Method: This study was approved by the UDM Institutional Review Board (Protocol 1112-49). Twenty-one adult patients who had implants for at least 4 months were involved in the study. Patient data including gender, age, periodontal diagnosis and prognosis, plaque index, gingival index, probing depth, generalized bone loss, smoking status, and implant system were recorded. Crevicular fluid was sampled from 71 sites, including 21 non-platform switched implant sites, 13 platform-switched sites, and 37 control sites. MMP-8 levels were determined by a commercial ELISA kit (RnD Systems, Minneapolis, MN), and results were statistically compared using probability at p < 0.05.
Result: Of the clinical parameters assessed, plaque index was found to be significantly higher in patients with the non-platform switched implants (48%) compared to those with the platform-switched implants (26%, p = 0.0308). MMP-8 levels in crevicular fluid sampled at initial visits were not different between controls (20.8 + 10.2 ng/ml), non-platform switched implants (14.3 + 10.3 ng/ml), and platform-switched implants (16.0 + 11.6 ng/ml) presumably because of the wide biological variation (p = 0.0659, Kruskal-Wallis). At re-evaluation, MMP-8 levels were found to be decreased in controls (11.9 + 7.7 ng/ml), non-platform switched implants (4.7 + 2.9 ng/ml), and platform-switched implants (3.9 + 5.9 ng/ml) and again wide biological variability was observed. However, control values were significantly higher than the platform-switched implant values (p < 0.05).
Conclusion: MMPs play central roles in wound healing and inflammatory response. However our study suggests that plaque index, not MMP-8 levels, may be a diagnostic indicator to assess clinical response post-function in implant abutment platform designs.