Page 96 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability

CHAPTER 4
■ DISCUSSION
This paper scrutinized the literature on peri-implant bone loss in relation to implant surface roughness. The main focus was on bone loss for two reasons. First, ongoing bone loss is a prerequisite in the diagnosis of peri-implantitis and second, stability of peri- implant bone is considered a crucial determinant for implant success.
Because the process of bone level changes due to disease may take some years before being diagnosed clinically,199 a minimal 5 year follow-up was set as inclusion criterion. Furthermore, since most of the surface modified implants have been launched commercially at the time of the millennium change and the scientific community has started to show serious interest in the peri-implantitis issue after some consensus meetings dating back to 2006200 and onwards,40–43 the authors decided to limit the search to papers published over the last 6 years to increase the likelihood of finding relevant papers. This also seems logical because some extra time passes before clinical research is reported and published in scientific journals. It is important to recall that the studies selected in this review reflect daily reality and are not limited to strictly selected patient groups. It may be an advantage that the inclusion was kept as broad as possible to ensure that all types of clinical studies were included. Conversely, this approach may also yield criticism and voice opposition based on how the literature was chosen. It may also account for the heterogeneity of the studies.
During data analysis we struggled especially with the time point of the first radiographic assessment of the bone level, used as baseline for bone loss comparisons. Indeed, it is well known that peri-implant bone loss may be affected by the time point considered as baseline for the evaluation. There is consensus that a radiograph should at least be taken at the time of loading to register the bone level as baseline for future comparison to ensure that bone loss can be calculated.43 Often this delayed assessment approach leads to an underestimation of the total bone loss because initial crestal bone remodeling is not included.201 Different authors described initial crestal bone loss as a consequence of biologic width re- establishment after implant placement in patients with thin soft tissues.19,202 Another effect on the crestal bone loss could be the microcap between the implant and abutment in 2 piece implants.203,204 This crestal bone
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