**8.6 Keratinized mucosa**

Compared to sites with a keratinized mucosa of greater than 2 mm, sites with a keratinized mucosa of less than 2 mm are associated with plaque accumulation followed by peri-implant inflammation in the soft tissue and radiographic bone loss [50]. The evidence is limited and controversial that the absence of a keratinized mucosa is a risk factor for peri-implantitis, but this factor may negatively affect selfperformed oral hygiene (**Figure 2**) [50].
