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Int J Prosthodont. 2009 May-Jun;22(3):277-82.

Short-term bone level observations associated with platform switching in immediately placed and restored single maxillary implants: a preliminary report.

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Department of Orthodontics, University of Bonn, Bonn, Germany.



The aim of this study was to evaluate the short-term bone level response around immediately placed and provisionally restored implants using a platform switching concept.


Twenty-two implants with a platform diameter of 5.5 mm were immediately placed in healthy maxillary sites in 22 patients. Resultant circumimplant spaces were filled with a mixture of bovine bone matrix and collagen. The implants were randomly divided into two equal groups: 11 implants connected with 3.8-mm-diameter abutments (test group) and 11 with 5.5-mm-diameter ones (control). Provisional crowns were adapted and adjusted for nonfunctional immediate placement on each implant and the final crowns were constructed 2 months later. Posttreatment assessments were carried out by an independent trained observer at the time of implant placement (baseline), at definitive prosthesis insertion, and every 6 months thereafter. These assessments included periapical radiographs, pocket probing depths (PPD), bleeding on probing (BOP), and modified Plaque Index (mPII) on both implants and first proximal teeth. An image analysis software application was used to compare the bone crestal heights at the mesial and distal aspects of the implants.


The mean follow-up observation period was 25 months and all implants were judged to be successfully osseointegrated. In the test group, radiographic analysis showed an average bone reduction level of 0.30 mm (SD = 0.16 mm). This mean value was statistically significantly different (P < or = .005) from the average reduction in the control group (mean = 1.19 mm, SD = 0.35 mm). No differences between the two groups in PPD, BOP, or mPII were found.


This preliminary study suggests that immediate single implant restorations in specific maxillary sites with subsequent platform switching may provide peri-implant alveolar bone-level stability.

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