Influence of platform switching on bone-level alterations: a three-year randomized clinical trial

Abstract

The concept of platform switching has been introduced to implant dentistry based on clinical observations of reduced peri-implant crestal bone loss. However, published data are controversial, and most studies are limited to 12 months. The aim of the present randomized clinical trial was to test the hypothesis that platform switching has a positive impact on crestal bone-level changes after 3 years. Two implants with a diameter of 4 mm were inserted crestally in the posterior mandible of 25 patients. The intraindividual allocation of platform switching (3.3-mm platform) and the standard implant (4-mm platform) was randomized. After 3 months of submerged healing, single-tooth crowns were cemented. Patients were followed up at short intervals for monitoring of healing and oral hygiene. Statistical analysis for the influence of time and platform type on bone levels employed the Brunner-Langer model. At 3 years, the mean radiographic peri-implant bone loss was 0.69 ± 0.43 mm (platform switching) and 0.74 ± 0.57 mm (standard platform). The mean intraindividual difference was 0.05 ± 0.58 mm (95% confidence interval: -0.19, 0.29). Crestal bone-level alteration depended on time (p < .001) but not on platform type (p = .363). The present randomized clinical trial could not confirm the hypothesis of a reduced peri-implant crestal bone loss, when implants had been restored according to the concept of platform switching.

Trial registration: ClinicalTrials.gov NCT01917305.

Keywords: alveolar bone loss; dental implant; dental implant-abutment connection; dental implant-abutment designs; dental implant-abutment interface; single-tooth dental implant.

Conflict of interest statement

The authors declare no potential conflicts of interest with respect to the authorship and/or publication of this article.

Figures

Figure 1.

The measured distances at the radiographs: (a) platform switching and (b) standard platform. The red area demonstrates the bone-level alteration since baseline (implant insertion operation). Measured distances from reference points: IBL, vertical bone level at the implant (reference point, microgap); HVD, horizontal aspect of the vertical bony defect at the implant (reference point, implant surface); GBL, general horizontal bone level (reference point, microgap).

Figure 2.

Mean ± standard deviation of the vertical implant bone-level alteration (∆IBL) at platform-switching and at standard-platform implants (data presentation adapted from Astrand et al., 2004). 0 months, implant insertion; 4 months, implant loading.

Figure 3.

Examples of radiographs at implant placement (baseline) and 12, 25, and 38 months postoperatively. (a–d) Platform switching (left) experienced more peri-implant crestal bone loss than did standard platform (right): standard platform better (ST). (e–h) Platform switching (left) experienced less peri-implant crestal bone loss than did standard platform (right): platform switching better (PS).