Effect of platform switching on crestal bone levels around implants in the posterior mandible: 3 years results from a multicentre randomized clinical trial

Abstract

Objective: Evaluation of differences in the clinical performance and crestal bone levels between implants restored with single crowns with platform-matched or platform-switched abutments after 3 years.

Material and methods: The study enrolled adult patients missing two or more adjacent teeth in the posterior mandible with natural teeth mesial to the implant site. Randomization followed open-flap implant insertion and the corresponding matching or switching healing abutments placed at surgery. Conventional loading was made with cemented crowns. Clinical follow-up took place annually after loading up to 3 years. Bone level changes were measured in standardized radiographs as the variation in crestal bone from one evaluation to the next.

Results: Sixty-three patients with a total of 135 implants (66 platform matching, 69 platform switching) were analysed. From surgery to 36 months, mean bone loss was 0.28 ± 0.56 mm for the platform-switching group and 0.68 ± 0.64 mm for the platform-matching group. A statistically significant difference was found between groups (p = 0.002) with an estimate of 0.39 mm (0.15-0.64, 95% CI) in favour of platform switching.

Conclusions: After 3 years, platform-switching restorations showed a significant effect in the preservation of marginal bone levels compared to platform-matching restorations.

Keywords: bone level; crestal bone preservation; implant; implant success; platform match; platform switching; randomized clinical trial; standardized radiograph.

Figure 1

Clinical images of a representative case. (a) Healing abutments inserted according to the randomization result, (b) individual metal‐ceramic crowns cemented (loading day), (c) 1 year post‐loading evaluation, and (d) 3 years post‐loading evaluation.

Figure 2

Standardized radiographic images of the case presented. (a) Surgery, (b) loading, (c) 1 year post‐loading, and (d) 3 years post‐loading.

Figure 3

Mean (95% CI) bone level measurements (in millimetres) for each group over the five evaluation points.

Figure 4

Categorization of bone level changes from loading to 36 months in 0.2 mm intervals. Relative frequencies (%) of the cases allocated to each interval per group.