The goal of moderndentistry is to restore the patient to normal contour, function, comfort,esthetics, speech and health, whether restoring a single tooth with caries orreplacing several teeth. What makes implant dentistry unique is the ability toachieve this goal regardless of the atrophy, disease or injury of thestomatognathic system.These days, patientsreceiving implant treatments not only expect restoration of masticatoryfunction, they also expect that the prostheses will be esthetically pleasing,easy to clean and permanent. To maintain long-term implant stability, it isimportant to minimize bone loss around the implant, as well as the soft tissueatrophy that accompanies it.
Dental implants areprimarily used to replace the teeth in a partial or complete edentulous patientor to retain removable prostheses. Thus, the typical purpose of a dentalimplant is to act as an abutment for a prosthetic device, similar to a naturaltooth root and crown. The restoring dentist usually designs and fabricated aprosthetic similar to one supported by the teeth, and as such, also similarlyevaluates and treat the dental implant as a natural tooth. Yet fundamentalsdifferences in the surrounding tissues and conditions between these devices areimportant to be recognized.Osseointegrated dentalimplants have become a predictable treatment option for single, partiallyedentulous and completely edentulous spans in selected patients. The survivalrates for implant supported’ single- and multiple tooth restorations have beenreported to be comparable to those for implant-supported prostheses incompletely edentulous patients.
The goal of implant therapy entails more thanjust the successful osseointegrated (survival) of the implant.A successful resultmust also include an esthetics and functional restoration surrounded by stableperi-implant tissue levels that are in harmony with the existing dentition. Thelongevity of the implants depend primarily on their stability at placement.
However, early peri-implant bone loss have been observed in many implantsystems and after different surgical approaches. The particular crestal bone isthe leading symptom of implant-supported after osseo-integration andachievement of primary stability.According toAlberktsson, a successful implant might lose an average of 1.5mm of crestalbone during the first year in function, followed by a marginal bone loss of<0.2mm during each succeding year. Maintenance of the peri-implant loss is amajor factor in the prognosis of prosthetic rehabilitation, supported byimplants.
Also, it is an important pre-requisite for preserving the integrityof the gingival margins and interdental papillae, which is most challenging forthe placement and subsequent restoration in the esthetically zone. Marginal crestal bone loss at implants isoften attributed to a microbial impact.It appears that with2-piece implants, an abutment-associated inflammatory cell infiltrate (ICT)forms between the implant and the abutment and extends from the microbialcoronally, apically and laterally for 0.
5-0.6mm.A comprehensiveunderstanding of crestal bone changes around endoosseous implants andsubsequent soft tissue reactions to these osseous changes hence becomeimperative.
In recent times,several techniques have been developed to minimize marginal bone loss such asthe non-submerged technique, scalloped implants, rough surface implant neckwith micro threads, progressive loading, immediate implant placement and so on.Platform switching isalso one such concept, which uses prosthetic abutments with reduced diameter inrelation to the implant platform diameter so as to move the implant abutmentfunction and supposedly the inflammatory reaction medially, away from thecrestal bone and thus, prevent thecrestal bone loss. This configuration results in a circular horizontal step,which enables a horizontal extension of the biological width.
The rationale forplatform switching is to locate the microbial of the implant-abutmentconnection away from the vertical to bone-to-implant contact area. Comparedwith the conventional restorative procedure using an identical size implant andSupra structural diameter, platform switching is suggested to prevent it reducecrestal bone loss.Platform switching is amethod of preserving crestal bone around the top of the wide-diameter implantsand seemingly alters the starting point from which crestal remodelling occurs.It has shown to limit both osseointegrated and soft tissue changes, thus,creating a predictable esthetics result.
The introduction ofwide-diameter dental implants in the late 1980’s created a situation in whichthe standard-diameter abutments were used simply because of the lack ofcommercially availability of the wider diameter abutments.Serendipitously, it wasfound that these implants exhibited less-than- expected initial crestal boneloss the effect of bone remodelling at the crest of the alvoelar bone intowhich dental implants are placed during healing. Several early clinical reportsdemonstrated enhanced soft (gingival) and hard (bone) tissue responses to theseplatform switched implants, leading many implant companies to incorporateplatform switching into their implant systems even for narrower-body implants.
Platform switching (theconcept was introduced in the literature by Lazzara and Porter and Gardner)limit the circumferential bone loss around the dental implants by usingprosthetic components having a platform diameter undersized when compared tothe diameter of the implant platform. In this way the implant abutmentjunctions is displaced horizontally inwards from the perimeter of the implantplatform, and further away from the abutment and the implant. Because itessentially is resting on the outer circumference of the implant platform, theinflamed connective tissue does not extend laterally to the same extent as itdoes within a traditional matched implant-abutment.In 1991, the 3i-ImplantInnovations Inc (Palm Beach Gardens, FL) introduced wide diameter 5.
0 and 6.0mmimplants that had identically dimensional platforms. These were designed to beused mainly for poor quality bones to achieve improved primary stability.However, when introduced, there were no matching wide-diameter prostheticcomponents available, and as a result, most of the intially placed implantswere restored with standard 4.1mm diameter components, which created a 0.45mmor 0.
95mm circumferential horizontal difference in dimension. Many platformswitched restored implants exhibited no vertical loss in crestal bone hieght.Thus the discovery of theconcept ‘Platform Switching’ comparative was coincidence.