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Table of Contents   
TECHNICAL NOTE  
Year : 2014  |  Volume : 25  |  Issue : 2  |  Page : 254-259
"Platform switching": Serendipity


1 Department of Prosthodontics, DAPM RV Dental College, Bengaluru, India
2 Private practitioner, Bangalore, Karnataka, India
3 Preventive and Community Dentistry, DAPM RV Dental College, Bengaluru, India

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Date of Submission17-Nov-2013
Date of Decision06-Jan-2014
Date of Acceptance23-May-2014
Date of Web Publication4-Jul-2014
 

   Abstract 

Implant dentistry is the latest developing field in terms of clinical techniques, research, material science and oral rehabilitation. Extensive work is being done to improve the designing of implants in order to achieve better esthetics and function. The main drawback with respect to implant restoration is achieving good osseointegration along with satisfactory stress distribution, which in turn will improve the prognosis of implant prosthesis by reducing the crestal bone loss. Many concepts have been developed with reference to surface coating of implants, surgical techniques for implant placement, immediate and delayed loading, platform switching concept, etc. This article has made an attempt to review the concept of platform switching was in fact revealed accidentally due to the nonavailability of the abutment appropriate to the size of the implant placed. A few aspect of platform switching, an upcoming idea to reduce crestal bone loss have been covered. The various methods used for locating and preparing the data were done through textbooks, Google search and related articles.

Keywords: Crestal bone loss, osseointegration, platform switching

How to cite this article:
Kalavathy N, Sridevi J, Gehlot R, Kumar S. "Platform switching": Serendipity. Indian J Dent Res 2014;25:254-9

How to cite this URL:
Kalavathy N, Sridevi J, Gehlot R, Kumar S. "Platform switching": Serendipity. Indian J Dent Res [serial online] 2014 [cited 2020 Aug 15];25:254-9. Available from: http://www.ijdr.in/text.asp?2014/25/2/254/135938
There are a range of factors involved in achieving good aesthetic result with implants. The correct positioning of the implant is one of the most important factors, along with establishing the optimum volume of hard and soft tissues. [1] The success of dental implants is highly dependent upon the integration between the implant and the intraoral hard/soft tissue. The initial breakdown of the implant-tissue interface generally begins at the crestal region in successfully osseointegrated endosteal implants regardless of surgical approaches used, with the potential to cause implant failure. [2]

The various methods used for locating and preparing the data was done through textbooks, Google search and related articles.


   Review of literature Top


The first report quantifying early crestal bone loss was a 15 year retrospective study by Adell et al. [3] He reported 1.2-mm marginal bone loss from the first thread during healing and in the first year after loading with an average 0.1-mm bone loss annually thereafter.

Vertical bone loss (<0.2 mm) annually following the 1 st year of implant function is the criteria for implant success as given by Smith and Zarb. [4] A post restorative remodelled crestal bone generally coincides with the level of the first thread on most standard diameter implants. The first thread changes the shear force of the crest module to a component of compressive force to which the bone is most resistant.

There are various factors that can lead to crestal bone loss, such as: [2]

  • Surgical trauma
  • Biologic width/seal
  • Microgap
  • Occlusal overload
  • Crest module.


During the first year of use, stabilization of the crestal bone at the level of the first thread of a screw-retained Brånemark type implant has always been observed and considered normal. In fact, it has been observed that resorption around the collar begins when the implant is exposed, and as long as the latter remains submerged, the crestal bone is stabilized at the level of the collar. Following loading, or surgical Stage II, bone stabilization beneath the collar seems to depend on several factors, such as, respecting the biological space, the location of an area of inflammatory connective tissue (ICT), and the state of the implant surface [Figure 1].
Figure 1: Crestal bone level around a nonrestored, covered, two staged implant placed subcrestally (left) and the postoperative crestal bone level located at the first dental implant approximately 1.5-mm apical to the implant-abutment junction (right), CT = connective tissue

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In 1997, Abrahamsson et al. showed that multiple screwing and unscrewing movements of the healing screw results in an apical migration of the epithelial attachment around the implant collar. [5] The authors stress that this epithelial migration results, in turn, in an apical relocation of the bone level, so that a biological space/biologic width compatible with the health of the peri-implant-tissues is restored.

Biologic width forms with in first 6 weeks after the implant-abutment junction (IAJ) is exposed to the oral cavity. It is the barrier against bacterial invasion and food ingress at the implant-tissue interface.

The ultimate location of the epithelial attachment following restoration in part, determines early postsurgical bone loss. Thus the implant bone loss is in part, a process of establishing the biological seal. [2] Several studies have also shown that crestal bone loss occurs following implant placement and its connection to the abutment.

Other studies indicate that such remodeling is the result of localized inflammation of soft tissue at the IAJ (microgap), as a biological seal becomes established. [1] Once the biologic width has been established, the soft tissue takes on a protective function toward the crestal bone. This situation has important consequences for the esthetics of the interdental papilla, which can suffer mesial and distal bone loss of around 0.07-mm after a 6 month follow-up period. [6]

Finally, unlike the parameter mentioned, the condition of the implant surface plays a positive role with regard to the resorption phenomenon. When the implant surface is rough and when significant stresses are applied the bone's capacity to adhere to the titanium is increased, particularly during immediate loading.

Surgical trauma due to heat generated during drilling, elevation of periosteal flap and excessive pressure at the crestal region during implant placement may contribute to implant bone loss during the healing period. Signs of bone loss due to surgical trauma and periosteal reflection are not commonly seen during Stage II surgery in successfully osseintegrated implants. [2]

Excessive stress on the immature bone implant interface is likely to cause bone loss during the early stage of prosthesis in function. However, bone loss due to occlusal loading is considered to be progressive rather than limited to first year of implant loading. [2]

The clinician's ability to reduce or eliminate crestal bone loss can result in significant aesthetic and clinical benefits.


   Concept of 'Platform-Switching' Top


Research on crestal bone loss around dental implants has largely focused on implant systems with matching diameter implant seating surfaces and restorative components. [2]

In most two piece implant systems, after the abutment is connected, a microgap exists between the implant and the abutment. The microgap - crestal bone level relationship studied radiographically by Hermann et al., demonstrated that the microgap between the implant and the abutment has a direct effect on crestal bone loss, independent of surgical approaches. Epithelial migration to establish biologic width could be responsible for crestal bone loss.

The histology of peri-implant-tissue was studied by Ericsson et al., who observed that the peri-implant bone crest was consistently located 1.0-1.5-mm apical to the IAJ [Figure 2]. The apical border of the implant associated inflammatory cell infiltrate (ICT) was always separated from the bone crest by approximately 1.0-mm of healthy connective tissue. Thus, he concluded that the presence of ICT is an etiological factor in crestal bone loss. [6]

In 1991, Implant Innovations, Inc. (3i, Palm Beach Gardens, FL) introduced 5-mm and 6-mm diameter implants with seating surfaces (i.e. restorative platforms) of the same dimensions [Figure 3]. These large-diameter implants, with a larger surface area, were intended to increase the amount of bone-to-implant contact when placing shorter implants in areas of limited bone height, such as under the maxillary sinus or above the inferior alveolar canal. [7]
Figure 2: Histologic picture of peri-implant-tissue

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Figure 3: The use of prosthetic abutments with reduced width in relation to the implant diameter (platform switching)

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The ability to increase the bone-to-implant contact by the use of wide-diameter implants also enhanced the likelihood of achieving primary stability in areas of poor-quality bone. At the time of introduction of the wide-diameter implants' no matching, similarly dimensioned prosthetic components were available. Hence, clinicians restored them with standard 4.1-mm abutments. After a 5-year period, the typical pattern of crestal bone resorption was not observed radiographically in cases where platform switching was utilized. Lazzara and Porter theorize that this occurred because shifting the IAJ inward also repositioned the inflammatory cell infiltrate and confined it within a 90° area that was not directly adjacent to the crestal bone, thus reducing crestal bone resorption. [8]


   Thus the Discovery of Platform Switching was Serendipity! Top


  • The design details of a platform switched implant are mentioned below and [Figure 4] depicts the same
  • The collar bevels medially into a smaller-diameter prosthetic platform
  • Restoring the 4.8-mm diameter collar (implant restorative platform) with the 4.1-mm prosthetic component medializes the IAJ. [2]
Figure 4: Design details of platform switched implant restoration

Click here to view


Hence, the platform switching concept implies the use of prosthetic components having a platform diameter undersized when compared with the diameter of the implant platform. In this way, the prosthetic connection is displaced horizontally inwards from the perimeter of the implant platform, creating an angle, or step between the implant and abutment.

Application

  • In situations where larger implant is desirable but prosthetic space is limited
  • In the esthetic zone
  • Where preservation of crestal bone can lead to improved esthetics
  • Where shorter implants must be utilized.


Advantages

  • The inflammatory cell infiltrate, which surrounds the IAJ in a collar like fashion, is contained within the angle formed at the interface and thus prevented from spreading further apically along the implant where it would otherwise result in inflammatory changes to the bone crest [5],[6],[9] [Figure 5] and [Figure 6]
  • The horizontal dimension of the step allows for an additional area where biologic attachment may take place, thus limiting the extent of physiologic remodeling of the bone crest needed to accommodate the biological zone [8]
  • Optimal management of restorative space. With the crestal bone preserved both horizontally and vertically, support is thus retained for the interdental papillae. Maintenance of midfacial bone height helps to maintain facial gingival tissues [2]
  • Improved bone support for shorter implants [2]
  • The possible influence of the microgap on bone resorption may be diminished by moving the junction inwards from the bone crest. [9]
Figure 5: Apical view from long axis of implant

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Figure 6: Apical view from long axis of implant. Note: Inflammatory connective tissue does not infiltrate beyond platform dimensions

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Disadvantages

  • Need for the components that have similar design
  • Need for sufficient space to develop proper emergence profile.



   Discussion Top


Hermann et al. reviewed biologic width, platform switching, and implant design in the cervical region, nano roughness, fine threads, insertion depths, abutment design and avoidance of microlesions in the periimplant soft tissue as factors that determine the preservation of crestal bone levels. According to them, these factors along with several others, determine the aesthetic outcomes of implant restorations. [10]

Vela-Nebot et al. concluded that platform switching improves aesthetic results and that when invasion of the biologic width is reduced, bone loss is reduced (P < 0.0005). However, he says that further microbiological, pathological and clinical studies are necessary to confirm both these results as well as the study's working hypothesis. [11]

Lazzara and Porter discovered that during a 13 year radiographic observation period of the periapical region of wider implants with reduced diameter abutments, improved crestal bone preservation was seen, but it was thought that further investigation was needed to prove the real advantages of this technique. [9]

Baumgarten et al. described the platform switching technique and its usefulness in situations where shorter implants must be used, where implants are placed in esthetic zones, and where a larger implant is desirable, but prosthetic space is limited. He believed that a sufficient tissue depth (approximately 3-mm or more) is necessary to accommodate an adequate biologic width. He stated that platform switching helps prevent the anticipated bone loss and also preserves crestal bone; he has cited a particular case report as the basis of his theory. [8]

Gardner discusses the literature dealing with the changes that occurred when an implant is placed in bone and he presented a case study using platform switching implants. He stated that the main advantage is that it is an effective way to control circumferential bone loss around dental implants but he concluded that platform switching needs further investigation. Furthermore, he noted several potential disadvantages of this procedure such as the need for components that have similar designs (the screw access hole must be uniform) and the need for enough space to develop a proper emergence profile. [12]

In his article "Platform switching with a new implant design," 2007, Calvo Guirado et al. noted the success of the placed implants after 8 months with minimal marginal resorption (<0.8 mm) and highly satisfactory esthetic results. [7]

In their prospective study, Hürzeler et al. revealed that although bone remodeling is encountered during the first year after the final restoration with platform switching implants, there are significant differences compared with non-platform switching implants. In his opinion, a larger number of patients should be studied to confirm these results. [13]

Degidi et al. evaluated the histology and histomorphology of three Morse cone connection implants in a real case report and explained that when there is zero microgap and no micromovement, platform switching shows no resorption. He also observed that this method provided better aesthetic results. [14]

Canullo et al. is in favor of platform switching and he evaluates the relation between immediate loading with these implants and its effects on soft and hard tissues. [15]

Esposito et al. tested different flap designs in order to determine the best techniques for soft tissue handling but he does not specify the implant system utilized. [16]

Becker et al. in a histomorphometric study conducted on dogs concluded that 28 days after implant placement, both computer-aided manufacturing (sand blasted and acid etched screw type implants with either matching) and Complete Prosthetic Set (smaller diameter healing abutments) revealed crestal bone level changes, but he found no significant differences between them. He thinks that further studies with a higher number of animals and implant sites are needed in order to clarify the influence of platform switching on crestal bone changes. [17]

Weiner et al. connects the development of biologic width with the implant surface. He does not mention platform switching but focuses his study on the use of soft tissue-engineered collars with microgrooving. Sarment et al. have found some changes in the width and height of bone when using platform switching implants. [18]

Maeda et al. utilized a three-dimensional finite element model to examine the biomechanical advantages of platform switching. He noted that this procedure shifts the stress concentration away from the bone-implant interface, but these forces are then increased in the abutment or the abutment screw. [19]

Furthermore in a prospective clinical study by Calvo-Guirado et al., platform-switched implants remained stable over the course of 5 years and had an overall survival rate of 97.1%. [20]

López-Marí et al. reviewed published articles dealing with platform switched implants and concluded that that platform switching helps to prevent crestal bone loss after implant placement and helps to obtain satisfactory aesthetic results. [1]


   Conclusion Top


Crestal bone loss has been documented as one of the important factors that affect the long term prognosis of a dental implant. In spite of thorough investigations, proper patient and implant system selection, together with appropriate modification of prosthetic design, the main problem a clinician comes across is crestal bone loss. Various methods have been tried to overcome this problem that include submerged implant technique, bone grafts/bone crushes, usage of sealants to reduce the bone loss around the crestal region, apart from modifying the design of the implants around the collar region.

A promising method to reduce crestal bone loss is "The concept of platform switching".

Platform switching is a method of preserving crestal bone around the top of wide diameter implants and seemingly altering the starting point from which the crestal bone resorption occurs. It provides the clinician with additional surgical and prosthetic treatment options with the use of wide diameter implants.

The clinical benefits of platform switching needs further investigations. The techniques of platform switching as illustrated by the authors require additional studies to establish the biologic process responsible for positive radiographic findings.

 
   References Top

1.López-Marí L, Calvo-Guirado JL, Martín-Castellote B, Gomez-Moreno G, López-Marí M. Implant platform switching concept: An updated review. Med Oral Patol Oral Cir Bucal 2009;14:e450-4.  Back to cited text no. 1
    
2.Deshpande SS, Sarin SP. Platform switching of dental implants: Panacea for crestal bone loss? J Clin Diagn Res 2009;3:1348-1352.   Back to cited text no. 2
    
3.Adell R, Lekholm U, Rockler B, Brånemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;10:387-416.  Back to cited text no. 3
    
4.Smith DE, Zarb GA. Criteria for success of osseointegrated endosseous implants. J Prosthet Dent 1989;62:567-72.  Back to cited text no. 4
    
5.Abrahamsson I, Berglundh T, Lindhe J. Soft tissue response to plaque formation at different implant systems. A comparative study in the dog. Clin Oral Implants Res 1998;9:73-9.  Back to cited text no. 5
    
6.Ericsson I, Persson LG, Berglundh T, Marinello CP, Lindhe J, Klinge B. Different types of inflammatory reactions in peri-implant soft tissues. J Clin Periodontol 1995;22:255-61.  Back to cited text no. 6
    
7.Calvo Guirado JL, Saez Yuguero MR, Pardo Zamora G, Muñoz Barrio E. Immediate provisionalization on a new implant design for esthetic restoration and preserving crestal bone. Implant Dent 2007;16:155-64.  Back to cited text no. 7
    
8.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;17:735-40.  Back to cited text no. 8
    
9.Lazzara RJ, Porter SS. Platform switching: A new concept in implant dentistry for controlling postrestorative crestal bone levels. Int J Periodontics Restorative Dent 2006;26:9-17.  Back to cited text no. 9
    
10.Hermann F, Lerner H, Palti A. Factors influencing the preservation of the periimplant marginal bone. Implant Dent 2007;16:165-75.  Back to cited text no. 10
    
11.Vela-Nebot X, Rodríguez-Ciurana X, Rodado-Alonso C, Segalà-Torres M. Benefits of an implant platform modification technique to reduce crestal bone resorption. Implant Dent 2006;15:313-20.  Back to cited text no. 11
    
12.Gardner DM. Platform switching as a means to achieving implant esthetics. N Y State Dent J 2005;71:34-7.  Back to cited text no. 12
    
13.Hürzeler M, Fickl S, Zuhr O, Wachtel HC. Peri-implant bone level around implants with platform-switched abutments: preliminary data from a prospective study. J Oral Maxillofac Surg 2007;65:33-9.  Back to cited text no. 13
    
14.Degidi M, Iezzi G, Scarano A, Piattelli A. Immediately loaded titanium implant with a tissue-stabilizing/maintaining design ('beyond platform switch') retrieved from man after 4 weeks: A histological and histomorphometrical evaluation. A case report. Clin Oral Implants Res 2008;19:276-82.  Back to cited text no. 14
    
15.Canullo L, Rasperini G. 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-month follow-up. Int J Oral Maxillofac Implants 2007;22:995-1000.  Back to cited text no. 15
    
16.Esposito M, Grusovin MG, Talati M, Coulthard P, Oliver R, Worthington HV. Interventions for replacing missing teeth: antibiotics at dental implant placement to prevent complications. Cochrane Database Syst Rev 2008 Jul;16:CD004152.   Back to cited text no. 16
    
17.Becker J, Ferrari D, Herten M, Kirsch A, Schaer A, Schwarz F. Influence of platform switching on crestal bone changes at non-submerged titanium implants: A histomorphometrical study in dogs. J Clin Periodontol 2007;34:1089-96.  Back to cited text no. 17
    
18.Weiner S, Simon J, Ehrenberg DS, Zweig B, Ricci JL. The effects of laser microtextured collars upon crestal bone levels of dental implants. Implant Dent 2008;17:217-28.  Back to cited text no. 18
    
19.Maeda Y, Horisaka M, Yagi K. Biomechanical rationale for a single implant-retained mandibular overdenture: An in vitro study. Clin Oral Implants Res 2008;19:271-5.  Back to cited text no. 19
    
20.Calvo-Guirado JL, Gómez-Moreno G, López-Marí L, Guardia J, Negri B, Martínez-González JM. Crestal bone loss evaluation in osseotite expanded platform implants: A 5-year study. Clin Oral Implants Res 2011;22:1409-14.  Back to cited text no. 20
    

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Correspondence Address:
N Kalavathy
Department of Prosthodontics, DAPM RV Dental College, Bengaluru
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.135938

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]

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