The aim of this review was to assess various systemic conditions and their treatments as risk factors for implant therapy.

Many patients who may benefit from implant placement present with concomitant systemic diseases. For many systemic diseases, there are no reports on the use of oral implants. The largest amount of information exists for diabetes mellitus, osteoporosis, and radiotherapy. Most of the information is in the form of case reports and case series.

The possibility of publication bias, leading to an overestimation of success, needs to be considered, and this is a major problem of case reports and case series. The published literature does not allow distinguishing between subtypes of systemic diseases, such as diabetes mellitus type 1 and 2, or primary and secondary osteoporosis. Patients may present with multiple risks that may be interrelated, making the estimation of the impact of a single factor difficult.

With respect to systemic conditions and treatments as risk factors for implant therapy, the following recommendations can be made:

• A thorough medical history is essential to identify potential systemic risks.
• Risks for implant failure and risks for medical complications should be differentiated and evaluated. In some instances, conditions and their treatments may pose increased risks for implant failure, whereas the risk for the patient may be minimal. As an example, there are no data to support withholding implant treatment for patients with diabetes or osteoporosis. However, these patients need to be informed of the possibility of implant complications.

Where there is a potential risk of a medical complication - for example, osteonecrosis of the jaw in patients taking oral bisphosphonates and patients undergoing radiotherapy - the option of implant therapy should be chosen restrictively, and the patient should be informed specifically, taking into account the current level of uncertainty with regard to the consequences. For patients with a life-threatening systemic disease, implant placement should be postponed until the patient’s medical condition is stabilized and has improved.