At a previous World Workshop on Periodontology the definition of a risk factor was agreed as, “an environmental, behavioral or biologic factor confirmed by temporal sequence, usually in longitudinal studies, which if present, directly increases the probability of a disease occurring and, if absent or removed reduces that probability.” To identify a true risk factor, prospective studies are required. The majority of studies available are cross‐sectional or retrospective in design and, therefore, in this review paper the term “risk” refers to a factor which is associated with peri‐implant mucositis or a risk indicator.

General risk indicators/factors

Factors which may affect host susceptibility to biofilm‐induced peri‐implant mucositis have been investigated. Cigarette smoking has been identified as a risk indicator for peri‐implant mucositis in three studies (Table 2). There is also evidence for radiation therapy as a risk indicator for peri‐implant mucositis. There is some evidence for diabetes mellitus as a risk indicator for peri‐implant mucositis. Poorly controlled diabetes mellitus (HbA1c levels > 10.1) was shown to be associated with increased bleeding on probing at implants. While a history of cardiovascular disaease has been associated with an increased risk of peri‐implantitis, there is no evidence for an association with peri‐implant mucositis. Máximo et al. reported a significant but weak correlation (r = 0.44, Pearson χ² test) between peri‐implant mucositis and increased time of loading of the implant. However, this study did not account for confounding factors, and the reported association may have been due to the increased time in function without regular removal of the biofilm.