ABSTRACT
With proper surgical and prosthetic treatment, the majority of today’s implants are predictably reliable. Manufacturers’ claims of superiority due to new and unique design characteristics often lack good scientific backing. Platform switching, while still unproven, might offer some advantages, however, clinicians should base their implant choice on patient needs and system simplicity rather than on unsubstantiated claims.
Implant platform switching is the use of prosthetic abutments with diameters smaller than the diameters of the implants to which they will be connected.
Using the key words “implant platform switching” to search the National Library of Medicine database (www.ncbi.nlm.nih.gov) produces four papers today.1-4 Applying the same search strategy to the search engine Google produces over 611,000 “hits”. In other words, it is a challenge for the peer reviewed literature to keep up with the growing interest in this subject.
In the late ’80s Nobelpharma introduced a 5mm diameter Brnemark implant without providing a corresponding 5mm platform abutment. Accordingly, for the prosthetic phase of treatment, restorative dentists had to use the available “standard” diameter abutments designed for use with the 3.75/4.0mm Brnemark implants.5
Similarly, in 1991, Implant Innovations commercialized two wide-diameter implants (5.0- and 6.0-mm) with no matching wide-diameter prosthetic components. Here too, restorative dentists had to use the available “standard”-diameter (4.1-mm) prosthetic components to restore their cases.2
Radiographic follow-ups of patients treated with both of these “platform-switched” implants appeared to show less crestal bone loss than expected for cases restored with matching diameter components. There is only anecdotal evidence for the benefits of platform-switched Brnemark implants5 and only one published retrospective review for the Implant Innovations platform-switched implants exists at this point.2 The latter used non-standardized x-ray monitoring.
AIMS AND OBJECTIVES
Aims and objective of this report were to examine the scientific validity of claims that platform switching improves implant performance. These claims were analyzed against the historic background and findings of published implant studies. The National Library of Medicine database (www. ncbi.nlm.nih.gov) was used as the primary source of data. Online implant study club communications were used as a secondary source.
FINDINGS
By the late eighties there was marked increase in the number of implant systems appearing on the market and it became evident that criteria of success needed to be identified. Based on their exhaustive review of the literature available at the time, Smith and Zarb proposed six.6 One of these was an acceptable rate of bone remodeling apically. In successful implants this remodeling, together with the associated soft tissue changes, stops to create a stable biologic width.
Controlling and limiting this apical remodeling or crestal bone loss became a holy grail of implant dentistry. Overlapping and competing hypotheses have been advanced and studied to explain the phenomenon. They include surgical trauma, occlusal overload, countersinking the osteotomy to receive the implant, peri-implantitis caused by the presence of a crestal level microgap, and so on.
Modern implant treatment consists of either a one-surgery or a two-surgery protocol using either a one-piece of two-piece implant design to provide a foundation for the prosthetic phase of treatment. One exhaustively and long-studied tactic for limiting crestal bone loss can be found in the one-surgery, one-piece implant procedure. Indeed, studies show the presence of inflammation and resulting crestal bone loss with two-piece, two-surgery treatment at the crestal level implant/ abutment interface and no such changes in the one-surgery, one-piece implant design which has no crestal level micro-gap.7-10
The Swiss-made Straumann one-surgery, one-piece implant was used in these studies some of which were carried out 30 years ago. Employing the same design philosophy to minimize crestal bone loss, the Canadian-made one-surgery, one-piece implant Tenax Implant System appeared on the market about 10 years ago.
While there are statistically significant differences among the one-surgery and the two-surgery protocol using either a one-piece or two-piece implant design, there appear to be no clinically significant differences.11 Further, the criteria of implant success are difficult to measure outside a dedicated research environment. Research measuring techniques include using a jig to standardize x-rays by mechanically fixing the film to implant to x-ray source, a resonance frequency analysis tool to measure implant stability and a Florida probe to measure pocket depth.
On the other hand, implant survival is relatively simple to monitor in a “real-life” clinical setting using everyday methods. Given the high success rates of today’s implants, implant survival measures provide an adequate yardstick.
Notwithstanding the demonstrated lack of scientific proof for many claims by implant manufacturers for specific implant advantages,12 platform switching appears to be promising. It resulted from the original lack of implant abutments to match new, wider diameter implants. Non-standardized radiographic follow-up of platform-switched cases often showed the accidental finding of less crestal bone loss than expected with abutments, which matched the outer diameter of the implant platform. That is, moving the implant-abutment microgap towards the axis of the implant suggested better outcomes.
In light of today’s high implant survival rates, finding true improvement in implant performance is in the arena of diminishing returns. Carefully designed studies involving large numbers of patients need to be conducted over long periods to validate claims of advantages.
CONCLUSIONS
Currently, a great deal of interest in platform switching has been generated by implant manufacturers as a morphologic feature which is purported to decrease the crestal bone loss usually expected in implant treatment. At this time, peer-reviewed literature provides no support for this alleged benefit. Design simplicity, actual rather than claimed by manufacturers’ marketing material, should be the guiding principle in selecting an implant system.
Disclaimer: Dr. Milan Somborac is the inventor of the Tenax Dental Implant System and a shareholder of Tenax Implant Inc.
Oral Health welcomes this original article.
REFERENCES
1.Otto M. Concept of implant platform switching. SADJ. 2007 Mar;62(2):080.
2.Lazzara RJ, Porter SS. Platform switching: a new concept in implant dentistry for controlling postrestorative crestal bone levels. Int J Periodontics Restorative Dent. 2006 Feb;26(1):9-17.
3.Baumgarten H, Cocchetto R, Testori T, Meltzer A, Porter S.A new implant design for crestal bone preservation: initial observations and case report. Pract Proced Aesthet Dent. 2005 Nov-Dec;17(10):735-40.
4.Gardner DM. Platform switching as a means to achieving implant esthetics. N Y State Dent J. 2005 Apr;71(3):34-7. Review.
5.Kitzis, G. Osseonews posting, Apr 10, 2006
6.Smith DE, Zarb GA. Criteria for success of osseointegrated endosseous implants. J Prosthet Dent. 1989 Nov;62(5):567-72.
7.Schroeder A, Pohler O, Sutter F. Tissue reaction to an implant of a titanium hollow cylinder with a titanium surface spray layer] SSO Schweiz Monatsschr Zahnheilkd. 1976 Jul;86(7):713-27.
8.Buser D, Weber HP, Donath K, Fiorellini JP, Paquette DW, Williams RC. Soft tissue reactions to non-submerged unloaded titanium implants in beagle dogs. J Periodontol. 1992 Mar;63(3):225-35.
9.Weber HP, Buser D, Fiorellini JP, Williams RC. Radiographic evaluati
on of crestal bone levels adjacent to nonsubmerged titanium implants. Clin Oral Implants Res. 1992 Dec;3(4):181-8
10.Hermann JS, Buser D, Schenk RK, Schoolfield JD, Cochran DL. Biologic Width around one- and two-piece titanium implants. Clin Oral Implants Res. 2001 Dec;12(6):559-71.
11.Becker W, Becker BE, Ricci A, Bahat O, Rosenberg E, Rose LF, Handelsman M, Israelson HA. A prospective multicenter clinical trial comparing one- and two-stage titanium screw-shaped fixtures with one-stage plasma-sprayed solid-screw fixtures. Clin Implant Dent Relat Res. 2000;2(3):159-65.
12.Jokstad A, Braegger U, Brunski JB, Carr AB, Naert I, Wennerberg A. Quality of dental implants. Int Dent J. 2003;53(6 Suppl 2):409-43.
