Page 177 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability

FOUR-IMPLANT-SUPPORTED OVERDENTURE TREATMENT IN THE MAXILLA
The time period between t0 and t1 is the period considered appropriate for initial bone remodeling, following biologic width establishment. After initial bone remodeling, the linear mixed-model analysis showed no clinical relevant effect of the implant type on the bone level at the t1 and t2. Although the implant position showed a significant effect on the bone level at t1 in favor of a posterior placed implant, the confidence limit (-0.365, -0.060) is suggestive for a clinically irrelevant difference. Moreover, at t2 no effect of implant position could be found.
Between t1 and t2 all implant types showed no relevant bone level change, indicative for a stable bone level over time after initial bone remodeling. However, some implants with high bone loss at t1 showed bone gain at t2. This could be explained by the effect of splinting the implants with a titanium bar after t1. The positive effect on bone level by splinting the implants was described earlier by De Bruyn and colleagues.16
The linear mixed-model analysis applied for probing pocket depth and the model logistic regression analysis applied for bleeding on probing and plaque showed no clinical relevant difference for implant type and implant position at t2. Only the probing pocket depth seems to be influenced by implant position, in favor of the posterior placed implant; however, the confidence limit (-0.617, -0.059) is suggestive of a clinically irrelevant difference.
Furthermore, it needs to be stated that these results have been established with the precondition that (1) all implants are placed in relation to the soft tissue thickness and (2) due to the use of the specific abutment a platform-shift between implant and abutment was created. The effect of adapting the vertical position of the implant in relation to the soft tissue thickness is published in several studies.17– 22 It could prevent early implant surface exposure by initial bone remodeling. The results of this study are in according to the aforementioned studies. The philosophy of a platform-shift between implant and abutment is to move the inflammatory cell away from the bone. A large meta-analysis of 28 publications with 1216 platform-switched implants and 1157 nonplatform-matched implants showed a significant effect on marginal bone loss in favor of the platform-shifted implants. However, they suggest a careful interpretation of the results due to the presence of uncontrolled con- founding factors.23
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