20 November 2021

---

Platform switching vs platform matching: a radiographic analysis of marginal bone loss

Authors: Graziano Montaruli, Susanna Maffione, Giuseppe Troiano, Michele Tepedino, Michele Laurenziello, Luigi Laino, Lorenzo Lo Muzio

---

A considerable literature claimed that the use of platform switching protocol reduces the exposure of bone crest to the effects of inflammation at implant-abutment junction.

The objective of this study was to evaluate differences in marginal bone loss (MBL) between sites treated with platform switching (PS) protocol and sites treated with platform matching (PM) protocol, evaluating the existence of an advantage that PS can bring in the process of bone remodeling.

Materials and methods
A retrospective study based on the analysis of a series of data on patients undergoing implant-prosthetic treatment was carried out. A total of 24 patients were included in the cohort, of these: 12 patients were treated with a PS approach and formed the test group, while 12 patients were treated with a PM protocol forming the control group.  A total of 36 external connection implants were evaluated: out of 15 implants the PS protocol was applied and on 21 the PM protocol. For each patient, periapical radiographs were made using the long-cone technique at the end of the surgical phase (T0) and at the end of the prosthetic phase.
A time range of 4-6 months was considered, between the surgical phase and the delivery of the definitive prosthesis. All the implants underwent a non-submerged healing process. After collecting all the oral radiographs in T0 and T1 for each implant of each patient from both study groups, the bone height around the implant with the AutoCAD® program was assessed on each oral radiograph.
Measurements have been made on both mesial and distal bone height of the fixture. In this way it was possible to evaluate both the initial marginal bone level at T0 (I-MBL) and the final marginal bone level at T1 (F-MBL) around to the implants treated with the PS or PM protocol.
Subsequently, the Marginal Bone Loss (∆-MBL) was calculated as a difference between I-MBL and F-MBL at both mesial and distal side of the implant, in addition the average ∆-MBL between mesial and distal aspect was also calculated.

Results
After elaborating the measurements taken at the mesial and distal levels for each implant at T0 and T1, and after calculating all the averages in both study groups, the total averages were calculated.
The data were subjected to statistical analysis by means of the independent samples Mann-Whitney U Test, in order to compare the MBL results obtained at implant level.
Results of this study revealed a significant lower distal ∆-MBL in the PS group than in the PM group. Indeed, both mesial ∆-MBL and average ∆-MBL showed no statistically significant differences between the two groups.

Conclusions
At mesial MBL and the average of the two MBL there were no statistically significant results that allow to prefer one protocol instead to the other. Radiographic evaluation of ∆-MBLs between implants treated with PS and PM protocols showed small differences in favor of the PS protocol at mesial side, while no differences were detected at distal side and as average between the two sites.
The results obtained can be integrated by a medium-long term radiographic follow-up, thus analyzing the changes of mesial and distal MBL over time.

Clinical significance
Within the limits of this study, it is considered advisable to apply the surgical/prosthetic platform switching protocol in order to obtain a homogeneous and predictable response of hard tissues, reducing the rate of peri-implantal bone resorption.