Comparison of peri-implant and periodontal marginal soft tissues in health and disease.

The integrity of the peri-implant soft-tissue seal is crucial for maintaining peri-implant tissue health. Whilst the transmucosal component of the restored implant shares some common features with teeth, namely the presence of a junctional epithelium and a connective tissue component, there are some important differences. A key difference is the nature of the relationship of the connective tissue with the implant surface, whereby there is 'adaptation' of collagen fibers in a parallel orientation in relation to the implant, but insertion of fiber attachment perpendicularly into cementum in the case of teeth. This, combined with reduced cellularity and vascularity in the peri-implant connective tissue, may make implants more susceptible to disease initiation and progression. Furthermore, the presence of a subgingival connection between the implant and the abutment/restoration poses some specific challenges, and maintaining the integrity of this connection is important in preserving peri-implant tissue health. Implant design features, such as the nature of the connection between the implant and the abutment, as well as the surface characteristics of the abutment and implants, may influence the maintenance of the integrity of soft tissue around implants. Iatrogenic factors, such as incorrect seating of the abutment and/or the restoration, and the presence of residual subgingival cement, will lead to loss of soft-tissue integrity and hence predispose to peri-implant disease.