Bibliographic reviews

International Journal of Prosthodontics, 22 (3):277-282, 2009

22 implants were placed immediately into fresh extraction sockets in the maxilla; 11 cases were treated with conventional prosthetic protocol and 11 with the Platform Switching technique. It was highlighted how this latter provides greater stability of the crestal module.

Clinical Oral Implant Research, 20 (4):414?420, 2009

This clinical study highlights that the rehabilitation of implants according to the switching platform concept allows better stability of the hard and soft tissues around the implant compared to rehabilitation with abutments of the same diameter.

As it often happens, this discovery occurred by accident: in the early phases of their marketing, abutments of the same size were not available for wide-diameter implants used in the restoration of posterior zones. Due to this “sales” difficulty, the fi rst users were forced to prosthesize them with standard healing abutments. Radiological analysis of the response of the peri-implant tissues, as described by Lazzara (2006), showed that bone reabsorption was signifi cantly lower than with implants prosthesized with conventional techniques. The reasons for such a positive behaviour are explained by the separation of the implant/abutment gap
(i.e. the infi ltrated infl ammatory source) from the vital bone and therefore, from the distribution, even horizontal, of the biological width (biological cause).
Although it is a retrospective study of limited scientifi c importance, this article marks an important step. In fact, it demonstrates the longitudinal reliability of this type of prosthetic protocol. Subsequently, different other works have confi rmed the radiological results of the Lazzara study both in implants placed
on native bone and in extraction sockets. At the same time, it was demonstrated that even the soft tissues draw advantages from the use of smaller abutments.
In the same years, the interest of researchers has led to histologically testing the application of the Switching Platform concept both on an animal model and on a human model. Although some authors have demonstrated that there are no statistically signifi cant differences between the test and control groups with regard to the behaviour of the vestibular bone, most of the works confi rm that the Platform Switching allows minimising peri-implant marginal reabsorption. The histological analysis identifi ed another reason for the positive response of the tissues to the use of the switching platform: the creation of a resting base for the connective tissue (the implant platform not occupied by the abutment) allows stabilising the collagen fi bres which in turn minimises bone reabsorption (anatomic cause).
Some studies seem to demonstrate that the biological and anatomical reasons are also joined by biomechanical factors. An analysis of the fi nished elements has demonstrated the biomechanical rationale of the platform switching: the difference in diameter between the implant and stump (mismatching) allows reducing the mechanical stress transmitted to the marginal bone, diminishing its reabsorption pattern. In recent years, the attention of researchers has shifted to the long-term response of hard and soft tissues to the platform switching. Various studies have proven the stability of the tissues even after 5 years. As further confirmation of the safety of this prosthetic protocol even in the long term, a microbiological study with PCR probe demonstrated that after 4 years the sub-gingival microbiological
flora in implants treated with Switching Platform do not present any statistically signifi cant difference compared to conventionally prosthesized implants.
A recently published study demonstrated that implants with small abutments not only presented a smaller vertical extension but also a smaller horizontal extension of the biological width, thus allowing the use of an inter-implant distance under 3 mm as proposed in standard protocols. In the same period, a randomised controlled study demonstrated how the width of the mismatching is inversely proportional to the size of the peri-implant reabsorption, suggesting, conditions permitting, the
use of wide-diameter implants with small prosthetic components. Obviously, the Switching Platform concept was demonstrated as being just as valid in vertically
reconstructed sites or in sinus lifts where, together with the use of new generation hydroxyapatite, it seemed to allow early loading (3 months) of the implants.

Italian Dental Journal, 2012; 08: 24

SURGICAL AND PROSTHETIC SWITCHING PLATFORM

One of the primary objectives of modern implantology is to maintain the crestal bone, so as to improve the aesthetic result and reduce the risk of late peri-implantitis. In comparison with traditionally designed implants, switching platform implants reduce early crestal bone loss in proportion to the size of the switch.
Switching platform implants are divided into two groups: implants with surgical switching (implants with a specially widened neck) and implants with prosthetic switching (implants with a standard neck with prosthetic posts having a reduced diameter). Both types of switching have proved to be effective and, in order to maximize the obtainable switch, for some years we have been using a switching platform protocol which combines the use of implants with surgical switching (Sweden & Martina Premium 3.80 SP implants) prosthesized with posts with a reduced diameter (posts for Premium 3.30). The combination of surgical and prosthetic switching has proved to be a valid and predictable protocol for minimizing crestal bone loss.
The clinical case illustrated below concerns the insertion of a single immediate post-extraction implant with immediate loading. Prosthetization was carried out according to the protocol described above.

Clinical Oral Implant Research, 21:115-121, 2010

This study on 80 implants, divided into four groups and rehabilitated with fixture/abutment mismatching increasing from 0 trough 0.85 mm, established an inverse relationship between the extension of the Platform Switching and the dimensional loss of the coronal bone, connecting this data to the horizontal repositioning of the biological width, and to a different stress distribution on the peri-implant bone.

Dental Cadmos, 77(9): 31-39, 2009

Two groups of 20 patients received single implant in an edentulous site, which was rehabilitated in a second surgical procedure with a standard abutment (control group) and with the Switching Platform technique (test group). One year after the loading of the prosthesis, the test group showed a significantly lower loss of crestal bone compared to the control group.

Journal of Periodontology, 81 (10):1350-1366, 2010

The authors conducted an extensive review of the literature relating to Platform Switching techniques and their respective results. They analysed 10 studies involving 1,239 implants; of these, three studies involved Global and Outlink² implants. A metanalysis of the data showed that the Switching Platform technique is on the average capable of preserving the bone height and the levels of soft tissue around the implant.

Clinical Oral Implant Research, Early View, First Published online on 2011, April 15th

This study demonstrated that the crestal placement of the implant and restoration according to the switching platform concept leads to greater maintenance of the bone levels and better adaptation of the soft tissues.

Italian Dental Journal, 4: 16, 2010

CLINICAL CASE: AGENESIS OF UPPER RIGHT LATERAL INCISOR

Unlike oligodontia and hypodontia, which are rare, usually related to serious genetic pathologies, single agenesis (i.e. no mono or bilateral dental morphology) is frequent, and has increased exponentially over the last 50 years, connected most likely to the adaptive phenomena of human species. The teeth most frequently affected by this agenetic condition are the upper lateral incisors, therefore, the clinical case studied by Dr Canullo is very important because it can form a valid reference for dentists who have to deal with the diffi cult prosthetic rehabilitation of these patients. In particular, the report briefly illustrates the immediate provisional technique of one abutment - one time and the roll-fl ap technique of treating soft tissues. This clinical case, supports, with results at 2 years, the validity of platform switching, even in the presence of a slight mismatching such as the one between the 4.3 mm platform of a Kohno implant (diameter of 3.80) and the relative abutment of 3.8 mm, and also clarifies the  aesthetic benefi ts of less bone reabsorption around the implant.

Journal of Clinical Periodontology, 2012; 39: 1097-1113

Another review of the literature on the theme of the efficacy of the platform switching technique in preserving crestal bone. 4 of the 10 articles included in the review concerned the use of Sweden & Martina implants. Also this review concludes that, from the data in the literature, the platform switching technique is effective in reducing marginal bone reabsorption.