Dental Tribune United Kingdom Edition

May 23-29, 2011United Kingdom Edition T hereisanassociationbe- tween bone and soft tis- sue preservation around implants with direct influ- ence on aesthetics. Some au- thors have proposed different methods to maintain support- ing bone: improved implant micro-geometry and implant surface treatment, improved implant abutment connection (elimination of bacterial res- ervoir, absence of movements under bending forces) as well as the use of wide implants with smaller-sized abutments (platform switching concept). An alternative in pre- serving marginal bone lev- els around implants is the platform switching concept that refers to the use of a smaller diameter abutment on a larger diameter implant platform. This connection shifts the perimeter of the implant— abutment junction (IAJ) in- ward towards the central implant axis. Lazzara and Porter demonstrated that the inward movement of IAJ also shifts the inflammatory cell infiltrate inward and away from the bone implant inter- face, creating a horizontal bio- logic width that will limit bone resorption around the coronal aspect of the implant. From a biomechanical per- spective, stress in the bone is concentrated around the cre- stal region because of the dif- ference in modulus of elastic- ity between bone and implant, as demonstrated in photo-elas- tic and finite element analysis studies.14 Peak bone stresses occur- ring in marginal bone have been hypothesised to cause bone micro-fracture and may be responsible, at least partial- ly, for peri-implant bone loss with saucerisation patterns af- ter prosthetic loading. The issue of whether platform switching may affect stress patterns by minimising peak bone stresses in the mar- ginal bone has not been dem- onstrated yet. The original criteria estab- lished for assessing implant success and survival6 identi- fied marginal bone levels as an important indicator for meas- uring the response of the peri- implant tissues to functional loading. More recent studies have considered the effect of stress- es established in bone by the direct influence of non-passive prosthetic work to be a causa- tive factor in marginal bone loss.7, 8 Another more recent expla- nation of marginal bone loss is the theory of establishing the biologic width directly related to the position of the implant- abutment microgap and its as- sociated microbial flora.9, 10 In addition, some studies have shown that certain de- signs in the geometry of im- plant coronal part may con- tribute to bone loss, while other studies have indicated that such bone loss can be pre- vented by incorporating a bio- mechanical stable connection and a more retentive surface on the implant collar.11, 12 Prevention of horizontal and vertical marginal peri-im- plant bone resorption during the post-loading period is fun- damental in maintaining sta- ble gingival levels around im- plant-supported restorations.13 It has been demonstrated that peri-implant marginal bone loss is time-related with sig- nificantly more acute bone loss during the preloading period than in the following loading phases (two years after sur- gery) and also during the first year after loading (six months to one year after surgery) than in the second one (one year to two years after surgery). Aesthetic outcomes cannot be attributed to a single pa- rameter. They are the result of a number of important factors, especially in the aesthetic area. Both biologic width and the integration of platform switch- ing concept are of utmost sig- nificance in preserving a stable marginal bone level around implant neck. It is important to understand mainly the mean- ing of biologic width. Hence, the stable bone serves as a sup- port for the soft tissue deter- mining the long-term aesthetic and functional treatment, the outcome stability being en- sured in this manner. Dr Stoianov continues exploring platform switching Are you sitting as you should ? Are you seeing all you should ? Contact us The Dental Magnification Specialists for current offers and recommendations on how to meet these challenges. Concept of “platform switch- ing” in implant dentistry: A literature review—Part II ‘Some studies have shown that certain de- signs in the geometry of implant coronal part may contribute to bone loss’