statistically significant when the implant-abutment diameter mismatch was greater than 0.8 mm, providing a 0.4 mm circumferential width of platform switch when the center of the abutment is aligned with and fixed to the center of the implant.[5]
 

Proposed benefits

Biologic width

Very much like teeth, implants exposed to the oral cavity exhibit what is known as a minimum  biologic width.[6] Biologic width is the minimum thickness of soft tissue that envelops the alveolar bone that surrounds teeth and into which 
omfskim11@gmail.com, 2014.06.05 오후 2:31:49 | 4813 hit(s) 0 comment(s)
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