Dental Tribune United Kingdom Edition

17Implant TribuneMay 23-29, 2011United Kingdom Edition 2mm from the implant abutment junction3 should occur circumfer- entially, noticeable on the buccal plate. Preliminary evidence sug- gests that anticipated bone loss occurring around two-stage implants, following loading, or surgical stage two, may be reduced or eliminated when implants are restored with smaller-diameter abutments on larger platforms.4, 5 The interface between abut- ment and implant, or the micro- gap, is subject to micro move- ments and bacterial seeding, and, if it lies at or below the crest of the bone, prompts osseous resorption for these reasons. Bone preserv- ing techniques such as platform switching have been utilised for more than ten years (Fig. 3). The answer to these questions may be of an important support in choosingtheimplantsystem,ableto switchtheplatform,whichcanface high implant— aesthetic demands. Is the concept of platform switching a bone preserving tech- niqueand,ifso,isthisreproducible? Is this concept alone able to pre- serve bone? Is the platform switching concept evidence based? Materials and methods The aim and objectives of this re- view have been to examine the scientific validity of claims that platform switching concept im- proves implant performance, be- ing a bone preserving technique. These claims have been analysed against historic back- ground, findings and conclusions of published implant studies. A literature search of paper published in reference journals in the English language was per- formed by computer using the Na- tional Library of Health. PubMed — the government search engine for the National Library of Health, National In- stitute of Health MEDLINE da- tabase: www.pubmed.gov, has been used as the primary source of data. Google Scholar Search engine and different Journals and books have been employed as a second- ary source. PubMed search for the key words “implant platform switching concept” ended in 10 and Google Scholar in 3,110 re- sults for the same key words in 0.07 seconds. These results show an ever— growing interest in this subject which is very challenging for the peer reviewed literature to keep up with. Manual search of IJOMI— International Journal of Oral and Maxillofacial Implants with back issues from 1996 to 2009 revealed very few results. The reference list of identified publications and textbooks were scanned. The first selection method consisted in a relevant references selection on the basis of titles and abstracts. The final selection method being possibly relevant full text publications have been re- viewed for a more detailed evalu- ation. Tables have been drawn up using data and findings extract- ed from relevant studies, further compared and analysed in view of establishing a final conclusion. Results Table 1 Jomi 2009; 24:103–109 Paolo Vigolo, Andrea Givani Platform Switched Restaurations on Wide-Diameter Implants: A five-year Clinical Prospective Study Result: Statistically significant differences in marginal bone loss have been observed between im- plants with platform switching (0.6 mm; SD 0.2 mm) and im- plants with the same abutment platform (0.9 mm; SD 0.3 mm) Table 2 J Oral Maxilofacial Surg. 2007 Jul;65 M, Fickl S, Zuhr O, Wachtel HC Peri-implant bone level around implants with platform switched abutments: Preliminary data from a prospective study Result: The concept of platform switching appears to limit crestal resorption and seems to preserve peri-implant bone levels. Signifi- cant differences concerning the peri-implant bone height in PS compared to non PS implants are still evident one year after final restauration. Table 3 Jomi 2007;22:995–1000 Luigi Canullo, Giulio Rasperini Preservation of Peri-implant Soft and Hard Tissues Using Platform Switching of Implants Placed in Immediate Extraction Sockets: A Proof-of-Concept Study with 12- to 36-months follow-up Result: Post-extractive immediate implants with platform switching can preserve hard and soft tissues and, therefore, may provide better aesthetic outcomes. Table 4 Int.JPeriodonticsRestorativeDent. 2008 Aug Cappiello M, Luongo R, Di Iorio D, Bugea C, Cocchetto R, Celletti R. Evaluation of Peri-Implant Bone loss around platform- switched implants Results: This data confirm the important role of the microgap be- tween the implant and abutment in the remodeling of the peri-im- plant crestal bone. Platform switching seems to reduce peri-implant crestal bone resorption and increase long-term predictability of implant therapy. Table 5 J Periodontol. 2001 Oct Hermann JS ,Schoolfield JD, Schenk RK, Buser D,Cochran DL Influence of the size of the mi- crogap on crestal bone changes around titanium implants. A his- tometric evaluation of unloaded non-submerged implants in ca- nine mandible. Results: All implants in the non- welded group had significantly increased amounts of crestal bone loss compared to the welded group. These findings demon- strate that crestal bone changes around 2-piece non-submerged titanium implants are significantly influenced by possible movements between implants and abutments, but not by the size of the micro- gap. Significant crestal bone loss occurs in 2-piece implant con- figurations even with the small- estsized microgaps (<10 micron) in combination with possible movements between implant components. Table 6 JOMI 2006; 21:777–784 Michael R. Norton Multiple Single-Tooth Restaura- tions in the Posterior Jaws: Main- tenance of Marginal Bone Levels with Reference to the Implant- Abutment Microgap Results: The way in which bone responds around an implant may be due to multiple factors. It is also plausible that the tight coni- cal joint, with its high resistance to bending moments and a microgap of only 2–4 microns, contribute significantly to the maintenance of marginal bone. With an overall mean margin- al bone loss of only 0.65mm from the microgap the data of this study is in close agreement with numerous studies on the Astra Tech System. The finding that some of the implants have demonstrated bone above the level of the microgap cast doubt on the theory of bio- logic width, with regard to the in- fluence of the location of the im- plantabutment microgap which requires re-evaluation. DT Figs. 1 & 2_Initial situation in region 031,041. State 3 months after the removal of the teeth 31, 41. In region 041 the vestibular lamella has completely collapsed Fig. 3_Noticeably visible three wall bone defect in region 031 vestibular