The effect of material characteristics, of surface topography and of implant components and connections on soft tissue integration: a literature review

To be functionally useful, oral implants have to pierce the gingiva or oral mucosa and enter the oral cavity, thus establishing a transmucosal connection between the external environment and the inner parts of the body. In order to avoid bacterial penetration that could jeopardize either initial healing or long-term behaviour of implants, the formation of an early and long-standing effective barrier capable of biologically protecting the peri-implant structures is mandatory. The establishment of this soft tissue barrier is a critical part of tissue integration and is fundamentally the result of wound healing that has to establish an effective interface between living tissues and a foreign body. The soft tissue interface has been histologically assessed in animals and has a dimension of 3–4 mm in the apico-coronal direction called ‘biological width’. The interface consists of two zones, one of epithelium which covers about 2 mm of the surface, while the rest is devoted to connective tissue adhesion. Both these tissues contribute to the establishment of the so-called biological width, which may prevent oral bacteria and their products from penetrating into the body (Berglundh et al. 1991; Buser et al. 1992; Berglundh & Lindhe 1996; Abrahamsson et al. 1996, 1997, 1998a, 1998b; Cochran et al. 1997).